U.S. patent application number 13/105065 was filed with the patent office on 2011-11-17 for reflex longitudinal imaging using through sensor insonification.
Invention is credited to Jack C. Kitchens, John K. Schneider.
Application Number | 20110279662 13/105065 |
Document ID | / |
Family ID | 44911455 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110279662 |
Kind Code |
A1 |
Schneider; John K. ; et
al. |
November 17, 2011 |
Reflex Longitudinal Imaging Using Through Sensor Insonification
Abstract
An ultrasonic reflex imaging device and a method are described.
A device according to the invention may include a platen, a
generator, and a receiver positioned between the platen and the
generator. A backer may be positioned so that the insonification
device is between the receiver array and the backer. The backer may
be configured to absorb or delay energy that originated from the
generator. The generator produces an energy pulse, which travels
through the receiver and the platen to reach a biological object.
Part of the energy pulse is reflected from the biological object.
The reflected energy pulse travels through the platen to the
detector. The detector converts the reflect energy pulse to
electric signals, which are then interpreted to create an image of
the biological object.
Inventors: |
Schneider; John K.; (Snyder,
NY) ; Kitchens; Jack C.; (Tonawanda, NY) |
Family ID: |
44911455 |
Appl. No.: |
13/105065 |
Filed: |
May 11, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61333304 |
May 11, 2010 |
|
|
|
Current U.S.
Class: |
348/61 ; 348/163;
348/E5.085; 348/E7.085 |
Current CPC
Class: |
A61B 5/1172 20130101;
G01S 15/18 20130101; G06K 9/0002 20130101; G01S 15/8913
20130101 |
Class at
Publication: |
348/61 ; 348/163;
348/E05.085; 348/E07.085 |
International
Class: |
G01S 15/89 20060101
G01S015/89; H04N 7/18 20060101 H04N007/18 |
Claims
1. An ultrasonic reflex imaging device comprising: a platen; an
insonification device; and, an ultrasonic receiver array positioned
between the platen and insonification device.
2. The imaging device of claim 1, wherein the ultrasonic receiver
array is in physical contact with the platen.
3. The imaging device of claim 1, further comprising a backer
positioned such that the insonification device is between the
receiver array and the backer.
4. The imaging device of claim 3, wherein the backer is configured
to absorb acoustic signals.
5. The imaging device of claim 3, wherein the backer is configured
to delay acoustic signals.
6. The imaging device of claim 1, wherein the insonification device
is a plane wave generator.
7. The imaging device of claim 1, wherein the platen is bonded to
the receiver array.
8. The imaging device of claim 1, wherein the receiver array is a
thin film transistor array with a piezoelectric sensing layer.
9. The imaging device of claim 1, wherein the receiver array is a
CMOS array with a piezoelectric sensing layer.
10. The imaging device of claim 1, wherein the receiver array is a
MEMS array with a piezoelectric sensing layer.
11. The imaging device of claim 1, wherein the platen is a plastic
plate.
12. The imaging device of claim 1, wherein the platen includes an
acoustic waveguide array.
13. The imaging device of claim 1, wherein the platen includes an
acoustic microlens array.
14. A method of capturing biometric information comprising:
emitting at least one ultrasonic pulse from an insonification
device, such that the pulse travels through a receiver array,
before reaching a biological object; detecting a portion of the
ultrasonic pulse reflected from the biological object with the
receiver array; converting the reflected ultrasonic pulse to a
plurality of electric charges; processing the plurality of electric
charges to assemble a digital image representation of the
biological object.
15. The method of claim 14, wherein the ultrasonic pulse also
travels through a platen, before reaching the biological object.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/333,304, which was filed on May 11, 2010, the
disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a system for gathering
information that can be used to create an image of an object. The
information is obtained using a longitudinal wave, such as an
ultrasound wave.
BACKGROUND OF THE INVENTION
[0003] Since the 1800's fingerprint information has been collected
from human fingers and hands by means of ink and paper. For the
purposes of this invention, the term fingerprint refers to the skin
surface friction ridge detail of a single digit, or part of the
friction ridge detail of a digit, or any portion of the skin
surface friction ridge up to and including the entire hand. In
recent years, various electronic fingerprint scanning systems have
been developed utilizing optical, capacitance, direct pressure,
thermal, and longitudinal-wave methods. Methods based upon
longitudinal waves, including ultrasound, have proven to be highly
accurate, since longitudinal waves are unaffected by grease, dirt,
paint, ink and other substances commonly found on a person's
skin.
