Note: Descriptions are shown in the official language in which they were submitted.
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PALM PRI~rrER
Field of the Invention
The present invention relates to a method and
apparatus for optically eliminating parallax distortion
in an image including a method and apparatus for
processing skin pattern images representative of a palm
print.
Backqround of the Invention
Parallax in optics describes the situation
when the apparent relative orientation of ob~ects
changes when the position from which the objects are
viewed changes. Parallax causes a condition generally
known as keystone distortion, which describes the
situation in which different portions of an image appear
disproportionate. Parallax distortion must be addressed
when capturing an image with a prism. Apparatus which
capture images with a prism include finger print
capturing apparatus.
In recent years, many law enforcement agencies
have turned to devices which optically process and
digitize fingerprint images as opposed to using ink and
rolling the fingerprint. Two apparatus and methods
which are commonly used by law enforcement agencies are
disclosed in commonly assigned U.S. Patent Nos.
4,933,976 and 5,230,025.
United States Patent No. 4,933,976 discloses a
method for generating data characteristic of a rolled
30 finger print in real time. The method includes the
steps of storing arrays of digital data characteristic
of a fingerprint and generating a composite array of
digital data characteristic of a rolled fingerprint
image. The device of United States Patent No. 4,933,976
~ 35 includes a prism, which utilizes the principle of total
internal reflection to capture the image of a
fingerprint, a video camera, a frame digitizer and a
processor.
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United States Patent No. 5,230,025 also
discloses a method for generating data characteristic o~
a rolled fingerprint. The device of United States
Patent No. 5,230,025 also includes a prism, which
utilizes the principle o~ total internal reflection to
capture the image of a fingerprint, a video camera, a
frame digitizer and a processor. However, the method of
United States Patent No. 5,230,025 includes the steps of
continuously recording images as a finger rolls across
the prism and converting those images into digital
signals.
Both United States Patent Nos. 4,933,976 and
5,230,025 utilize CCD arrays to capture a pattern of
light reflected through the prism when the finger is
placed upon a surface of the prism. The CCD array of
both United States Patent Nos. 4,933,976 and 5,230,025
are two dimensional CCD arrays, for example, 768 x 960
array. Through the use o~ a lens and mirrors, the image
of the fingerprint is ~ocused onto the CCD array so that
the image of the fingerprint may be captured.
Many foreign countries, including Japan, as
well as many private organizations (such as,
corporations desiring high security) desire devices
which optically capture the image of a palm print, in
addition to the image of a finger print. A palm print
is desirable because, for example, it includes
approximately 17 times the data contained on a
fingerprint. Also, palm prints are often left at crime
scenes.
Some countries, including Saudi Arabia,
regularly take a palm print when processing an
individual who has been arrested. The methods currently
employed in Saudi Arabia and other ~oreign countries,
include the use of ink and are dif~icult to administer.
The greater volume of data associated with the palm is
beneficial in categorizing individuals and comparing
di~ferent palm print images to determine whether there
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is a match. In fact, it is estimated that up to
one-third of all criminal identifications are made in
~ part on the basis of a palm print.
The CCD arrays and lens of both United States
Patent Nos. 4,933,976 and 5,230,025 have an associated
resolution sufficient to provide detailed images of the
patterns of the fingerprint. The CCD arrays associated
with the devices of the prior art are capable only of
providing the desired resolution for a fixed surface
area of the prism. This fixed surface area is
approximately four times the size of an ordinary
fingerprint. Significant problems are presented in
merely increasing the size of the prisms and the other
equipment disclosed in United States Patent Nos.
4,933,976 or 5,230,025 in order to capture the image of
a palm print. These problems are related to parallax
distortion, resolution, and lighting.
A problem associated with any optical system
which, for example, captures an image, such as a
fingerprint or palm print through the utilization of a
prism, is parallax distortion, and in particular
keystone distortion. Specifically, keystone distortion
describes the condition when the top of a image is
disproportionately narrower or wider than the bottom
portion of an image. Keystone distortion is directly
related to parallax.
