Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MULTIPLEXER FOR A PIEZO CERAMIC IDENTIFICATION DEVICE
BACKGROUND OF THE 1NVENTION
Field of the Invention
[0002] The present invention relates generally to a piezoelectric
identification
device and applications thereof. More particularly, it relates to a
piezoelectric
device for obtaining biometric information, such as a fingerprint, and using
the
obtained information to recognize and/or identify an individual.
Background Art
[0003] Biometrics are a group of technologies that provide a high level of
security. Fingerprint capture and recognition is an important biometric
technology. Law enforcement, banking, voting, and other industries
increasingly rely upon fingerprints as a biometric to recognize or verify
identity. See, Biometr ics Explained, v. 2.0, G. Roethenbaugh, International
Computer Society Assn. Carlisle, PA 1998, pages 1-34 (incorporated herein
by reference in its entirety).
[0004] Optical fingerprint scanners are available which detect a reflected
optical image of a fingerprint. To capture a quality image at a sufficiently
high
resolution, optical fingerprint scanners require at minimum optical
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components (e.g., lenses), an illumination source, and an imaging camera.
Such components add to the overall cost of a fingerprint scanner. Mechanical
structures to maintain alignment also increase manufacturing and maintenance
costs.
[0005] Solid-state silicon-based transducers are also available in fingerprint
scanners sold commercially. Such silicon transducers measure capacitance.
This requires the brittle silicon transducers to be within a few microns of
the
fingerprint sensing circuit reducing their durability. To detect a rolled
fingerprint, the sensing array of the solid-state transducer needs to have an
area of 1 inch x 1 inch and a thickness of about 50 microns. This is a big
geometry for silicon that increases the base cost of a fingerprint scanner and
leads to greater maintenance costs. Durability and structural integrity are
also
more likely to suffer in such a large silicon geometry.
[0006] What is needed is an inexpensive, durable fingerprint scanner with low
maintenance costs. What is also needed is a low cost biometric device that
can protect individuals and the general populace against physical danger,
fraud, and theft (especially in the realm of electronic commerce).
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides a multiplexer for a biometric apparatus.
In. the present invention, a multiplexer includes a plurality of first
conductors
coupled to the first ends of piezo ceramic elements in corresponding rows and
a plurality of first switches each of which is coupled to a respective one of
the
first conductors and a plurality of second conductors coupled to the second
ends of piezo ceramic elements in corresponding columns. The multiplexer
also includes a plurality of second switches each of which is coupled to a
respective one of the second conductors. The first conductors are
approximately orthogonal to the second conductors, and the first switches are
controlled to couple a signal output from an output port of the signal
generator
to a particular piezo ceramic element of the at least twenty five thousand
piezo
ceramic elements. The second switches are controlled to couple a signal
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associated with the particular piezo ceramic element of the at least twenty
five
thousand piezo ceramic elements to an input port of the processor.
[0008] Further features and advantages of the present invention, as well as
the
structure and operation of various embodiments of the present invention, are
described in detail below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
[0009] The accompanying drawings, which are incorporated herein and form
part of the specification, illustrate the present invention and, together with
the
description, further serve to explain the principles of the invention and to
enable a person skilled in the pertinent art to make and use the invention.
[0010] FIG. 1 illustrates a piezoelectric identification device according to
an
embodiment of the invention.
[0011] FIG. 2 illustrates a piezoelectric element according to an embodiment
of the invention.
[0012] FIG. 3 illustrates a row of piezoelectric elements according to an
embodiment of the invention.
[0013] FIG. 4 illustrates an array of rectangular piezoelectric elements
according to an embodiment of the invention.
[0014] FIG. 5 illustrates an array of circular piezoelectxic elements
according
to an embodiment of,,the invention.
[0015] FIG. 6 illustrates a row of rectangular piezoelectric elements having a
fill material between elements according to an embodiment of the invention.
[0016] FIGs. 7A and 7B illustrate sensor arrays according to embodiments of
the invention.
[0017] FIG 8 illustrates a more detailed view of the sensor array of FIG. 7A.
[0018] FIG. 9 illustrates how the sensor array of FIG. 8 is connected to an
application specific integrated circuit.
[0019] FIG. 10 illustrates how to connect a sensory array to multiplexers
according to an embodiment of the invention.
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[00201 FIG. 11 illustrates an identification device according to an embodiment
of the invention.
[0021] FIG. 12 illustrates circuit components of an identification device
according to an embodiment of the invention.
[0022] FIG. 13A illustrates how to apply an input signal to the sensor array
of
FIG. 12 and receive an output signal from the sensor array according to an
embodiment of the invention.
[0023] FIG. 13B illustrates how to- control the switches of FIG. 13A according
to an embodiment of the invention.
[0024] FIG. 14 illustrates an example voltage sensing circuit according to an
embodiment of the invention.
[0025] FIG. 15 illustrates how to niinim.ize cross-talk in a sensor array
according to an embodiment of the, invention.
[0026] FIG. 16 is a flowchart of a method according to an embodiment of the
invention.
[0027] FIG. 17 illustrates using an identification device to obtain biometric
information according to an embodiment of the invention.
[0028] FIG. 18 illustrates an identification device wake-up circuit according
to
an embodiment of the invention.
[0029] FIG. 19 illustrates the impedance of a piezoelectric element loaded by
a fingerprint valley according to an embodiment of the invention.
[0030] FIG. 20 illustrates the impedance of a piezoelectric element loaded by
a fingerprint ridge according to an embodiment of the invention.
[0031] FIG. 21 illustrates a sensor array input signal according to an
embodiment of the invention.
[0032] FIG. 22 illustrates a sensor array output signal according to an
embodiment of the invention.
[0033] FIG. 23 illustrates how an identification device is used to obtain
biometric information according to an embodiment of the invention.
[0034] FIG. 24 illustrates how an identification device is used to obtain a
bone
map according to an'embodiment of the invention.
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[00351 FIG. 25 illustrates a transmitting and/or receiving beam directivity
according to an embodiment of the invention.
[0036] . FIG. 26 illustrates how an identification device is used to obtain
arteriole blood flow information according to an embodiment of the invention.
[0037] FIG. 27 illustrates a transmitting beam directivity and a receiving
beam
directivity according to an embodiment of the invention.
[0038] FIG. 28 illustrates a transmitting and/or receiving beain directivity
according to an embodiment of the invention.
[.0039] FIG. 29 illustrates how an identification device is used to obtain
capillary blood flow information according to an embodiment of the iiivention.
[0040] FIG. 30 illustrates a transmitting and/or receiving beam directivity
according to an embodiment of the invention.
[0041] FIG. 31 is a flowchart of a method according to an embodiment of the
invention.
[0042] FIG. 32 illustrates a biometric device according to an embodiment of
the invention.
[0043] FIG. 33 illustrates a mobile biometric device according to an
embodiment of the invention.
[0044] FIG. 34 illustrates a wireless transceiver biometric device according
to
an embodiment of the invention.
[0045] FIG. 35 illustrates a more detailed view of the wireless transceiver
biometric device of FIG. 34.
[0046] FIG. 36 illustrates using the wireless transceiver biometric device of
FIG. 34 to complete an electronic sales transaction.
[0047] FIG. 37 illustrates various applications for the wireless transceiver
biometric device of FIG. 34.
[0048] FIG. 38 illustrates a wireless transceiver biometric device according
to
an embodiment of the invention.
[0049] FIG. 39 is a diagram of an example piconet having coupling
BLUETOOTH devices with a public service layer.
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DETATLED DESCRIPTION OF THE INVENTION
Table of Contents
1. Overview of the Invention
II. Example Devises and Systems According to the Invention
A. Piezo Ceramic Sensors
B. Piezo Film Sensors
C. Sensor Array Address Lines
D. Example Identification Device
E. Example Multiplexer
III. Example Methods According to the Invention
A. hnpedance Mode
B. Attenuation/Voltage Mode
C. Doppler-Shift and Echo Modes
IV. Example Application of the Invention
A. Biometric Capture Device
B. Mobile Biometric Capture Device
C. Wireless Transceiver Biometric Device
D. Electronic Sales and/or Transactions
E. Other Wireless Transceiver Biometric Device Applications
F. Personal Area Network Applications
G. Public Service Layer Applications
I. Overview of the Invention
[0050] The present invention relates generally to a piezoelectric
identification
device and applications thereof. More particularly, it relates to a
piezoelectric
device for obtaining biometric data or information, such as a fingerprint, and
using the obtained information to recognize and/or verify the identity of an
individual.
