Low power fingerprint capture system, apparatus, and method

• US 20050169506A1
• Filed: 01/07/2005
• Published: 08/04/2005
• Est. Priority Date: 01/07/2004
• Status: Active Grant

• Current Assignee: Identification International, Inc.
• Original Assignee: Identification International, Inc.
• Inventors: Hutchins, Jeremy, Gaebe, Carl, Pedigo, Michael, Salerno, Nicholas, Fenrich, Richard
• Granted Patent: US 7,822,236 B2
• Time in Patent Office: Days
• US Class Current: 382/127
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop

Abstract

The present invention provides a large format fingerprint capture apparatus, system and method that is low power, compact, and lightweight and has a platen area greater than 3.0 square inches. The present system is typically powered, controlled, and exchanges data over a single data/control/power connection to a host PC, e.g., a desk top computer, PDA, or laptop computer although the system can also be used in a wireless fashion with a power subsystem so no physical connections are required. In a preferred embodiment the large format fingerprint device is directly connected to a completely disconnected portable PC, such as a laptop having only a battery power source. The primary system components of the present invention combine to minimize power, size and weight and, thus, enhance portability and battery life. The system typically includes a light source, a prism, a camera (including the lens), and a case. Optional elements comprise holographic elements such as gratings and holographic optical elements (HOEs), a battery subsystem, magnetic stripe reader, barcode reader, platen heater, platen blower, and mirrors to divert the image beam.

Claims

1. An apparatus comprising a large format fingerprint device that performs at least one function for collection of a friction ridge signature of a subject, comprising:

a prism capable of transmitting light rays;

a platen comprising a first light-reflecting surface proximate said prism;

a light source for producing light rays that propagate within said prism during a capture sequence including at least one image frame, said light rays to illuminate a subject placed in contact with said platen;

a camera for capturing at least one image frame of the subject during a capture sequence;

a component for exchanging data with the device; and

a controller that controls the at least one function of the device; and

wherein said apparatus comprises at least one feature selected from the group consisting of (a) at most one physical connection port comprising an electrical power source for the device and (b) said apparatus weighs at most 10 pounds.

2. The apparatus of claim 1, wherein at least one member selected from the group consisting of the component for exchanging and the component for controlling comprises said connection port.

3. The apparatus of claim 1, wherein the device includes at least part of the controller.

4. The apparatus of claim 1, wherein at least one member selected from the group consisting of the component for exchanging and the component for controlling comprises a wireless interface.

5. The apparatus of claim 1, further comprising a processor in communication with said camera for generating a composite image of the friction ridge signature from said capture sequence.

6. The apparatus of claim 1, wherein said apparatus further comprises:

means for beginning the capture sequence; and

means for ending the capture sequence.

7. The apparatus of claim 6, wherein said means for beginning the capture sequence comprises at least one technique selected from the group consisting of the subject making contact with the platen, successive image frames of a capture sequence differing by more than a pre-determined amount, a change in a direction of a fingerprint image in successive image frames, and image processing of at least one image frame of the subject.

8. The apparatus of claim 7, wherein the beginning of the capture sequence is delayed until constant pre-determined level of illumination exists for a pre-determined period of time.

9. The apparatus of claim 6, wherein means for ending the capture sequence comprises at least one technique selected from the group consisting of removal of the subject from contact with said platen, a condition that successive images are within a pre-determined difference tolerance occurs more than a pre-determined number of times, and image processing of at least one image frame of the subject.

10. The apparatus of claim 6, wherein the light source, the prism, and the camera are located such that when the subject is placed in contact with the platen and the light source is on, light rays incident upon the subject are propagated through the prism to a light-transmitting surface and are propagated along an optical path to fall incident upon said camera such that beginning the capture sequence directs the computer device to collect and merge at least one successive image frame to form a composite image.

11. The apparatus of claim 6, wherein at least one of the means for beginning a capture sequence and the means for ending a capture sequence comprises a switching mechanism operatively coupled to the device and selected from the group consisting of a foot pedal, a button, a key of a keyboard, a touchscreen, and a mouse.

12. The apparatus of claim 1, wherein said light source comprises a light pipe arranged to provide a light and having a plurality of micro structures for guiding the light in a collimated or semi-collimated manner into the prism.

13. The apparatus of claim 12, wherein said light pipe is located proximate to said prism such that light therefrom intersects the platen at an angle greater than a critical angle of the prism.

