Fingerprint recognition module having a thin-film structure and comprising resistive temperature-sensitive elements

• US 20060050935A1
• Filed: 05/15/2003
• Published: 03/09/2006
• Est. Priority Date: 05/17/2002
• Status: Active Grant

• Current Assignee: NEXT Biometrics Group ASA
• Original Assignee: Inabillion As
• Inventors: Aurich, Joachim, Urban, Gerald, Igel, Gunter, Bustgens, Burkhard
• Granted Patent: US 7,720,265 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing

Abstract

The invention relates to a fingerprint recognition module comprising a substrate consisting of a material that is electrically insulating at least on its upper side and at least partially thermally insulating. Said substrate receives a composite of structured thin films on its surface, which directly forms a measuring field on the surface of the substrate for measuring a fingerprint. Said composite consists of an array of resistive, temperature-dependent elements, and contains strip conductors which connect the resistive, temperature-dependent elements to at least one connection field located on the substrate, outside the measuring field, and form part of the composite of structured thin films. The substrate also contains at least one microelectronic switching circuit which is electrically connected to the at least one connection field and contains the switching circuits by which means the thin film structures are controlled in order to heat the resistive, temperature-sensitive elements, the resistive, temperature-sensitive elements are read out, and the data is retransmitted.

Claims

1. A fingerprint recognition module, characterized by

a substrate,

a composite of structured thin films of the surface of the substrate, that forms a measuring field on a portion of the substrate for measuring a fingerprint, including resistive, temperature-sensitive elements arranged in rows and columns, and

that contains thin-film structures for heating the resistive, temperature-sensitive elements, and

that contains strip conductors, connecting the resistive, temperature-dependent elements with a connection field located on the substrate outside of the measuring field,

a microelectronic analyzing switching circuit, electrically connected with the connection field and contains the switching circuit with which the thin-film structures for heating the resistive, temperature-sensitive elements are controlled, the resistive, the temperature-sensitive elements are read out, and data are relayed.

2. The fingerprint recognition module according to claim 1, further characterized in that the thin-film structures for heating are longitudinal heating conductors with constant or variable width, situated under or above the resistive, temperature-dependent elements in such a way that, when current flows through them, they heat, at the same time, the resistive, temperature-dependent elements of a column.

5. The fingerprint recognition module according to claim 1, further characterized in that the microelectronic analyzing switching circuit holds the electrical potential of all row conductor strips at the same value.

6. The fingerprint recognition module according to claim 1, further characterized in that the microelectronic analyzing switching circuit contains a process computer, including computing and memory storage units, that, by means of software, verify the measured fingerprint in relation to one or several stored fingerprints.

7. The fingerprint recognition module according to claim 1, further characterized in the substrate includes glass.

8. The fingerprint recognition module according to claim 1, further characterized in the portion of the substrate adjoining the composite of thin layers is elastic in comparison to the composite of structured thin layers.

9. The fingerprint recognition module according to claim 1, further characterized in the portion of the substrate adjoining the composite of thin layers has a thermally insulating effect.

10. The fingerprint recognition module according to claim 1, further characterized in the substrate includes rigid or flexible plastic.

11. The fingerprint recognition module according to claim 1, further characterized in the portion of the substrate adjoining the composite of thin layers includes plastic.

12. The fingerprint recognition module according to claim 1, further characterized in the substrate includes a metal-plastic laminate and the plastic side of the laminate serves as substrate surface.

20. The fingerprint recognition module according to claim 1, further characterized in that the longitudinal heating conductors are each connected at their one end with the column lead of exactly one column strip conductor and at their other end with the other end of further heating conductors in the form of a switching junction.

21. The fingerprint recognition module according to claim 1, further characterized in that a switching junction is connected in each case with an electric switching element, contained in the microelectronic switching circuit, by means of which the heating function can be switched.

22. The fingerprint recognition module according to claim 1, further characterized in the surface layer made of electrically conductive material is grounded.

23. The fingerprint recognition module according to claim 1, further characterized in the electric circuit comprising the heating conductors is closed via the surface layer made of electrically conductive material.

24. The fingerprint recognition module according to claim 1, further characterized in the heating conductors are constructed as surface layer made of electrically conductive material.

25. The fingerprint recognition module according to claim 1, further characterized in the surface layer includes transparent, electrically conductive material.

26. The fingerprint recognition module according to claim 1, further characterized in the thin-film composite is coated additionally in whole or in part with a poorly wetting surface layer or with a layer with Lotus effect.

27. The fingerprint recognition module according to claim 1, further characterized in the thin-film composite is coated additionally in whole or in part with a surface abrasion-reducing layer.

3-4. -4. (canceled)

14-19. -19. (canceled)

28. A method for detecting a fingerprint in a system including a substrate, and a composite of structured thin films on the substrate, including resistive, temperature-sensitive elements arranged in rows and columns to form a detection area, the method comprising:

heating the resistive, temperature-sensitive elements using thin-film structures;

selectively applying a voltage to a temperature-sensitive element, using a switch located outside of the detection area; and

measuring a current through the temperature-sensitive element.

29. A system for detecting a fingerprint, the system comprising:

a substrate;

a composite of structured thin films on the substrate, including resistive, temperature-sensitive elements arranged in rows and columns to form a detection area;

means for heating the resistive, temperature-sensitive elements using thin-film structures;

means for selectively applying a voltage to a temperature-sensitive element. using a switch located outside of the detection area; and

means for measuring a current through the temperature-sensitive element.