Parallax distortion is created because the
object, in this case one surface of the prism, is
slanted relative to the other sur~aces. Because of the
slant, the image focused through the lens will also be
slanted. The slanted image can be focused onto a
vertical CCD array (i.e., one that is not slanted) if
the depth of field associated with the lens the image is
being focused through is great enough. Depth of field
describes the distance toward and away from the focal
point of the lens in which clear focus is available. It
is well known that depth of field is a function of the
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f-stop, or the size of the aperture of the lens. As the
f-stop increases, that is as the aperture becomes
smaller, the depth of field becomes greater. Similarly,
as the f-stop decreases the depth of field becomes less.
Additionally, as the f-stop increases so does the amount
of light necessary to properly expose the CCD.
Elimlnation of parallax distortion and
providing adequate resolution are critical for optical
systems which capture fingerprints. For example, if the
fingerprint image is keystoned, it is skewed with
respect to fingerprints it is being compared against.
The skew makes it almost impossible to compare the two
images. Additionally, if the resolution is too low, the
image will be smudged, which is also virtually useless
in comparing fingerprints.
Parallax distortion can be solved either
optically, or by computer enhancement. It is understood
that most law enforcement agencies throughout the world
require that the parallax distortion be corrected
optically. In some finger printing devices of the prior
art, parallax distortion is minimized through the use of
a slanted CCD array in combination with a lens having a
high f-stop and an anamorphic prism. Specifically, the
CCD array is slanted to the objective distribution plane
of the prism. The objective distribution plane is
positioned at an angle equal in magnitude but opposite
in phase from the plane in which the clearest focus is
possible. The image achieved in the objective
distribution plane does not include significant parallax
distortion. ~owever, a drawback in positioning the CCD
array in the objective distribution plane is that a
greater depth of field is necessary to achieve
acceptable resolution. Therefore, a greater f-stop is
required to achieve a greater depth of field which in
turn requires more illumination. The anamorphic prism
is used to properly orient the image for reception by
the CCD array.
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The devices disclosed in United States Patent
Nos. 4,933,976 and 5,230,025 could be utilized to
-capture the image of a palm print at great financial
expense. Because the palm is of much greater surface
~5 area than a finger, a CCD array including a much larger
configuration would be necessary to capture the palm
print image. These larger CCD arrays are substantially
more expensive than those utilized by United States
Patent Nos. 5,230,025 and 4,933,976. For example,
MEGAPLUS array manufactured by KODAK, having a 2,000 x
2,000 array, would have adequate capacity to produce the
required resolution needed for a palm print. However,
such CCD arrays cost almost as much as entire commercial
systems for capturing fingerprints.
Further, to eliminate parallax distortion and
gain the required resolution in a system of the prior
art, if it was large enough to capture the image of a
palm, the f-stop would need to be substantially
increased with a corresponding increase in illumination.
However, if f-stop is increased too far, the entire
image will fall out of focus. Assuming an acceptable
focus was possible, the level illumination required to
capture the image of a palm with a very high f-stop
would require considerable energy and probably would
cause thermal problems.
Despite increased costs associated with
capturing a palm print through utilization of the
methods and apparatus disclosed in United States Patent
Nos. 4,933,976 and 5,230,025, a need exists to provide a
method and apparatus for digitizing the image of a palm.
The prior art has provided limited devices and
methods to scan palm prints. One such device is
disclosed in United States Patent No. 4,032,889 to
Nassimbene and assigned to International Business
Machines Corporation. United States Patent No.
4,032,889 utilizes photocells to capture the image of a
palm. The photocells used in U.S. Patent No. 4,032,889,
-~~ CA 02207664 1997-0~-29
as well as the method taught by U.S. Patent No.
4,032,889, are basic methods which may be useful in
comparing two dif~erent palm prints, but lack other
desirable characteristics. For example, the device
disclosed in United States Patent No. 4,032,889 does not
provide the necessary resolution to print an image of a
palm print, a task often required by law enforcement
agencles.
European Patent Application 326,497 shows an
electronic video dental camera which uses an image
device such as a CCD. The camera may have three
different types of lenses: wide angle, telephoto and
relay lenses. However, EP-A 326,497 does not discuss
the problem o~ parallax distortion. Nor does it provide
a solution for this problem.
