Measurement sensor based on an indirect measurement of the permitivity between two electrically conducting bodies forming measurement probe and reference element has improved compensation for signal perturbations

摘要

Measurement device comprises a measurement probe (10), means (30) for sequential application of controlled supply voltage to a measurement probe and a reference element (20) and means (50) for integration of the electrical charge accumulated by the measurement probe. In addition means (60) are provided to ensure an offset correction at the input to the integrator. A differentiator (70) stage receives input signals from the probe heads to provide similar offset correction, but receive different controlled supply voltages. The reference element can be an earth, in automotive applications, for example, the vehicle chassis.