ELECTRIC MEASURING INSTRUMENT Russian patent published in 1998 - IPC

FIELD: electric measurement technology. SUBSTANCE: variable-capacitance transducer is formed by pointer indicator and immovable electrodes made of current-conducting material applied on scale. Immovable electrode system is insulated electrically from both scale and remaining members of instrument construction. It is represented by arc shaped layer with center on pointer rotation axle. Layer is divided into two parts by groove. Each of two electrodes thus obtained is connected to separate auxiliary terminal. Instrument may have auxiliary arc-shaped layer of current-conducting material with center on pointer rotation axle applied on scale and separated from main layer by groove. This layer is insulated electrically from both scale and other members of instrument construction and connected electrically to separate terminal. Determination of pointer position relative to scale marks is provided due to form of groove located between electrodes. This form is such that overlapping areas of electrodes and pointer, when the latter moves to one side, vary monotonically and differentially relative to each other. Output capacitances of transducer with also change monotonically and differentially, which allows setting up of unambiguous correspondence between angular position of pointer and values of output capacitances. Consequently it is possible to determine position of pointer on scale knowing the dependence of transducer output from pointer angle of turn. Auxiliary arc-shaped layer is used for taking into account variations of clearance between pointer and scale. EFFECT: enhanced accuracy and sensitivity. 2 cl, 2 dwg