Abstract: A contact detector having power switches for disconnecting power to portions of the contact sensor when an over current is detected is disclosed. The power switches thus protect the contact sensor from over-current as the result of latch-up or other current-generating conditions. These current-generating conditions are often the result of ESD events on a surface of the contact detector. A contact detector comprises an exposed surface for detecting the presence of an object, an insulating surface, and a protection element disposed under the insulating surface for controlling power to the contact detector. The protection element is configured to disconnect power to the contact detector when a current to the contact detector is detected above a threshold. Preferably, the contact detector is a finger swipe sensor, but it can be a finger placement sensor or any other type of device that functions on contact with a finger or other patterned object.

Abstract: The present invention discloses an apparatus for determining the presence of a patterned object on the surface of a sensor. The apparatus comprises a sensor system coupled to a means for generating a control signal. The sensor system is configured to sense an image corresponding to the patterned object and to translate the image into image data. The means for generating a control signal generates a control signal if statistics of the image data exceed a pre-determined number of threshold levels. In a preferred embodiment, the patterned object is finger with a fingerprint on its surface and the sensor is fingerprint swipe sensor. Preferably, the threshold levels are software programmable.

Abstract: An automatic gain amplifier is disclosed that dynamically improves the quality of scanned biometric information. According to one embodiment, an image distribution of the scanned biometric is generated. Next, areas of higher image distribution are identified. An iterative process of adjusting the gain of, for instance, a capacitive sensing, is employed until an optimum separation of the areas of higher image distribution is achieved. Once the optimum separation is achieved, the gain is applied to the biometric sensing device so that biometric information can be scanned with improved image clarity. Electronic circuitry and software for implementing the methods are disclosed.