# US 5,333,205 A · Microphone assembly

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- Number: US 5,333,205 A
- Document ID: US5333205A
- Status: Granted
- Kind: A
- Application number: 08/024,012
- Filed: 1993-03-01
- Granted: 1994-07-26
- Earliest claimed: 1993-03-01
- Assignees: Motorola, Inc.
- Inventors: Henry A. Bogut; Joseph Patino
- Web page: https://patentgrep.com/patent/US5333205A

## CPC

- H04R 11/04: Microphones
- 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)

## Abstract

A microphone assembly (134) includes a movable diaphragm (124) and a linear light gradient (130) which causes the movement of diaphragm (124) to be translated into a corresponding amplitude of light to be received at a photo-detector (116). Thereby providing for a fully optical microphone assembly which is immune to radio frequency interference and resistance losses.

## Claims

### Claim 1

A communication device assembly, comprising:
a transmitter for transmitting information signals; and
a microphone assembly coupled to the transmitter, the microphone assembly comprising:
a microphone housing having a sound port for receiving sound waves;
a diaphragm coupled to the microphone housing and movably responsive to said sound waves;
a light source located within the housing for providing an optical signal;
a reflective means coupled to the diaphragm for reflecting said optical signal in response to movement of said diaphragm;
a variable gradient for receiving said reflected optical signal and attenuating the reflected optical signal by an amount which is related to the amount of movement experienced by the movable diaphragm;
an optical push-to-talk (PTT) switch coupled to the microphone housing for selectively attenuating the optical signal; and
a photo-detector for receiving the attenuated optical signal when the optical push-to-talk (PTT) switch is activated and converting the attenuated optical signal into an electrical signal which controls the transmitter.

### Claim 2 (depends on 1)

A communication device assembly as defined in claim 1, wherein the reflective means comprises a mirror which is attached to the diaphragm.