# US 6,166,998 A · Moulded transducer

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- Number: US 6,166,998 A
- Document ID: US6166998A
- Status: Granted
- Kind: A
- Application number: 09/178,699
- Filed: 1998-10-26
- Granted: 2000-12-26
- Earliest claimed: 1997-10-24
- Assignees: Milltronics Ltd.
- Inventors: Ronald Gregory Hare; John William Thomas
- Web page: https://patentgrep.com/patent/US6166998A

## CPC

- G10K 11/02: Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
- B06B 1/0651: {of circular shape}
- B06B 1/067: {which is used as, or combined with, an impedance matching layer}
- B06B 1/0685: {on the back only of piezoelectric elements}
- H04R 17/00: Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00})
- B06B 2201/55: Piezoelectric transducer
- Y10T 29/42: Piezoelectric device making
- Y10T 29/49005: Acoustic transducer
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An electro-acoustic transducer is manufactured by forming a transducer assembly at least one piezoelectric element, electrodes contacting the element, and acoustic loading blocks, and applying successive superposed mouldings of material of differing acoustic properties around said transducer assembly to form the transducer, while maintaining electrical coupling between the transducer assembly and the exterior of the transducer, the mouldings providing at least one acoustic matching layer covering a radiating surface of the transducer assembly, a casing surrounding the remainder of the transducer assembly, at least one layer of acoustic isolating material between the casing and the transducer assembly. The successive layers may either be moulded in situ, or moulded separately and then assembled.

## Claims

### Claim 1

A method of manufacturing an electro-acoustic transducer comprising forming a transducer assembly comprising at least one piezo-electric element, electrical connections to the assembly, and acoustic loading blocks, one of which forms the front of the assembly, and applying successive superposed moldings of material of differing acoustic properties around said transducer assembly to form the transducer, while maintaining electrical coupling between the electrical connections to the transducer assembly and a location exterior of the transducer, the moldings providing at least one acoustic matching layer covering a radiating surface of the transducer assembly, a casing surrounding the remainder of the transducer assembly, and at least two layers of material including a layer of acoustic isolating material between the casing and the transducer assembly;
wherein successively applied preformed moldings are shaped such that they do not completely envelop the assembly thus allowing for easy application to the assembly of the moldings used to form those layers.

### Claim 2 (depends on 1)

A method according to claim 1, wherein successively applied preformed mouldings are shaped such that they do not completely envelope the assembly thus allowing for easy application to the assembly of the mouldings used to form those layers.

### Claim 3 (depends on 1)

A method according to claim 1, wherein certain of the preformed mouldings are configured to leave a cavity around electronic components of the transducer assembly, and the cavity is filled with a potting compound.

### Claim 4 (depends on 1)

A method according to claim 1, wherein superposed layers of material applied around the transducer assembly within a cylindrical wall of the casing have alternating degrees of hardness.

### Claim 5 (depends on 1)

A method according to claim 1, wherein superposed layers of material applied around the transducer assembly within a cylindrical wall of the casing have alternating degrees of hardness.

### Claim 6 (depends on 1)

A method according to claim 1, wherein the layer forming the casing is separately moulded, and pressed onto the assembly after the application of the successive layers of material thereon.