Note: Descriptions are shown in the official language in which they were submitted.
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FINGER GUIDE DEVICE
FIELD OF THE INVENTION
The invention relates generally to a finger guide called a finger guide device
used to position
a finger, thumb or human digit containing unique minutiae upon a scanner or
sensor or other
means to capture an image of the miniature features of a relevant portion of
the said
minutiae or underlying tissue, which is equivalently called a fingerprint.
This finger guide
device would be used with electronic, optical, electromagnetic, capacitive,
electroluminescent, or similar scanners or sensors requiring repeated and
reasonably accurate
positioning in alignment with the scanner or sensor. Applications include the
accurate
identification of an individual with a minimal number of false rejects or
repeats of the
process for scanning or reading the enrolled portions of the fingerprint.
BACKGROUND OF THE INVENTION
U.S. Patent Application No. 2004101172 (Lane) discloses a finger imaging
system for receiving
the finger of a person being fingerprinted by an automated fingerprint reader.
The system
includes a finger imaging device having a finger receiving portion for
receiving the finger to
be fingerprinted. Extending outward from the finger receiving surface is a
locator bar that
engages a crease of the subject finger when it is in about in the desired
position. U.S. Patent
Application 2004101171 (Lane et al.) discloses a finger imaging system for
receiving and
holding a finger of a person being fingerprinted by an automated fingerprint
reader. The
system includes a finger imaging device having a finger receiving portion and
a finger
=
positioning portion, together forming a recess of reducing dimension such that
a subject
finger forcibly inserted into it is held in a stable position. And finally,
U.S. Patent Application
No. US2004076314 (Cheng) discloses an apparatus that includes a fingerprint
sensor and a
guiding means. The sensing site of the fingerprint sensor makes a relative and
obtuse angle
with a guiding plane of the guiding means.
Traditionally, in order to record a fingerprint, ink was applied to a finger
and then the finger
was "rolled" across a paper or other ink receptive surface to print an image
of the
fingerprint. Fingerprints left by touching a surface and leaving oil residue
are captured
forensically by a variety of process techniques that "lift" and reveal the
fingerprint.
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In more recent years, alternative technologies have been developed that can
reveal the fine
features within a fingerprint and capture the fingerprint directly from the
finger. Electronic
sensing technology involves holding the finger on a sensing system as the
system detects skin
or living tissue differences across the finger area or just a relevant portion
of the finger area
in order to reveal an image of the fingerprint or in order to create an
electronic
representation of the fingerprint, for example as a digital file. Examples
include but are not
limited to optical scanners, electro-luminescent pressure sensitive systems,
integrated
circuits with the ability to measure individual pixel sized capacitance, and
more.
The production cost for some types of fingerprint scanning systems is driven
by the size of the
fingerprint area to be sensed. This is especially true for silicon based or
integrated circuit
(IC) type sensors. Like most IC's, the larger the IC, the more costly it is to
produce assuming
equal device geometries and layer count. The production cost of the sensor is
directly
related to the sensing area, and mass production of sensors the size of a
thumb is not optimal
when only a relevant portion of a fingerprint needs to be scanned in order to
build a
fingerprint authentication system. If just a portion of the fingerprint is to
be used in order to
reduce system cost, then it becomes important to place substantially the same
relevant
portion of the finger that was originally enrolled upon the sensor for every
authentication or
identification event.
Clearly a smaller sensor would cost less and, assuming the area of the
fingerprint sensed is
still necessarily large enough to provide an acceptable matching capability or
security level,
then the optimal solution would be this smaller sensor, leaving out unneeded
portions of the
total fingerprint area. The finger guide device invention is a device which
may be used to
reliably reposition a finger upon a small sensor to enable more efficient
identification. The
device reduces false rejects caused by failure to position the finger close
enough to its
original enrollment position or positions so that the sensor can read a
matching relevant
portion of the fingerprint. The finger guide device reduces the incidence of
false rejects by
naturally, intuitively, and non-forcibly guiding the subject finger to
approximately the same
and original enrollment position each time the fingerprint identification
system is used.
When smaller sensors are used, if the finger is enrolled in a manner that
scans one relevant
area of the finger, or perhaps several overlapping relevant portions of the
fingerprint which
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are then electronically assembled by a computer into a completed "template"
representing a
larger area of the original subject's fingerprint than any single scan could
produce alone, then
the system depends upon a subject person or user being able to touch the
sensor consistently
in the same approximate place so that a relevant portion of the fingerprint is
read by the
sensor so that matching and therefore authentication or identification may
take place.
Failure to replace the finger accurately onto the fingerprint sensor or
scanner causes false
rejects; or, in other words, because the sensor sees a different area of the
fingerprint it can
not match with the previously enrolled area or portions of the fingerprint, it
rejects a known
subject as not matching. This is a false reject. If the system permits
additional attempts,
and if the second or subsequent try finally aligns the minutiae containing a
relevant potion of
the fingerprint originally stored during enrollment with the scanner or
sensor, the known
subject will then be accepted (identified or "authenticated"). The finger
guide reduces the
average number of attempts to authenticate known subjects by providing a
simple, funnel
like or inverted pyramid like guide for the finger that physically but non-
forcibly encourages
the finger into the correct position so that a relevant portion of the finger
is in alignment
with the sensor or scanner and provides a variety of tactile and other
feedback means for the
subject user in order to make it easier to "find" the right position again,
even after
substantial time has passed between enrollment and the next authentication
event. If the
finger is in the correct position, but the touch pressure is too hard or too
light, the scanner or
sensor may capture a distorted image and this may also cause a false reject.
