Electrostatic transducer backplate having open ended grooves

• US 4,311,881 A
• Filed: 07/05/1979
• Issued: 01/19/1982
• Est. Priority Date: 07/05/1979
• Status: Expired due to Term

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Reynard, John M.
• Primary Examiner(s): Brigance, Gerald L.
• Application Number:
  US06/054,983
• Time in Patent Office: 929 Days
• Field of Search: 179/111 R, 179/111 E
• US Class Current: 381/163
• CPC Class Codes: B65D 39/12 expansible, e.g. inflatable
• CPC Class Codes: H04R 19/00 Electrostatic transducers

Abstract

The desired groove shape in a backplate of a combination transmitting and receiving, capacitance type, electrostatic transducer are more consistently reproduceable in a die forming operation by utilizing an open ended grooved configuration so that groove shape deforming lubricating fluid, necessary in said die forming operation, and air, can escape from between the die tool and the transducer backplate through said open ended grooves as said grooves are die formed on said backplate.

Claims

1. An electrostatic transducer comprising a relatively inflexible support plate for a flexible diaphragm, said support plate having at least one major irregular surface of conductive material formed in a die forming operation employing a liquid lubricant, said major surface being defined by a series of projections spaced apart by intervening grooves, said grooves and said projections extending fully across said major surface to the peripheral edges thereof so as to provide open channels thereacross between each of said projections to eliminate entrapment of the liquid lubricant in each of said grooves during said die forming operation.

2. The transducer of claim 1 wherein said projections and grooves are parallel linear projections and grooves.

3. The transducer of claim 2 wherein said peripheral edges define a circle.