14. The apparatus of claim 12, wherein said light pipe has a feedback loop for providing a constant output.

16. The apparatus of claim 1, further comprising:

a module for collecting and storing diagnostic data;

a non-volatile storage for storage of said diagnostic data; and

a computer processor in communication with said device and configured to obtain the diagnostic data from said non-volatile storage.

17. The apparatus of claim 1, wherein said capture sequence is one of a roll capture sequence and a slap capture sequence.

18. The apparatus of claim 1, wherein the camera requires at most between 1.8 and 2 watts, inclusive, of power.

19. The apparatus of claim 1, wherein the light source requires at most between 0.7 and 1 watt, inclusive, of power.

20. The apparatus of claim 1, wherein said apparatus further comprises at least one member selected from the group consisting of aberration corrector, offset and gain controller, perspective corrector, high-pass filter, noise filter, and deviant pixel corrector.

21. The apparatus of claim 1, further comprising at least one power source selected from the group consisting of a computer electronically coupled to said fingerprint device and a power subsystem of the device.

22. The apparatus of claim 18, wherein said power subsystem utilizes a power source selected from the group consisting of a solar cell, a lithium ion battery, and a capacitor.

23. The apparatus of claim 5, further comprising at least one member of the group consisting of a barcode reader, a magnetic stripe reader, radio frequency identification module, smart card reader, and proximity card reader to capture demographic data.

24. The apparatus of claim 1, further comprising at least one member of the group consisting of a platen heater and a platen blower arranged to minimize condensation on the platen.

25. The apparatus of claim 1, further comprising:

a device-resident computer processor;

a device-resident non-volatile memory; and

an updatable fingerprint matching system.

26. The apparatus of claim 1, wherein said platen further comprises:

a holographic element affixed to said prism surface for correcting light transmitted therethrough;

a light transmitting substrate affixed to said holographic element;

wherein said holographic element and said light transmitting substrate are arranged such that light rays emitted by the source further pass through the holographic element and the substrate, intersect the subject and are then reflected back further passing through the substrate and the holographic element and being corrected on the way back through the holographic element.

27. The apparatus of claim 1, further comprising:

a pair of opposing cutouts in a handle of the imaging system; and

a slip-case cover for the imaging system having a pair of opposing tabs for locking into the pair of opposing cutouts when the imaging system is slipped into the slip-case.

28. The apparatus of claim 1, comprising a case having a slidable cover attached to the casing for covering the platen.

29. The apparatus of claim 1, comprising a dip-coating selected from the group consisting of an elastomer and a polymer.

30. The apparatus of claim 1, wherein the camera further comprises a sensor arranged at an acute angle α

_i to an optical axis of the device according to the equation

α

_i=tan<sup>−

1</sup>(m*tan(ƒ

)/n)

wherein

m=optical magnification ratio of the device

θ

=an internal angle between the platen and a surface of the prism

n=refractive index of the prism.

31. The apparatus of claim 1, further comprising a case for the device, the case selected from the group consisting of injection molded case, extruded case, die-cast case, and investment-cast case.

15. The apparatus of clam 12, wherein an exposure rate of said camera is adjusted to achieve a pre-determined level of illumination.

32. A device for producing an image of a friction ridge of a subject as a fingerprint signature comprising:

a light pipe as a primary light source wherein said light pipe has micro-prismatic structures allowing light to escape the said light pipe in a semi-collimated fashion;

a prism having a platen on a first light-reflecting surface of the prism;

a camera; and

a computer device,

wherein, the light source, the prism, and the camera are located such that when the subject is placed in contact with the platen and the light source is on, light rays incident upon the subject are propagated through the prism to a light-transmitting surface and are directed toward said camera such that the computer device starts a capture sequence and creates a composite image from the capture sequence to form a fingerprint signature of the subject.

33. An apparatus comprising a device for capturing an image of a friction ridge of a subject as a fingerprint signature comprising:

a prism capable of transmitting light rays;

a platen comprising a first light-reflecting surface proximate said prism;

a light source for producing light rays that propagate within said prism during a capture sequence to illuminate a subject placed in contact with said platen;

a camera for capturing at least one image frame of the subject during said capture sequence; and

wherein, when said subject is placed in contact with the platen and the light source is on, light rays propagated by the light source and incident on the subject are directed to fall incident upon said camera;

a processor for capturing an image of a friction ridge of a subject as a fingerprint signature using image processing of a sequence of images of the subject to detect the beginning and the ending of the capture of the image.