The finger guide
device also assists users in learning and repeating the correct touch pressure
using a variety
of feedback means including but not limited to tactile feedback, mechanical
motion
feedback, audio or visual feedback, the field of possible feedback means being
known to
those skilled in the art of human factors engineering. In contrast with basic
flat surface
sensors or even poorly designed sensors, the described false reject rate for
untrained subjects
can range from ten to twenty percent of all subjects. Systems using the finger
guide device
will experience less than ten percent false rejects and fingerprint
authentication systems
using the finger guide device may be optimized for even lower rates of false
rejects.
SUMMARY OF THE INVENTION
Much like a round or rectangular funnel guides a fluid into a container; the
finger guide
device includes a finger recess which acts to guide the finger towards the
same position on
the sensor in a repeatable manner. Another simple analogy is to describe a
ball on the point
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of a pyramid, which is unstable versus a ball in an inverted pyramid, wherein
the ball always
rolls to the same global minimum and position through the natural force of
gravity and
guiding effect of the sidewalls of the inverted pyramid recess. In the case of
the finger guide
device, analogous action is initiated by muscles applying force to move the
finger into the
finger guide device recess and towards the sensor area, such movement being
guided by
disclosed and described physical shape recess elements in the finger guide
device invention.
The guiding effect of the mechanical recess and overall performance of the
finger guide
device may be further enhanced through tactile or other feedback communication
to the
subject, such as feedback caused by tactile properties of the finger guide
material or
surfaces, additional physical shape elements intended to cause tactile
feedback, mechanical
movement, or other visual or audio feedback means. The sensor would sit in
alignment with
the finger guide device in correct position and adjacent to the desired area
of the finger in
order to "see" a relevant portion (projection) of the fingerprint.
Previous devices to locate fingers for fingerprint imaging focused upon the
need to hold
(literally press and flatten) the finger against a flat scanning surface and
tended to either
locate the finger crudely from the front edge of the nail or the skin crease
under the first
joint in the finger. The intent was to substitute for the effect of rolling a
print and pressure
to flatten the finger was an important element. Modern semiconductor sensors
require only a
Light touch and, as noted, often focus on repeating the scan or capture of the
same relevant
portion of the fingerprint over and over again. What is needed is a device
that reduces the
average number of attempts to authenticate known subjects by providing a
simple circular,
oval, rectangular, or square funnel like recess or guide for the finger that
physically
encourages the finger into the correct position opposite a scanner or sensor
and may be
further improved by providing a variety of tactile, mechanical movement,
audio, or visual
feedback means for the subject user in order to make it easier and more
natural to "find" the
right finger position again, even after substantial time has passed between
enrollment and
the next authentication attempt. In contrast, with basic flat surface sensors
or even poorly
designed sensors, this false reject rate for untrained subjects can range from
ten to fifteen
percent of all attempts.
The finger guide device of the present invention provides an effective aid in
positioning the
finger in essentially the same position on a repeatable basis and a learning
mechanism that
assists subject users in developing the right position and touch (pressure) as
well through a
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set of basic design and construction elements including physical shape,
material properties,
and surface finish properties. Additional feedback means may also be used to
aid in the
effectiveness of the finger guide device.
In practice, the preferred embodiment of the finger guide device invention is
designed to
relocate a relevant portion of the finger between .20 and .90 inch in distance
from the
underside of the fingernail in alignment with a sensor or scanner, and, as
such, locates from
the finger tip rather than the ridge under the first joint in the finger. In
addition, the finger
guide device top edge at the front is of a low enough profile to avoid contact
with the
fingernail. Such contact would introduce error because subjects trim their
nails to different
lengths and most would also find pressure against the nail tip uncomfortable,
both conditions
having been found in previous devices claimed to help position a finger upon a
fingerprint
reader or scanner.
The physical design of the finger guide device enables sufficiently accurate
placement of the
finger over the sensor to facilitate a substantial increase in the percentage
of first time
acceptance (of enrolled subjects), said result being equivalent to reducing
the percentage of
false rejects. This preferred embodiment includes a relatively short concave
radius (or
relatively steep slope) at the front of the finger guide device where the
finger tip just below
the finger nail touches or is proximal to the front of the finger guide device
and a longer
radius concave shape (or less steep slope) adjacent to the opposite side of
the sensor where
the guide extends up the finger towards the body. The portions of the sides
opposite the
scanner or sensor are quite steep to keep the finger centered laterally.
Overall, the finger
guide device is sized for an average finger, yet accommodates a wide range of
digit sizes
because it only interfaces with a small curved portion of the finger or digit,
said portion to
include a relevant portion of the finger.
The tolerance allowed for finger placement on smaller electronic sensors
mounted on flat
surfaces is fairly liberal, yet positioning the finger on these devices
remains challenging for
untrained subjects. This relevant portion of the fingerprint might be
limited to
approximately half to two thirds of the fingerprint area that will be scanned
as necessarily
overlapping with relevant portions of the fingerprint previously scanned
(enrolled) and
existing in the matching template, depending on the algorithm used and
accuracy of the
system. Low accuracy systems may operate with even less than half a sensor
window overlap.
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The actual relevant portion required for a security match depends upon the
algorithm and,
within the algorithm, the actual desired security level or security setting.
This is related to
the relevant portion of the scanned subject print that correlates with the
subject's enrolled
template.