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II. Example Devises and Systems According to the Invention
[0051] FIG. 1 is a schematic diagram of a piezoelectric identification device
110 according to an embodiment of the invention. Identification device 100
has a piezoelectric sensor 100, a sensor input signal generator 120, a sensor
output signal processor 130, and a memory 140. The input signal generated
by input signal generator 120 is coupled to sensor 110 by two multiplexers
150. The output signal of sensor 110 is similarly coupled to output signal
processor 130 by two inultiplexers 150.
A. Piezo Ceramic Sensors
[0052] Sensor 110 is preferably an array of piezo ceramic elements. For
example, sensor 110 can comprise an array of polycrystalline ceramic
elements that are chemically inert and immune to moisture and other
atmospheric conditions. Polycrystalline ceramics can be manufactured to have
specific desired physical, chemical, and/or piezoelectric characteristics.
Sensor 110 is not limited to comprising an array of piezo ceramic elements,
however. Sensor 110 can comprise, for example, a piezoelectric film. A
polarized fluoropolymer film, such as, polyvinylidene flouride (PVDF) film or
its copolymers can be used.
[0053] FIG. 2 illustrates the operating characteristics of a single
rectangular
piezo ceramic element 200 having surfaces 210, 220, 230, and 240. When
force is applied to surfaces 210 and 220, a voltage proportional to the
applied
force is developed between surfaces 210 and 220. When this occurs, surfaces
230 and 240 move away from one another. When a voltage is applied to
surfaces 210 and 220, surfaces 230 and 240 move towards one another, and
surfaces 210 and 220 move away from one another. When an alternating
voltage is applied to surfaces 2:10 and 220, piezo ceramic element 200
oscillates in a manner that would be known to a person skilled in the relevant
art.
[0054] FIG. 3 illustrates a row of five rectangular piezo ceramic elements
200A, 200B, 200C, 200D, and 200E. Each of these rectangular piezo ceramic
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elements 200 is attached or integral to support 302. Support 302 inhibits the
movement of one surface of each rectangular piezo ceramic elements 200.
Thus, when an alternating voltage is applied to surfaces 210 and 220 of piezo
ceramic element 200C, a sonic wave is generated at surface 210 of piezo
ceramic element 200C. The frequency of the generated sonic wave is
dependent on the physical characteristics of piezo ceramic element 200C.
[00551 FIG. 4 illustrates a two-dimensional array 400 of rectangular piezo
ceramic elements 200. Array 400 can be made from lead zirconate titanate
(PZT). PZT is an inexpensive material. In an embodiment, array 400 is
similar to a PZT 1-3 composite used in medical applications. The piezo
ceramic elements of sensor 110 according to the invention can have shapes
other than rectangular. As illustrated in FIG. 5, sensor 110 can comprise an
array 500 of circular piezo ceramic elements.
[0056] In one embodiment, array 400 can comprise rectangular piezo ceramic
elements that are from about 40 microns square by 100 microns deep, thereby
yielding a 20 MHz fundamental frequency sonic wave. A spacing of 10
microns is used between elements in this embodiment in order to provide a 50-
micron pitch between elements. A pitch of 50-micron enables an
identification device according to the invention to meet the Federal Bureau of
Investigation's quality standards for fingerprints.
100571 Other embodiments of the invention use geometries different than the
preferred embodiment. For example, a pitch of greater than 50 microns can be
used. Other embodiments also operate at frequencies other than 20 MHz. For
example, embodiments can operate at frequencies of 30 MHz and 40 MHz, in
addition to other frequencies.
[0058] Also, for example, in another embodiment, array 400 can comprise
cuboid (rectangular parallelepiped) piezo ceramic elements that are from about
80 square by 220 microns deep., A spacing of about 20 microns is lised
between elements in this embodiment in order to provide about
[00591 In yet another embodiment, array 400 can comprise rectangular piezo
ceramic elements that are from about 200 microns square by 500 microns
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deep. The cuboids can be modified to prisms or extruded stars, or have
chamfered corners or be a to reduce cross talk, facilitate molding
respectively.
[0060] As shown in FIG. 6, the spacing between the elements of a sensor
array according to the invention can be filled-in with a flexible type
material
or filler 602 to suppress any shear waves and give the sensor improved
mechanical characteristics. Micro-spheres 604 can be added to the filler 602
(e.g., vinyl micro-spheres) to reduce weight and/or increase the suppression
of
shear waves. In order to optimize,the signal-to-noise ratio of an
identification
device, and the device sensitivity, fillers (e.g., araldite filled with air
filled
vinyl micro-spheres) that provide high acoustical attenuating and electrical
isolation should be used.
[0061] At least four fabrication methods exist for producing array 400. These
methods include: laser cutting, dicing, molding, and screen-printing. Laser
cutting involves using an excimer laser to cut small groves and thereby form
the elements of array 400. Dicing involves using high performance dicing
equipment to form groves and the elements of array 400. Molding involves
using injection molding equipment to form array 400. Screen-printing is a
technique similar to that of solder printing in the assembly of printed
circuit
boards, where highly automated screen printing machines are adapted with
laser cut stencils. This method is particularly suited to producing 20 MHz
sonic wave elements since the ceramic elements are only 100 microns thick.
This method involves producing a ceramic slurry of appropriate consistency,
and has the advantage of not requiring surface grinding as may be required
with the molding method. I
[0062] FIG. 7A illustrates a sensor array 700 comprising rectangular piezo
ceramic elements according to a preferred embodiment of the invention.
Sensor array 700 is a multi-layer structure that includes a two-dimensional
array of rectangular piezo ceramic elements 200, similar to array 400.
Conductors (such as conductors 7,06 and 708) are connected to each of the
rectangular piezo ceramic elements 200. The conductors connected to one end
of each element 200 (e.g., conductor 706) are oriented orthogonal with respect
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to the conductors connected to another end of each element 200 (e.g.,
conductor 708). A shield layer 702 can be added to one side to provide a
protective coating where a finger can be placed proximate to sensor array 700.
A support 704 can be attached to the opposite end of the sensor array. Sensor
array 700 is described in more detail below.
B. Piezo Film Sensors
[0063] FIG. 7B illustrates a sensor array 750 comprising piezoelectric film
(piezo film) according to an embodiment of the invention. FIG. 7B is a cross-
sectional view of sensor array 750. Sensor array 750 is a multi-layer
structure
that includes a piezoelectric layer 752 sandwiched by two conductor grids 754
and 756. Conductor grids 754 and 756 each consist of rows of parallel
electrically conductive lines. Preferably, the lines of grid 754 are oriented
orthogonal with respect to the lines of grid 756 (that is, in x and y
directions,
respectively): This orientation creates a plurality of individually
addressable
regions or elements in the piezo film. As used herein, the term element refers
to any region of a sensor array that can be addressed, either individually or
as
part of a larger region, using the rows of parallel electrically conductive
lines
(conductors). Piezoelectric polymer film sensors are fiuther described in
Piezo Film Sensors: Technical Manual, available from Measurement
Specialities, Inc. Norristown, PA, April 2, 1999 REVB (incorporated by
reference herein in its entirety).
[0064] Shield layer 758 can be added to one side where a finger is placed to
provide a protective coating. Foam substrate 760 can be used as a support. As
shown in FIG. 7B, the multiple l4yers of sensor array 750 are stacked along
one direction (e.g., a z-direction).
[0065] In an embodiment, piezo layer 752 is a polarized fluoropolymer film,
such as, polyvinylidene flouride (PVDF) film or its copolymers. Conductor
grids 754 and 756 are silver ink electrodes printed on opposite sides of the
PVDF fihn 752. Shield layer 758 is made of urethane or other plastic. Foam
substrate 760 is made of TEFLON. An adhesive 762, 764 holds shield layer
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758 and foam substrate 760 on opposite sides of the printed PVDF film 752 as
shown in FIG. 7B.
[0066] In an embodiment, the PVDF film, including the printed electrodes,
can be peeled off like a label for easy replacement. As shown in FIG. 7B,
sensor array 750 can be mounted by adhesive 766 onto wax paper or other
material (not shown) for easy peel off. This allows the piezo sensor to be
installed and/or replaced simply and easily at minimum cost. Compared to
optical and silicon technologies, maintenance of the piezo sensor array 750 is
trivial.
