Method of dertermining the living character of an bearing carrying a fingerprint

• US 20060159314A1
• Filed: 12/19/2003
• Published: 07/20/2006
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Morpho (Advent International Corporation)
• Original Assignee: Morpho (Advent International Corporation)
• Inventors: Foundeur, Jean-Christophe, Lambert, Laurent
• Granted Patent: US 7,657,066 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 40/13 Sensors therefor

Abstract

The present invention concerns a method of determining the living character of an element carrying a fingerprint. The method according to the invention is characterised in that it consists of making on the one hand at least one electrical measurement and on the other hand taking an image of the said fingerprint, and then validating the said or each electrical measurement by comparing it with the range of values of electrical measurements defined by a pre-established relationship linking the said range to characteristics of the said image.

Claims

1-7. -7. (canceled)

8. A method of determining the living character of an element carrying a fingerprint and placed on a fingerprint sensor having an optical system, the method comprising the steps of:

(a) measuring an electrical quantity of the element;

(b) determining the living character of the element when the electrical quantity measured belongs to a range of quantities judged acceptable;

(c) taking of an image of the fingerprint carried by the element by means of the optical system;

(d) measurement of a particular characteristic of the image and deducing of a range of values from the electrical quantity judged in principle acceptable using a relationship established between values of a particular characteristic of the image and a range of values judged acceptable; and

(e) validation of the value of the electrical quantity measured if this measurement is situated in the range.

9. A method according to claim 8, wherein the particular characteristic is selected from the group consisting of:

the contrast of the image, the average greyscale of the image, the width of the images of the ridges formed by the said fingerprints, and the average greyscale of the ridges.

10. A method according to claim 9, wherein the electrical quantity is the impedance whose value is measured at the terminals of electrodes that the sensor has.

11. A fingerprint sensor adapted to determine the living character of an element carrying a fingerprint placed on the sensor, the sensor comprising:

(a) means of measuring an electrical quantity of the element;

(b) means of determining the living character of the element when the electrical quantity measured belongs to a range of values judged acceptable;

(c) an optical system for taking an image of the fingerprint carried by the element and for measuring a particular characteristic of the image thus taken;

(d) means for establishing the relationship between values of a particular characteristic of the image and a range of values judged acceptable;

(e) means of deducing a range of values of the electrical quantity judged in principle acceptable from the particular characteristic measured; and

(f) means of validating the value of the electrical quantity measured if this measurement is situated in the range.

12. A sensor according to claim 11, further comprising an optical system for measuring a quantity selected from the group consisting of:

the contrast of the image, the average greyscale of the image, the width of the images of the ridges formed by the said fingerprints, and the average greyscale of the said ridges.

13. A sensor according to claim 12, wherein the means of measuring an electrical quantity is a means of measuring impedance at the terminals of electrodes.

14. A sensor according to claim 13, wherein the electrodes are formed on a transparent plate, the connections to the electrodes being conductive and also transparent.