The ability to place generally the same portion of the print opposite and
aligned with the
active area (window) of the sensor on a consistent and repeatable basis helps
facilitates rapid
and accurate matching and reduces the false reject rate substantially. The
finger guide
device invention reduces false rejects among enrolled, but unpracticed
subjects to less than
ten percent. Practice using the finger guide device or system optimization or
both will
further reduce the false reject rate.
This reduction in false reject rates from an average of about 15 percent to
less than ten
percent makes a significant difference in security system acceptance and
marketability.
Frustration within the user population is substantially reduced if people do
not need to touch
the sensor multiple times to be accepted. In late 2003 a new keyboard was
introduced to
approximately 250,000 users and had no effective finger guide solution. There
was
considerable frustration in the user base and the company that deployed the
system faced
considerable criticism. Such problems cause users to question how well a
system works, even
though the problem may be technically termed user error or the fault of the
user because of
inaccurate finger placement during the authentication process. The finger
guide device
reduces this expected user error and increases the likelihood of subject user
acceptance on
the first touch. This saves a great deal of time over the life of a system and
is a critical
element to developing biometric systems that are competitive with passwords or
PINs in
terms of user time and efficiency.
Using the finger guide device of the present invention for both enrollment and
authentication
enhances the efficacy of the finger guide device in actual practice and
application. This is
because the natural feel of the finger guide device non-forcibly and
ergonomically guides
users to approximately the same position or alignment of a relevant portion of
the finger with
the active sensor area each time. This guiding process is both physical and
neural, providing
tactile feedback that is important to first use and subsequent learning.
During enrollment,
the system may ask the subject to touch and remove the finger several times.
The finger
guide device is generally designed to accommodate fingers, thumbs, or any
digits from left or
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right appendages. This means that it aids placement but does not strictly
limit placement to
an exact and repeatable placement; instead, it simply brings the placement
within the
tolerance ranges of the sensor and fingerprint template matching algorithm.
This allows for
the template to extend beyond the strict limits of the ideal or "perfect"
window frame
(projection) and thus create a template that has guard banding designed in for
the purpose of
accommodating future misalignment within the tolerance and alignment
capability of the
finger guide device. This function is important to long term, repeatable
performance, and
the alignment improvement facilitated by the finger guide device need only
rise to the limits
required by the matching system, template dimensions and security level of the
algorithm. In
fine tuned (optimized) systems, false rejects among experienced user subjects
can be
reduced to less than two percent with the assistance of the finger guide
device invention.
Some sensors drive an electrical potential into the finger tissue. This may be
a radio
frequency or RF electromagnetic signal. The finger guide device may be
electrically
conductive to aid these applications during enrollment and subsequent
authentication events.
In this case, conductive material property and mechanical design elements of
the finger guide
device are said to help "illuminate" the subject finger tissue with the
necessary RF signal
generated by the sensor and passed through or reflected by the finger guide
device or its
smooth and conductive surface. The generally parabolic elements of one
preferred
embodiment of the finger guide device invention emit and reflect this
electromagnetic
radiation into a relevant finger tissue and aid the sensor in image data
capture of a relevant
portion of the fingerprint. Flat sloping conductive sides will also improve
the illumination of
a relevant area of a fingerprint.
The mechanical surface properties and material selected for the finger guide
device are
important to performance. Since the finger must slide easily into position,
low coefficient of
friction (sliding coefficient or static coefficient or both) is useful to
permit the finger to come
to rest at its natural local minimum, which is at the bottom of the finger
guide device
properly positioned in alignment with the scanner or sensor. This surface
property and non-
forcible guiding process positions the finger in the same proximal location
time and time
again wherein a relevant portion of the fingerprint is captured in order to
reduce false rejects
and reduce the need for additional touches to the sensor. Examples of
materials with such
low coefficient of friction properties include but are not limited to smooth
metals, smooth
plastics, and even painted, polished, or waxed surfaces. Lubricants may also
be used. If the
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surface material has a high coefficient of friction (for example, rubber,
urethane based
material, or rough plastic), the utility and function of the finger guide
device would be
reduced or compromised because the finger would not slide into position as
easily.
Other feedback elements may be included in various additional preferred
embodiments of the
present invention. Humans will develop the ability to feel the right position.
The finger
guide device may be made of a material with a high thermal conductivity.
Examples include
but are not limited to metals, metal plated surfaces, certain ceramics, or
certain carbon
based materials. In this case, the finger guide device would tend to feel cold
to the touch at
room temperature, not because of its absolute temperature but because it has a
thermal
conductivity that conducts heat quickly out of the finger when touched. If the
finger guide
device is made of metal, this property will make it feel like metal to the
touch (e.g. - cold
feeling). By feeling colder than the rest of the parts and colder than the
sensor, the subject
will learn the correct "feel" of the finger guide device and will also better
feel the sensor in
order to determine its location.
Additional bumps may be added to help orient the finger or enable subjects to
"fine tune"
their finger position. These may be unnecessary for normal or average sized
fingers but may
be worthwhile in applications where the subjects have very small fingers that
contact little of
the finger guide's surface area.
Braille may be added to the finger guide device for assisting blind users or
users having
impaired vision.