C. Sensor Array Address Lines
[0067] FIG 8 illustrates a more detailed view of sensor array 700. As
described above, sensor array 700 comprises piezo ceramic elements having
an filler 602. Filler 602 preferably contains micro-spheres 604. This
structure
is then sandwiched between several layers. This central composite layer is an
active structure that can be used, for example, to map fingerprint mechanical
impedances into a matrix of electrical impedance values.
[0068] Each rectangular piezo ceramic element 200 of sensor array 700 is
connected to two electrode lines (e.g., conductors 706 and 708) . The
electrode lines on one end of sensor array 700 ran perpendicular to the
electrode lines on opposite end of sensor array 700. Thus, any single element
200 of the array can be addressed by selecting the two electrode lines
connected to it. The electrode lines are preferably created by vacuum
despoliation and lithography, and they are connected to the switching
electronics via an interconnect technique described below.
[0069] On top of the one set of, electrode lines is a protection layer 702.
Protective layer 702 is preferably made of urethane. This protecting layer 702
is intended to be in contact with a finger during operation of the sensor.
[0070] A support 704 or backing layer serves as a rear acoustical impedance
for each of the rectangular piezo ceramic elements 200. In a preferred
embodiment, support 704 is made of TEFLON foam. In order to provide a
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large variation of the electrical impedance of an element when loaded and
unloaded, the acoustical impedance support 704 should be acoustically
mismatched to the sensor element material. Either a very low or a very high
acoustic impedance material can be used. For embodiments using piezo
ceramic materials, the preferred impedance mismatch can be obtained by an
air backing rather than by a hard backing. This is because the sensor has a
high acoustic impedance. '
[0071] The materials described herein for constructing sensor array 700 are
illustrative and not intended to limit the present invention. Otller materials
can
be used, as would be known to a person skilled in the relevant art.
[0072] FIG. 9 illustrates how sensor array 700 can be connected to an
application specific integrated circuit. As described herein, an individual
piezo ceramic element (m, n) of sensor array 700 can be addressed by
selecting (addressing) conductor m on the top of sensor array 700 and
conductor n on the'bottom of sensor array 700. Other conductors can be either
grounded or open (high impedance state), particularly those conductors used
to address elements in the neighborhood of the element being selected, in.
order to reduce cross-talk. Parasitic currents in the neighborhood of the
selected element are minimized mechanically by the interstitial filler 602,
described above with regard to FIGs. 6 and 7A. Since in one embodiment, the
spacing between elements (pitch) is about 50 microns and standard bonding
technologies require a pitch of about 100 microns, alternate rows on an "East"
and "West" and alternate columns on a "North" and "South" sides of sensor
array 700, as shown in FIG. 9, connect the sensor to the "outside world". As
shown in FIG. 9, These conductors can be terminate in a "Bump" technology
around three edges 908 of an ASIC multiplexer 902. In an embodiment, side
908 of ASIC multiplexer 902 is about 3 mm.
[0073] In an embodiment, ASIC' multiplexer 902 is connected to a high
density flex 906. High density flex 906 is connected to an epoxy substrate
904. Conductors can be formed or attached to the high flex to couple the
conductors of the array to ASIC multiplexer 902. For example, a conductor
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on high density flex 906 is shown in FIG. 9 coupling conductor 708 to ASIC
multiplexer 902. Conductor is coupled to ASIC multiplexer 902 by bump
soldering. Anisotropic glue can be used to couple the conductor on high
density flex 906 to conductor 708 of the sensor array.' Other means for
connecting and electrically coupling ASIC multiplexer 902 to sensor array 700
are known to persons skilled in the relevant art, and these means also can be
used in accordance with the invention.
[0074] FIG. 10 illustrates how to connect a sensory array 1002 to four ASIC
multiplexers 902 according to an embodiment of the invention. As described
herein, electrode lines or conductors can be vapor deposited on both sides of
the substrate 902 (not shown in FIG. 10) and then etched into the desired
pattern. Before the line and row pattern is etched, substrate 902 should be
polarized in a manner similar to that of medical transducers.
[0075] A polarized substrate is connected to a socket or multi chip module
case that is compatible with available printed circuit board technologies. The
piezo ceramic matrix or sensor array 1002 can be backed by an air equivalent
foam or aluminum oxide. Either backing is designed to miss-match the
composite piezo material at 8 Mrayls to cause any energy coupling to occur
only at the front face of sensor array 1002, where for example a fingerprint
can be scanned. It should be noted in FIG. 10 that the conductors on both the
top and bottom of sensor array 1002 are interleaved in the manners described
above to facilitate bonding technologies requiring a pitch of about 100
microns.
[0076] FIG. 11 illustrates an identification device 1100 according to an
embodiment of the invention. In a preferred embodiment, device 1100 has a
piezo ceramic sensor array 1102 that is physically lager enough to capture any
fingerprint placed without accuracy on sensor array 1102 (e.g., about 25 mm.
square). Sensor array 1102 is preferably compliant with CJIS ANSII NIST
standards in resolution (500 points per 25.4 mm), and it has a pixel dynamic
range sufficient to provide 256 distinct shades of gray.
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[00771 As show in FIG. 11, in an embodiment, substrate 1110 is attached to a
printed circuit board 1104. The conductors of sensor array 1102 are coupled
to two integrated circuits 1106 an4 two integrated circuits 1108, which couple
sensor array 1102 to other circuits, which are described elsewhere herein.
Integrated circuit 1112 is a wireless transceiver that enables embodiments of
the invention to communicate with other devices as part of a personal area
network. This connectivity permits embodiments of the invention to supply,
for example, a standard secure identification and/or authorization token to
any
process or transactions that need or require it. The connection scheme shown
is FIG. 11 is an alternative connection scheme that can be used to implement
embodiments of the invention.
[0078] The above sensor array descriptions are illustrative and not intended
to
limit the present invention. For example, piezo layer 752 can be any material
exhibiting a piezoelectric effect including, but not limited to, piezoelectric
polymers. Conductor grids 706, 708, 754 and 756 can be any electrically
conductive material including, but not limited to, metals. Likewise, other
types of protective material can be used for shield layers 702 and 758 as
would
be apparent to a person skilled in the art given this description. Other types
of
supportive material can be used in place of support 704 or foam substrate 760.
D. Example Identification Device
[0079] FIG. 12 illustrates an identification device 1200 according to an
embodiment of the invention. Device 1200 comprises an input signal
generator 1202, a sensory array .1220, an output signal processor 1240, a
memory controller 1260, and a memory 1270. Sensor array 1220 is coupled to
input signal generator 1202 and output signal processor 1240 by multiplexers
1225A and 1225B, respectively. A controller 1230 controls the operation of
multiplexers 1225A and 1225 B. The operation of identification device 1200
is further described below.
[0080] In an embodiment, input signal generator 1202 comprises an input
signal generator or oscillator 1204, an variable amplifier 1206, and a switch
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1208. In one embodiment, oscillator 1204 produces a 20 MHz signal, which
is amplified to either a low or a high voltage (e.g., about 4 volts or 8
volts) by
variable amplifier 1206, depending on the mode in which device 1200 is
operating. Switch 1208 is used to provide either no input signal, a pulsed
input signal, or a continuous wave input signal. Switch 1208 is controlled to
produce the various types of input signals described herein in a manner that
would be known to a person skilled in the relevant art. As shown in FIG. 12,
the input signal generated by input signal generator 1202 is provided to
sensor
array 1220, through multiplexer 1225A, and to controller 1230 and output
signal processor 1240.
[0081] The structure and details of sensor array 1220 are explained above. In
a preferred embodiment, sensor array 1220 is a piezo ceramic composite of
rectangular elements designed to operate with a 20MHz input signal.
E. Example Multiplexer
[0082] FIGs. 13A and 13B illustrate how to apply an input signal generated by
input signal generator 1202 to the sensor array 1220, and how to receive an
output signal from sensor array 1220 according to an embodiment of the
invention. In one embodiment, sensor array 1220 comprises 200,000 elements
200 arranged in a two-dimensional' array (i.e., a 500 x 400 element array).
The
500 conductors of array 1220 that connect, for example, to the element rows
on the bottom of array 1220 must be connected to input signal generator 1202,
either one at a time or in various groupings, while the 400 lines that connect
to
the columns on the top of the array 1220 must be connected, for example, to
an impedance meter or Doppler circuit, either one at a time or in various
groups. This task is accomplished by multiplexers 1225.
