PLL adjustment to find and maintain resonant frequency of piezo electric finger print sensor
First Claim
1. A method for determining a resonant frequency of a non-optical biometric sensor, comprising:
- obtaining first pixel data from a first scan by scanning the non-optical biometric sensor with a first frequency;
obtaining second pixel data from a second scan by scanning the biometric sensor with a second frequency that is different from the first frequency;
calculating a respective first and second reference value from the first and the second pixel data;
deciding a highest reference value from the first and the second reference values; and
selecting the first or the second frequency as the resonant frequency based on the highest reference value.
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Abstract
Provided is a method for determining a resonant frequency of a biometric sensor. The method includes obtaining first pixel data from a first scan by scanning the biometric sensor with a first frequency. Second pixel data is obtained from a second scan by scanning the biometric sensor with a second frequency that is different from the first frequency. A respective first and second reference value is calculated from the first and the second pixel data. A highest reference value is determined from the first and the second reference values. The first or the second frequency is selected as the resonant frequency based on the highest reference value.
66 Citations
27 Claims
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1. A method for determining a resonant frequency of a non-optical biometric sensor, comprising:
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obtaining first pixel data from a first scan by scanning the non-optical biometric sensor with a first frequency; obtaining second pixel data from a second scan by scanning the biometric sensor with a second frequency that is different from the first frequency; calculating a respective first and second reference value from the first and the second pixel data; deciding a highest reference value from the first and the second reference values; and selecting the first or the second frequency as the resonant frequency based on the highest reference value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 18)
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9. A non-transitory computer-readable medium containing instructions for controlling at least one processor to determine a resonant frequency of a non-optical biometric sensor by a method, comprising:
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obtaining first pixel data from a first scan by scanning the non-optical biometric sensor with a first frequency; obtaining second pixel data from a second scan by scanning the biometric sensor with a second frequency that is different from the first frequency; calculating a respective first and second reference value from the first and the second pixel data; deciding a highest reference value from the first and the second reference values; and selecting the first or the second frequency as the resonant frequency based on the highest reference value. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 19, 22, 23, 24)
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17. A biometric sensing apparatus, comprising:
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a piezoelectric sensing device; and a processor coupled to the piezoelectric device; wherein the processor is configured to; obtain first pixel data from a first scan by scanning the biometric sensor with a first frequency; obtain second pixel data from a second scan by scanning the biometric sensor with a second frequency that is different from the first frequency; calculate a respective first and second reference value from the first and the second pixel data; decide a highest reference value from the first and the second reference values; and select the first or the second frequency as the resonant frequency based on the highest reference value.
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20. A system for selecting a frequency for resonating a piezoelectric sensing device comprising:
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a piezoelectric sensing device which in response to an applied selected frequency provides pixels having pixel values representing an image of a fingerprint of a finger when placed upon said sensing device; and a frequency generating device for applying to said piezoelectric sensing device different frequencies to provide different ones of said image in which one of said different frequencies is said selected frequency when the image associated with said one of said different images has more pixels of higher values than said different ones of said image associated with any other of said different frequencies. - View Dependent Claims (21, 25)
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26. A system for selecting a frequency for resonating a piezoelectric sensing device comprising:
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a piezoelectric sensing device which in response to an applied resonant frequency provides pixels having pixel values representing an image of a fingerprint of a finger when placed upon said sensing device; and a frequency generating device for first applying to said piezoelectric sensing device different frequencies spaced from each other in succession over a first range of frequencies to provide different ones of said image in which one of said different frequencies over said first range is a selected frequency when the image associated with said one of said different images has more pixels of higher values than said different ones of said image associated with any other of said different frequencies over said first range, and then applying to said piezoelectric sensing device different frequencies spaced from each other in succession over a second range of frequencies to provide different ones of said image in which one of said different frequencies in said second range is said resonant frequency when the image associated with said one of said different images has more pixels of higher values than said different ones of said image associated with any other of said different frequencies in said second range, and said second range of frequencies lies within said first range of frequencies and spaced closer to each other than said different frequencies in said first range. - View Dependent Claims (27)
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Specification