The finger guide device may also use physical elements and material properties
to discourage
improper use. For example, a preferred method of practicing this invention
surrounds the
finger guide with a relatively hard and distinct ridge. While not felt as
dangerously "sharp"
this ridge is designed so that it feels uncomfortable to users. When a finger
is placed across
this ridge, while not harmful, it is not comfortable because it applies a high
pressure (PSI) to
the skin across a very narrow area. This high pressure per square inch signals
through the
sense of touch (tactile feedback) that the finger guide device is not being
used correctly. The
feet of the misaligned finger is said to feel unnatural and the user will
instinctively reposition
his or her finger for a more natural and comfortable feel in the recess of the
finger guide
device. The natural tendency is to avoid finger placement against the
uncomfortable outer
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ridge of the finger guide, instead sliding the finger or thumb down into the
finger guide and
onto the sensor (the desired position). It is in this correct position that
the finger or thumb
placement feels both natural and secure to the subject user.
Additional embodiments of the invention may include feedback mechanisms
including those
designed to alert (and train) subjects regarding the correct positioning of
their finger or
feedback designed to alert subjects to the fact that they have been accepted
into the system
(which is to say that their fingerprint has been scanned, compared, and
correctly matched).
Sound may be used to "guide" the finger to the sensor. Visual indicators may
also be used.
Examples include but are not limited to icons, marking of a fingerprint
drawing, fiducial
markings, tight sources (such as LED's), and colored circles. Finally,
physical mechanical
movement feedback mechanisms such as vibration or "click" feedback may be
applied much
like the stick shaker that alerts pilots of a stall warning when flying a
plane or the click keys
found in keyboards and control panels, all such feedback methods being known
to those
skilled in the art of human factors engineering.
These feedback mechanisms may also be used to correct misuse of the system.
For example,
extreme pressure on the sensor or a lack of touch pressure can cause scanning
problems.
Overpressure can flatten minutiae and saturate the sensor and cause inability
to resolve
minutiae accurately. Conversely, the lack of pressure in the form of too light
a touch may
cause the minutiae to remain irresolvable by the sensor so that good image
cannot be
generated. in either case, a voice command or sound or vibration or other
feedback means
could be used to communicate the need to relax the grip or even to press or
squeeze a bit
harder. Said feedback means may communicate to the subject the need to lighten
up touch
pressure or lift the finger a bit. Use of a click feedback means may require
that a user apply
the minimum acceptable pressure required for the scanner or sensor to "see" a
relevant
portion of the finger. Another viable approach is to move the sensor up or
down slightly in
the finger guide sensor window in order to adjust for differences in finger
pressure on the
scanner or sensor.
A preferred method of practice for this invention is an assembly with the
sensor and finger
guide designed to work together as one unit, which is to say a system. This
requires
configuring the sensor for operation on a circuit board, likely containing
additional support
circuitry for its application. The combination of finger guide, sensor,
sealing gasket, and
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printed wiring board with connector may or may not be placed in its own
housing. As such,
this subassembly may be placed in a variety of devices for its application.
The unit is a
security platform with a plurality of uses. Examples include but are not
limited to vehicle
doors or dashboards, countertops, doors or doorframes, keyboards, personal
digital assistants,
telephonic devices, secure fax machines, computing devices, appliances,
instruments,
machinery controls, medical devices, cash registers, and much more.
Fingerprint sensors or scanners use a variety of solutions to sense and
capture image data
detailing the unique individual features of a human fingerprint minutiae or
the living minutiae
tissue directly under the fingerprint. In this discussion and throughout this
document, the use
of the words finger and fingerprint are intended to refer to any digit and its
unique minutiae
from left or right appendages and to be the same and equivalent to the use of
the word
thumb or thumbprint. The use of the words he and his are not intended to be
gender specific
and are intended to be equivalent to she or her.
The finger guide device of the present invention may be used as a device to
provide inputs to
a system from a user. This embodiment of the present invention would include
mechanical
communication of the finger guide device to one or more pressure sensors or
electrical
capacitive sensors to sense when the finger guide device is touched or
pressed. When the
device is touched it may serve as an input or switch control device and when
the device is
pressed in one or more directions and with varying pressure or surface contact
movement, it
may serve as a proportional input device to facilitate a variety of input
applications including
but not limited to controlling machinery or equipment or as a pointing device
for a computer.
Placement of a finger in the finger guide device and applying pressure in
axial or lateral
directions or combined directions will allow a second utility use of the
finger guide as a
pointing device when the finger guide device is in communication with pressure
sensors or
switches. Changing or moving the points of touch contact with the sides of the
recess wilt
also facilitate utility use of the finger guide device as a pointer or control
device if the
surface contains sensors to detect the changes, said touch sensor means being
known to those
skilled in the art of producing touch sensitive pointing and control devices.
A user subject may be under duress during use of the finger guide device of
the present
invention; for example, a crime might be underway wherein a user might be at
gunpoint and
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forced to authenticate against his will. In such a circumstance, it may be
desirable for the
user to have a different digit enrolled as an emergency signal that the device
user is in
danger, said emergency digit not necessarily being known to others.
If the user is
experiencing another type of emergency, or even forced illegally to use the
device, then he
may use his "911" digit to call for help. In such a case, the system cannot
match the enrolled
fingerprint, but it will recognize a match with the user subject's emergency
finger and
therefore recognize the need to respond differently and accordingly.