[0083] In another embodiment, the sensor array 1220 can include about
25,000 to about 64,000 elements 200 (e.g., with 80 X 80 X 200 micron
elements). Yet another embodiment can include about 16,000 elements 200
(e.g., with 200 X 200 X 500 micron elements).
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[0084] In an embodiment, multiplexers 1225 are incorporated into four
identical ASICs (see FIG. 10). These four ASICs comprise analog
multiplexers, amplifiers, detection circuits, and logic. In a preferred
embodiment, the voltage of the input signal to sensor array 1220 is restricted
to less than 8 volts, which permits the ASICs to be constructed using 3-
rriicron
geometry, and to attain a switch impedance of less than 5 ohms. The four
basic sections of each of these ASIC are: (1) multiplexers as described
herein;
(2) amplifier/automatic gain controllers; (3) Doppler detectors; and (4) a
digital signal processor (DSP) interface. The structure and implementation of
items (2) through (4) are known to persons skilled in the relevant art.
[0085] In an embodiment, multiplexers 1225 comprise seventeen 16:1
multiplexers, thus giving one output or 16 outputs as selected. The function
of
each switch in the multiplexer is determined by a shift register 1302 that is
272
bits long and 2 bits wide (see FIG. 13B). The loading and clocking of shift
register 1302 is performed by controller 1230, which comprises a counter and
logic that would be known to a person skilled in the relevant art. As shown in
FIG. 13A, the conductors of sensor array 1220 can be connected to either
ground, signal input generator 1202, or they can be unconnected (high
impedance). Multiplexer 1225A is designed for lowest "on" resistance.
Multiplexer 1225B connects all (256) conductors of one side of sensor array
1220 to one or sixteen sense nodes. Both multiplexers 1225A and 1225B are
connected to the same function logic (i.e, controller 1230) so that the proper
sensor elements are selected and used, for example, for voltage sensing.
Element columns and rows, in the neighborhood of an element or group of
elements selected for sensing, can be switched to ground to prevent coupling
and interference.
[0086] FIG. 13B illustrates how to control the switches of multiplexers 1225
according to an embodiment of the invention. As described herein, each
switch of multiplexer 1225 connected to a conductor of array 1220 can be in
one of three states: connected to ground, connected to signal input generator
1202, or open (high impedance). This can be implemented, for example, using
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two CMOS gates, as shown in FIG. 14. A 272 bit long by 2 bit wide shift
register can then be used to control the position of each switch. Bits from
controller 1230 are shifted into shift register 1302 to control the position
of the
switches of multiplexers 1225. In an embodiment, shift register 1302 is
coupled to the switches of multiplexer 1225 using latches so that the position
of the multiplexer switches remain constant as new bits are being shifted into
shift register 1302. How to implement this embodiment would be known to a
person skilled in the relevant art. Other means for implementing the
functionality of multiplexers 1225 can be used without departing from the
scope of the invention.
[0087] FIG. 14 illustrates an example voltage detector 1244 according to an
embodiment of the invention. As will be understood by a person skilled in the
relevant art, the voltage drop in each conductor of sensor array 1220 is large
compared to the voltage drop of the elements of the array because all the
elements coupled to a particular conductor are drawing from a signal source
(i.e., input signal generator 1202). If each element has an impedance of 500
ohms, the impedance of 400 elements connected in parallel is 1.25 ohms. This
situation can be compensated for, however, by using a second multiplexer to
measure the true output voltage of the elements. As can be see in FIG. 14,
multiplexer 1402 is used to move the virtual zero-point of the amplifier 1404
before the switch of multiplexer 1406.
[0088] As explained herein, the choice of apertures, their relative position
in
sensor array 1220, and the number of apertures intended to be operated
simultaneously will affect the complexity of the logic of for multiplexer
1225.
Thus, in a preferred embodiment, this logic is implemented using a DSP. The
mode of operation of device 1200 can be selected on the four identical ASICs
described above using mode switches. These mode switches can be used to
operate switches 1250 (see FIG. 12) to direct the output of multiplexer 1225 B
to the proper detector of output signal processor 1240.
[0089] The operation of impedance detector 1242, signal time of travel
detector 1246, and Doppler shift detector 1248 are described below. Circuits
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to implement the functionality of these detectors will be known to persons
skilled in the relevant art given their descriptions herein.
[0090] The output of output signal'processor 1240 is biometric data. This data
can be stored in memory 1270 using memory controller 1260. FIG. 21 is a
flowchart of a method according to an embodiment of the invention. Use of
this biometric data is described below.
[0091] FIG. 15 illustrates means for increasing scanning speed and
minimizing cross-talk in a sensor array 1500 according to an embodiment of
the invention. As seen in FIG. 15, multiple elements can be active
simultaneously and a first means for minimizing cross-talk is to separate
geographically the active elements 1502 of array 1500. As explained herein,
a dynamic grounding scheme (i.e., coupling the elements 1504 in the
neighborhood of an active eleme:4t 1502 to ground) can be used that moves
with the active elements 1502 as they scan across the sensor array 1500. This
reduces the capacitive coupling to ground and electrical cross-talk while
maintaining a Faraday Cage for all sensed frequencies. In addition, an
interstitial filler can be used to reduce cross-talk and thereby the parasitic
currents in the neighborhood of the selected elements 1502. Other elements of
array 1500, e.g., elements 1506, are connected to conductors that are open.
III. Example Method Embodiments of the Invention
[0092] FIG. 16 is a flowchart of a method 1600 according to an embodiment
of the invention. Method 1600 comprise two steps 1610 and 1620. In step
1610, a biological object, for example, a finger or a hand, is place proximate
to
a piezoelectric ceramic array. In step 1620, an output is obtained from the
sensor array. The obtained output is processed as explained below to obtain
biometric data that can be used to recognize or verify the identity of a
person,
whose finger or hand, for example, was placed proximate to the sensor array.
Each of the steps 1610 and 1620 ai'e described further below with regard to
the
various operating modes of device 1200, described above.
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[0093] As described herein, identification device 1200 is operated in
different
modes depending on the biometric'data to be obtained. The biometric data that
can be obtained using device 1200 includes fingerprints, bone maps, arteriole
blood flow, and/or capillary blood flow.
[0094] FIG. 17 illustrates using identification device 1200 to obtain a
fingerprint of a fmger according to an embodiment of the invention. As seen
in FIG. 17, finger 1702 is place proximate to the sensor array 1220 of device
1200. In a preferred embodiment, sensor array 1220 is similar to piezo
ceramic sensor array 700. '
[0095] Two fingerprint ridges 1704 of finger 1702 are in direct contact with
protective shield 702. A fingerprint valley (i.e., cavity) 1706 of finger 1702
is
not in direct contact with protective shield 702. As can be seen in FIG. 17,
there are approximately six piezo ceramic elements 200 between the adjacent
fingerprint ridges 1704. 1
[0096] Initially, device 1200 is in a power saving mode. This mode is
particularly useful for prolonging battery life in mobile versions of device
1200. When finger 1702 applies a force to sensor array 1220, a wake-up
circu:it 1800 (see FIG. 18) operates to turn-on device 1200.
[0097] Wake-up circuit 1800 comprises a capacitor 1802, a diode 1804, and a
switch 1806. When finger 1702 applies a force to piezo ceramic elements
200, a voltage is developed by the elements causing capacitor 1802 to
accumulate a charge. When enough charges has been accumulated, the voltage
so produced causes switch 1806 to be turned-on. Voltage source 1808 is used
to power device 1200 once switch 1806 is turned-on. Power will continue to
be supplied to device 1200 until capacitor 1802 is discharged using a turn-off
circuit (discharging resister not shown).
[0098] After device 1200 wakes-up, device 1200 can be operated in either an
impedance detection mode or an attenuation mode (voltage mode) in order to
obtain an output from sensor array 1220 that can be processed to obtain the
fingerprint of finger 1702. Each of these modes are explained below.
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[0099] The outputs of the elements of piezo sensor 200 can be summed to
determine the centroid of the point of contact of the finger with the device.
Any movement of the fmger across the device can thus be sensed and the
sensor 200 can be used as a pointing device. For example, the centroid of a
finger in contact with piezo sensor 200 can be used to point on interconnected
viewing devices. The sum of the sensors elements can also used to determine
if the user is pressing with too little or two much force and the result fed
back
to the user.
