System and method of using an electric field device
A biometric scanner having an electric field device and a method of using that scanner are disclosed. The electric field device (a) has no electric field generator or an electric field generator that is prevented from providing an electric field to a biometric object, such as a finger, and (b) has an electric field sensor array comprised of a plurality of electric field sensors. Capacitance readings from the sensor array are used to generate values that are attributed to locations corresponding to the sensors.
1. A biometric scanner, comprising:
a TFT array, including:
an electric field generator that is prevented from providing an electric field to a biometric object or the TFT array not having an electric field generator, and having an electric field sensor array comprised of a plurality of electric field sensors, each of the electric field sensors including:
a first capacitor;
a diode;
a first transistor; and
a second transistor;
wherein the first capacitor is configured to capacitively couple to the biometric object;
wherein the first capacitor is in electrical series with the diode, the first transistor, and the second transistor;
wherein a first bias is in electrical series with the diode and the first transistor; and
wherein the second transistor is coupled to an output; and
a computer coupled to receive capacitance readings from each output of the plurality of electric field sensors on the TFT array.
2. The biometric scanner of claim 1 , wherein the computer is further programmed to create an image of the biometric object using the values.
3. The biometric scanner of claim 1 , wherein the computer is further programmed to use the values in determining whether the biometric object matches information in a database.
4. The biometric scanner of claim 1 , wherein the computer is programmed to process the capacitance readings as follows:
(i) identify a particular one of the electric field sensors that is providing a capacitance reading;
(ii) sum the capacitance reading of the identified electric field sensor with capacitance readings from adjacent electric field sensors;
(iii) divide the sum by the number of sensors contributing to that sum to provide a value;
(iv) attribute the value to the identified sensor; and
(v) repeat steps (i) through (iv) until a value has been attributed to all sensors.
5. The biometric scanner of claim 1 , wherein the diode, the first transistor, and the second transistor are each separately in series with the first capacitor.
6. A method of scanning a biometric object, comprising:
(i) provide a TFT array (a) having no electric field generator, or an electric field generator that is prevented from providing an electric field to a biometric object or the TFT array, and (b) having an electric field sensor array comprised of a plurality of electric field sensors, each of the electric field sensors including:
a first capacitor;
a diode;
a first transistor; and
a second transistor;
wherein the first capacitor is configured to capacitively couple to the biometric object;
wherein the first capacitor is in electrical series with the diode, the first transistor, and the second transistor;
wherein a first bias is in electrical series with the diode and the first transistor and
wherein the second transistor is coupled to an output; and
(ii) capacitively couple a biometric object to the TFT array;
(iii) receive capacitance readings from each output of the plurality of electric field sensors on the TFT array;
(iv) determine values representative of the biometric object based upon the received capacitance readings.
7. The method of claim 6 , further comprising using the provided values to generate a visual image of the biometric object.
8. The method of claim 6 , further comprising using the provided values to determine whether the biometric object matches information in a database.
9. The method of claim 6 , wherein determining values representative of the biometric object includes repeating the following steps until a value has been attributed to all sensors:
identify a particular one of the electric field sensors that is providing a capacitance reading;
sum the capacitance reading of the identified electric field sensor with capacitance readings from adjacent electric field sensors;
divide the sum by the number of sensors contributing to that sum to provide a value;
attribute the value to the identified sensor.
10. The method of claim 6 , wherein the diode, the first transistor, and the second transistor are each separately in series with the first capacitor.