Multiple sensor detector systems and detection methods of magnetic cards and devices

Abstract

A powered card may include a plurality of types of sensors used to detect a read-head of a card reader. Detection of a read-head may include comparing characteristics of a detection event to characteristics of an expected detection event and/or a sequence of expected detection events. An inductive read-head sensor may include a coil of a dynamic magnetic stripe communication device.

1 - 19 . (canceled) 
     
     
         20 . A method comprising:
 detecting, by a device, a change in capacitance of a capacitive element using first circuitry, the capacitive element including a conductor of the device and at least a portion of an object external to the device;   activating, by the device, second circuitry based on the detecting a change in capacitance, the second circuitry including an inductive element;   detecting, by the device, a state of the inductive element, the state indicative of an object external to the device; and   communicating, by the device, information based on the detecting a state of the inductive element.   
     
     
         21 . A method comprising:
 detecting, by a device, a change in capacitance of a capacitive element using first circuitry, the capacitive element including a conductor of the device and at least a portion of an object external to the device;   activating, by the device, second circuitry based on the detecting a change in capacitance, the second circuitry including an inductive element;   detecting, by the device, a state of the inductive element, the state indicative of an absence of an external object; and   activating a low power mode of the device based on the detecting a state of the inductive element.   
     
     
         22 . The method of  claim 20 , further comprising:
 deactivating third circuitry.   
     
     
         23 . The method of  claim 21 , further comprising:
 deactivating third circuitry.   
     
     
         24 . The method of  claim 20 , further comprising:
 deactivating a coil driver.   
     
     
         25 . The method of  claim 21 , further comprising:
 deactivating a coil driver.   
     
     
         26 . The method of  claim 20 , further comprising:
 deactivating a coil driver,   wherein the deactivating a coil driver includes decoupling the coil driver from one or more coils of the device.   
     
     
         27 . The method of  claim 21 , further comprising:
 deactivating a coil driver,   wherein the deactivating a coil driver includes decoupling the coil driver from one or more coils of the device.   
     
     
         28 . The method of  claim 20 , further comprising:
 deactivating, by a processor of the device, an ASIC including a coil driver.   
     
     
         29 . The method of  claim 21 , further comprising:
 deactivating, by a processor of the device, an ASIC including a coil driver.   
     
     
         30 . The method of  claim 20 , further comprising:
 deactivating a coil driver,   wherein the activating second circuitry includes activating an oscillator and at least one sensor circuit.   
     
     
         31 . The method of  claim 21 , further comprising:
 deactivating a coil driver,   wherein the activating second circuitry includes activating an oscillator and at least one sensor circuit.   
     
     
         32 . The method of  claim 20 , further comprising:
 deactivating a coil driver,   wherein the activating second circuitry includes coupling an oscillator circuit to one or more coils of the device.   
     
     
         33 . The method of  claim 21 , further comprising:
 deactivating a coil driver,   wherein the activating second circuitry includes coupling an oscillator circuit to one or more coils of the device.   
     
     
         34 . The method of  claim 20 , wherein the detecting a state of the inductive element includes sensing a difference between a signal at a first node of the second circuitry and a signal at a second node of the second circuitry. 
     
     
         35 . The method of  claim 21 , wherein the detecting a state of the inductive element includes sensing a difference between a signal at a first node of the second circuitry and a signal at a second node of the second circuitry. 
     
     
         36 . The method of  claim 20 , wherein the inductive element includes at least a portion of a coil, and
 the detecting a state of the inductive element includes sensing a difference between a signal at a first end of the coil and a signal at a second end of the coil.   
     
     
         37 . The method of  claim 21 , wherein the inductive element includes at least a portion of a coil, and
 the detecting a state of the inductive element includes sensing a difference between a signal at a first end of the coil and a signal at a second end of the coil.   
     
     
         38 . The method of  claim 20 , wherein the inductive element includes at least a portion of a coil,
 the detecting a state of the inductive element includes sensing a difference between a signal at a first end of the coil and a signal at a second end of the coil, and   the difference exceeds a threshold.   
     
     
         39 . The method of  claim 21 , wherein the inductive element includes at least a portion of a coil,
 the detecting a state of the inductive element includes sensing a difference between a signal at a first end of the coil and a signal at a second end of the coil, and   the difference is substantially zero.