[0004] Use of ultrasound typically employs a piezoelectric
transducer to send an ultrasonic energy wave, often referred to as
a pulse, through a transmitting media. The pulse partially reflects
back at each interface between media. The reflected portion of the
pulse can be used to determine the distance traveled by the pulse,
and this can be done for each partially reflecting interface.
However, not all of the reflected pulses are of interest. For
example, when a fingerprint is of interest, the pulse reflected by
interfaces other than where the finger resides are not of interest.
Since pulses reflected by the various interfaces will arrive at
different times, it is possible to identify those pulses that are
of interest by monitoring a time interval during which the
reflected pulse for that interface is expected to arrive. This
process is often referred to as range gating or biasing. The
reflected pulse received during the expected time is then
processed, often by converting it to digital values that represent
signal strength. Through a single pixel sweep scanning device,
information from a reflected pulse can be graphically displayed as
a three-dimensional contour map of the object of a human finger,
thumb or other skin surface. With respect to interface surfaces
that are not flat, the depth of any gap structure detail (e.g.
fingerprint valleys) can be displayed as a gray-scale bitmap
image.
[0005] Although ultrasound imaging of a fingerprint is superior in
detail to a similar image collected by an optical system or other
means, we have discovered an arrangement of components which
provides a superior image.
SUMMARY OF THE INVENTION
[0006] The invention may be embodied as an ultrasonic reflex
imaging device. Such a device may include a platen, an
insonification device (also known as a generator), and a receiver
array positioned between the platen and insonification device. The
receiver array may be in physical contact with the platen. A backer
may be positioned so that the insonification device is between the
receiver array and the backer. The backer may be configured to
absorb or delay energy that originated from the generator.
[0007] The insonification device may be a plane wave generator.
That is to say that the energy generated may be substantially
planar. The energy may be in the form of a longitudinal wave, such
as an ultrasonic wave.
[0008] The platen may include an array of waveguides, or a
microlens array. The platen may be suitable for resting a
biological object such as a finger while the biological object is
analyzed using the longitudinal wave generated by the
insonification device.
[0009] The invention may be embodied as a method of capturing
biometric information from the biological object. In one such
method, an ultrasonic pulse emanates from an insonification device,
and the pulse travels through a receiver array, before reaching a
biological object. Part of the pulse is reflected by the biological
object, and the reflected energy is detected and converted to a
plurality of electric charges. The electric charges are processed
(for example, by a computer) to assemble a digital image
representation of the biological object.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a fuller understanding of the nature and objects of the
invention, reference should be made to the accompanying drawings
and the subsequent description. Briefly, the drawings are:
[0011] FIG. 1 is an exploded perspective view of one embodiment of
a device according to the invention;
[0012] FIG. 2 is an assembled view of the device depicted in FIG.
1; and
[0013] FIG. 3 is a flow chart describing a method according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The invention described herein is illustrated by way of one
or more particular embodiments. Initially, a general overview of
the invention is provided, followed by additional details. The
invention may be embodied as an ultrasonic reflex imaging device
comprising a platen, an insonification device, and an ultrasonic
receiver array positioned between the platen and the insonification
device. The ultrasonic receiver array may be in physical contact
with the platen. The platen may be bonded to the receiver array
through an adhesive, such as an epoxy, a two-part acrylic, or a
cyanoacrylate super glue. Also, the insonification device may be a
plane wave generator. In another embodiment, the imaging device
further comprises a backer positioned such that the insonification
device is between the receiver array and the backer. The backer may
be configured to absorb or delay acoustic signals.
[0015] The receiver array can be constructed from a number of
suitable materials for receiving ultrasonic pulses. For example,
the receiver array can be a thin film transistor array with a
piezoelectric sensing layer, a CMOS array with a piezoelectric
sensing layer, or a MEMS array with a piezoelectric sensing
layer.
