Low frequency sound transducer

A magnetostrictive vibrator for producing low frequency sound, said vibrator comprising:

• a plurality of laterally related rods each formed of rare earth magnetostrictive material;
• permanent magnets for providing a permanent magnet bias in said rods;
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and
• means for compressively prestressing said rods, said prestressing means including magnetic keepers for conducting flux between said coil means.

A magnetostrictive vibrator for producing low frequency sound, said vibrator comprising:

• a plurality of laterally related rods each formed of rare earth magnetostrictive material;
• permanent magnets for providing a permanent magnet bias in said rods;
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and
• means for compressively prestressing said rods, prestressing means including magnetic keepers for conducting flux between said coil means through said permanent magnets.

A low frequency sound producer, comprising:

• at least three magnetostrictive vibrators arranged seriatim end-to-end to define a ring, each vibrator comprising:
• a plurality of laterally related rods each formed of rare-earth magnetostrictive material and each having a cross section;
• permanent magnets for providing a permanent magnetic bias in said rods;
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and
• means defining facial abutments at opposite ends of successive vibrators;
• and wherein said permanent magnets comprise means compressively urged against at least one end of the rods for transmitting to the rods compressive pre-stressing forces.

A low frequency sound producer, comprising:

• at least three magnetostrictive vibrators arranged seriatim end-to-end to define a polyhedral ring, each vibrator comprising:
• a pair of spaced apart rods in parallel with one another formed of rare-earth magnetostrictive material and each rod having a cross section;
• rare-earth permanent magnets for providing a permanent magnetic bias in said rods;
• and
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and wherein said permanent magnets comprise means compressively urged against at least one end of the rods for transmitting to the rods compressive pre-stressing forces.

A low frequency sound producer comprising a plurality of magnetostrictive vibrators arranged seriatim end-to-end to define a polyhedral ring, each vibrator comprising:

• a pair of parallel spaced rods formed of rare earth magnetostrictive material;
• means for compressively prestressing said rods;
• rare earth permanent magnet means for providing a permanent magnetic bias in said rods;
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and
• keeper means for coupling the coil means in series.

A low frequency sound producer comprising a plurality of magnetostrictive vibrators arranged seriatim end-to-end to define a polyhedral ring, each vibrator comprising:

• a pair of parallel spaced rods formed of rare earth magnetostrictive material;
• means for compressively prestressing said rods;
• rare earth permanent magnet means for providing a permanent magnetic bias in said rods;
• coil means magnetically coupled to said rods for causing magnetostriction of the rods corresponding to an input AC signal applied to said coil means;
• and
• keeper means for coupling the coil means in series, said keeper means being arranged to direct compressive forces against the opposite ends of the rods.

A magnetostrictive vibrator, comprising:

• a rare earth rod having a first cross section;
• a permanent magnet urged against at least one end of said rod, providing a permanent magnetic bias in said rod;
• and
• a coil coupled to said rod causing magnetostriction of said rod corresponding to an input signal;
• and wherein said permanent magnet comprise means compressively urged against at least one end of the rod for transmitting to the rod compressive pre-stressing forces.