[0100] The embodiment shown in FIG. 18 can also be used as a switch to
make a selection on an interconnected viewing device. For example, if an
analog-to-digital converter (not shown) is coupled to capacitor 1802, the
voltage across capacitor 1802 is converted to a digital signal that can be
used
interactively to make the selection by a user. As a user varies the pressure
applied to sensor 200, the voltage across capacitor 1802 will vary. The
analog-to-digital converter converts this time varying voltage, for example,
to
a series of numbers between 00000000 (base 2) and 11111111 (base 2). The
output of the analog-to-digital converter is periodically sampled and used to
make and/or indicate a selection (e.g., the number can be input to a processor
and used to make and/or indicate a particular selection). A graphical user
interface on a viewing device provides feedback to the user and indicates to
the user which of the possible seledions is being selected by the user based
on
the pressure applied to sensor 200. To change a selection, the user simply
applies either more or less pressure to sensor 200.
A. Impedance Mode
[0101] FIG 19 illustrates the impedance of a single piezo ceramic element 200
loaded by a fingerprint valley 1706 according to an embodiment of the
invention. At a frequency of about 19.8 MHz, the impedance of an element
2001oaded by a fingerprint valley is approximately 800 ohms. At a frequency
of 20.2 MHz, the impedance is approximately 80,000 ohms. At a frequency of
20 MHz, the impedance is approximately 40,000 ohms. As can be seen when
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FIG. 19 is compared to FIG. 20, both the absolute impedance of an element
200 loaded with a fmgerprint valley and the change in impedance with
frequency of an element 200 loaded with a fingerprint valley is significantly
different from that of an element 200 loaded with a fingerprint ridge. This
difference can be used to obtain an output from sensor array 1220 that can be
processed by output signal processor 1240 to produce fingerprint data.
[0102] FIG 20 illustrates the impedance of a single piezo ceramic element 200
loaded by a fingerprint ridge 1704 according to an embodiment of the
invention. As can be seen in FIG. 20, at a frequency of about 19.8 MHz, the
impedance of an element 200 loaded by a fingerprint ridge is approximately
2,000 ohms. At a frequency of 20.2 MHz, the impedance is approximately
40,000 ohms. At a frequency of 20 MHz, the impedance is approximately
20,000 ohms. Thus, both the absolute impedance of an element 200 loaded
with a fingerprint ridge and the change in impedance with frequency of an
element 200 loaded with a fingerprint ridge is significantly different from
that
of an element 200 loaded with a fingerprint valley.
[0103] When operating in the impedance mode, identification device 1200
determines the absolute impedance of an element 200 and/or the change in
impedance of an element 200 with frequency to determine whether a given
element 200 is loaded by a fingerprint ridge 1704 or a fingerprint valley
(cavity) 1706. To obtain a measure of the impedance of an element 200, input
signal generator 1202 is used to p'roduce low voltage pulses that are input to
the elements of sensor array 1220 using multiplexer 1225A.
[0104] The output signals obtained at multiplexer 1225B are related to the
absolute impedance of the elements 200 of array 1220. These output signals
are routed by switch 1250 to impedance detector 1242 to determine a measure
of the absolute impedances of the elements of array 1220. To obtain a
fingerprint, it is only necessary that impedance detector 1242 be able to
determine whether a given element 200 is loaded by a fingerprint ridge or a
fingerprint valley. These determinations of whether a particular element 200
is loaded by a fingerprint ridge or fingerprint valley can be used to generate
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pixel data that represents. the fmgerprint of finger 1702. The fingerprint is
stored in memory 1270. The fingerprint can also be transmitter to other
devices as described below.
[0105] If the fingerprint of finger 1702 is scanned twice usirig two different
input signal frequencies, the change in the impedances of the elements 200
with frequency cari be calculated. As already described herein, the change in
the impedances of the elements 200 with frequency is different depending on
whether an element 200 is loaded by a fingerprint ridge or fingerprint valley.
As can be seen in FIG. 12, the input signal generated by input signal
generator
1202 is supplied to output signal processor 1240. Thus, output processor 1240
can determine both the frequency and the voltage of the signals being input to
sensor array 1220.
[0106] An impedance detector circuit (not shown) can be implemented using
an op amp. The output of multiplexer 1225B is supplied to the negative port
of the op amp and an amplified signal is obtained at the output port. As would
be known to a person skilled in the relevant art, the positive port of the op
amp
is coupled to ground and a resistance is placed between the negative port and
the output port of the op amp. '
[0107] If the amplified voltage at the output port exceeds a predetermined
threshold voltage, the particular element 200 being measured is loaded by a
fingerprint ridge. This is due to the fact that the absolute impedance of an
element 200 loaded by a fingerprint ridge (for a given frequency) is
approximately half of the impedance of an element 200 loaded by a finger
print valley. Thus, the voltage of the output signal provided to the op amp
from an element 200 loaded by a fingerprint ridge is approximately twice the
voltage of the output signal provided to the op amp from an element 200
loaded by a fingerprint valley.
[010$] In general, slightly different processing techniques can be used in
association with smaller piezo ceramic sensor arrays (e.g.,, less than about
100,00 elements) that include larger individual elements (e.g., greater than
about 40 microns by 100 microns). For example, an exemplary piezo ceramic
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element can be comprised of a capacitor having PZT as the
dielectric. The permitivity of PZT can be relatively high (e.g., above 1500
(coulombs/volt-meter).
[0109] At 1500, the piezo electric effect causes the capacitor to mechanically
expand or contract under a voltage. At various frequencies, the elen'ient will
exhibit preferential oscillation or clamping based on the interaction of the
wavelength, the speed of sound in theelement, and the physical dimensions of
the element. The most useful osciflations are the series resonance and
parallel
resonances which are at 7.6 and 8.3 MHz for in one exemplary embodiment.
An expected exponential lowering of the impedance, of a capacitor, with
increasing frequency, has deviations at these two frequencies, as energy is or
is not consumed.
[0110] It has been discovered that the point spread function of mechanical
coupling to a fingerprint ridge is offset for the parallel resonance. This
concept facilitates spatial sampling frequencies of up to four times the
spatial
element frequency. Additionally, the sensitivity to a ridge or valley is very
biased as a valley causes no transfer of energy. A ridge, however, will be
insonified and a distant valley can be detected through the ridge. The net
result is that the a sensor can detect valleys better than ridges and the
valleys
can be much smaller than the element pitch.
B. Attenuation/Voltage Mode
[0111] As stated above, device 1200 can also operate in an attenuation or
voltage mode to obtain the fingerprint of finger 1702. This mode of operation
is available whether sensor array 1220 is a piezo ceramic array (e.g., array
700) or a piezo fihn array (e.g., array 750). The attenuation mode of device
1200 is based on the principle that energy imparted to an element 2001oaded
by a fingerprint ridge 1704 can be transferred to finger 1702, while energy
imparted to an element 200 loaded by a fingerprint valley 1706 cannot be
transferred to finger 1702.
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[0112] In the attenuation mode, input signal generator 1202 produces a high
voltage, pulsed signal that is provided to the elements of sensor array 1220
using multiplexer 1225A. FIG. 21 illustrates a one-cycle input pulse. An
input signal is typically longer than one-cycle, however. In an embodiment,
an input signal is about ten-cycles long. These input signal causes the
elements of the array to vibrate and produce sonic waves. These sonic waves
can travel from an element through the shield layer to a fingerprint ridge
1704
above the element. These sonic waves can pass into a fingerprint ridge 1704
because the acoustic impedance of the shield layer is matched to the acoustic
impedance of finger 1702. No acoustic barrier to the sonic waves is formed
by the interface between a fingerprint ridge 1704 and the shield layer. The
energy imparted to an element loaded by a fingerprint ridge is thus
dissipated.
In the case of an element loaded by a fingerprint valley, the energy imparted
to
an element remains trapped in the element for a longer period of time. This is
because the air in the fingerprint valley acts as an acoustic barrier.
[0113] After a number of cycles, the voltages of output signals obtained for
the array are determined and processed to obtain the fingerprint of finger
1702. FIG. 22 illustrates an example output signal. In an embodiment, since
the energy imparted to an element loaded by a fingerprint ridge 1704 is
dissipated more quickly that then energy imparted to an element loaded by a
fingerprint valley 1706, the voltage of an output signal obtained from an
element loaded by a fingerprint ridge 1704 is only about 1/10th of the voltage
of the input signal. In this embodiment, the voltage of an output signal
obtained from an element loaded by a fmgerprint valley 1706 is about %2 of the
voltage of the input signal. This- difference in voltages can be detected by
voltage detector 1244 and processed to generate the fingerprint of finger
1702.
