US 8,947,980 B2Granted

Micro-geophone

AssigneeGeospace Technologies Corporation

InventorDaniel M. Woo

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Abstract

A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Claims8

Dependent claims

A geophone (110) comprising:

a magnet (114) having an upper end and a lower end, said magnet characterized by a magnet width;
a pole piece (116) secured to said upper end of said magnet (114), said pole piece having substantially the same width as said magnet width, with no pole piece lip extending downwardly from said pole piece (116), said pole piece (116) being conductively bonded to said upper end of said magnet;
a tubular coil form (130) disposed around said magnet (114) and said pole piece, said coil form (130) having a first recess formed at a first end of said coil form so as to define a first shoulder (137) bounded by a first circumferential lip (139);
a generally planar first spring (132) defining first and second obverse faces, a perimeter portion of said first face of said first spring directly adjoining said first shoulder (137), an interior portion of said first spring (132) coupled to said magnet (114) via said pole piece (116) so that said perimeter portion of said first face of said first spring is axially movable with respect to said magnet (114);
a first adhesive fillet disposed between a perimeter portion of said second face of said first spring (132) and said first circumferential lip (139) so as to bond said first spring (132) to said coil form (130);
and
a coil (140, 142) wound about said coil form (130).

4 more elements

A geophone coil form assembly comprising:

a tubular first bobbin (170) having first and second ends and a recess formed at said first end of said first bobbin so as to define a first shoulder (137) bounded by a first circumferential lip (139);
a generally planar first spring (132) defining first and second obverse faces seated within said recess of said first bobbin (170) with said first face directly adjoining said first shoulder;
a first adhesive bead disposed between said second face of said first spring and (132) said first circumferential lip (139) so as to bond said first spring to said first bobbin (170);
a first coil (140) wound about said first bobbin (170);
and a tubular second bobbin (172) having first and second ends and a recess formed at said first end of said second bobbin so as to define a second shoulder (137) bounded by a second circumferential lip (139), said second end of said second bobbin coupled to said second end of said first bobbin (170);
a generally planar second spring (134) defining first and second obverse faces seated within said recess of said second bobbin with said first face of said second spring (134) directly adjoining said second shoulder;
a second adhesive bead disposed between said second face of said second spring (134) and said second circumferential lip (139) so as to bond said second spring (134) to said second bobbin (172);
and
a second coil (140) wound about said second bobbin, wherein
said first bobbin (170) is formed of a first material;
and
said second bobbin (172) is formed of a second material having greater density than said first material.

9 more elements

Dependencies are inferred from the claim text.