For a more complete understanding of the finger guide device of the present
invention,
reference is made to the following detailed description and accompanying
drawings in which
the presently preferred embodiments of the invention are shown by way of
example. As the
= invention may be embodied in many forms without departing from the spirit
of essential
characteristics thereof, it is expressly understood that the drawings are for
purposes of
illustration and description only, and are not intended as a definition of the
limits of the
invention. Throughout the description, like reference numbers refer to the
same component
throughout the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 discloses a preferred embodiment of the finger guide device of the
present
invention mounted in alignment with a fingerprint sensor and mounted in a
commonly used
biometric touch pad similar to fingerprint touch pads ordinarily used with
computers for the
purpose of identifying and authenticating system users;
FIGURE 2 is an assembly drawing of the preferred embodiment of the finger
guide device of
the present invention of FIGURE 1 comprising the finger guide device, gasket,
aligned
fingerprint sensor with drive ring, and printed circuit board;
FIGURE 3A discloses an overhead view of the preferred embodiment of the finger
guide device
of FIGURE 1, with a finger mounted thereon, the finger being positioned onto
the finger guide
device and a relevant portion of the finger in alignment with the fingerprint
sensor in order to
enable matching of a relevant partial fingerprint with the matching template;
and FIGURE 3B
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discloses a side view of the steep forward slope of the finger guide device
aligning the finger
in axial alignment to position a relevant portion of the finger in alignment
with the sensor;
FIGURES 44 and 4B disclose another preferred embodiment of the finger guide
device of the
present invention mounted in the grip of a handheld computer, enabling a
continuous
touching and alignment of the fingerprint sensor while holding the handheld
computer, and
accordingly, a continuous or frequently repeating authentication or
identification process;
and,
FIGURE 5 depicts another preferred embodiment of the finger guide device, the
finger guide
device having flat side surfaces forming a recess for receiving a finger for
placement in
alignment on a fingerprint sensor, and mounted in a computer display, enabling
a user to
touch the finger guide device and align a relevant portion of the finger with
the sensor for
identification and authentication in order to gain access to data to be
displayed on the
computer display; and, when used to control a computer pointer, to place
finger in the finger
guide device to apply pressure or touch movement in axial or lateral
directions or combined
directions in order to use the finger guide as a pointing control device; and,
if desired, while
scanning or sensing a relevant portion of the fingerprint for continuous or
frequently
repeating authentication or identification.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fingerprint scanners or sensors are used in a variety of applications to
capture relevant image
data of a fingerprint for comparison with one or more stored fingerprint
images or fingerprint
templates. Devices that include fingerprint sensors may be designed only for
the purpose of
capturing a relevant portion of a fingerprint or the fingerprint sensor device
may be included
as part of a device with other additional purposes, such as a keyboard or a
door lock or other
device. The finger guide device of the present invention is intended for use
in all of these
devices and applications where a fingerprint scanner or sensor is desired.
Referring now to the drawings, in FIGURE 1 the preferred embodiment of finger
guide device
12 of the present invention is shown in alignment with a fingerprint sensor 16
wherein both
the finger guide device and fingerprint sensor reside in a simple touch pad 26
housing to sit
on a desk, countertop or other surface. This simple fingerprint pad
configuration of the
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preferred embodiment is normally used with a computer or terminal or payment
cash register
to identify a subject in order to grant access to data, files, or network
communications or to
identify the subject for another purpose; for example, completing a payment
transaction. The
touch pad combined with the computer and fingerprint matching software
algorithm is a
fingerprint identification system. The finger guide device reduces the number
of false rejects
experienced during repeated use of the fingerprint identification system.
FIGURE 2 discloses an inverted assembly drawing of the preferred embodiment of
the finger
guide device 12 of the present invention comprising the finger guide device
12, gasket 14,
sensor 16 and drive ring 17, and printed circuit board 18. The left and right
sides of the
finger guide device next to the sensor area are steeper than the front (lower
portion in
FIGURE 2) and back (upper portion in FIGURE 2) and of a concave nature in this
embodiment.
The front portion of the finger guide device is concave from the sensor
alignment portion to
the top ridge and has shape derived from a short set of radii to create its
generally concave
contour. The fingertip will contact this front portion of the finger guide
device (see next
FIGURE 38). For certain handheld devices including but not limited to handheld
computers
(see FIGURES 4A and 48) or remote controls, this feature also aids in
maintaining a secure
grip. The rear section radii create the least steep concave contour and are
meant to guide
the portion of the finger or digit between a relevant portion of the finger
and the remainder
of the finger adjacent to the body. The end of the finger guide device
furthest from the
fingernail contains a continuation of the relatively sharp feedback ridge but
is not intended to
use the finger joint or skin fold under the joint as a means for positioning
the fingerprint
adjacent to the sensor. Instead, this relatively sharp ridge provides a
tactile feedback to the
user to communicate an incorrect placement of the finger and a need to
reposition the finger
within the recess of the finger guide device.
The sides of the finger guide device form a recess that receives the finger of
the user and
guides the finger laterally to center a relevant portion of the print over the
fingerprint sensor
16 and drive ring 17. Accordingly, the sides of the finger guide device have
the same general
shape as the finger. In this first preferred embodiment of the finger guide
device 12 of the
present invention the sides are concave, having a varying radius of curvature.
This includes a
relatively short concave radius (or relatively steep slope) at the front of
the finger guide
device where the finger tip just below the finger nail touches or is proximal
to the front of
the finger guide device and a longer radius concave shape (or less steep
slope) adjacent to
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the opposite side of the sensor where the guide extends up the finger towards
the body. The
sides opposite the sensor portion are quite steep to keep the finger centered
laterally.
Overall, the finger guide device is sized for an average finger, yet
accommodates a wide
range of digit sizes because it only interfaces with a small curved portion of
the finger or
digit. In a second preferred embodiment of the present invention (see FIGURE
5), the finger
guide device has a plurality of flat sides, said opposite sides being of equal
slope while still
practicing the present invention in this second preferred embodiment.