A means for implementing voltage detector 1244 is described above. Other
.means will be known to a person skilled in the relevant art.
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C. Doppler-Shift and Echo Modes
[0114] Identification device 1200 can be operated in at least two other modes.
These modes are signal time of travel (echo) mode and Doppler-shift mode.
Echo mode can also be referred to as imaging mode. These modes are used to
obtain biometric data such as bone'maps, arteriole-veinal maps, arteriole
blood
flow and capillary blood flow, as described below. Combinations of these
biometrics and/or others can also be obtained. For example, a ratio of
arteriole
blood flow to capillary blood flow can be obtained and used to indicate the
emotional state or well-being of a host.
[0115] FIG. 23 illustrates how an identification device 1200 operating in echo
or Doppler-shift mode can be used to obtain biometric information according
to embodiments of the invention. As described herein, a high voltage signal
can be input to the elements of sensor array 1220 to produce sonic waves.
These sonic waves travel through finger 1702 and are reflected by various
features of finger 1702, such as, , for example the bone of finger 1702, -the
fingernail of finger 1702, or the blood flowing.in finger 1702.
[0116] FIG. 24 illustrates how an identification device 1200 is used to obtain
a
three-dimensional bone map according to an embodiment of the invention. To
generate a map of a bone 2402 of finger 1702, device 1200 is operated in its
echo mode. Sound waves traveling from the skin surface into finger 1702 will
be reflected from the bone structure of bone 2402. This structure can be
identified from the large echo amplitude that it causes. Since the echo travel
time is a measure of the sensor to bone distance, a three-dimensional map of
the shape of bone 2402 can be attained.
[0117] To obtain a map of bone 2402, a high voltage, pulsed input signal is
generated by input signal generato'r 1202 and provided to the elements of
array
1220. This input signal causes the elements to generate sonic waves that
travel into finger 1702. As shown in FIG. 24, only certain elements 200 of
array 1220 are actively generating sonic waves at any given time. In
accordance with the invention, and as described herein, active sonic wave
transmitting and receiving apertures are configured and moved (scanned)
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across sensor array 1220 using controller 1230 and multiplexers 1225. The
generated sonic waves travel through finger 1702 and are reflected by the
structure of bone 2402. These reflected sonic waves are then detected by the
receiving apertures. The time of travel of the sonic waves are obtained by
detector 1246 of device 1200 and used to detect whether bone structure is
located at a various distances fro,m array 1220. As would be known to a
person skilled in the relevant art, this mode of operation is similar to liow
radars operate.
[0118] The wavelength of the sonic waves and the aperture selected define the
transmit and receive beam shape. Various aperture sizes and beam directivity
can be formed in accordance with the invention. FIG. 25 illustrates a example
beam directivity that can be used to obtain a bone map of bone 2402 according
to an embodiment of the invention. Other beams can also be used.
[0119] FIG. 26 illustrates how identification device 1200 is used to obtain
arteriole blood flow information according to an embodiment of the invention.
An artery 2602 and capillaries 2604 are shown for finger 1702. As seen in
FIG. 26, arteriole blood flow is parallel to the surface of sensory array
1220.
[0120] Arteriole blood flow data is obtained from device 1200 while it is
operating in Doppler-shift mode. To receive a Doppler-shift signal back-
scattered from red blood cells flowing in artery 2602, the transmit and
receive
directivity beam patterns of sensor array 1220 must form one or more
overlapping volumes 2606.
[0121] FIG. 27 illustrates a transmitting aperture 2610A and a receiving
aperture 2610B according to an embodiment of the invention that form an
overlapping volume 2606. One approach for creating transmitting apertures
2610A and receiving *apertures 2610B is to make the apertures less than about
six wavelengths square (e.g.,. 30Q microns or six elements on a side) and
spaced at a pitch of two wavelengths (600 microns). These apertures create
side beams or grating lobes at about 30 degrees and form overlapping regions
2606 at a depth appropriate for detecting arteriole blood flow. FIG. 28
illustrates a transmitting and/or receiving beam formed by such apertures
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according to an embodiment of the invention. Other apertures can. also be
used. The angle at which grating lobes can be created are controlled by the
ratio of the pitch between apertures and the wavelength of the sonic waves
generated, as would be known to a person skilled in the relevant art given the
description of the invention herein.
[0122] As seen in FIGs. 26 and 27, sonic energy produced by aperture 2610A
is scattered by blood cells flowing in artery 2602 and received at aperture
2610B. The input signal provided to the elements of array 1220 that make up
aperture 2610A is a high voltage, continuous wave signal. This input signal is
also provided to output signal processor 1240 as a reference signal for
Doppler-shift detector 1248. This input or reference signal is mixed by
Doppler-shift detector 1248 with the output signal received from aperture
2610B to obtain Doppler -shift ~ information. Circuits for implementing
Doppler-shift detector 1248 are known in the relevant art, and thus not
reproduced here.
[0123] FIG. 29 illustrates how an identification device 1200 is used to obtain
capillary blood flow information according to an embodiment of the invention.
As seen in FIG. 29, capillary blood flow is in a direction normal to the
surface
of sensor array 1220. To separate the capillary flow from the arteriole flow,
multiple apertures of nine elements (3 x 3, 150 micron square) can be
selected.
This aperture will create a very small and close area of sensitivity that can
be
replicated in many parts of sensor 1220 simultaneously. The sensitivity of the
apertures can be increased by adding the Doppler signals of multiple apertures
together. The sensitivity apertures is focused in the first half millimeter of
finger 1702 closest to the surface of array 1220. FIG. 30 illustrates a
transmitting and/or receiving beam directivity that can be used to detect
capillary blood flow according to an embodiment of the invention.
[0124] When using device 1200 to detect blood flow, using a pulsed Doppler
embodiment has the advantage of'having the same aperture perform both the
transmit and receive fianctions. In addition, by gating the received signal,
only
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back-scattered information resulting from a well-defined sample volume is
analyzed to obtain the blood flow pattern.
[0125] FIG. 31 is a flowchart of a more detailed method 3100 for obtaining
biometric data using device 1200. Method 3100 is described with reference to
a particular embodiment of device 1200 having a piezo film sensor array.
[0126] In step 3102, device 1200 is awakened and piezo film sensor array
1220 is switched to detect an initial pixel or a group of pixels. Controller
1230
switches multiplexers 1225A and 1225B to a designated initial pixel or group
of pixels. In one example, piezo film sensor array 1220 is a 512x512 pixel
array. Multiplexers 1225A and 1225B are each used to addressed and/or
select a particular grid line (conductor) at a designated address of the
initial
pixel or group of pixels being detected.
[0127] In step 3104, an input signal is applied to piezo film array 1220. A
pulse is applied in one 30 MHZ cytle. Oscillator 1204 generates an oscillation
signal at 30 MHZ. Multiplexer 1225A forwards the input pulse to an initial
pixel or group of pixels. This input signal is also sent to controller 1230
and
output signal processor 1240.
[0128] In step 3106, an output signal is obtained from piezo film array 1220.
Output signal processor 1240 waits a number of cycles before detecting a
signal at the pixel. For example, in response to the signal sent from input
signal generator 1202, output signal processor 1240 waits a number of cycles
after the input pulse is applied to the pixel (or group of pixels). In step
3108,
when the wait is complete, a voltage, for example, is evaluated using voltage
detector 1244.
[0129] For example, one 30 MHZ cycle corresponds to approximately 33
nanoseconds. The wait can be approximately 5 cycles or 150 nanoseconds.
Other wait durations (e.g. a greater or smaller number of periods) can be used
depending upon the oscillator frequency and/or other design considerations.
This wait allows the ring down oscillation due to the presence of a
fingerprint
ridge to occur, in response to the applied electrical pulse at the pixel, as
described above.
