Sensor employing overlapping grid lines and conductive probes for extending a sensing surface from the grid lines

• US 10,095,906 B2
• Filed: 02/19/2015
• Issued: 10/09/2018
• Est. Priority Date: 02/21/2014
• Status: Active Grant

• Current Assignee: IDEX Biometrics ASA
• Original Assignee: Idex ASA
• Inventors: Benkley, III, Fred G., Bernstein, Ralph W., Christie, Nicolai W., Bredholt, Geir Ivar, Slogedal, Oyvind
• Primary Examiner(s): Kholdebarin, Iman K
• Application Number:
  US14/626,653
• Publication Number:
  US 20150242672A1
• Time in Patent Office: 1,328 Days
• Field of Search: None
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop

Abstract

An electronic sensor forms a grid to detect surface features of a proximally located object, such as a fingerprint. The grid includes a plurality of parallel drive lines connectable to a drive source and a plurality of parallel pickup lines oriented substantially perpendicular to the drive lines and overlapping the drive lines. The drive lines are separated from the pickup lines by an insulating dielectric layer. The overlaps where the drive lines and pickup lines cross define impedance-sensitive electrode pairs which act as pixels at which surface features of the proximally located object are detected. One or more conductive probes extend from one or more corresponding impedance-sensitive electrode pairs, through an overlay layer of insulating material, to the sensing surface.

Claims

1. A fingerprint sensor, comprising:

a first conductor formed as a drive line;

a second conductor formed as a pickup line, wherein the drive line is oriented substantially transversely to the pickup line;

a dielectric layer separating the drive line and the pickup line, wherein a crossover location at which the pickup line overlaps the drive line defines an impedance sensitive electrode pair;

a detecting circuit configured to detect a signal at the impedance sensitive electrode pair;

an overlay layer formed of an insulating material and located over a crossover location at which the pickup line overlaps the drive line; and

a conductive probe embedded within the overlay layer and having a first end and a second end, wherein the first end is in proximity to the crossover location and the second end is in proximity to a top surface of the overlay layer to extend a sensing surface of the fingerprint sensor from a top surface of the pickup line to the top surface of the overlay layer.

2. The fingerprint sensor of claim 1, wherein the conductive probe is configured and oriented so that the thickness of the conductive probe partially overlaps the pickup line at the crossover location.

3. The fingerprint sensor of claim 2, wherein the conductive probe is configured and oriented so that half thickness of the conductive probe overlaps the pickup line at the crossover location and half the thickness of the conductive probe overlaps insulating material adjacent the pickup line.

4. The fingerprint sensor of claim 1, wherein the first end of the conductive probes is in contact with the pickup line at the crossover location.

5. The fingerprint sensor of claim 1, wherein the first end of the conductive probe is separated from the pickup line at the crossover location by a dielectric region.

6. The fingerprint sensor of claim 4, wherein the second end of the conductive probe is coplanar with the top surface of the overlay layer.

7. The fingerprint sensor of claim 1 further comprising a second conductive probe that is electrically connected to a ground potential.

8. The fingerprint sensor of claim 7, further comprising a ground layer between the overlay layer and the drive line and the pickup line, wherein the second conductive probe is electrically connected to the ground layer.

9. The fingerprint sensor of claim 1, wherein the fingerprint sensor structure is part of a touch screen of a touch-enabled device.

10. The fingerprint sensor of claim 1, wherein the overlay layer is formed from a material selected from the group consisting of:

glass, poly methyl methacrylate, polycarbonate, polycarbonate, and a flexible polymer substrate.

11. The fingerprint sensor of claim 1, wherein the conductive probes is formed from a material selected from the group consisting of:

copper, indium tin oxide, a conductive paste made of carbon nanotubes, graphite powder, or copper, a conductive adhesive comprising silver, copper, or graphite, and a conductive polymer.

12. The fingerprint sensor of claim 1, further comprising an activation circuit configured to supply a signal to the drive line.