The first preferred embodiment (FIGURE 2) of the present invention of the
finger guide device
12 contains a window for the sensor 16 and drive ring 17 to align and reveal
them to a
relevant fingerprint portion of the subject digit or finger. The AES3400
sensor or AES3500
sensor both manufactured by AuthenTec in Melbourne, FL would both be equally
suitable as
fingerprint sensors to sit in alignment with the finger guide device, as would
other similar
devices made by a variety of different manufacturers known to those skilled in
the art of
fingerprint identification and authentication systems. This window may be
sufficient to
contain a drive ring 17 needed for certain types of sensors (shown) or it may
cover the drive
ring and substitute its own electrical conductivity for that provided by a
drive ring. In the
preferred embodiments this may also be the case and its performance is
equivalent,
aesthetics being the only substantive difference. In FIGURE 1 the drive ring
is equivalently
exposed and the finger guide device 12 is used as a supplement to the drive
ring and is
conductive and reflective of electromagnetic energy. This feature is desirable
but not
required for the finger guide device to function. Thus, in yet another
preferred embodiment,
the finger guide device is non-conductive yet the electrical signal provided
by the drive ring is
itself sufficient to illuminate the relevant minutiae portions of the
fingerprint wherein the
assembly functions sufficiently but not necessarily optimally.
The surface of the fingerprint sensor 16 lies on a plane with the top of the
window at the
bottom of the finger guide device 12; however, within reasonable limits
compliance with this
plane is not critical to performance as long as the subject finger can contact
both the finger
guide device and the example fingerprint sensor. The pliant and flexible
nature of living
fingers facilitates this, and while there is utility gained from an optimal
match of vertical
positions (planes), the invention works across a range of vertical positions.
Another preferred
embodiment, not shown, allows for the relative mounting planes of either the
finger guide
device or fingerprint sensor to be altered either by adjustment of during the
authentication
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touching process to optimize the distance between sensor and a relevant
portion of the finger
minutiae tissue or the contact pressure between the fingerprint sensor and a
relevant portion
of the finger in order to obtain the best possible image or fingerprint data.
This adjustment
may be made manually or automatically using an electronic control system.
In the preferred embodiment of the present invention shown in FIGURE 2, a
gasket 14 is
provided to keep oil, fluids, dirt, or other unwanted material away from the
sensor leads and
circuit board. This gasket is made of a flexible material that is impervious
to solvents and
other undesired contaminants. In another preferred embodiment, not shown, the
gasket and
its function may be replaced with conformal coating material applied in liquid
form which
solidifies or partially solidifies to provide a protective barrier, or
equivalent sealing materials
known to those skilled in the art of electronic device design and assembly
without
diminishing the function and purpose of the present invention. The invention
will also
function without including a sealing gasket or equivalent sealing or means of
forming a
protective barrier.
The finger guide device 12 of the present invention shown in FIGURE 2 contains
one or more
mounting bosses shown in this preferred embodiment as opposite and adjacent.
These are
used to align the finger guide device with the sensor and its printed wiring
board or other
mounting means and, in turn, to mount the subassembly of fingerprint sensor,
gasket, and
finger guide device to a housing, counter top, appliance case, or other device
or system
housing. The present invention works with any mounting means known to one
skilled in the
art of mechanical assembly and alignment of mounted parts. Examples include,
but are
not limited to adhesive mounting, welding, soldering, pinning, fastening,
clamping, hooking,
or locking.
The front portion of the finger guide device 12 serves as a stop and location
reference
designed to meet the fingertip or thumb below the nail and avoid differences
in position
which could result from differences in length of the subject user's finger or
thumbnail. This
is a distinct advantage over devices that clamp over or cross over the top
(nail) side of the
finger.
FIGURE 3A discloses an overhead view of the preferred embodiment of the finger
guide device
12, with a finger mounted thereon, said finger being positioned onto the
finger guide device
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so that a relevant portion of the finger is in alignment with the fingerprint
sensor 16 and
therefore enabling accurate matching of the relevant portion of the
fingerprint; and FIGURE
3B discloses a side view of the steep forward slope 27 of the finger guide
device 12 aligning
the finger in an axial position with a relevant portion of the finger in
alignment with the
fingerprint sensor and therefore enabling accurate matching of the relevant
partial
fingerprint portion. The top edge of the finger guide device is lower than the
extension of a
tong fingernail so that the fingernail will not contact the finger guide
device. This feature
avoids the possibility of misalignment caused by differences in fingernail
length that might
occur between enrollment and later use of the finger guide device, either from
normal
fingernail growth or trimming of the fingernail during the time between
enrollment and use of
the finger guide device.
FIGURES 4A and 4B disclose another preferred embodiment of the finger guide
device 12A of
the present invention disposed in the grip of a handheld computer 22, enabling
a continuous
touching of the fingerprint sensor; and accordingly, a continuous
authentication or
identification. Certain devices may be made more secure by requiring
continuous or
frequently repeating authentication of users. This avoids the security risk of
having one
authorized person touch the finger guide device and fingerprint sensor to
access the system
or turn on the device and then pass or release the device to an unauthorized
user in a
security breach process known as "tailgating." Tailgating may be avoided by
mounting the
finger guide device 12A, wherein the finger guide device 12A having flat side
surfaces with
each pair of opposite sides having roughly equal slope, and said combination
of sides forming
a recess for non-forcible receiving of a finger for placement in alignment on
a fingerprint
sensor in a handheld computer 22 as shown in FIGURES 4A and 4B in a manner
compatible
with normal grasping and holding of the handheld device so that continuous or
frequent
authentication can be conveniently achieved without changing the grip on the
device or
diverting away from other data input activities during repeat authentication
of the user.
