Patent ID: 11565531

Abstract:
A physical quantity detection device including a container that accommodates a detection object formed of a dielectric, a first electrode provided at an outer side of the container, a second electrode that is provided separately from and to face the first electrode, and an electrostatic capacitance detector that detects an electrostatic capacitance between the first electrode and the second electrode. The electrostatic capacitance detector includes a waveform generation source coupled to the first electrode and a voltage detection circuit coupled to the second electrode. A relationship of |Zc|/|Z1|+|Zc|>|Zc|/|Z2|+|Zc| is satisfied in which |Zc| is an absolute value of an input impedance of the electrostatic capacitance detector, |Z1| is an absolute value of an impedance when the detection object is present between the first electrode and the second electrode, and |Z2| is an absolute value of an impedance when no detection object is present between the first electrode and the second electrode.