Ultrasonic Fingerprint Scanning Using a Plane Wave

• US 20100251824A1
• Filed: 06/16/2010
• Published: 10/07/2010
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Baker, James T., Kitchens, Jack C., Schneider, John K.
• Granted Patent: US 8,601,876 B2
• Time in Patent Office: Days
• US Class Current: 73/620
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: A61B 8/0858 involving measuring tissue layers, e.g. skin, interfaces
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: G01N 29/2437 Piezoelectric probes
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• 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

Abstract

The invention may be embodied as a fingerprint scanner having an ultrasonic wave detector, a platen, an ultrasonic wave generator located between the detector and the platen. The invention may be embodied as a method of scanning a finger. One such method includes providing a platen, a detector and a generator, the generator being placed between the platen and the detector. A finger may be provided on the platen, and an ultrasound wave pulse may be sent from the generator toward the finger. The wave pulse may be reflected from the finger, and received at the detector. The received wave pulse may be used to produce an image of the finger.

Claims

1. A fingerprint scanner, comprising:

an ultrasonic wave detector;

a platen; and

an ultrasonic wave generator located between the detector and the platen.

2. The scanner of claim 1, wherein the generator is an area-array generator.

3. The scanner of claim 1, wherein the generator is a line-array generator.

4. The scanner of claim 1, wherein the generator includes a piezoelectric film.

5. The scanner of claim 4, wherein the generator includes a first electrode layer on a first side of the film, and a second electrode layer on a second side of the film.

6. The scanner of claim 5, wherein the first electrode layer is attached to the platen.

7. The scanner of claim 6, wherein an adhesive resides between the first electrode layer and the platen and serves to attach the first electrode layer to the platen.

8. The scanner of claim 5, further comprising a backing plate attached to the second electrode layer.

9. The scanner of claim 8, wherein an adhesive resides between the second electrode layer and the backing plate and serves to attach the second electrode layer to the backing plate.

10. The scanner of claim 1, further comprising a linear actuator attached to the detector.

11. The scanner of claim 1, further comprising a fluidic transmission medium located between the detector and the generator.

12. The scanner of claim 1, further comprising a gel transmission medium located between the detector and the generator.

13. The scanner of claim 1, wherein the detector is arranged as a line array.

14. The scanner of claim 13, the detector has a length-to-width ratio greater than 50.

15. The scanner of claim 14, wherein the detector is movable in a direction that is substantially perpendicular to a length of the detector.

16. The scanner of claim 13, wherein the line array is angularly movable in a plane that is substantially parallel to the platen.

17. The scanner of claim 13, wherein the line array is angularly movable in a plane that is substantially parallel to the generator.

18. The scanner of claim 13, wherein the line array is linearly movable in a plane that is substantially parallel to the platen.

19. The scanner of claim 13, wherein the line array is linearly movable in a plane that is substantially parallel to the generator.

20. The scanner of claim 13, wherein the line array is arcuately movable.

21. The scanner of claim 20, wherein the line array is arcuately movable about an axis of rotation that is substantially parallel to the platen.

22. The scanner of claim 20, wherein the line array is arcuately movable about an axis of rotation that is substantially parallel to the generator.

23. The scanner of claim 20, further comprising a Fresnel surface capable of guiding toward the detector ultrasonic waves reflected from a finger.

24. The scanner of claim 23, wherein the refracted ultrasonic waves are those that have been reflected by the finger substantially back upon a path of unreflected ultrasonic waves.

25. The scanner of claim 23, wherein the Fresnel surface is a Fresnel grating.

26. The scanner of claim 1, wherein the detector is arranged as an area array.

27. The scanner of claim 1, wherein a position of the detector and a position of the generator are fixed relative to each other.

28. The scanner of claim 27, wherein the detector and the generator are linearly movable in a plane that is substantially parallel to the platen.

29. The scanner of claim 28, wherein a distance between the generator and the platen is substantially fixed.

30. The scanner of claim 29, wherein the platen permits movement of a finger.

31. A method of scanning a finger, comprising:

providing a platen;

providing a detector;

providing a generator between the platen and the detector;

providing a finger on the platen;

sending an ultrasound wave pulse from the generator toward the finger;

receiving a reflected ultrasound wave pulse from the finger; and

using the received reflected ultrasound wave pulse to produce an image of the finger.

32. The method of claim 31, wherein the generator includes a film, and sending an ultrasound wave pulse includes changing the volume occupied by the film.

33. The method of claim 32, wherein the film volume is changed by applying a voltage difference across the film.

34. The method of claim 31, further comprising moving the detector relative to the platen in order to receive reflected ultrasound wave pulses from different parts of the finger.

35. The method of claim 34, wherein the detector is moved angularly.

36. The method of claim 34, wherein the detector is moved arcuately.

37. The method of claim 34, wherein the detector is moved linearly.