34. An apparatus comprising a large format fingerprint device that performs at least one function for collection of a friction ridge signature of a subject, comprising:

a prism capable of transmitting light rays;

a platen comprising a first light-reflecting surface proximate said prism;

a light source for producing light rays that propagate within said prism during a capture sequence including at least one image frame, said light rays to illuminate a subject placed in contact with said platen;

a camera for capturing at least one image frame of the subject during said capture sequence; and

an internal or external, to the device, processor for beginning the capture sequence using image processing; and

an internal or external, to the device, processor for ending the capture sequence using image processing.

35. An apparatus for collecting the friction ridge signature of a subject, comprising a device comprising:

a platen;

a camera requiring at most about 2 watts of power;

a light source requiring at most about 1 watt of power; and

wherein when said subject is placed in contact with the platen and the light source is on, light rays propagated by the light source and incident on the subject are directed to fall incident upon said camera.

36. The apparatus of claim 35, wherein, said system requires a total of less than 3 watts of power, weighs a total of less than 10 lbs and has a total volume of less than 400 in³.

37. The apparatus of claim 35, wherein:

the camera requires at most about 1.8 watts of power; and

the light source requires at most about 0.7 watts of power;

wherein the system requires in total at most about 2.5 watts of power, weights at most 5 lbs and has a total volume of at most 315 in³.

38. The apparatus of claim 35, further comprising:

a computer system;

a single cable connecting said computer to said imaging system for providing data exchange between said computer and said imaging system, power to said imaging system and control of said imaging system by said computer system.

39. The apparatus of claim 35, further comprising image processing means for determining from the images the beginning and end of a capture of a friction ridge signature.

40. The apparatus of claim 39, wherein said image processing means comprises a software algorithm executed by said computer system.

41. The apparatus of claim 39, wherein said image processing means comprises a functionally dedicated chip resident in one of said camera and said imaging system.

42. A method for using the apparatus of claim 35 for capturing a large format fingerprint of a subject, comprising the steps of:

powering a camera for capturing images of finger print ridges with at most about 2 watts of power;

powering a source of collimated or semi-collimated light with at most about 1 watt of power; and

controlling the camera and light in collecting images of the finger print ridges with a computer system.

43. The method of claim 35, further comprising the step of attaching the computer system to the device by a single cable connection that provides (1) for data exchange between said computer and said device, (2) the power to said camera and source of collimated or semi-collimated light, and (3) control of said device.

44. The method of claim 35, further comprising the step of using image processing of a sequence of image frames of the subject captured by the camera to detect the beginning and the ending of the capture sequence.

45. The method of claim 35, wherein:

the step of powering a camera for capturing images of finger print ridges provides at most about 1.8 watts of power; and

the step of powering a source of collimated or semi-collimated light provides at most about 0.7 watts of power.

46. An apparatus comprising a fingerprint device that performs at least one function for collection of a friction ridge signature of a subject, comprising:

a prism capable of transmitting light rays;

a platen comprising a first light-reflecting surface proximate said prism;

a light source for producing light rays that propagate within said prism during a capture sequence including at least one image frame, said light rays to illuminate a subject placed in contact with said platen;

a camera for capturing at least one image frame of the subject during a capture sequence comprising a sensor arranged at an acute angle α

_i to an optical axis of the device according to the equation

α

_i=tan<sup>−

1</sup>(m*tan(θ

)/n)

wherein

m=optical magnification ratio of the device

θ

=an internal angle between the platen and a surface of the prism

n=refractive index of the prism.

47. The apparatus of claim 46, wherein the fingerprint device is a large format fingerprint device.

48. An apparatus comprising a large format fingerprint device that performs at least one function for collection of a friction ridge signature of a subject, comprising:

a prism capable of transmitting light rays;

a platen comprising a first light-reflecting surface proximate said prism;

a light source for producing light rays that propagate within said prism during a capture sequence including at least one image frame, said light rays to illuminate a subject placed in contact with said platen, the light source having ears;

a camera for capturing at least one image frame of the subject during a capture sequence;

a component for exchanging data with the device; and

a controller that controls the at least one function of the device; and

wherein the device has a metal or plastic case, a prism bracket within the case for holding the prism and light source so that the prism is flush with the surface of the case or extends slightly beyond the case, the prism bracket comprising ear slots, the prism bracket is loaded with the light source by placing the ears of the light source into the ear slots on the prism bracket, tabs are screwed into tab holes to retain the light source and permit the light source constrained but free movement for expansion and contraction;

the prism is flush with the tabs and a retaining sill on the prism bracket, a radiused edge of the prism bracket fits into a scallop of the case creating a hinge for swinging the prism bracket into place; and

the prism bracket is fastened to the case.