Electrostatic transducer having narrowed directional characteristic

Claim 2

An electrostatic sonic transducer comprising a backplate, a layer of conductive material stretched over one major surface of said backplate with an insulating layer interposed between said conductive layer and said backplate said backplate being formed of substantially non-conductive material having a metallized coating extending across said one major surface and at least portions of said opposite major surface thereof, said backplate carrying indentations at its periphery for providing metallized connections between said one and said opposite surfaces, and means for connecting an external voltage source to said portions of said coating on said opposite major surface.

Claim 3

The transducer of claim 1 wherein said one major surface is formed with a plurality of generally concentric projections spaced by intervening grooves, and said plate includes at least one radially extending slot extending to a depth approximately equal to said grooves thereby insuring connection of the metallized coating on said one surface from one projection to the next.

Claim 4

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer, a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between layers, said one major surface being defined by a plurality of projections spaced apart by intervening grooves, with the configuration of said projections and grooves being optimized for maximum output at a given frequency near the center of said one major surface and varied from said optimum near the periphery thereof so as to reduce the side lobe radiation of said transducer.

Claim 5

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer, a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between layers, said one major surface being defined by a plurality of projections spaced apart by intervening grooves, with the configuration of said projections and grooves being optimized for maximum output at a given frequency near the center of said one major surface and varied from said optimum near the periphery thereof so as to reduce the side lobe radiation of said transducer.

Claim 6

The transducer of claim 3 wherein said projections and grooves are concentric circles.

Claim 7

The transducer of claim 3 wherein the depth of said grooves are different near said periphery of said one major surface as compared to the depth of said grooves near said center thereof.

Claim 8

The transducer of claim 3 wherein said projections and grooves are concentric, and the depth of said grooves are shallower near said periphery of said one major surface as compared to the depth of said grooves near the center thereof.

Claim 9

The transducer of claim 3 wherein said projections and grooves are concentric, and the depth of said grooves are approximately constant from said center of said plate to about one-half the radius of said plate and then progressively decrease in depth to a relatively shallow groove at said periphery.

Claim 10

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer and a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said one major surface being defined by a plurality of projections spaced apart by intervening grooves, and the crest of said projections include substantially uniform surface variations formed by substantially uniform striations.

Claim 11

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer and a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said one major surface being defined by a plurality of projections spaced apart by intervening grooves, and the crest of said projections include substantially uniform surface variations formed by substantially uniform striations.

Claim 12

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material stretched across said one major surface with a layer of insulative material disposed between said flexible conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between said layers, said one major surface being defined by a plurality of projections spaced by intervening grooves, the crest of one said projection deviating from said convex curvature as compared to an adjacent or next adjacent projection to define an undulating convex curvature of said one major surface.

Claim 13

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material stretched across said one major surface with a layer of insulative material disposed between said flexible conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between said layers, said one major surface being defined by a plurality of projections spaced by intervening grooves, the crest of one said projection deviating from said convex curvature as compared to an adjacent or next adjacent projection to define an undulating convex curvature of said one major surface.

Claim 14

The transducer of claim 9 wherein said projections and grooves are concentric circles, and said crest of said one projection deviates by 5 to 10 μm from said curvature as compared to said adjacent or next adjacent projection.

Claim 15

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer, a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between said layers, said one major surface being defined by a plurality of projections spaced by intervening grooves, and the crests of said projections include sequentially uniform scribing.

Claim 16

An electrostatic sonic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material so as to provide a first conductive layer, a relatively flexible layer of conductive material forming a second conductive layer stretched across said one major surface with a layer of insulative material disposed between said second conductive layer and said one major surface, said major surface being formed so that portions thereof in contact with said insulative material define a generally convex curvature to provide reliable contact between said layers, said one major surface being defined by a plurality of projections spaced by intervening grooves, and the crests of said projections include sequentially uniform scribing.

Claim 17

The transducer of claim 11 wherein at least some said grooves are to a depth of approximately 0.25 mm and said scribing ranges up to a depth of approximately 10 μm.

Claim 18

An electrostatic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material tightly stretched across said one major surface with a layer of insulative material disposed between said conductive material and said one major surface, said major surface being defined by a series of projections spaced apart by intervening grooves, and the configuration of said projections and grooves being optimized for maximum output at a given frequency near the center of said one major surface and varied from said optimum near the periphery thereof so as to reduce the side lobe radiation of said transducer.

Claim 19

An electrostatic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material tightly stretched across said one major surface with a layer of insulative material disposed between said conductive material and said one major surface, said major surface being defined by a series of projections spaced apart by intervening grooves, and the configuration of said projections and grooves being optimized for maximum output at a given frequency near the center of said one major surface and varied from said optimum near the periphery thereof so as to reduce the side lobe radiation of said transducer.

Claim 20

The transducer of claim 13 wherein said projections and grooves are concentric and wherein the dimensions of width and height of said projections and grooves are optimized for maximum output at said given frequency near said center of said one major surface, and at least one of said dimensions being varied from said optimum near said periphery of said one major surface to reduce said side lobe radiation.

Claim 21

The transducer of claim 13 wherein the configuration of said grooves are different near said periphery of said one major surface.

Claim 22

The transducer of claim 13 wherein said grooves are shallower near said periphery of said one major surface thereby suppressing the sidelobes of said transducer.

Claim 23

The transducer of claim 13 wherein the depth of said grooves are approximately constant from said center of said one major surface to about one-half the radius thereof and then progressively decrease in depth to a relatively shallow groove near said periphery.

Claim 24

The transducer of claim 16 wherein said grooves are substantially concentric circles.

Claim 25

An electrostatic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material tightly stretched across said one major surface with a layer of insulative material disposed between said flexible layer of conductive material and said one major surface, said major surface being defined by a series of projections spaced apart by intervening grooves, and the crests of said projections having substantially uniform striations.

Claim 26

An electrostatic transducer comprising a relatively inflexible support plate having at least one major surface thereof formed of conductive material, a relatively flexible layer of conductive material tightly stretched across said one major surface with a layer of insulative material disposed between said flexible layer of conductive material and said one major surface, said major surface being defined by a series of projections spaced apart by intervening grooves, and the crests of said projections having substantially uniform striations.

Claim 27

The transducer of claim 19 wherein said projections are approximately 0.25 mm high and said striations are uniform scribing on the crests thereof to a depth of 5 to 10 μm.

Claim 28

The transducer of claim 19 wherein said striations extend approximately perpendicularly across said projections.

Claim 29

The transducer of claim 19 wherein said striations comprise raised ridges extending approximately transversely across the crests of said projections, said ridges being substantially uniformly spaced along the length of said projections and of narrow width and relatively short height as compared to said projections.

Claim 30

The transducer of claim 22 wherein at least some of said projections have a height of approximately 0.25 mm and said ridges thereon range up to a height of 10 μm.