Canadian Patent 1,286,032 describes an opticaI
scanning and recording apparatus for fingerprints.
Improved image capture and contrast is achieved by
addltional lighting shown at the inter~ace o~ the
truncated apex and the surrounding air. However,
C 1,286,023 does not address the problem of parallax
distortion. Nor does it provide a solution for this
problem.
Therefore, a need has arisen to provide a
device and method for digitizing the image o~ a palm
which solves these and other problems of the prior art.
Summary of the Invention
The present invention relates to an apparatus
for eliminating keystone distortion in an image. The
image is dividable into a plurality of linear segments
where each of the segments has an associated length.
The apparatus includes a lens operative in selectively
magnifying each of the segments of the image by a
different amount as to create a plurality of magnified
lines of equal length. A medium operable in being
selectively exposed by one of the magnified segments is
AME~ ,CET
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6a
also included. In the first preferred embodiment, the
medium is a fixed horizontal distance from the lens.
The first pre~erred embodiment of the present
invention is an apparatus for generating digital data
characteristic of a palm. The apparatus includes a
prism including a receiving surface and an object
surface. The receiving surface receives the palm. The
palm is dividable into a plurality of linear segments.
A source o~ light illuminates the receiving surface so
that an image representative of the palm is propagated
from the object surface. The propagated image includes
a plurality of linear segments corresponding to the
linear segments of the palm. Each of the segments of
the propagated image includes an associated length. A
~ 15 medium for capturing the image of the palm is movable
.. ..
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between a plurality of locations relative to the ob~ect
surface of the prism as to capture each of the segments
~ of the propagated images at a different location.
The first preferred embodiment may also
include a lens operable in magnifying the segments of
the propagated image so that they are all of equal
length.
Brief DescriPtion of the Drawinqs
Figure 1 is a block diagram representation of
a system which can be used to generate rolled palm print
images in accordance with the present invention.
Figure 2 is a diagrammatic side view of the
palm print device of the first preferred embodiment of
the present invention.
Figure 3 is a diagrammatic view of an image
recorder of the first preferred embodiment.
Figure 4 is a side view of a hollow prism.
Figure 5 is a diagram of a palm including a
plurality of segments.
Figure 6 is a side view of a fingerprint
device included with the palm print device of Figure 2.
Figure 7 is a side view of the palm print
device of the second preferred embodiment.
Figure 8 is a cut-away of Figure 7 taken along
the line 8-8.
Figure 9 is a side vie~w of the device of
Figure 7 with a palm being rolled.
Figure 10 is a cut away of a cylinder in the
second preferred embodiment showing a light and an image
recorder within the cylinder.
Figure 11 is a side view of a palm being
rolled across the device of Figure 7.
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Petailed PescxiPtion of the Preferred Embodiments
In the following detailed description of the
preferred embodiments, reference is made to the
accompanying drawings which form a part hereof, and
which is shown by way of illustration, specific
embodiments in which the invention may be practiced. It
is to be understood that the other embodiments of the
invention may be utilized and structural changes may be
made without departing from the scope of the present
invention.
To understand the concept behind the
invention, one can divide the palm image into a
plurality of linear segments so that the parallax
distortion may be characterized by segments having
different lengths and widths. The segments are spaced
between a far segment at one end and a near segment at
the other end. The far segment is the furthest from the
lens while the near segment is the closest to the lens.
Parallax distortion is created because the dif~erent
segments of the image are subject to different
magnifications within the prism, thereby creating
segments having different dimensions, i.e. length and
width. The different dimensions are eliminated by
selectively adjusting the magnification of the lens
relative to each segment of the image so that each
segment includes the same dimensions.
The prism of the present invention includes a
palm receiving surface and a object surface. The palm
is placed upon the palm receiving surface. The object
surface is the surface of the prism from which the image
of the palm is projected. The object surface is slanted
with respect to the palm receiving surfac~e. Because the
object surface is slanted with respect to the palm
receiving surface, light reflected from different
portions of the palm, i.e. the far segment relative to
the near segment, must travel different distances within
the prism before being projected. The different
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distances the light must travel creates parallax.
