Overmolding Electronic Instrument Keys and Seals
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Solution Overview
Problem
The production of electronic measuring, conditioning, and regulating instruments is hindered by the need for precise positioning of spacers and sealing elements, leading to increased production times and costs, as well as potential oxidation issues with conductive materials.
Innovation Solution
A method that simultaneously produces the main bodies of keys, optical screening elements, and perimeter sealing elements through overmolding or over-injection on the front-piece, reducing the number of production steps and eliminating the need for separate assembly of these components on the PCB, while using insulating paint to prevent oxidation and reduce capacitive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spacers and sealing elements are produced separately and positioned precisely on the PCB, then manufacturing precision is improved, but production time and device complexity increase
Solution Approach 1:
The patent merges the production of spacers, sealing elements, and key main bodies into a single overmolding operation. The mold simultaneously produces all these components in one cavity, eliminating separate production and assembly steps. This resolves the contradiction by maintaining precision through integrated production while dramatically improving productivity.
Solution Approach 2:
The mold system is designed with multi-functionality, serving as both a production tool and a positioning fixture. The same mold that produces the components also defines their final positions relative to each other, eliminating the need for separate positioning operations and reducing production complexity.
2Reliability
If conductive polymer material is used for key bodies to increase equivalent capacity, then key sensitivity is improved, but oxidation risk increases
Solution Approach 1:
The patent uses composite material construction where the key body is made of conductive polymer material embedded in an insulating polymer matrix. This composite structure provides the necessary capacitive sensitivity while the insulating matrix protects against oxidation, resolving the contradiction between sensitivity and oxidation resistance.
Solution Approach 2:
The insulating polymer material acts as an intermediary between the conductive polymer key body and the external environment. It allows the conductive material to maintain its capacitive function while protecting it from oxidative degradation, thus mediating between sensitivity requirements and oxidation protection.
3Manufacturing precision
If multiple components are produced in separate steps, then manufacturing precision is maintained, but ease of manufacture decreases
Solution Approach 1:
The patent combines multiple manufacturing operations into a single overmolding step. The mold produces spacers, sealing elements, and key main bodies simultaneously in one cavity, making the manufacturing process simpler while maintaining precision through the integrated mold design that defines all component positions.
4Measurement precision
If separate assembly steps are used for spacers and sealing elements, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the production and positioning of spacers and sealing elements into a single overmolding operation. The mold cavity design inherently defines the precise positions of all components relative to each other, eliminating complex assembly steps while maintaining positioning accuracy through the integrated production process.
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
This approach significantly reduces production times and costs, enhances standardization, and increases the reliability of the instruments by integrating key components in a single operating pass and minimizing the criticality of component positioning.
Implementation Method 1
the key body is made of a conductive polymer material obtained for example by doping a basic polymer material with particles of graphite or metal. In this way, the first of the two capacitors, internal in series, is bypassed by a conductor body and consequently the capacity of the internal capacitor increases
Implementation Method 2
painting, which allows to obviate problems of oxidation of the conductive platens 24
Data Source
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AI summary
A method to produce an electronic measuring, conditioning and regulating instrument provided with at least a display front-piece (11), with one or more keys (14) and with an electronic card (20), comprising a step of preparing the electronic card (20) in which at least one or more light emission devices (21) and electric components comprising one or more conductive platens (24) are prepared on a surface of a PCB (129b), and a step of positioning the PCB (129b) associated with the front-piece (11) and substantially parallel and in proximity to the latter. The method also comprises a simultaneous production step of main bodies (32) of the keys (14), an optical screening element (22) of the light emitted by the light emission devices (21), a perimeter sealing element (25) associated with an external perimeter edge of the front-piece (11), by means of simultaneous overmolding or over-injection on the front-piece (11) of said components.