Touch detection circuit, fingerprint module and control method thereof

A control method of a fingerprint module, comprising:

• switching a processing unit to a touch detection mode when a touch operation signal is received by the processing unit;
• in the touch detection mode, generating, by the processing unit, a finger touch signal when a first trigger signal generated by a touch detection circuit and/or a fingerprint sensing signal generated by a fingerprint sensor is received by the processing unit;
• switching the processing unit to a fingerprint recognition mode when a fingerprint operation signal is received by the processing unit;
• and
• in the fingerprint recognition mode, receiving, by the processing unit, the fingerprint sensing signal generated by the fingerprint sensor and generating a fingerprint image signal.

A touch detection circuit, comprising:

• a driving signal source, a driving resistor, an operational amplifier, and an analog-to-digital converter;
• wherein a first input of the operational amplifier is connected to the metal decorative part, the first input being further connected to the driving signal source via the driving resistor;
• an input of the analog-to-digital converter is connected to an output of the operational amplifier, and an output of the analog-to-digital converter is connected to the processing unit;
• or
• a voltage source, a first switch, a second switch, a third switch, a capacitor, an operational amplifier, and an analog-to-digital converter;
• wherein:
• the first switch is connected between the metal decorative part and a first input of the operational amplifier, the second switch is connected between the metal decorative part and the voltage source;
• the third switch is connected in parallel with the capacitor between the first input of the operational amplifier and an output of the operational amplifier;
• an input of the analog-to-digital converter is connected to the output of the operational amplifier, and an output of the analog-to-digital converter is connected to the processing unit;
• and the control terminals of the first switch, the second switch, and the third switch respectively receive a control signal for switching on and switching off.