Apparatus and method for finger activity on a fingerprint sensor
First Claim
1. A method for detecting the presence of a biometric object on or in the vicinity of a biometric object sensing area in a biometric object imaging apparatus, the method comprising:
- transmitting a probing signal to the biometric object sensing area, comprising a capacitive gap between at least one of a plurality of transmitter electrodes and a single receiver electrode or at least one of a plurality of receiver electrodes and a single transmitter electrode, the probing signal comprising a burst of high frequency pulses, transmitted across the capacitive gap between the at least one of a transmitter electrode from the plurality of transmitter electrodes to the single receiver electrode or to the at least one of a plurality of receiver electrodes from the single transmitter electrode;
receiving a response signal on the respective receiver electrode in response to the probing signal, the response signal comprising a burst of high frequency pulses;
establishing an upper reference level for the amplitude of pulses in the burst of high frequency pulses comprising the response signal; and
monitoring whether the peaks of the response signal exceed the upper reference level to determine the presence of the biometric object in the biometric object sensing area due to the presence of the biometric object modifying the amplitude of the pulses in the burst of high frequency pulses in the response signal from the amplitude of the pulses in the probing signal.
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Abstract
An apparatus and method for detecting the presence of a finger on a fingerprint sensor is disclosed in one embodiment of the invention as including transmitting a probing signal, comprising a series of probing pulses, to a fingerprint sensing area. A response signal, comprising a series of response pulses, is received from the fingerprint sensing area in response to the probing signal. An upper reference signal is generated and finger activity is detected on the fingerprint sensing area by monitoring whether the peaks of the response pulses exceed the reference signal.
432 Citations
20 Claims
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1. A method for detecting the presence of a biometric object on or in the vicinity of a biometric object sensing area in a biometric object imaging apparatus, the method comprising:
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transmitting a probing signal to the biometric object sensing area, comprising a capacitive gap between at least one of a plurality of transmitter electrodes and a single receiver electrode or at least one of a plurality of receiver electrodes and a single transmitter electrode, the probing signal comprising a burst of high frequency pulses, transmitted across the capacitive gap between the at least one of a transmitter electrode from the plurality of transmitter electrodes to the single receiver electrode or to the at least one of a plurality of receiver electrodes from the single transmitter electrode; receiving a response signal on the respective receiver electrode in response to the probing signal, the response signal comprising a burst of high frequency pulses; establishing an upper reference level for the amplitude of pulses in the burst of high frequency pulses comprising the response signal; and monitoring whether the peaks of the response signal exceed the upper reference level to determine the presence of the biometric object in the biometric object sensing area due to the presence of the biometric object modifying the amplitude of the pulses in the burst of high frequency pulses in the response signal from the amplitude of the pulses in the probing signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A biometric object sensor in a biometric object imaging apparatus, comprising:
a probing signal generator configured to generate a probing signal and transmit the probing signal to a biometric object sensing area, comprising a capacitive gap between at least one of a plurality of transmitter electrodes and a single receiver electrode or at least one of a plurality of receiver electrodes and a single transmitter electrode, the probing signal comprising a burst of high frequency pulses, transmitted across the capacitive gap between the at least one of a transmitter electrode from the plurality of transmitter electrodes to the single receiver electrode or the at least one of a plurality of receiver electrodes from the single transmitter electrode; a response signal receiver receiving a response signal on the respective receiver electrode in response to the probing signal, the response signal comprising a burst of high frequency pulses; a reference signal generator generating an upper reference level signal for the amplitude of pulses in the burst of high frequency pulses comprising the response signal; and a signal processor configured to monitor whether the peaks of the response signal exceed the upper reference level to determine the presence of the biometric object in the biometric object sensing area due to the presence of the biometric object modifying the amplitude of the pulses in the burst of high frequency pulses in the response signal from the amplitude of the pulses in the probing signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A non-transitory machine readable medium storing instructions that, when executed by a computing device, cause the computing device to perform a method, the method comprising:
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transmit a probing signal to a biometric object sensing area, comprising a capacitive gap between at least one of a plurality of transmitter electrodes and a single receiver electrode or at least one of a plurality of receiver electrodes and a single transmitter electrode, the probing signal comprising a burst of high frequency pulses, transmitted across the capacitive gap between the transmitter electrode of the plurality of transmitter electrodes to the single receiver electrode or to the receiver electrode of the plurality of receiver electrodes from the single transmitter electrode; receive a response signal on the respective receiver electrode in response to the probing signal, the response signal comprising a burst of high frequency pulses; establish an upper reference level for the amplitude of pulses in the burst of high frequency pulses comprising the response signal; and monitor whether the peaks of the response signal exceed the upper reference level to determine the presence of the biometric object in the biometric object sensing area due to the presence of the biometric object modifying the amplitude of the pulses in the burst of high frequency pulses in the response signal from the amplitude of the pulses in the probing signal.
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Specification