Method and Apparatus for Determining Existence of Foreign Material on Surface of Fingerprint Sensor, and Terminal

Abstract

A method and an apparatus for determining existence of a foreign material on a surface of a fingerprint sensor, and a terminal are provided. The method includes the following. A current capacitance value of the fingerprint sensor of the terminal is obtained. A first difference between the current capacitance value and a preset capacitance reference value is calculated. Determine that the foreign material is present on the surface of the fingerprint sensor when the first difference is within a preset foreign-material threshold range.

What is claimed is: 
     
         1 . A method for determining existence of a foreign material on a surface of a fingerprint sensor, comprising:
 obtaining a current capacitance value of the fingerprint sensor of a terminal;   calculating a first difference between the current capacitance value and a preset capacitance reference value; and   determining that the foreign material is present on the surface of the fingerprint sensor, when the first difference is within a preset foreign-material threshold range.   
     
     
         2 . The method of  claim 1 , further comprising:
 subsequent to determining that the foreign material is present on the surface of the fingerprint sensor, removing the foreign material in a preset manner.   
     
     
         3 . The method of  claim 2 , wherein removing the foreign material in the preset manner comprises:
 sending a message indicating that the foreign material is present on the surface of the fingerprint sensor to prompt a user to remove the foreign material.   
     
     
         4 . The method of  claim 2 , wherein removing the foreign material in the preset manner comprises:
 increasing a temperature of the fingerprint sensor to remove the foreign material.   
     
     
         5 . The method of  claim 4 , further comprising:
 after increasing a temperature of the fingerprint sensor:   obtaining the current capacitance value of the fingerprint sensor of the terminal that has been subjected to the removing of the foreign material, when a preset time has elapsed;   calculating a second difference between the current capacitance value of the fingerprint sensor of the terminal that has been subjected to the removing of the foreign material and the preset capacitance reference value;   determining that the foreign material is present on the surface of the fingerprint sensor when the second difference is within the preset foreign-material threshold range; and   sending a message indicating that the foreign material is present on the surface of the fingerprint sensor to prompt a user to remove the foreign material.   
     
     
         6 . The method of  claim 4 , wherein increasing the temperature of the fingerprint sensor comprises one of:
 increasing a power of the fingerprint sensor to increase the temperature of the fingerprint sensor; and   controlling a heating device corresponding to the fingerprint sensor to heat the fingerprint sensor for increasing the temperature of the fingerprint sensor.   
     
     
         7 . The method of  claim 1 , further comprising:
 before determining that the foreign material is present on the surface of the fingerprint sensor when the first difference is within the preset foreign-material threshold range, setting the preset foreign-material threshold range according to experimental data of capacitance change tests performed on the fingerprint sensor when different conductive foreign materials are present on the surface of the fingerprint sensor.   
     
     
         8 . An apparatus for determining existence of a foreign material on a surface of a fingerprint sensor, comprising:
 a processor; and   a memory, coupled with the processor and configured to store program codes which when executed by the processor become operational with the processor configured to:
 obtain a current capacitance value of the fingerprint sensor of a terminal; 
 calculate a first difference between the current capacitance value and a preset capacitance reference value; and 
 determine that the foreign material is present on the surface of the fingerprint sensor, when the first difference is within a preset foreign-material threshold range. 
   
     
     
         9 . The apparatus of  claim 8 , wherein the processor is further configured to:
 remove the foreign material in a preset manner.   
     
     
         10 . The apparatus of  claim 9 , wherein the processor configured to remove the foreign material in the preset manner is further configured to:
 send a message indicating that the foreign material is present on the surface of the fingerprint sensor to prompt a user to remove the foreign material.   
     
     
         11 . The apparatus of  claim 9 , wherein the processor configured to remove the foreign material in the preset manner is further configured to:
 increase a temperature of the fingerprint sensor to remove the foreign material.   
     
     
         12 . The apparatus of  claim 11 , wherein the processor configured to increase the temperature of the fingerprint sensor is further configured to:
 obtain the current capacitance value of the fingerprint sensor of the terminal when a preset time has elapsed after increasing the temperature of the fingerprint sensor;   calculate a second difference between the current capacitance value of the fingerprint sensor of the terminal and the preset capacitance reference value;   determine that the foreign material is present on the surface of the fingerprint sensor when the second difference is within the preset foreign-material threshold range; and   send a message indicating that the foreign material is present on the surface of the fingerprint sensor, to prompt a user to remove the foreign material.   
     
     
         13 . The apparatus of  claim 11 , wherein the processor configured to increase a temperature of the fingerprint sensor is further configured to execute one of:
 increasing a power of the fingerprint sensor, to increase the temperature of the fingerprint sensor; and   controlling a heating device corresponding to the fingerprint sensor to heat the fingerprint sensor, wherein the temperature of the fingerprint sensor is increased.   
     
     
         14 . The apparatus of  claim 8 , wherein the processor is further configured to:
 set the preset foreign-material threshold range according to experimental data of capacitance change tests performed on the fingerprint sensor when different conductive foreign materials are present on the surface of the fingerprint sensor.   
     
     
         15 . A terminal, comprising:
 a fingerprint sensor;   a capacitance-value obtaining unit, coupled with the fingerprint sensor, and configured to obtain a current capacitance value of the fingerprint sensor at different stages;   a difference calculating unit, configured to calculate a difference between the current capacitance value and a preset capacitance reference value; and   a foreign-material determining unit, configured to determine that a foreign material is on a surface of the fingerprint sensor, when the difference is within a preset foreign-material threshold range.   
     
     
         16 . The terminal of  claim 15 , further comprising:
 a foreign-material removal control unit, configured to remove the foreign material in a preset manner.   
     
     
         17 . The terminal of  claim 16 , wherein the foreign-material removal control unit comprises:
 an alerting unit, configured to send a message indicating that the foreign material is present on the surface of the fingerprint sensor to prompt a user to remove the foreign material.   
     
     
         18 . The terminal of  claim 16 , wherein the foreign-material removal control unit comprises:
 a temperature controller, configured to increase a temperature of the fingerprint sensor to remove the foreign material.   
     
     
         19 . The terminal of  claim 18 , wherein
 the capacitance-value obtaining unit is configured to obtain the current capacitance value of the fingerprint sensor of the terminal when a preset time has elapsed after increasing the temperature of the fingerprint sensor.   
     
     
         20 . The terminal of  claim 18 , wherein the temperature controller is configured to execute one of:
 increase a power of the fingerprint sensor to increase the temperature of the fingerprint sensor; and   control a heating device corresponding to the fingerprint sensor to heat the fingerprint sensor, wherein the temperature of the fingerprint sensor is increased.