[0016] The platen may also be constructed in a number of
configurations, from a variety of suitable materials. For example,
the platen can be a plastic plate. In one embodiment, the platen is
an acoustic waveguide array, an example of which is described in
U.S. patent application Ser. No. 12/555,220, the disclosure of
which is incorporated herein by reference. In another embodiment,
the platen is an acoustic microlens array, an example of which is
described in U.S. Pat. No. 5,230,990, the disclosure of which is
incorporated herein by reference. Microlens arrays can be used to
shape, focus, or direct pulses produced by an ultrasonic
generator.
[0017] In one embodiment, the invention can capture biometric
information from a biological object by emitting at least one
ultrasonic pulse from an insonification device, such that the pulse
travels through a receiver array before reaching a biological
object. Upon reaching the biological object, a portion of the
ultrasonic pulse is reflected from the biological object and the
reflected pulse is detected by the receiver array. The receiver
array converts the reflected ultrasonic pulse to a plurality of
electric charges, and processes the plurality of electric charges
to assemble a digital image representation of the biological
object.
[0018] The receiver array may include detecting elements that are
arranged in a two-dimensional array. A high resolution ultrasound
receiver array formed by the detecting elements may be made to work
in concert with a physically separate piezoelectric plane wave
pulse generator that is capable of emitting an energy wave in the
ultrasonic frequency range. Fingerprint image data may be captured
by the receiver array. Each detector in the receiver array can
produce information corresponding to part of that image. Each
detector may be addressable using software such that the image
information can be processed and feature manipulated by dedicated
devices. In this manner, a fingerprint template can be created
locally on the device, using for example an integrated circuit or
chip set, thereby relieving a system of the need for subsequent
image acquisition processing.
[0019] Having provided a general overview of devices that are in
keeping with the invention, additional details are now provided.
FIGS. 1 and 2 depict an embodiment of a reflection based (reflex)
ultrasonic imaging device 9 having a backer 4 that may absorb or
delay ultrasonic energy. The figures also depict an ultrasonic
plane wave generator 1, which can be fabricated from a
piezoelectric device 6, which can be a film or ceramic element, and
metalized electrodes 5 attached to the piezoelectric device 6.
Since the piezoelectric device 6 may reside substantially in a
plane, the wave generated by the device 6 may emanate in a
substantially planar fashion.
[0020] A device according to the invention may include an
ultrasonic receiver array 2 and a platen 3. The skin of a finger 10
may be applied to the platen 3 for purposes of generating an image
of the fingerprint. Once applied to the platen 3, the generator 1
produces an energy wave at an ultrasonic frequency, the energy wave
travels through the receiver array 2, through the platen 3, to the
finger 10. A portion of the energy wave is reflected by the finger
10, and the reflected energy wave travels through the platen 3
toward the receiver array 2.
[0021] The receiver array 2 may include an array 7 of piezoelectric
detectors 11 that are sensitive to pressure changes, for example
those caused by an ultrasonic pulse. An insulating substrate 8 may
be associated with the receiver array 2. The insulating substrate 8
may be constructed from quartz glass or borosilicate glass. The
insulating substrate 8 may be made from a material that
electrically insulates the receiver array 2 from the generator
1.
[0022] The detectors 11 of the array 7 may each be a semiconductor
device, which are each addressable by row and column (or another
method of identification), and each detector 11 in the array 7 may
be thought of as an individual pixel element. For example, the
detectors 11 of the array 7 may also each be a thin film transistor
device, a CMOS device, or a MEMS device.
[0023] The platen 3 may be included to help convey ultrasonic
energy to and from the skin that is in contact with the exposed
surface of the platen 3. The platen 3 may be a homogeneous plastic
plate, a waveguide array, or a microlens array. The advantages of
using a waveguide array or microlens array include benefits arising
from a finer aperture acoustic energy path between the skin of the
finger 10 and the piezoelectric receiver array 2, which will
produce a sharper and clearer image of the object that is in
contact with the exposed surface of the platen 3.
