Abstract A pressure sensitive seismic detector is formed of at least two elongated sheets or layers of flexible, rubberous material having particulated magnetic material embedded therein. The particulated magnetic material is preferably barium ferrite. The layers are connected together at spaced apart locations and magnetized across the width thereof so as to form a plurality of parallel bar magnets along the length thereof with the poles of adjacent magnets reversed. Coils are wound between the bar magnets on at least one of the layers. Preferably, the sense of winding of adjacent coils is reversed, and the magnets formed in adjacent flexible sheets are aligned so that they repel each other. To form a hydrophone, the apparatus is encased in a thin flexible bag or enclosure and positioned in a liquid filled cable housing. In one embodiment, magnetic metal foil is affixed to the nonengaging surfaces of two adjacent layers of rubberous material.
The apparatus of claim 1 wherein the poles of adjacent magnetized strips are oppositely oriented.
Claim 2
Dependent Claim
22 words
The apparatus of claim 1 wherein each of the flexible magnetic members comprises an elongated rubberous material impregnated with particulated magnetic material.
Claim 3
Dependent Claim
13 words
The apparatus of claim 3 wherein the particulated magnetic material is barium ferrite.
Claim 4
Dependent Claim
25 words
The apparatus of claim 1 wherein the spacing between locations at which the magnetic members are connected together between 5 cm and about 35 cm.
Claim 5
Dependent Claim
25 words
The apparatus of claim 1 wherein adjacent coils are wound in an opposite sense, and are connected together so that voltages produced thereby are additive.
Claim 6
Dependent Claim
15 words
The apparatus of claim 1 wherein the members are encased in an abrasion resistant housing.
Claim 7
Dependent Claim
41 words
The apparatus of claim 1 wherein the flexible magnetic members are two in number, a magnetic metal layer is on each of the outer surfaces of the flexible magnetic members, and coil means are supported on each of the magnetic members.
Claim 8
Dependent Claim
60 words
The apparatus of claim 1 wherein the flexible magnetic material is magnetized in parallel strips extending along the width dimension thereof to form a plurality of magnets and wherein the magnetized strips are spaced apart along the length dimension of the flexible magnetic material so that the center line of adjacent magnetized strips are between 3 and 15 mm apart.
Claim 9
Dependent Claim
22 words
The apparatus of claim 8 further including a closed fluid impermeable membrane enveloping the magnetic members, magnetic metal layers, and coil means.