Acoustic transducer of improved construction

• US 4,272,654 A
• Filed: 01/08/1979
• Issued: 06/09/1981
• Est. Priority Date: 01/08/1979
• Status: Expired due to Term

• Current Assignee: Knowles Electronics LLC A Delaware Limited Liability Company
• Original Assignee: Industrial Research Products, Inc.
• Inventors: Carlson, Elmer V.
• Primary Examiner(s): BROWN, THOMAS
• Application Number:
  US06/001,949
• Time in Patent Office: 883 Days
• Field of Search: 179/119 A, 179/119 R, 179/117, 179/114 A, 179/114 R, 179/184, 179/180, 179/179, 179/107 R, 179/138, 179/145, 179/115 A, 179/115 R, 179/115.5 PC, 29/594, 29/602 A, 29/602 R, 219/100, 219/104, 219/105
• US Class Current: 310/20
• 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 25/604 of acoustic or vibrational transducers
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

An improved transducer construction of the type having a U-shaped armature mounted to have a vibrating arm extending through the tunnel of a cooperating coil. The arms of the armature are joined by a smooth bend to provide improved shock-resistant characteristics. The coil is initially located and properly positioned relative to the arm extending through the tunnel by means of shims. The transducer includes a case comprising a cup, and a cover for the cup, both being of a magnetic material. The cup and cover are joined together by welding to insure low reluctance flux paths therebetween to retain the magnetic fields developed by the transducer within the casing.

Claims

1. A transducer comprising in combination a case including a motor positioned therein, said motor comprising an armature, a self-supporting coil having a tunnel formed therein for receiving the armature, a U-shaped armature in said transducer, said armature having a pair of parallel extending arms positioned or joined together by a folded portion, said folded portion of said armature being formed in an arcuate shape, said coil including a tunnel or passageway formed through the center thereof, and ridges extending inwardly into said passageway to limit the movement of said armature to protect said armature against shock damage.

2. A transducer as in claim 1 wherein said ridges extend longitudinally along the center of the tunnel.

3. The method of fabricating a transducer, said transducer including a case and a motor positioned therein, said motor including an armature, a coil including a tunnel or passageway formed therein, a U-shaped armature, said armature having a pair of parallel extending arms positioned to be joined together by a folded portion and one of the armature arms being affixable in place and the other arm being free to vibrate, consisting of the steps of:

(a) forming ridges extending inwardly into said coil passageway;

(b) securing one arm of the armature in place;

(c) positioning shims along the vibratable arm of the armature;

(d) inserting the passageway of the coil around the shims and vibrating arm of the armature; and

,

(e) affixing the coil in position in said case.