| 摘要 |
A method and apparatus for detecting the presence of a finger on a biometric minutiae sensor is disclosed. According to one embodiment, one or more capacitive sensing strips are disposed on a biometric minutiae sensor. A low frequency clock periodically charges and then discharges the one or more capacitive sensing strips. After a predetermined period, a charge remaining on the capacitive strips is sampled and then compared to a threshold charge. If the sampled charge exceeds the threshold charge then a switch enables a higher frequency clock so that the biometric minutiae sensor is enabled. A finger sensing electronics is also disclosed, which, in one embodiment, includes the one or more capacitive sensing strips and a frequency switch. In still another embodiment, the finger sensing electronics further includes a comparator configured to enable or disable the frequency switch. |
