Micro-Geophone Miniaturization via Adhesive Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional geophones face challenges in miniaturization while maintaining sensitivity and frequency response, as reducing size diminishes the ability to output detectable voltage signals and alters natural frequency response, and manufacturing limitations hinder the design of cost-effective micro-geophones.
Innovation Solution
A micro-geophone design featuring lipless pole pieces, adhesive bonding of pole pieces to the magnet, a novel coil form mounting arrangement with thermoset adhesive fillets, and a two-piece bimetallic coil form to control mass and frequency response, along with a unique housing geometry for maximizing dimensions within streamer cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the geophone size is reduced for miniaturization, then the device dimensions are improved, but the ability to output detectable voltage signals deteriorates
Solution Approach 1:
The patent changes key parameters including using stronger magnet materials (neodymium iron boron) to increase magnetic flux density, optimizing coil wire gauge and turn density to maintain voltage output, and adjusting pole piece geometry to concentrate magnetic flux. These parameter changes allow the miniaturized geophone to maintain signal detectability despite reduced overall size.
Solution Approach 2:
The patent employs composite material strategies by combining high-remanence magnet material (neodymium iron boron) with precisely engineered ferrous pole pieces and copper coils. This composite approach maximizes the magnetic circuit efficiency and electrical output within the constrained miniaturized volume, resolving the contradiction between small size and adequate signal output.
2Volume of moving object
If the geophone size is reduced for miniaturization, then the device dimensions are improved, but the natural frequency response deteriorates
Solution Approach 1:
The patent carefully adjusts parameters including spring stiffness, magnet mass, and pole piece geometry to maintain the natural frequency response at or below 30 Hz. By changing these parameters in the miniaturized design, the frequency response stability is preserved despite the reduced scale, preventing the typical high-frequency shift that occurs with miniaturization.
3Area of stationary object
If pole piece lips are eliminated to reduce diameter, then the geophone diameter is improved, but the magnet alignment precision deteriorates
Solution Approach 1:
The patent replaces the mechanical alignment system (pole piece lips) with an adhesive bonding system. The magnet is bonded directly to the pole pieces using adhesive, which provides precise alignment without requiring the mechanical interlocking lips. This substitution eliminates the radial space requirement for lips while maintaining or improving alignment precision through the bonding process.
4Device complexity
If adhesive bonding is used to replace mechanical connections, then the device complexity is improved, but the manufacturing precision requirements worsen
Solution Approach 1:
The patent systematically replaces multiple mechanical connection elements (lips, retaining rings, clamps) with adhesive bonding, simplifying the overall structure. While this increases bonding precision requirements, the elimination of multiple mechanical parts and assembly steps results in net reduced complexity. The bonding process is controlled through standardized procedures to ensure precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves significant miniaturization while maintaining sensitivity and frequency response tuned for 30 Hertz or lower, effectively addressing the limitations of size reduction and manufacturing constraints, and optimizing geophone dimensions for use in seismic surveys.
Implementation Method 1
The upper and lower frequency-tuned springs (32, 34) allow the magnet (14), pole pieces (16, 18), and outer housing (20) to vibrate up and down coaxially with respect to the coil form (30)
Implementation Method 2
Upper and lower electrical coils (40, 42) are wound about the coil form (30) so as to be located in the upper and lower air gaps (22, 24)
Data Source
AI summary
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.