[0024] A reflex imaging device according to the invention may
operate in the following manner. An electrical excitation pulse, or
series of pulses, may be applied to the plane wave generator 1
which, in turn emits an ultrasonic pulse or series of pulses. The
ultrasonic pulse travels through the insulating substrate 8 and the
receiver array 2, and then through the platen 3, to the surface of
the platen 3 where the finger 10 resides. The pulse is reflected
back wherever the fingerprint is not in contact with the platen 3,
for example the valleys of the finger's friction surface. Where the
platen 3 contacts skin, for example at fingerprint ridges, the
acoustic energy is absorbed and/or scattered. The portion of the
ultrasonic energy pulse that reflects back carries information
about the fingerprint valleys. Areas where there is a relative lack
of a reflected signal indicate the locations of the ridges of the
fingerprint that contact the platen 3. When the ultrasonic pulse
arrives at the ultrasonic receiver array 2, it is converted by the
detectors 11 to electric charges, and these may be accessed by row
and column using externally controlled electronics. This array of
charges is converted from an analog to a digital form by an
analog-to-digital converter. The digital form may then be operated
upon by applying a fixed pattern offset and gain corrections, which
may be previously characterized and stored, and which correspond to
and are characteristic of the receiver array 2. The result is a
digital image representation of the finger residing on the platen
3.
[0025] The backer 4 may be fixed by an adhesive to the ultrasonic
plane wave generator 1, for example to the metalized electrode 5.
In one embodiment, the backer 4 may absorb parasitic ultrasonic
energy from the plane wave generator 1 that might otherwise
interfere with ultrasonic pulses reflected from the biological
object, or be misinterpreted as ultrasonic pulses reflected from
the finger 10. In another embodiment, the backer 4 delays
ultrasonic energy such that the delayed ultrasonic energy arrives
at the receiver array 2 outside of the expected range gate period.
Delayed ultrasonic responses are detected by the receiver array 2,
however they can be categorically discarded because they arrive at
a distinguishably later time than the pulses that are reflected
from the finger 10. A material that may be used as the backer 4 is
borosilicate glass. Another material that may be used as the backer
4 is quartz glass. The backer 4 and the platen 3 may be arranged as
an integral piece, thereby embedding the receiver array 2 and the
plane wave generator 1 between them. The backer 4 may also be made
from the same material as the platen 3.
[0026] An advantage of placing the plane wave generator 1 outside
of the path between the finger 10 and the receiver 2 is that the
materials of construction for the piezoelectric element 6 may be
either a polymer or a ceramic piezoelectric. Another advantage is
that the excitation signal to the generator 1 can be larger and
there will be less loss of usable acoustic energy. By way of
contrast, the prior art devices that use a single device for both
generation and detection require that care be given to the
excitation electric signal so as not to damage the sensitive
electronic receiver elements. By making the plane wave generator 1
and the receiver 2 different devices, a more robust generator 1 can
be employed. Also, a configuration according to the invention
reduces the number of interfaces between the finger 10 and the
receiver 2, when compared to prior art devices. Reducing the number
of interfaces between the receiver 2 and the object being imaged
reduces signal loss, since every material interface is a potential
source of acoustic reflection.
[0027] Physical separation of the ultrasound pulse creation device
from the reflected ultrasound pulse detector device allows the
ultrasound pulse generation to be optimized without the compromises
required of a dual purpose device that serves both to generate and
detect. The present invention situates the ultrasonic receiver
array between the target and the generator of the ultrasonic pulse.
The invention may be configured to permit the use of ultrasonic
devices between the generator and the target object in order to
allow the ultrasonic energy to be optimally focused or aperture
limited for improved image acquisition. Situating the receiver
array between the pulse generator and the object to be imaged
allows the use of pulse emitting appliances that would not be
suitable for other configurations due to the acoustic impedance
mismatch between the generator and the other components within the
acoustic signal path.
[0028] The present invention may also be implemented as a method of
capturing biometric information. FIG. 3 depicts one such method in
which at least one ultrasonic pulse is emitted 21 from an
insonification device, for example, a plane wave generator 1. The
pulse travels through a receiver array 2 and reaches a biological
object that is resting on a platen 3, for example, a human finger
10. A portion of the ultrasonic pulse is reflected from the finger
10. The reflected pulse travels through the platen 3 and is
detected 23 by the receiver array 2. The detected ultrasonic pulse
is converted 25 into a plurality of electric charges. These charges
are processed 27 to assemble a digital representation of the
biological object. The processing step 27 may be performed on a
processor embedded within the scanning device 9 or located
externally from the device 9.
[0029] Although the present invention has been described with
respect to one or more particular embodiments, it will be
understood that other embodiments of the present invention may be
made without departing from the spirit and scope of the present
invention. Hence, the present invention is deemed limited only by
the appended claims and the reasonable interpretation thereof.
* * * * *