While not being bound to any particular
~ theory, the present invention focuses on the length of
the linear segments rather than their width. It may be
assumed that the different lengths associated with
different segments of the palm creates the parallax
distortion. Parallax distortion may be eliminated by
magnifying each linear segment of the palm by a
different amount and making them the same length. For
example, the near segment may be magnified so that its
length is the same as the far segment. A11 of the
segments may then be added to create an image of a palm
print. The added segments may then be processed,
according to the methods of either U.S. Patent Nos.
4,933,976 or 5,230,025, both of which are incorporated
by re~erence.
In the first preferred embodiment of the
present invention a linear CCD array travels along a
predetermined angled vector relative to a prism. The
vector includes vertical and horizontal components.
Specifically, a lens moves horizontally relative to the
prism while maintaining a constant horizontal distance
from a CCD. A CCD moves vertically relative to the
lens. The linear CCD array is capable of only capturing
one segment of the palm image at a time. For each
segment of the palm image being captured, the lens and
linear CCD array are repositioned relative to the prism.
By repositioning the lens and the CCD array, different
segments of the palm image may be magnified by different
amounts. By magnifying the segments o~ the palm image
different amounts, segments of otherwise unequal length
can be made equal.
The invention also provides a movable light
source which illuminates only that portion of the prism
corresponding to the portion of the palm, the image of
which is being captured. The movable light source
preferably includes a light bar and a mirror positioned
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on a movable arm. The mirror reflects light into the
prism at different locations dependent upon the position
of the arm. In the preferred embodiment, the palm
printer also includes, in combination, a fingerprint
capture device.
According to the first preferred embodiment of
the invention, the lens and linear CCD array will be
closer to the prism when the near segment is captured,
thereby providing increased magnification for that
segment, and the lens and CCD array will be farther away
when the far segment is captured, thereby providing less
magnification. A standard length for a segment of the
image may be chosen, and each segment of the image may
then be scanned individually and magnified by a
different amount so that each segment has the same
length when projected onto the CCD.
The second preferred embodiment of the present
invention optically eliminates parallax distortion by
providing a clear cylinder over which a palm may be
rolled. The second preferred embodiment utilizes a
linear CCD array in a fixed position relative to the
cylinder. Parallax distortion is not an issue in the
second preferred embodiment because the portion of the
palm in contact with the clear cylinder, as it is rolled
across the cylinder, is a constant distance away from
the lens and CCD array.
A palm print system 10 which can be used to
optically produce palm print images in accordance with
the present invention is illustrated generally in Figure
1. Palm print system 10 is a microprocessor-based
system which includes processor 12 and associated random
access memory (RAM) 14 and read only memory (ROM) 16.
Image recorder 22, digitizer 24, video monitor 26, alarm
30, printer 28, and terminal 18 are interfaced into
processor 12. The palm print images are captured by
utilizing a prism 250. Prism 250 includes a receiving
surface 256 and an ob~ect surface 258.
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A palm is placed in contact with receiving
surface 256 which is illuminated, and an image is
propagated from object surface 258 which is imaged by
recorder 22 and digitized by digitizer 24.
Specifically, a light source 200 is directed through
prism 250 and reflects off of receiving surface 256.
Through the principle of total internal reflection those
portions of a palm in contact with receiving surface
absorb light and those portions of the palm not in
contact with receiving surface reflect light. For
example, a valley or crease in the palm will reflect
light, while a ridge of the palm will absorb light. The
reflected light is propagated from object surface 258
and is characteristic of the image of a palm. The image
of the palm is projected towards image recorder 22. An
array of digital data representative of the palm print
image is provided to processor 12.
Image recorder 22 generally includes a lens, a
shutter mechanism, and a recorder medium for controlled
recording of palm print images. Terminal 18 includes a
keyboard (not separately shown) which is used by an
operator to interface with palm print system 10. Palm
print images generated by system 10 can be displayed on
video monitor 26 or printed onto a standard palm print
card by printer 28. Alarm 30 is activated when a palm
print is not properly captured, providing the operator
with an indication that the capture procedure must be
repeated. Systems operative in optically digitizing a
fingerprint are disclosed in commonly assigned Fishbein
et al. U.S. Patent No. 4,933,976, and Fishbein et al.
