Fingerprint identification device-equip with a touch sensor for detecting a human finger

The method of sensing a human finger, comprising:

• outputting a high-frequency signal from an oscillator unit;
• applying said high-frequency signal to the human finger;
• detecting a variation of impedance values varied by said human finger contacting a pair of electrodes, and outputting an output signal based on said variation of impedance values;
• and
• determining whether the human finger is in contact with said pair of electrodes by comparing said output signal with a predetermined reference value,
• wherein a capacitance between said human finger and said pair of electrodes increases when the human finger is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the human finger and a circuit resistance value including said pair of electrodes matches output impedance at a predetermined frequency of said oscillator unit, allowing the determining that the contact is that of the human finger.

The method of sensing an object, comprising:

• applying a high frequency signal to the object which is in proximity of a pair of electrodes, and detecting a variation of impedance values varied by said object contacting said pair of electrodes, and outputting a signal based on the variation of impedance values;
• and
• determining whether the object is in contact with the electrodes by comparing the signal with a predetermined reference value,
• wherein a capacitance between said object and said pair of electrodes increases when the object is in contact with said pair of electrodes, and a total resistance value of a high-frequency impedance real value of the object and a circuit resistance value including said pair of electrodes matches output impedance at a predetermined frequency of said high frequency signal, allowing the determining that the contact is that of the object.