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[0130] In step 3108, a filtered voltage is evaluated by output signal
processor
1240 and a grey scale or a binary pixel value is output representative of the
detected voltage (step 3110). A filter circuit (not shown) is a band-pass
filter
that filters the output voltage to detect an output voltage signal in a
passband
centered about a frequency of approximately 30 MHz. The grey scale or
binary pixel value is output to memory controller 1260 for storage in image
memory 1270. In one example, the output grey scale or binary pixel value is
stored in an address in image memory 1270 that corresponds to the detected
pixel.
[0131] In step 3112, a check is made to determine if the scan is complete. In
other words, a check is made to determine whether each pixel in the 500 x 400
sensor array 1220 has been scanned and a corresponding output value has been
stored and accumulated in image memory 1270. If the scan is complete, then
the routine ends. A signal or other indication can then be generated and
output
from device 1200 to indicate, for 'example, that a fingerprint image has been
successfully captured. If the scan is not complete, then the piezo fihn sensor
array 1220 is switched to detect the next pixel or next group of pixels (step
3114). Control then returns to perform steps 3104 through 3112 at the next
pixel or next group of pixels.
[0132] As described above, piezo ~film sensor array 1220 can be switched by
multiplexers 1225 to detect voltage values at a single pixel or a group of
pixels. In general, any pattern for scanning pixels can be used. For example,
a raster scan of pixels can be performed. Pixels can be scanned row by row or
column by column.
[0133] In one preferred example, when multiple groups of pixels are read out
at a given instant, each pixel in a group of pixels are separated by a
predetermined distance. In this way interfering effects from the ring down
oscillation in neighboring pixels are minimized or avoided. In one example,
pixels detected in a given cycle are separated by a minimum distance of at
least 8 pixels. In this way any ring down oscillations between neighboring
pixels are attenuated significantly.
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IV. Example Applications of the Invention
A. Biometric Capture Device
[0134] FIG. 32 illustrates a biometric device 3202 according to an
embodiment of the invention. Device 3202 has a sensor array 3204 according
to the invention. Device 3202 is particularly adapted for obtaining and
storing
fingerprint data according to the invention. Device 3202 is intended, for
example, to be used by law enforcement personnel.
.B. Mobile Biometric Capture Device
[0135] FIG.. 33 illustrates a mobile biometric device 3300 according to an
embodiment of the invention. Device 3300 has a sensor array 3302 according
to the invention at one end of the device, and a handle 3306 at an opposite
end.
The circuitry of the device is located in a portion 3304 of the device. Device
3300 is battery operated. Device 3300 is also intended, for example, to be
used by law enforcement personnel.
C. Wireless Transceiver Biometric Device
[0136] FIG. 34 illustrates a wireless transceiver biometric device 3400
according to an embodiment of the invention. Device 3400 is intended to be
used by the general populace, for,example, as an electronic signature device.
Device 3400 has a sensor 3402 for obtaining biometric data, such as a
fingerprint; according to the invention. Device 3400 is shown as having three
indicator lights 3404 for communication information to a user.
[0137] FIG. 35 illustrates a more detailed view of the wireless transceiver
biometric device 3400. As can be,seen in FIG. 35, sensor 3402 is powered by'
a battery 3504. Device 3400 has an antenna 3502 that can be used for sending
information to and receiving information from other device. Device 3400 can
be made to be compatible with BLUETOOTH wireless technology. A key
ring 3506 can be attached to device 3400. As illustrated by FIGs. 36 and 37,
device 3400 has a multitude of possible uses.
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D. Electronic Sales and/or Transactions
[0138] FIG. 36 illustrates using the wireless transceiver biometric device
3400
to complete an electronic sales transaction. In step 1 of the transaction,
device
3400 is used to obtain a fingerprint of the individual wanting to make a
purchase. Device 3400 then transmits the fingerprint to a device coupled to
cash register 3602 (step 2), which sends the fingerprint to a third party
verification service 3604 (step 3). The third party verification service uses
the
received fingerprint to verify the identity of the purchaser (step 4) by
matching
the received fingerprint to fingerprint data stored in a database. The
identity
of the purchaser can then be sent to cash register 3602 (step 5) and to a
credit
card service 3606 (step 6). The credit card service uses the data from the
third
party verification service to approve sales information received from cash
register 3602 (step 7) and to prevent the unauthorized use of a credit card.
Once cash register 3602 receive verification of the purchaser's identity and
verification that the purchaser is authorized to use the credit card service,
cash
register 3602 can notify device 3400 to send a credit card number (step 8.).
Cash register 3602 can then send the credit card number to the credit card
service 3606 (step 9), which then transfers money to the sellers bank account
(step 10) to complete the sales transactions. These steps are illustrative of
how
device 3400 can be used as an electronic signature device, and are not
intended to limit the present invention.
E. Other Wireless Transceiver Biometric Device Applications
[0139] FIG. 37 illustrates other applications for which the wireless
transceiver
biometric device 3400 is well suited. For example, device 3400 can be used
for: building access control; law enforcement; electronic commerce; financial
transaction security; tracking ernployee time and attendance; controlling
access to legal, personnel, and/or medical records; transportation security; e-
mail signatures; controlling use of credit cards and ATM cards; file.
security;
computer network security; alarm control; and identification, recognition, and
verification of individuals. These are just a few of the many useful
application
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of device 3400 in particular, and the present invention in general. Additional
applications for device 3400 and the invention will be apparent to those
skilled
in the relevant arts given the description of the invention herein.
F. Personal Area Network Applications
[0140] As described herein, embodiments of the invention are capable of
interacting with other devices as part of a personal area network. FIG. 38
illustrates one embodiment of a wireless transceiver biometric device 3800
according to the invention. Device 3800 comprises a biometric device similar
to device 1200, described above, a DSP chip 3802, a BLUETOOTH chip
3804, a display 3806, and a battery 3808. As described above, device 1200
has a piezo ceramic sensor array 700 and four multiplexers 1225 according to
the invention.
[0141] Biometric device 1200 is coupled to a DSP 3802. DSP 3802 controls
device 1200 and stores biometric data. DSP 3802 is also coupled to
.BLUETOOTH chip 3804 for sending and receiving data. A display 3806 is
used to communicate information to a user of device 3800. Device 3800 is
powered by a battery 3808. As would be known to a person skilled in the
relevant art, BLUETOOTH is an agreement that goverris the protocols and
hardware for a short-range wireless communications technology. The
invention is not limited to implementing only the BLUETOOTH technology.
Other wireless protocols and hardware can also be used.
[0142] Wireless transceiver biometric device 3800 enables an individual to be
in communication with compatible devices within about 30 feet of device
3800. Device 3800 can connect, for example, with to telephones, cell phones,
personal computers, printers, gas pumps, cash registers, Automated teller
machines, door locks, automobiles, et cetera. Because device 3800 can
connect to and exchange information or data with any compatible device
within a personal area network, dr piconet, device 3800 is able to supply a
standardized secure identification or authorization token to any device, or
for
any process or transaction that needs or requests it.
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G. Public Service Layer Applications
[0143] The present invention provides a "public services layer" (PSL) high up
in a BLUETOOTH stack. The PSL layer rationalizes identification and access
control for BLUETOOTH devices communicatively coupled to each other. In
embodiments, the PSL layer supports authorization and identification based on
a fmgerprint biometric signal provided by a fingerprint scanner. In one
example, a wireless transceiver biometric device 3800 can be used with a
BLUETOOTH module including a BLUETOOTH protocol stack to provide
the fingerprint biometric signal. See, e.g., the description of BLUETOOTH
module, protocol stack, and compliant devices by Jennifer Bray and Charles
Sturman, BluetoothTM Connect without Cables, Prentice-Hall, Upper Saddle
River, NJ 2001 (entire book incorporated in its entirety herein by reference),
and Brent Miller and Chatschik Bisdikian, Bluetooth Revealed, Prentice-Hall,
Upper Saddle River, NJ 2001 (entire book incorporated in its entirety herein
by reference).
[0144] In embodiments, the PSL layer functionality is defined by a protocol
(also called a specification). The PSL layer interprets simple requests from
devices in the piconet and acknowledges back with capabilities and level of
capability in a predefined form. ' Vendors of BLUETOOTH appliances can
add services in the PSL layer of the present invention to enhance the features
of their product.
[0145] The PSL layer, which would in most cases act transparently to the
norm-al fun.ction of the device until a PSL request was broadcast that
requested
one of the functionality groups that the device supported. One minimum level
of support re-broadcasts an unsatisfied request in the aid of extending the
scatter net to eventually fmd a device with the requested function. In this
way,
other devices outside of the range of a requesting device can be contacted to
fulfill the PSL request.
