초록 ▼

A magnetostrictive waveguide position measuring apparatus includes a waveguide extending between opposed anchored ends. A magnet is displaceable along the waveguide and generates torsional strain in the waveguide in response to an electrical excitation signal transmitted along the waveguide. A piezo

A magnetostrictive waveguide position measuring apparatus includes a waveguide extending between opposed anchored ends. A magnet is displaceable along the waveguide and generates torsional strain in the waveguide in response to an electrical excitation signal transmitted along the waveguide. A piezoelectric film element is coupled to the waveguide to sense the torsional strain signal on the waveguide. A signal processor determines the relative elapsed time between the excitation signal and the output signal of the piezoelectric film element to determine the position of the magnet along the waveguide. The piezoelectric film element is coupled to the waveguide along an axis transverse to the axis of stretch of the element. Alternately, a differential piezoelectric film element formed of two piezoelectric elements contacts a waveguide, with the two elements connected in differential parallel or series configuration and in or out of phase to double the output current or the output voltage. The output of the differential piezoelectric elements are connected to an amplifier in either charge or voltage mode for noise, EMI and transient signal suppression.

대표청구항 ▼

[ What is claimed is:] [1.] A position measurement apparatus including a magnetostrictive waveguide extending through a measurement field and anchored at opposite ends, means for electrically exciting the waveguide to transmit an electrical excitation signal along the waveguide, a magnet displaceabl

[ What is claimed is:] [1.] A position measurement apparatus including a magnetostrictive waveguide extending through a measurement field and anchored at opposite ends, means for electrically exciting the waveguide to transmit an electrical excitation signal along the waveguide, a magnet displaceable along the waveguide and inducing a torsional strain signal in the waveguide in response to the excitation signal, and signal means for producing a signal representative of the position of the magnet along the waveguide, the apparatus comprising:a piezoelectric film element having an active area with a first axis oriented along a direction of stretch of the piezoelectric element and a second axis transverse to the first axis;the active area of the piezoelectric film element disposed in contact with the waveguide, with the waveguide aligned along the second axis of the piezoelectric film element; andthe torsional strain signal transmitted along the waveguide and coupled to the piezoelectric film element to produce a stress wave in the piezoelectric film element in the direction of the first axis of the piezoelectric film element.