Electro-acoustic transducer

• US 4,379,212 A
• Filed: 02/24/1981
• Issued: 04/05/1983
• Est. Priority Date: 02/29/1980
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Martin, Erwin
• Primary Examiner(s): Fuller, Benjamin R.
• Application Number:
  US06/237,692
• Time in Patent Office: 770 Days
• Field of Search: 179/110 A, 179/180, 179/178, 179/179, 310/322, 310/324, 310/326, 310/327, 181/157, 181/160, 181/182, 181/151, 181/292
• US Class Current: 381/351
• CPC Class Codes: H04R 1/22 for obtaining desired frequency characteristic only circuit for combining transducers having different responses H04R3/00; for hearing aids H04R25/407
• CPC Class Codes: 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
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's

Abstract

An electrical acoustical transducer is provided having a piezoelectrical layer in a housing with a transducer plate. The transducer plate divides the housing into a front chamber and a rear chamber. In the rear chamber, there is provided a Helmholtz resonator for the attenuation of resonance increases. With the invention a Helmholtz resonator is designed such that its acoustical characteristics do not change through environmental influences. Instead of covering the resonator by means of a customary silk disk, several narrow slots are arranged in the carrier plate.

Claims

1. An electro-acoustic transducer, comprising:

a transducer plate arranged in a housing and by which a space in the housing is divided into a front chamber and a rear chamber;

a fitting which closes off the front chamber;

at least one Helmholtz absorption resonator means arranged in conjunction with a plate in the rear chamber for attenuating rises in resonance;

the Helmholtz resonator means comprising a cylindrical collar zone having one end closed off except for narrow slot-like sound openings arranged in said plate and the other end of the collar being substantially completely open; and

the slot-like openings being die cast in the plate and the specific dimensions being chosen to establish a desired air friction resistance of the Helmholtz resonator means to achieve a desired attenuation response.

2. A transducer according to claim 1 wherein the plate comprises a carrier plate above which the transducer plate is supported.

3. A transducer according to claim 1 wherein said narrow slot-like sound openings are formed by parallel slots in the carrier plate.

4. A transducer according to claim 1 wherein the slot-like sound openings are formed by annular gaps in the plate.

5. A transducer according to claim 3 wherein the slots possess a range of length of 0.25 to 0.5 mm, a range of width of 0.05 to 0.1 mm, and a range of depth of 2 to 3 mm, and where the resonator collar possesses a diameter of approximately 2.4 mm and a length of approximately 3.4 mm.

6. A transducer according to claim 4, wherein a sum of the depths of the annular gaps amounts to approximately 8 mm, and they have a width of 0.05 to 0.1 mm, and the resonator collar possesses a diameter of approximately 2.4 mm and a length of approximately 3.4 mm.

7. A method for producing an electro-acoustic transducer, comprising the steps of:

providing a transducer plate arranged in a housing and by which a space in the housing is divided into a front chamber and a rear chamber;

providing a cover which closes off the front chamber;

providing a carrier plate in the rear chamber above which the transducer plate is supported;

providing at least one Helmholtz absorption resonator means provided in the rear chamber for attenuating rises in resonance, said Helmholtz resonator means being formed by a plurality of slot-like openings in said carrier plate and a collar projecting rearwardly of the carrier plate with an end of the collar below the slots substantially completely open; and

selecting a desired air friction resistance of the Helmholtz chamber by die-casting the slot-like openings in the carrier plate so as to set desired specific dimensions to achieve a desired attenuation response of the Helmholtz chamber.