[01461 FIG. 39 is a diagram of an example piconet 3900 coupling
BLUETOOTH devices 3910, 39200 according to the present invention.
Device BLUETOOTH is a fingerprint scanner with a public service layer and
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BLUETOOTH stack or chipset. The public service layer can support
authorization and identification. Device 3920 is any BLUETOOTH appliance.
Device 3920 includes a PSL layer and BLUETOOTH stack or chipset.
Piconet 3900 can include any number of BLUETOOTH devices within the
area of the piconet, within a scatternet, or coupled to the piconet through
other
communication links.
[01471 Completing a task may require many functions to be performed in
concert among a constellation of distributed BLUETOOTH appliances. The
user would have to purchase and install sufficient appliances to cover all the
functions in a task. The PSL scheme enables efficiency and cost savings as
the appliances would be shared amongst users and in some cases providing
multiple uses.
[0148] One example operation of the PSL layer is physical access control. A
PSL layer of wireless transceiver biometric device 3920 sends or broadcasts
one or more request access signals. Such request access signals in the PSL
layer can include a request for extract/match/access and data representative
of
detected fingerprint from outside the secured perimeter via BLUETOOTH.
The PSL layer in a Desktop PC with BLUETOOTH inside the secured area
receives the request from the wireless transceiver biometric device 3920 for
extract/match/access and matches the, print data to the personnel database
which could be stored in a server and sends an access granted to the door. The
BLUETOOTH door lock then opens and the task is completed.
[0149] The savings are illustrated by; using a desktop PC that is used for
other
purposes, to perform the function of access control, time and attendance,
personnel tracking and security. The only dedicated hardware is the
BLUETOOTH door lock as the PC and the wireless transceiver biometric
device 3800 are used for other tasks. The installation cost is minimal and the
convenience of record keeping and data base management is also minimal.
The three appliances involved in this task could be purchased from different
vendors who have only communicated to the PSL standard. The function of
fingerprint extract/match/access cduld be pattern, minutiae, local or central
or
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even changed at any time for greater security and convenience etc, without
effecting the door lock or wireless transceiver biometric devices 3800. The
turning off or on of say lights, air conditioners, telephones, could all be
added
'to this task if desired.
[0150] Another advantage in savings is obsolescence. A building fitted with
BLUETOOTH door locks, BLUETOOTH air-conditioning, BLUETOOTH
smoke detectors, BLUETOOTH lighting etc. could be upgraded with
biometric controls without installation costs.
[0151] Appliances such a smoke alarms and light fixtures can act as alarms
and extend piconets into scatter nets that will bridge gaps in parks, gardens
and car parks adding security an functionality to gates in remote areas.
[0152] Telephones could be marketed with BLUETOOTH PSL functionality
meaning that they can dial 911 if an emergency code is received.
BLUETOOTH PSL could signify functionality to be programmed to dial a
specific number for private emergency services.
[0153] Protocols could be define&which log events in a FIFO so false alarms
could be traced and minimized.
[0154] In one embodiment, the PSL Specification has the elements identified
below.
[0155] A decimal filing system is included. A request is broadcast for a
function that can be as specific as the number of decimal places in the
request.
In this way a manufacturer can keep the task in his constellation of devices
if
the devices are available as is expected. If the request is not serviced by
the
exact'function number (FN) required the next nearest FN in the scatter net is
used. Clusters of FN are used around areas of development.
j01561 For example, a light fixture can have a FN of 551.263, which indicates
500 a facility utility, 550 a light, 551 a plug in, 551.2 a table lamp, 551.26
a
halogen low voltage, 551.263 made by a person or company (not exclusive).
A request for this specific function of turning on 551.263 may be serviced by
557.789 a wall neon as that is all that is available at the time and the
numerically nearest number though limited to the group of 55X lighting. The
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FN 551.26 can be defined in the PSL specification, digits after this are for
manufacturers uses and may be registered. In this way a lighting manufacturer
may supply software for a PC that orchestrates visual effects.
[0157] A requesting device or a PSL manager (Piconet Master Device) could
arbitrate in the scatter net to match requests and functions.
[0158] The PSL can also define the structure of how functions are allocated. A
FN allows one to negotiate with vend.ors of door locks with minimal effort.
The PSL also give manufacturers of other appliances insight into task
implementation where a wireless transceiver biometric device 3800 could play
a key roll.
[0159] Function Numbers in the PSL are grouped for request and function
suitability in one example as:
100 Emergency
200 Communications
300 Security
400 Positional
500 Facilities and Utilities
600 Entertainment
700 Computation and Information
800 Transportation
900 Miscellaneous
Sub-functional Groups are defined in one example as follows:
210 Internet connection(for transfer of credentials to local DB)
310 Personal identification via PIN
311 Personal identification via Signature
312 Personal identification via Fingerprint
313 Personal identification via Voice
314 Personal identification via Face
315 Personal identification via Eye
342 Fingerprint Feature Extraction Matching
520 Door Locks
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550 Lighting
[0160] Requests and Events can also be used in the PSL specification.
[0161] Off/ON/More/Less are universal requests. User specific requests would
not be in the specification. Events such as ACK, NAC, can also be added in
the PSL specification.
[0162] Protocols or the structure of the request and acknowledgment include
the following features broadcasted in a packet.
(a) PSL indicates this packet is a PSL function request.
(b) FUNCTION NUMBER indicates the function requested
(c) REQUE indicates the operation to be performed (off/on,
lock/unlock)
(d) KEYS authenticates rights of the packet.
(e) PAYLOAD data if applicable [0163] The PSL specification can but does not
need to repeat the
BLUETOOTH stracture of encryption, error checking et cetera.
[01641 The following series of examples serve to illustrate the PSL layer in
several real-world applications:
[0165] Help I have fallen and I can't get up.
a) I press my BLUETOOTH alert button and emergency services
are requested.
b) A PC in the scatter net connects to the world wide web and
executes a call to a contracting service supplier ( a level one (preferred
level)
BLUETOOTH service) or in addition to or upon a failure the next level
occurs.
c) A telephone with BLUETOOTH calls 911 or a service provider
with a recorded message (a level two BLUETOOTH service) or upon a
failure the next level occurs.
d) A fire alarm with BLUETOOTH activates (a level three non
preferred but applicable BLUETOOTH service) or upon a failure the next
level occurs.
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e) A smoke detector activates is audio alarm in the hopes of
attracting attention ( a level four non preferred but applicable BLUETOOTH
service)
f) An Automobile within the scatter net activates its horn and
flashes its lights to alert personnel to an emergency situation. ( a level
five non
preferred but applicable BLUETOOTH service)
[01661 I would like access to my office.
a) I press my wireless transceiver biometric device 3800 wireless
transceiver biometric device 3800.
b) The wireless transceiver biometric device 3800 requests and
negotiates fingerprint identification function from a PC with BLUETOOTH
connected to the server in the office.
c) The server then authorized the door lock with BLUETOOTH to
be unlatched.
[0167] I woiild like to get through an airport
a) Baggage check in via kiosk with non reputable ID
b) Seat allocation and gate pass with ID at kiosk
c) Baggage claim with ID
[0168] Television programs could broadcast to BLUETOOTH TV that will
add effects to a BLUETOOTH home to assist future versions of Friday the
13th.
[0169] I would like to make a sizable trade on margin.
a) I verify my identity via wireless transceiver biometric device
3800 to my PC
b) The PC requests additional GPS location for the log of the trade
verification.
[0170] = Other example uses will be apparent to a person skilled in the
relevant
art given the description of the invention herein. The public service layer
according to the present invention can be used with any wireless transceiver
biometric device including any type of fingerprint scanner. For example,
fingerprint scanners which can be used include, but are not limited to,
silicon-
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based fmgerprint scanners, optical fmgerprint scanners, piezoelectric
fmgerprint scanners, piezo-film fmgerprint scanners and piezo-ceramic
fmgerprint scanners.
CONCLUSION
[0171] While various embodiments of the present invention have been
described above, it should be understood that they have been presented by way
of example only, and not limitation. It will be understood by those skilled in
the art that various changes in form and details may be made therein without
departing from the spirit and scope of the invention as defined in the
appended
claims. Thus, the breadth and scope of the present invention should not be
limited by any of the above-described exemplary embodiments, but should be
defined only in accordance with the following claims and their equivalents.