5,230,025, the specification and drawings of which are
hereby incorporated by reference.
The first preferred embodiment of the present
invention is diagrammatically shown in Figures 2 and 3.
Figure 2 includes a prism 250 positioned to receive a
palm. Prism 250 is large enough to receive the entire
palm surface. In the first preferred embodiment,
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receiving surface is at least 144 square centimeters
although larger receiving surfaces are also
contemplated.
With reference to Figure 4, and in an
alternative embodiment, prism 250 may be hollow with
sidewalls constructed from plexiglass. The prism may be
filled with a clear fluid having a refractive index
ranging from approximately 1.1 to 4.0, although an index
above 1.5 is preferred.
Referring to Figure 5 there is generally shown
a palm which has been divided into a plurality of
segments, 1 through N. Segment 1 represents the segment
closest to the lens, while segment N represents the
segment farthest from the lens. Absent the present
invention, when imaged through a prism segment N will be
disproportionately longer than segment 1.
The mechanism of the present invention
positions image recorder 22 such that each segment, 1
through N, is the same length when recorded. With
reference back to Figures 2 and 3, image recorder 22
includes a lens 110 and a high-latency linear CCD array
device 120 adapted to receive images over the desired
period of time. Lens 110 is preferably a 60mm lens,
available from a variety of manufacturers, for example
Thompson Composants Militaires et Spatiaux of France or
Dalsa of Waterloo, Ontario. In the preferred embodiment
CCD array device 120 is purchased from Dalsa as a Dalsa
CCD array model CL-C73456. Referring speci~ically to
Figure 3, lens 110 is rigidly held into place by an
image recorder frame or carriage 121. Carriage 121 is
slidably positioned on gear bar 102 which is positioned
proximate prism 20. Gear bar 102 is engaged to a linear
stepper motor 140 operable in moving carriage 121
horizontally toward and away from prism 250, along gear
bar 102, as best illustrated in Figure 2. The segments
of the image are magnified by moving the lens toward and
away ~rom the prism.
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Stepper motor 140 is configured to receive
digital input ~rom a processor (not separately shown) so
that it may be precisely controlled. Such motors are
commercially available from THK, as model 306K. Lens
110 is rigidly fixed to carriage 121 and operates to
magnify each segment of the palm a different amount as
it moves toward and away from prism 250. The rate at
which carriage 121 moves is dependent upon the
sensitivity of linear CCD 120. Typical scan rates in
the present invention may be 220 ~ per line.
As best shown in Figure 3, linear CCD 120 is
positioned a fixed horizontal distance from lens 110.
In the ~irst pre~erred embodiment, CCD 120 is slidably
positioned on a vertical rail 122 of carriage 121.
Specifically, CCD array 120 is connected to a rolling
guide 124 on vertical rail 122 so that CCD 120 may move
up and down vertical rail 122. The top of guide 124 is
hinged to a slanted rail 126. Slanted rail 126 is in a
fixed position relative to gear bar 102. As carriage
20 121 moves toward and away from prism 250 along gear bar
102, rolling guide 124 and CCD array 120 move up and
down vertical rail 122. In this fashion, CCD array 120
is at a different vertical position for each different
horizontal position of carriage 121.
Moving CCD array 120 up and down as carriage
121 moves horizontally toward and away from prism 20
defines an angled vector at an angle e . Angle 0 is
determined by the configuration o~ prism 250.
Specifically, angle 6 is determined by the refractive
index of the prism material and in the first preferred
embodiment is 47~.
The present invention provides significant
advantages. Utilization of a linear CCD array 120 is
significantly cheaper than the two dimensional CCD
arrays of the prior art. This is especially true
because o~ size limitations placed on two dimensional
CCD arrays large enough to capture the image of a palm.
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14
Further, by moving the CCD array up and down the CCD can
be positioned at the focal point of the lens for any
given segment of the palm which is being captured. By
continuously positioning the CCD array at the focal
point of the lens, the f-stop of the lens does not need
to be very high to obtain the proper resolution.
