Transducer shielding enclosure

• US 4,430,520 A
• Filed: 04/07/1982
• Issued: 02/07/1984
• Est. Priority Date: 04/07/1982
• Status: Expired due to Term

• Current Assignee: Tibbetts Industries Incorporated (Intricon Corporation)
• Original Assignee: Tibbetts Industries Incorporated (Intricon Corporation)
• Inventors: Tibbetts, George C., Sawyer, Joseph A.
• Primary Examiner(s): Prescott, A. C.
• Assistant Examiner(s): Tone, D. A.
• Application Number:
  US06/366,332
• Time in Patent Office: 671 Days
• Field of Search: 174/35 R, 174/50, 174/52 R, 174/52 PE, 174/65 R, 179/114 A, 179/117, 179/119 A, 336/84 C
• US Class Current: 174/377
• CPC Class Codes: H04R 11/00 Transducers of moving-armature or moving-core type acoustic diaphragm of magnetisable material directly coacting with electromagnet H04R13/00
• CPC Class Codes: H04R 2225/49 Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils
• CPC Class Codes: H05K 9/0007 Casings standardised racks H05K9/0062

Abstract

A shielding enclosure for a magnetic flux producing device comprises inner and outer casings with closely fitting side walls. One or more leads extending from within the enclosure are laid down during assembly in a clearance slot or groove formed between the casing side walls, and thereafter threaded back out of the clearance slot or groove and extended through a closed aperture in the outer casing for terminal attachment.

Claims

1. The combination of

a magnetic device having at least one electrical lead and means to produce magnetic flux in response to a current in said lead, and

a magnetic shielding enclosure substantially surrounding said device and comprising fitted inner and outer casings of high permeability magnetic material, each casing comprising a first wall and side walls each integral with and extending from said first wall to an unbroken annular skirt edge, a number of said side walls of each casing having major areas closely fitting with corresponding side walls of the other casing, a side wall of one of said casings having a portion formed away from a corresponding side wall of the other casing and being adapted to provide a clearance space therebetween for said lead extending to the skirt edge of the outer casing, the side wall of the outer casing having a closed aperture located to permit said lead to be threaded out from said clearance space and extended through said aperture.

2. The combination according to claim 1, in which said formed portion comprises a portion of a side wall of the inner casing formed inwardly thereof.

3. The combination according to claim 2, in which the formed portion is spaced from the skirt edge of the inner casing and the inner casing has a perforation located within the area of said formed portion to permit the lead to extend therethrough into said clearance space.

4. The combination according to claim 1, in which said formed portion comprises a portion of a side wall of the inner casing formed inwardly thereof and the outer casing has a strap bounded by said aperture and the skirt edge of the outer casing, said strap being deformed inwardly into said formed portion.

5. The combination according to claim 1, with a terminal board having a perforation receiving said lead extending through said aperture, said terminal board being secured to said shielding enclosure.

6. The combination according to claim 5, in which the terminal board is inserted in said aperture and secured to a side wall of the inner casing.

7. The combination according to claim 1, in which at least one of the side walls of the inner casing is deformed outwardly, prior to fitting the casings together, to provide an interference fit with the outer casing.

8. The combination according to claim 7, in which the outer casing has a strap bounded by said aperture and the skirt edge of the outer casing and adapted to sustain the hoop stress therein developed by said interference fit.

9. The combination according to claim 8, in which said formed portion comprises a portion of a side wall of the inner casing formed inwardly thereof and the strap is substantially straight.

10. The combination according to claim 7, in which said deformation is arched outwardly in a region between the ends of said side wall.