Resonant vibrating structure with electrically driven wire coil and vibration sensor
US4887032A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 2, 1988 |
| Grant date | Dec 12, 1989 |
| Priority date | — |
| Expiry date | May 2, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/023
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A vibration type sensor can make a noncontacting measurement of position or sense the passage of an object past a point. The sensor has a coil of wire placed on a vibrating structure. A power supply causes current to be passed through the coil at the resonant frequency of the vibrating structure. As an object with an attached magnet approaches the coil, a force is exerted on the current carrying coil thereby exciting the structure at its resonant vibrational frequency. A piezoelectric bimorph is attached to the structure so that it flexes with the structure producing an emf output proportional to the vibrational amplitude. As the object moves, the field strength at the coil, the amplitude of the vibration and the induced emf change. The latter quantity is used to sense the motion of the object. Alternatively, the magnet remains fixed with respect to the coil while a material of high magnetic permeability approaches the coil and magnet combination thereby perturbing the magnetic field and changing the induced emf. This method can be used to obtain a linear variation of sensor output with position or to enable the use of the device as a timing sensor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.