Additionally, the illumination requirements are
minimized which in turn decrease power requirements of
the device.
It is to be understood that the image segments
may be magnified using a variety of other techniques.
For example, instead of moving the lens toward and away
from the prism as described above, the lens may be of
the telephoto variety magnifying the image segments by
15 rotating the telephoto mechanism. Also, the medium, or
CCD could be moved toward or away from a lens where the
lens is a fixed distance from the prism.
In the first preferred embodiment a movable
light source 200 is provided. With reference to Figure
20 2, movable light source 200 illuminates approximately a
single segment of the palm on receiving surface 256.
Specifically, light source 200 illuminates a different
portion of receiving surface for each different position
of carriage 121. In the first preferred embodiment,
25 light source 200 is a quartz rod 202. As best seen in
Figure 2, quartz rod 202 projects light toward a mirror
206 positioned on an arm 204. Arm 204 is mounted to a
guide 208 which in turn is received on a rail 210 so
that arm 204 and guide 208 are movable thereon. As arm
30 204 moves on rail 210, arm 204 rotates through
approximately 7~. Arm 204 rotates so that light is
reflected toward receiving surface 256. Specifically,
arm 204 is driven along rail 210 by a second stepper
motor 214. Mirror 206 has a length sufficient to
35 project light across the width (corresponding to the
length of the segment of the palm) of prism 250. As
shown by phantom line 275 in Figure 2, light reflects
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off of mirror 206 and into prism 250. In an alternative
embodiment, arm 204 may be replaced with a cam (not
shown) rotatable about 7 degrees and movable along rail
210. Quartz light 202 may be replaced with a fiber
optic light source.
In the first preferred embodiment, the data
captured by CCD array 120 is delivered to digitizer 24
and processor 12 each time the lens mo~es. The rate at
which carriage 121 reciprocates horizontally toward and
away from prism 250 is a function of the sensitivity of
CCD array 120 and the strength o:~light source 20o. The
preferred embodiment includes scan rates of
approximately 220 ~ per line. A scan is defined by the
time it takes CCD array 110 to gather the in~ormation
from a segment of the image of the palm print propagated
~rom object surface 258. As the information is
gathered by CCD array 120, it is integrated together to
process an image of the palm print. The integration can
occur "piece meal" as the information is gathered and
then the integrated pieces can be integrated together,
or, the integration may be over the entire time required
to gather the information representative of the palm
print. However, operation under both methods require
that CCD array 110 be cleared prior to each segment of
the palm being captured. The methods for capturing a
palm print through the above-described methods are
described in commonly assigned U.S. Patent Nos.
4,933,976 and 5,230,025, respectively, which have been
previously incorporated by reference.
In operation, a palm is placed on receiving
sur~ace 34 o~ prism 20, and quartz light 202 projects
light which is reflected off mirror 206. Mirror 206
reflects light onto a limited portion of the receiving
surface 256 such that a single portion of the palm is
illuminated. Through the principle of total internal
reflection, light images representative of that portion
of the palm print will pass through lens 110 and will be
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focused onto CCD array 120. By selectively positioning
carriage 121, including lens 110, each segment of the
palm will be magnified by a different amount such that
their lengths will be a constant value. CCD array 120
is oriented such that it is at the focal point of lens
110 relative to any given segment of the palm which is
being captured. Arm 204 repositions mirror 206 so that
each time carriage 121 is repositioned, mirror 206 is
repositioned to illuminate a different portion of
receiving surface. For example, if segment 1 of palm,
as shown in Figure 5, was captured initially, carriage
121 and thereby lens 110 would move forward towards
prism 250 and CCD array 120 would move upward relative
to lens 110. Correspondingly, arm 204 and mirror 206
would be also repositioned. By positioning lens 110
closer to prism 250 when segment 2 is captured, segment
2 is magnified a greater amount than the segment 1. The
difference in magnification is such that the segments
are the same length. CCD array 120 is moved vertically
upward because the focal point of lens moves upward when
capturing the second segment. This process continues
until the entire palm print is captured.
