Biometric sensing device with isolated piezo ceramic elements

• US 20050225212A1
• Filed: 06/10/2005
• Published: 10/13/2005
• Est. Priority Date: 03/23/2000
• Status: Active Grant

• Current Assignee: Sonavation, Inc.
• Original Assignee: Sonavation, Inc.
• Inventors: Scott, Walter G., Jones, Donald E.
• Granted Patent: US 7,489,066 B2
• Time in Patent Office: Days
• US Class Current: 310/334
• CPC Class Codes: G06V 40/10 Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H10N 39/00 Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00

Abstract

The present invention provides an apparatus for sensing biometric information in a finger with piezo ceramic elements. In one embodiment, the apparatus includes an array of discrete piezo ceramic elements and filler. The array of discrete piezo ceramic elements is responsive to acoustic characteristics of parts of the finger. The filler is distributed between the discrete piezo ceramic elements and provides acoustic attenuation and electric isolation between the discrete piezo ceramic elements. A protective layer can receive a ridge pattern of the finger positioned proximate to the array. Air in valleys between ridges of the ridge patten of the finger acts as an acoustic barrier. A backing layer (air or foam) can also be provided.

Claims

1. A method for sensing biometric information in a digit, comprising:

piezo electrically sensing acoustic characteristics of the digit via an array of discrete piezo ceramic elements; and

facilitating (i) acoustic attenuation and (ii) electrical isolation between the discrete piezo ceramic elements by distributing a filler therebetween.

2. The method of claim 1, wherein the distributing further suppresses shear waves between the discrete piezo ceramic elements and mechanically supports the discrete piezo ceramic elements.

3. The method of claim 1, comprising including micro-spheres within the filler.

4. The method of claim 3, comprising providing micro-spheres that include vinyl.

5. The method of claim 1, comprising providing a plurality of discrete columnar piezo ceramic elements within the discrete piezo ceramic elements, each columnar element having first and second ends.

6. The method of claim 5, further comprising electrically coupling the first and second ends to first and second grids of conductors, respectively.

7. The method of claim 6, further comprising coupling the first grid of conductors to a protective layer that can receive a ridge pattern of the digit positioned proximate to the array;

wherein air in valleys between ridges of the ridge pattern acts as an acoustic barrier.

8. The method of claim 7, further comprising coupling the second grid of conductors to a backing layer.

9. The method of claim 7, further comprising providing an air backing to the second grid of conductors, the air backing being acoustically mismatched with the discrete columnar piezo ceramic elements.

10. The method of claim 5, further comprising acoustically coupling a protective layer to the first ends of the elements, wherein the protective layer receives a ridge pattern of the digit positioned proximate to the array;

wherein air in valleys between ridges of the ridge pattern acts as an acoustic barrier.

11. The method of claim 5, further comprising acoustically mismatching a backing layer with the discrete columnar piezo ceramic elements.

12. The method of claim 11, further comprising providing air within the backing layer.

13. The method of claim 11, further comprising providing foam within the backing layer.

14. The method of claim 1, further comprising providing discrete piezo ceramic elements that include lead zirconate titanate.

21. The method of claim 1, further comprising providing a polymer as the medium.

22. The method of claim 1, further comprising providing urethane as the medium.

15. A method for performing biometric sensing, comprising:

piezo electrically sensing via a ceramic sensor; and

performing processing via a processor, coupled the sensor, configured to receive an input from the sensor and produce an output;

wherein the sensor comprises an array of piezoelectric ceramic elements and includes a sonic barrier between each of the elements.

16. The method of claim 15, comprising providing air as the sonic barrier.

17. The method of claim 15, comprising providing an epoxy containing micro-spheres as the sonic barrier.

18. The method of claim 17, further comprising providing micro-spheres that include vinyl.

19. The method of claim 15, further comprising:

coupling a medium that conducts sonic energy to the sensor such that a low sonic energy barrier is formed between the medium and the sensor.

20. The method of claim 19, further comprising providing an impedance within the medium that facilitates conducting sonic energy into tissue.

23. A method for sensing biometric information in a digit, comprising:

piezo electrically sensing via an array of discrete piezo ceramic elements responsive to acoustic characteristics of parts of the digit; and

distributing a material between the discrete piezo ceramic elements to provide acoustic attenuation and electric isolation therebetween.