Torsional fork transducers

Claim 2

A torsional transducer comprising a. a torsional rod, and b. means to sustain said rod in vibration at its natural frequency, said means including a piezoelectric crystal operating in the longitudinal mode, one end of said crystal being tangentially attached to said rod, the other end being attached to a fixed support, said crystal having a drive electrode and a pick-up electrode, said pick-up electrode being coupled to the input of an electronic amplifier whose output is coupled to said drive electrode to provide a positive feedback loop.

Claim 3

A torsional fork transducer comprising a. a pair of torsional tines in parallel relation, a supporting rod at an intermediate position between said tines and a strip interconnecting said tines and said rod at the feet thereof, b. means attaching said rod to a fixed mount, c. and means to sustain said tines in torsional vibration, said means including a piezoelectric crystal operating in the longitudinal mode, the ends of said crystal being tangentially attached to said tines on one side at the feet thereof, said crystal having a drive electrode and a pick-up electrode, said pick-up electrode being coupled to the input of an electronic amplifier whose output is coupled to said drive electrode to provide a positive feedback loop.

Claim 4

A torsional fork transducer comprising a. a pair of torsional tines in parallel relation, a supporting rod at an intermediate position between said tines and a strip interconnecting said tines and said rod at the feet thereof, b. means attaching said rod to a fixed mount, c. and means to sustain said tines in torsional vibration, said means including a piezoelectric crystal operating in the longitudinal mode, the ends of said crystal being tangentially attached to said tines on one side at the feet thereof, said crystal having a drive electrode and a pick-up electrode, said pick-up electrode being coupled to the input of an electronic amplifier whose output is coupled to said drive electrode to provide a positive feedback loop.

Claim 5

A transducer as set forth in claim 2, wherein said strip is of resilient material.

Claim 6

A transducer as set forth in claim 3, wherein said strip has a predetermined temperature coefficient which is adapted to effect frequency compensation with respect to the temperature coefficient of said tines.

Claim 7

A transducer as set forth in claim 2, further including a second crystal attached tangentially to the feet of said tines on the opposite side thereof, said second crystal having a drive electrode coupled to the output of said amplifier, said second crystal operating in the longitudinal mode in phase opposition to the first crystal.

Claim 8

A transducer as set forth in claim 2, further including optical elements secured to the free ends of the tines.

Claim 9

A transducer as set forth in claim 2, further including cross pieces attached to the free ends of the tines.

Claim 10

A torsional fork transducer comprising a. an elongated shaft supported at its center by a compliant mount, the upper section of the shaft constituting a first torsional rod and the lower section a second torsional rod vibrating in phase opposition to the first rod, b. a pair of frame elements disposed on either side of the shaft and attached to said mount, and c. means to sustain said first and second rods in torsional vibration, said means including a crystal operating in the longitudinal mode and attached at its ends between a rod section and one of said frame elements, said crystal having a drive electrode and a pick-up electrode, said pick-up electrode being coupled to the input of an electronic amplifier whose output is coupled to said drive electrode.

Claim 11

A torsional fork transducer comprising a. an elongated shaft supported at its center by a compliant mount, the upper section of the shaft constituting a first torsional rod and the lower section a second torsional rod vibrating in phase opposition to the first rod, b. a pair of frame elements disposed on either side of the shaft and attached to said mount, and c. means to sustain said first and second rods in torsional vibration, said means including a crystal operating in the longitudinal mode and attached at its ends between a rod section and one of said frame elements, said crystal having a drive electrode and a pick-up electrode, said pick-up electrode being coupled to the input of an electronic amplifier whose output is coupled to said drive electrode.