The digital information gathered by CCD array
120 will then be integrated according to the methods
disclosed in U.S. Patent Nos. 4,933,976 or 5,230,025,
both of which have been previously incorporated herein
by reference. Once the image of the palm print has been
processed, it can be transmitted to monitor 26 for
visual inspection or to printer 28. If the image is not
satisfactory, alarm 30 will sound and the palm print can
be taken again.
With reference to Figure 6, the preferred
embodiment of the present invention may also include, in
combination, a device for optically capturing the image
of a fingerprint.
The fingerprint device includes two lenses 100
and 101 positioned adjacent one another operating to
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focus the image o~ a finger onto two separate, two
dimensional CCD arrays, 110 and 111. CCD arrays 110 and
111 gather light and convert it into a dlgital data
representative o~ the fingerprint. Data gathered by CCD
arrays 110 and 111 is then integrated separately or
integrated in its entirety according to the methods
disclosed above, which are ln accordance with commonly
assigned U.S. Patent Nos. 4,933,976 and 5,230,025, which
have been previously incorporated by re~erence.
Each lens 100 and 101 needs to be adjusted so
that there is a slight overlap of data gathered by each
CCD array 110 and 111. The overlap is then compensated
for by techni~ues known in the art, and the images are
integrated together.
The second pre~erred embodiment of the
invention is disclosed in Figures 7-10. With initial
reference to Figures 7 and 8, the second preferred
embodiment utilizes a clear cylindrical tube 400. As
shown in Figure 9, a palm can be rolled across clear
cylinder 400 in order to capture the image o~ the palm.
Cylinder 400 includes a cylindrical surface 402. As
best shown in Figures 7 and 8, the palm capturing device
of the second preferred embodiment also includes an
encoder 410, an image recorder 422 and a light 440.
Image recorder includes a lens and a CCD.
The palm printer of the second pre~erred
embodiment also utilizes the principle of total internal
reflection. As best shown in Figure 8, light reflects
through cylindrical surface 202 at an angle ~. Places
where the palm is in contact with cylinder surface 402
of cylinder 400 absorb light, while those portions of
the palm which are not in contact with skin reflect
light. In operation, the palm is rolled over cylinder
400 either in a frontways or a sideways configuration as
best shown in Figures 9 and 11.
Clear cylinder 400 is rotatable about an axis
404. Clear cylinder 400 may include two open ends
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having a lumen therebetween, or may be of solid
construction. Clear cylinder 400 may be rotated by a
motor 406. If cylinder 400 is rotated by motor 406,
cylinder 400 will pull the palm across it. If no motor
is utilized, clear cylinder 400 will rotate in response
to the palm being drawn across it.
As the hand is rolled across cylinder 4Q0,
light propagated from light source 440 will reflect or
be absorbed relative to that portion of the palm in
contact with cylinder surface 202 of clear cylinder 200.
The reflected light is captured by recorder 422 which is
fixed in position relative to cylinder 400. CCD array
430 then communicates the data to a digitizer and a
processor in a similar manner or described above.
The processor then correlates the amount of
rotation determined by encoder 410 against the data
collected from CCD array 230 and integrates that data in
accordance with the method of either U.S. Patent Nos.
4,933,976 or 5,230,025. The image may then be used in
the same fashion as disclosed above_
Image recorder 422 may be positioned within
the clear cylinder, as shown in Figure 10, or external
to cylinder 400, as shown in Figure 8. If image
recorder 422 is positioned within the cylinder, mirrors
450 are required to increase the distance which the
reflected light travels so that the proper resolution is
achieved.
In the second embodiment, the curved surface
which receives the palm provides easy operation as the
palm can be rolled across the cylinder. The edge of a
palm may also be captured by taking a second roll of the
edge of the palm and integrating it with the first.
Each system also includes the advantages of both the
4,933,976 and 5,230,025 patents insofar as those patents
describe the general nature of the method used to
process the fingerprint.
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19
While the foregoing detailed description of
the present invention describes the invention of the
preferred embodiments, it will be appreciated that it is
the intent of the invention to include all modifications
and equivalent designs. Accordingly, the scope o~ the
present invention is intended to be limited only by the
claims which are appended hereto
