| 摘要 |
A circuit and method are provided for ensuring that a fingerprint sensor is started automatically when a finger is rested thereon such that a sufficiently contrasting image can be produced. A difference between a maximum and a minimum value of the sensor signals is generated wherein, if the difference is sufficiently large, indicating a sufficient contrast of an image to be produced, a normal scanning operation of the fingerprint sensor is initiated, thus ensuring that the complete fingerprint image is produced, a normal scanning operation of the fingerprint sensor is initiated, thus ensuring that the complete fingerprint images produced are of satisfactory quality.
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