Device and Method for Detecting Film Thickness

A device for detecting a film thickness, comprising:

• a common electrode, a detection electrode, a common electrode voltage generating circuit, and a detection electrode signal processing circuit;
• the common electrode and the detection electrode are set oppositely and at interval in a first direction;
• a first common surface of the common electrode is opposite to a first detection surface of the detection electrode;
• a detection channel for a film to be detected is formed between the first common surface and the first detection surface;
• wherein,
• the common electrode voltage generating circuit is configured to generate a voltage on the common electrode, as to induce an effective signal voltage on the detection electrode;
• the detection electrode signal processing circuit comprises:
• a reset voltage time sequence control circuit, a time sequence control circuit for transferring the effective signal voltage on the detection electrode and a differential amplifier;
• wherein, the reset voltage time sequence control circuit is configured to control the detection electrode to reset a voltage;
• the time sequence control circuit for transferring the effective signal voltage on the detection electrode is configured to transfer the effective signal voltage on the detection electrode;
• and the differential amplifier is configured to, after performing differential amplification on the reset voltage and the effective signal voltage on the detection electrode, output an effective signal used for detecting the film to be detected.