13. The fingerprint sensor of claim 12, further comprising a switch associated with the drive line configured to selectively connect the drive line to the activation circuit.

14. The fingerprint sensor of claim 1, further comprising a switch associated with the pickup line configured to selectively connect the pickup line to the detecting circuit.

15. The fingerprint sensor of claim 1, further comprising an insulating layer above the conductive probe on the top surface of the overlay layer.

16. A fingerprint sensor, comprising:

a first conductive layer formed as a plurality of parallel drive lines;

a second conductive layer formed as a plurality of parallel pickup lines, wherein the plurality of parallel drive lines are oriented transversely to the plurality of parallel pickup lines;

a dielectric layer separating the first conductive layer and the second conductive layer, wherein each crossover location at which one of the pickup lines overlaps one of the drive lines defines an impedance sensitive electrode pair;

a detecting circuit configured to detect a signal at each impedance sensitive electrode pair;

an overlay layer formed of an insulating material and located over the first conductive layer and the second conductive layer; and

a plurality of conductive probes embedded within the overlay layer, wherein each of the plurality of conductive probes has a first end and a second end, wherein the first end of each conductive probe is in proximity to an associated one of the crossover locations, and wherein the second end of each of the conductive probes is in proximity to an outer surface of the overlay layer to extend a sensing surface of the fingerprint sensor from a top surfaces of the pickup lines to the outer surface of the overlay layer.

17. The fingerprint sensor of claim 16, wherein each conductive probe is configured and oriented so that the thickness of the conductive probe partially overlaps the pickup line at the crossover location.

18. The fingerprint sensor of claim 17, wherein each conductive probe is configured and oriented so that half thickness of the conductive probe overlaps the pickup line at the crossover location and half the thickness of the conductive probe overlaps insulating material adjacent the pickup line.

19. The fingerprint sensor of claim 16, wherein the first end of each of the conductive probes is in contact with one of the plurality of pickup lines at the associated crossover location.

20. The fingerprint sensor of claim 16, wherein the first ends of the conductive probes are separated from the pickup lines by a dielectric region.

21. The fingerprint sensor of claim 16, wherein the second end of each of the conductive probes is coplanar with the top surface of the overlay layer.

22. The fingerprint sensor of claim 16, further comprising a second plurality of conductive probes that are each electrically connected to a ground potential.

23. The fingerprint sensor of claim 22, further comprising a ground layer between the overlay layer and at least one of the drive line and the pickup line, wherein the second plurality of conductive probes are each electrically connected to the ground layer.

24. The fingerprint sensor of claim 16, wherein the fingerprint sensor structure is part of a touch screen of a touch-enabled device.

25. The fingerprint sensor of claim 16, wherein the overlay layer is formed from a material selected from the group consisting of:

glass, poly methyl methacrylate, polycarbonate, polycarbonate, and a flexible polymer substrate.

26. The fingerprint sensor of claim 16, wherein each of the conductive probes is formed from a material selected from the group consisting of:

copper, indium tin oxide, a conductive paste made of carbon nanotubes, graphite powder, or copper, a conductive adhesive comprising silver, copper, or graphite, and a conductive polymer.

27. The fingerprint sensor of claim 16, further comprising an activation circuit configured to supply a signal to each drive line.

28. The fingerprint sensor of claim 27, further comprising a switch associated with each drive line configured to selectively connect the associated drive line to the activation circuit.

29. The fingerprint sensor of claim 16, further comprising a switch associated with each pickup line configured to selectively connect the associated pickup line to the detecting circuit.

30. The fingerprint sensor of claim 16, further comprising a plurality of electrodes extending across the outer surface of the overlay layer and configured to couple the second ends of two or more conductive probes.

31. The fingerprint sensor of claim 30, wherein each electrode is connected to two or more conductive probes to galvanically couple the conductive probes connected to the electrode, or the electrode is electrically insulated from two or more conductive probes and is configured to capacitively couple the two or more conductive probes.

32. The fingerprint sensor of claim 16, further comprising an insulating layer above the conductive probes on the top surface of the overlay layer.