Mechanically biased semiconductor strain sensitive microphone

• US 4,182,937 A
• Filed: 09/21/1978
• Issued: 01/08/1980
• Est. Priority Date: 09/21/1978
• Status: Expired due to Term

• Current Assignee: STC PLC (f/k/a Standard Telephones and Cables)
• Original Assignee: International Standard Electric Corporation (ITT, Inc.)
• Inventors: Greenwood, John C.
• Primary Examiner(s): Stellar, George G.
• Application Number:
  US05/944,425
• Time in Patent Office: 474 Days
• Field of Search: 179/100.41 T, 179/110 B, 179/110 D, 179/121 R, 179/138, 73/777, 338/4, 338/2, 357/26
• US Class Current: 381/162
• CPC Class Codes: H04R 17/02 Microphones
• CPC Class Codes: H04R 21/02 Microphones

Abstract

A piezo-electric transducer element is disclosed which is formed by selected etchings from boron doped silicon. The transducer includes a diaphragm and a spring lever adapted to bias the transducer element into a state of strain so that a vibration of the diaphragm is transmitted to the transducer element. The transducer element is particularly suitable for use in a telephone microphone.

Claims

1. A microphone transducer element of the type in which acoustic vibration generates corresponding resistance changes, including:

at least two semiconductor plate members;

an integral flexible laminar semiconductor support upon which said plate members are situated; and

at least one laminar semiconductor filament for interconnecting said plate members such that said at least one filament is strain-sensitive.

2. A transducer element as claimed in claim 1, further including means for maintaining said at least one filament in tension.

3. A transducer element as claimed in claim 1 wherein said semiconductor plate members are comprised of boron doped silicon.

4. A transducer element as claimed in claims 1, 2 or 3 wherein the resistance of said semiconductor is within the range of 50 to 200 ohm.

5. A microphone assembly comprising:

housing means;

flexible diaphrgam means mounted in said housing means;

semiconductor strain gauge transducer element;

first and second contact springs for securing said transducer element to said housing;

spring lever means mounted on said housing proximate to said contact springs for biasing said transducer element into a state of strain; and

fulcrum means mounted on said diaphragm and in abutment with the spring lever means such that acoustic vibrations of the diaphragm are transmitted to said transducer element.

6. In a telephone subscriber instrument, a microphone assembly comprising:

housing means;

flexible diaphragm means mounted in said housing means;

semiconductor strain gauge transducer element;

first and second contact springs for securing said transducer element to said housing;

spring lever means mounted on said housing proximate to said contact springs for biasing said transducer element into a state of strain; and

fulcrum means mounted on said diaphragm and in abutment with the spring lever means such that acoustic vibrations of the diaphragm are transmitted to said transducer element.