Apparatus for fingerprint sensing and other measurements
Apparatus for measuring a pattern in a surface of an object, comprising a plurality of pixel or sensor elements being responsive to a physical parameter of the object surface, and means for establishing an overall, segmented picture related to said pattern, and also comprising at least one diode functionally associated with each sensor element for contributing to one or more of the following functions: selectively addressing said sensor element; activating said sensor element; and sensing of said physical parameter.
1. Apparatus for measuring fingerprint patterns in skin, said apparatus comprising
a sensor that includes a plurality of sensor elements configured to be responsive to a physical parameter of the skin, and
means for establishing an overall, segmented picture related to said pattern coupled to the plurality of sensor elements, wherein the sensor elements are adapted to be activated by being heated with an applied electric current while the fingerprint is in contact with the sensor and to detect thermal changes in each sensor element due to heat loss from the sensor element to the skin during the heat activation, wherein upon the heat activation, sensor elements with relatively larger heat loss, thus smaller temperature changes, will map fingerprint ridges,
and wherein each sensor element has either:
at least one diode configured to selectively address said sensor element, activate said sensor element, and sense said physical parameter; or
at least one diode configured to selectively address said sensor element and contribute to sensing said physical parameter and at least one resistor configured for activating/heating said sensor element and for sensing said physical parameter.
2. Apparatus according to claim 1 , wherein said at least one diode is adapted to be activated by being heated with the applied electric current.
3. Apparatus according to claim 1 , wherein each sensor element comprises a resistor connected in series with said at least one diode.
4. Apparatus according to claim 1 , wherein each sensor element comprises a series connection of two or more diodes (D 1 -Dn).
5. Apparatus according to claim 1 , wherein there is provided for heat activation of one sensor element at a time.
6. Apparatus according to claim 1 , wherein heat activation of the sensor elements is provided for by a current source, and temperature sensing is performed on the basis of a voltage change caused by the heat activation.
7. Apparatus according to claim 1 , wherein heat activation of the sensor elements is provided for by a voltage source, and temperature sensing is performed on the basis of a current change caused by the heat activation.
8. Apparatus according to claim 1 , comprising controllable main switches for activation of sensor elements, and signal switches connected to sensor elements at points between the sensor elements and respective main switches.
9. Apparatus according to claim 1 , wherein the sensor elements are arranged as a pixel array in rows and columns on one substrate part, and said means for establishing an overall, segmented picture is provided on another substrate part.
10. Apparatus according to claim 8 , wherein said main and signal switches are provided on one substrate part.
11. Apparatus according to 9 , wherein at least one of said substrate parts is flexible.
12. Apparatus according to claim 1 , comprising control circuit means adapted to selectively address one sensor element or a small group of sensor elements at a time, by means of said at least one diode.
13. Apparatus according to claim 1 , wherein heat activation of sensor elements is provided for by an electric current, and sensing of thermal changes is performed on the basis of a current change caused by the heat activation.
14. Apparatus according to claim 1 , wherein the segmented picture is provided on a processing chip.
15. Apparatus according to claim 1 , wherein the apparatus comprises more than one diode (D 1 -Dn) functionally associated with each sensor element, said more than one diode configured to give a thermal voltage signal proportional to n, the number of diodes connected in series, for activating/heating said sensor element, and sensing of said physical parameter.
16. Apparatus according to claim 1 , wherein the apparatus is adapted to address and heat one sensor element at a time, or a small number of sensor elements at a time for parallel processing.
17. Apparatus according to claim 16 , wherein said one sensor element or said small number of sensor elements are heated using a current source.