Method and system for calibration of a fingerprint sensing device

Abstract

There is provided a method of initiating a calibration operation of a fingerprint sensing device comprising an array of sensing elements for sensing a fingerprint pattern, the method comprising acquiring information indicative of a change of an environmental parameter influencing the operation of the fingerprint sensing device; and if the change is larger than a predetermined threshold value, performing a calibration operation of the fingerprint sensing device. There is also provided a method of initiating a calibration operation of a fingerprint sensing device comprising an array of sensing elements for sensing a fingerprint pattern, the method comprising: receiving information indicative of an event in a device in which the fingerprint sensing device is arranged; if the event is one of a group of predetermined events, performing a calibration operation of the fingerprint sensing device.

1 - 18 . (canceled) 
     
     
         19 . A fingerprint sensing device comprising an array of sensing elements for sensing a fingerprint pattern, said device comprising a calibration control unit configured to:
 acquire information indicative of a change of an environmental parameter influencing the operating of said fingerprint sensing device;   if said change is larger than a predetermined threshold value, perform a calibration operation of said fingerprint sensing device;   receive information indicative of an event in a device in which said fingerprint sensing device is arranged; and   if said event is one of a group of predetermined events, perform a calibration operation of said fingerprint sensing device.   
     
     
         20 . The fingerprint sensing device according to  claim 19 , further comprising a temperature sensor, a humidity sensor, and/or an electromagnetic field sensor. 
     
     
         21 . The device according to  claim 19 , wherein said control unit is further configured to:
 determine a present value of an environmental parameter;   determine a difference between said present value of said environmental parameter and a predetermined value of said environmental parameter; and   if said difference is larger than said predetermined threshold value, perform said calibration operation of said fingerprint sensor.   
     
     
         22 . The device according to  claim 21 , wherein said predetermined value of said environmental parameter is a value determined at the last performed calibration operation. 
     
     
         23 . The device according to  claim 21 , wherein said environmental parameter is selected from the group comprising humidity, temperature and electrical field strength. 
     
     
         24 . The device according to  claim 21 , wherein determining a present value of an environmental parameter comprises acquiring information from a sensor integrated in said fingerprint sensing device. 
     
     
         25 . The device according to  claim 21 , wherein determining a present value of an environmental parameter comprises acquiring information from a sensor external to said fingerprint sensing device. 
     
     
         26 . The device according to  claim 21 , wherein determining a present value of an environmental parameter comprises acquiring information via a network connection. 
     
     
         27 . The device according to  claim 19 , wherein said control unit is further configured to initiate a second calibration operation of said fingerprint sensing device a predetermined time after a first operation has been performed resulting from said change in environmental parameter. 
     
     
         28 . The device according to  claim 19 , wherein said group of predetermined events comprises events requiring a user interaction with said user device in which said fingerprint sensing device is arranged. 
     
     
         29 . The device according to  claim 19 , wherein said group of predetermined events comprises an incoming call, an alarm, an incoming message and an incoming notification. 
     
     
         30 . The device according to  claim 19 , wherein said event comprises a change in a network connection. 
     
     
         31 . The device according to  claim 30 , wherein said change in network connection comprises a change in cell ID in a cellular network. 
     
     
         32 . The device according to  claim 30 , wherein said change in network connection comprises a change of strength in a wireless network connection. 
     
     
         33 . The device according to  claim 19 , wherein said event comprises a change in location of said user device in which said fingerprint sensing device is arranged. 
     
     
         34 . The device according to  claim 19 , wherein said event comprises connecting a charger to said user device in which said fingerprint sensing device is arranged. 
     
     
         35 . The device according to  claim 19 , wherein said control unit is further configured to wait for a minimum period of time between consecutive calibration operations. 
     
     
         36 . The method according to  claim 19 , wherein said control unit is further configured initiate a second calibration operation of said fingerprint sensing device a predetermined time after a first operation has been performed resulting from said indication of said event.