# US 2014/0022867 A1 · Micro-geophone > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0022867 A1 - Document ID: US20140022867A1 - Status: Published application - Kind: A1 - Application number: 13/553,597 - Filed: 2012-07-19 - Published: 2014-01-23 - Earliest claimed: 2012-07-19 - Assignees: Geospace Technologies Corporation - Inventors: DANIEL M. WOO - Web page: https://patentgrep.com/patent/US20140022867A1 ## CPC - G01V 1/183: {with moving magnet} - H04R 9/04: Construction, mounting, or centering of coil - H04R 9/043: {Inner suspension or damper, e.g. spider (outer suspension or surround H04R7/16)} - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## 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. ## Claims ### Claim 1 A geophone (110) comprising: a magnet (114); a tubular coil form (130) disposed around said magnet (114) and 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, an interior portion of said first spring coupled to said magnet so that said perimeter portion of said first face of said first spring is axially movable with respect to said magnet; a first adhesive fillet disposed between a perimeter portion of said second face of said first spring and said first circumferential lip (139) so as to bond said first spring to said coil form; and a coil (140, 142) wound about said coil form (130). ### Claim 2 (depends on 1) The geophone (110) of claim 1 further comprising: a second recess formed at a second end of said coil form so as to define a shoulder (137) bounded by a circumferential lip (139); a generally planar second spring (134) defining first and second obverse faces, a perimeter portion of said first face of said second spring directly adjoining said second shoulder, an interior portion of said second spring coupled to said magnet so that said perimeter portion of said first face of said second spring is axially movable with respect to said magnet; and a second adhesive fillet disposed between a perimeter portion of said second face of said second spring and said second circumferential lip (139) so as to bond said second spring to said coil form. ### Claim 3 (depends on 1) The geophone (110) of claim 1 further comprising: a notch (104) formed at the circumference of said first spring (132); and an adhesive column (193) formed in said notch and bonded to said shoulder. ### Claim 4 (depends on 1) The geophone (110) of claim 1 wherein: said coil form is bimetallic. ### Claim 5 A method of producing a geophone (110) comprising the steps of: providing a tubular 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); centering a generally planar first spring (132) within said first circumferential lip; disposing said first spring (132) directly against said first shoulder; then disposing a bead of a first adhesive along a first circumferential lip (139) so as to bond said first spring to said coil form. ### Claim 6 (depends on 5) The method of claim 5 further comprising the steps of: forming a plurality of notches (104) about the circumference of said first spring (132); and disposing said bead along a first circumferential lip (139) so as to fill said plurality of notches with said first adhesive and bond said first spring to said coil form. ### Claim 7 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 with said first face directly adjoining said first shoulder; a first adhesive bead disposed between said second face of said first spring and said first circumferential lip (139) so as to bond said first spring to said first bobbin; and a first coil (140) wound about said first bobbin. ### Claim 8 (depends on 7) The geophone coil form assembly of claim 7 further comprising: 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; 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 directly adjoining said second shoulder; a second adhesive bead disposed between said second face of said second spring and said second circumferential lip (139) so as to bond said second spring to said second bobbin; and a second coil (140) wound about said second bobbin. ### Claim 9 (depends on 8) The geophone coil form assembly of claim 8 wherein: said first bobbin is formed of a first material; and said second bobbin is formed of a second material having greater density than said first material. ### Claim 10 (depends on 9) The geophone coil form assembly of claim 9 wherein: said first bobbin is formed of aluminum; and said second bobbin is formed of one of the group consisting of brass, bronze, and copper. ### Claim 11 (depends on 9) The geophone coil form assembly of claim 9 wherein: said first bobbin is anodized aluminum. ### Claim 12 (depends on 8) The geophone coil form assembly of claim 8 wherein: said first bobbin is adhesively bonded to said second bobbin.