Helmet with a magnetostrictive actuator

• US 20050201584A1
• Filed: 04/18/2005
• Published: 09/15/2005
• Est. Priority Date: 03/19/2001
• Status: Abandoned Application

• Current Assignee: Brian Douglas Smith
• Original Assignee: Brian Douglas Smith
• Inventors: Smith, Brian Douglas
• Application Number:
  US11/108,305
• Publication Number:
  US 20050201584A1
• Time in Patent Office: Days
• US Class Current: 381/376
• CPC Class Codes: H04R 11/02 Loudspeakers
• CPC Class Codes: H04R 15/00 Magnetostrictive transducers magnetostrictive elements in general H10N30/00
• CPC Class Codes: H04R 23/00 Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: H04R 2460/13 Hearing devices using bone conduction transducers
• CPC Class Codes: H04R 7/045 using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

A magnetostrictive actuator comprises a rod of giant magnetostrictive material, biasing permanent magnets arranged at each end thereof and coaxially therewith so as to pass a magnetic field through the rod. An energizing electromagnetic coil is connected to an energizer so as to superimpose on the magnetic field passing through the rod an alternating magnetic field to cause variation in the length of the rod in response thereto. The permanent magnets are each in the form of a disc having a cross-sectional area substantially greater than that of the rod and are spaced from the ends of the rods by material of low magnetic permeability. The magnetic field in the rod is thereby substantially linear along the length thereof.

Claims

1. A helmet or protective hat having an audio frequency actuator acoustically coupled therewith, and means for supplying an audio frequency drive signal to the actuator.

2. A helmet or protective hat according to claim 1, wherein the audio frequency actuator is a magnetostrictive actuator.

4. A helmet or protective hat according to claim 2, wherein the means for supplying an audio frequency signal comprises a radio receiver.

3. A hat comprising a headband carrying an audio frequency actuator connected to means for supplying an audio frequency drive signal thereto, the actuator being positioned so as to engage the wearer'"'"'s head, in use, to couple acoustic energy directly into the wearer'"'"'s skull.

5. A hat of claim 3, wherein the means for supplying an audio frequency signal comprises a radio receiver.