Optical microphone transducer with methods for changing and controlling frequency and harmonic content of the output signal

• US 20050238188A1
• Filed: 04/27/2004
• Published: 10/27/2005
• Est. Priority Date: 04/27/2004
• Status: Abandoned Application

• Current Assignee: Peter Ray Wilcox
• Original Assignee: Peter Ray Wilcox
• Inventors: Wilcox, Peter Ray
• Application Number:
  US10/833,661
• Publication Number:
  US 20050238188A1
• Time in Patent Office: Days
• US Class Current: 381/172
• CPC Class Codes: H04R 23/008 using optical signals for detecting or generating sound
• CPC Class Codes: H04R 2410/00 Microphones

Abstract

A reflective optical position or object detector, containing a light source (LED) and detector (phototransistor) is placed proximate to an acoustic membrane such that the output of the detector produces an electric signal corresponding to the motion of the membrane toward and away from the detector. Groups of these detectors can be placed at different locations under a single membrane to reproduce the frequency and harmonic content of the motion of the membrane at those locations, and the signals from each can be combined in variable proportion to a resultant electrical signal. These groups can be bounded by isolating frames and several bounded groups can be placed under a single membrane, or be covered by separate membranes. The groups with their bounding frames can be moved toward or away from the membrane, placing more or less tension upon the membrane, thereby altering the harmonic and frequency content of its vibration.

Claims

1. ) A reflective object sensor, in which are integrated an electromagnetic (light) source such as an LED, and a photosensitive device, such as a phototransistor, (many of which are currently available as position sensors such as Fairchild QRE1113, Vishay TCNT1000, or Marktech MTRS9520, or of which may be made available in the future specifically optimized for the use described herein, either as single devices or in the form of an array on a common substrate) is mounted or placed under a reflective (not necessarily specular) membrane, (which may be piano, concave, convex, ribbed, corrugated or of other deformation, and which can take one of many shapes—

circular, elliptical, polygonal, ribbon, and which may vary in thickness or have damping materials affixed to it to alter the frequencies or harmonics of its vibration), which moves in response to acoustic waves impinging upon it, in such a manner that the reflected electromagnetic (light) signal is captured by the photosensitive element in its linear region with respect to distance from the membrane, generating an electrical signal which varies in intensity as the membrane increases or decreases its distance from the photosensitive device as it responds to the acoustic signal.

2. ) Two or more of these devices, or an array of these devices, are mounted or placed on a substrate in proximity to the membrane, at varying distances from the geometric center axis of the membrane and possibly including the geometric center axis, and each device will respond to and generate an electrical signal corresponding to the particular frequencies and harmonics generated by the membrane at that location.

7. ) In a third embodiment of the invention, there can be a multiplicity of membrane units as described in claim #2, each set upon the same base foundation, each with one or more reflective sensors of the same or different sizes set under it, and with the outputs of the sensors mixed as in claim #3.

3. ) These two or more electrical signals will then be combined, summed or mixed to a single signal which is the output of the circuit, and the combination of these signals can be effected and varied through analog means, such as potentiometers, variable resistors or voltage controlled amplification, or by a combination of analog and digital means, such as digitally controlled amplification, or by analog to digital conversion and further combination and processing in the digital realm.

4. ) In a second embodiment of the invention, one or more of these sensors on the base substrate may be bounded or encircled by a frame, which frame may be of any circular or polygonai shape, and which impinges upon the membrane, thus isolating the movement of that portion of the membrane from the rest of the membrane, and there may be one or more of these bounded units on the base substrate.

5. ) The outputs of each of these units can be mixed with outputs from the others to yield an electrical signal containing the desired frequencies and harmonics.

6. ) The tension or force of the impingement of these bounding frames on the membrane can also be varied by mechanical means, such as thumbscrews or other method of moving the base substrate toward or away from the membrane, thereby allowing the membrane to be tuned to respond differentially to various frequencies.