Cross coil type instrument
US4988944A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 2, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Aug 2, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R7/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A cross coil type instrument includes a plurality of coils cross-arranged around a movable permanent magnet, a needle fastened to the movable permanent magnet through a shaft projecting from the movable permanent magnet and penetrating the coils, a reset-to-zero permanent magnet arranged in the vicinity of the movable permanent magnet, and a stopper so as to make contact with the needle at a reference indication position when the movable permanent magnet is driven only by the reset-to-zero permanent magnet. Further the instrument has a circuit which receives an input signal related to a quantity to be measured and generates drive signals to be supplied to the respective coils based on the input signal so that a composite magnetic field formed by the coils presents a first error in deflection angle of the movable permanent magnet, and an error obtained by adding the first error in deflection angle and a second error in deflection angle due to the reset-to-zero permanent magnet changes linearly as a function of an electrical angle of the drive signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.