FIGURE 5 depicts and discloses another preferred embodiment of the finger
guide device 12A,
wherein the finger guide device 12A having flat side surfaces with each pair
of opposite sides
having roughly equal slope, and said combination of sides forming a recess for
non-forcible
receiving of a finger for placement in alignment on a fingerprint sensor 16;
and, in this
application example FIGURE 5, mounted in the housing of a computer display,
enabling a user
to touch the finger guide device 12 and align a relevant portion of the finger
with the sensor
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in a reasonably repeatable position for identification and authentication in
order to gain
access to data to be displayed on the computer display; and, to also be used
to control a
computer pointer through the application of additional pressure to the finger
guide device
12A, said pressure communicated to one or more pressure sensing means in
mechanical
communication with the finger guide device. Another similar preferred
embodiment would
include touch and location sensitive material to the inner surfaces of the
finger guide device
to facilitate use as a pointing control device, such material known to those
skilled in the state
of the art of design of computer pointing control devices.
As a substitute for a computer mouse point device, the finger guide device of
this preferred
embodiment of FIGURE 5 permits a subject user to place his finger in the
finger guide device
to apply pressure in axial or lateral directions or combined directions in
order to use the
finger guide as a pointing control device; and, if desired, to do so while
authenticating or
identifying himself to the system. Another similar preferred embodiment would
include
mounting the finger guide device in mechanical communication with one or more
electromechanical switches or equivalent switching means to permit the finger
guide device
12 to serve as a component of a pressure activated single switch, a three way
rocker switch,
or a nine way bilateral rocker switch wherein the subject user is
authenticated just before or
during the switching process.
In any of the various preferred embodiments described herein, additional bumps
may be
added to the finger guide device 12 or 12A to help further orient the subject
finger or enable
subjects to "fine tune" their finger position. These may be unnecessary for
normal or
average sized fingers but may be worthwhile in applications where the subjects
have very
small fingers that contact relatively little of the finger guide device
surface area. Braille may
be added to the finger guide device for assisting blind or visually impaired
users.
The finger guide devices of the present invention in any of its various
preferred embodiments
described herein may also use physical elements and specific material
properties to
discourage improper use. For example, the preferred method of practicing this
invention
shown in FIGURE 1 surrounds the finger guide device 12 with a relatively hard
and distinct
ridge. While not
felt as dangerously "sharp" this ridge is intended to be felt as
uncomfortable. When a finger is placed across this ridge, while not harmful,
it is not
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comfortable because it applies a high pressure per square inch (PSI) to the
skin across a very
narrow area. This high pressure per square inch signals through the sense of
touch that the
finger is not being positioned correctly in the recessed area. The feel of the
misaligned finger
is meant to feel unnatural and the user will instinctively reposition his
finger to find a more
natural and comfortable feel. The natural tendency is to avoid placing the
finger against the
outer ridge of the finger guide device, instead easily sliding the finger or
thumb down
comfortably and non-forcibly into the finger guide device and onto the sensor
(the desired
position).
The material property of high thermal conductivity may be used to cause any of
the preferred
embodiments of the finger guide devices disclosed herein to feel colder to the
touch than the
surrounding surfaces and the sensor surface. Although all surfaces are
normally at the same
temperature, the ability to draw heat from the skin (thermal conductivity)
creates the feeling
that something is cold. For example, by stipulating a finger guide device (or
surface coating)
made of metal (or other thermally conductive material such as ceramic or
nanoparticle
ceramic paint), any of the preferred embodiments will have this property of
feeling colder
than the surrounding surfaces provided that the surrounding surfaces are of a
material with a
lower thermal conductivity, such as plastic or cloth. The result is the
subject user's tactile
feedback based ability to distinguish the finger guide device surfaces from
other surfaces and
thereby guide his finger onto the finger guide device.
A smooth inner surface is also important to any of the preferred embodiments
of the finger
guide devices disclosed herein. A low coefficient of sliding friction permits
the subject finger
to slide downward into the recession in a non-forcible manner until it reaches
a stable global
minimum which corresponds by design with a finger position in reasonably
repeatable
fingerprint sensor alignment with a relevant portion of the finger. A low
coefficient of static
friction allows the subject finger to begin its sliding into position in a non-
forcible manner and
also prevents the subject finger from stopping part way into the recession at
a local minimum
rather than the desired and most stable global minimum which corresponds, by
design, with a
final finger position in reasonably repeatable fingerprint sensor alignment
with a relevant
portion of the finger. The lower the coefficients of friction, the better
the preferred
embodiments will work; such acceptable coefficients of friction being
available through the
surface properties of materials like, but not limited to, polished metals,
polished plastics,
plated metals like chromium, surface waxes, lubricants, or special paints or
coatings.
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Examples of materials which may be applied after cleaning of the finger guide
device, or
formulated in cleaning wipes for application during cleaning, include but are
not limited to
wet and dry lubricants (e.g. - lubricants such as those used as bottle
lubricants by bottling
plants) and fatty acid based static suppressants like Jojoba oil.
Any of the preferred embodiments of the finger guide devices disclosed herein
may be
designed to work with active feedback mechanisms including those designed to
alert subjects
or to train subjects regarding the correct positioning of their finger or with
other feedback
means designed to alert subjects to the fact that they have been accepted into
the system
(which is to say that their fingerprint has been scanned, compared, and
correctly matched).
