Device for measuring quantities of electric charges or similar electric parameters

摘要

A device for measuring quantities of electric charges, or other electric parameters whose magnitudes can be obtained from measurements of quantities of electric charges. The device includes a capacitor having a measuring plate and another plate or an intermediate element. The electrical parameter is applied to the capacitor so that a charge representative of its magnitude is induced on the measuring plate. This induced charge is modulated at a frequency fo and at a frequency f1, the frequency f1 being less than fo/2. An electrical signal representative of the modulation of the induced charge is generated. This signal has a first component of frequency fo whose magnitude represents the quantity of the induced charge and a second component of frequency f1 whose magnitude varies according to the distance between the measuring plate and the location at which the electrical parameter is applied to the capacitor. The second component can be used as a correction signal which reduces errors due to changes in the said distance.