Sound or voice commands may be used to instruct users how to "guide" the
finger into proper
alignment with the sensor. Active or passive visual indicators may also be
used with any of
the preferred embodiments of the finger guide devices disclosed herein.
Examples include
but are not limited to light indicators, icons, fingerprint drawings or
markings, indicia
markings, text instructions, or colored markings, wherein such indicators are
known to those
skilled in the art of human factors engineering.
Finally, physical movement used as a mechanical movement feedback mechanism
such as
vibration or "click" may be applied much like the stick shaker that alerts
pilots of a stall
warning when flying a plane, such mechanical movement feedback means being
known to
those skilled in the art of human factors engineering.
These feedback mechanisms may also be used to correct misuse of the system in
any of the
preferred embodiments of the finger guide devices disclosed herein. For
example, extreme
pressure on the sensor or a lack of touch pressure can cause scanning
problems. Overpressure
can flatten minutiae and saturate the sensor and cause inability to resolve
minutiae
accurately. Conversely, the lack of pressure in the form of too light a touch
may cause the
minutiae to remain irresolvable by the sensor and a good image cannot be
generated. In
either case, a voice command or sound or other feedback means as described
above could be
used to communicate the need to relax the pressure (or grip) or even to press
(or squeeze) a
bit harder. An indicator light, vibration, or other feedback means as
described above or
known to those skilled in the art of human systems engineering may communicate
to the
subject the need to lighten up touch pressure or Lift the finger a bit.
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Another viable approach is to move the sensor up or down slightly in the
finger guide device
sensor area. Although the preferred embodiments of the finger guide devices 12
and 12A do
not disclose the ability to adjust the depth of the sensor relative to the
plane of the bottom
of the recess, additional preferred embodiments permit this and this element
may be
incorporated in any of the preferred embodiments of the finger guide devices
disclosed
herein. One such preferred embodiment of the finger guide device permits
manual
adjustment of the level of the sensor to modify for finger contact pressure in
order to
= optimize the image or image data properties. Yet another preferred
embodiment of the
finger guide device is in communication with the system computer to make a
real time
determination of the need to move the sensor in closer or further proximity to
the plane at
the bottom of the recess and thereby in closer or further proximity to a
relevant portion of
the finger or living minutiae tissue, and thereby resulting in a real time
optimization of the
image of a relevant portion of the fingerprint, regardless of whether or not
pressure is the
determining factor in image optimization. For example, if an optical sensor is
used, then the
disclosed real time adjustment may be related to focal length rather than
contact pressure;
or, if a sensor detecting sub-surface tissue properties is used, then the
pressure against the
finger causing reduced blood circulation may require adjustment.
A user subject may be under duress or in peril during use of the finger guide
device of the
present invention; for example, a crime might be underway wherein a subject
might be at
gunpoint and forced to authenticate against his will. In such a circumstance,
it may be
desirable for the user to have a different digit enrolled as an emergency
signal that the
device user is in danger, said emergency digit selection not necessarily being
known to
others. If the user is experiencing another type of emergency, or forced
illegally to use the
device as previously described, then he may use his "911" digit to call for
emergency
assistance. In such a case, the system cannot match the enrolled fingerprint,
but it will
recognize a match with the user subject's emergency finger and therefore
recognize the
user's instruction need to respond differently and accordingly. In one
possible embodiment
of the finger guide device of the present invention, this emergency digit
match is taken as an
instruction to trigger so-called "silent alarms" to provide immediate aid
(e.g. police
assistance). In addition, the system, rather than reject the user subject,
could be
programmed to appear to malfunction, or for other revealed reason than
subject's failure to
authenticate, be rendered unable to complete the desired security controlled
event or
CA 02582886 2012-11-13
otherwise delay the event to allow extra time for assistance to arrive, such
approach
intended to minimize the risk to the subject under duress.
For any of the preferred embodiments of the finger guide devices disclosed
herein, a
preferred method of practice for this invention is within an assembly with the
sensor and
finger guide device designed and aligned to work together as one unit, which
is to say in a
complete system. This requires configuring the sensor for operation on a
circuit board, likely
containing additional support circuitry for its application with said sensor
in communication
with said support circuitry. The combination of finger guide device, sensor,
sealing gasket (or
an equivalent or otherwise no protective barrier means), and printed wiring
board may or
may not be placed in its own discrete housing. This subassembly may be placed
in a variety
of devices or products for use. The system unit disclosed is a security system
platform device
having a plurality of applications in products or other more complex systems.
Examples
include vehicle doors or dashboards, countertops, doorframes or doors,
keyboards, personal
digital assistants, telephonic devices, secure fax machines, computing
devices, displays,
appliances, instruments, machinery controls, medical devices, cash registers,
and much more.
Throughout this specification, there are various patent/applications that are
referenced by
application number and inventor. The disclosures of these patents/applications
describe
the state-of-the-art. In order to maintain a reasonable length of disclosure,
additional
elements using common means known to those skilled in various arts are not
included herein.
Any of the preferred embodiments of the finger guide devices disclosed herein
may use future
means to facilitate disclosed elements, such means not being reasonably
anticipated by the
inventor at this time.
It is evident that many alternatives, modifications, and variations of the
finger guide devices
12 and 12A and any others disclosed herein of the present invention will be
apparent to those
skilled in the art in light of the disclosure herein. It is intended that the
metes and bounds of
the present invention be determined by the appended claims rather than by the
language of
the above specification, and that all such alternatives, modifications, and
variations which
form a conjointly cooperative equivalent are intended to be included within
the scope of
these claims.
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