Arc-Shaped Resistance Substrate for Linear Rheostat Output
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Solution Overview
Problem
Conventional resistance substrates with arc-shaped resistance parts formed by screen printing struggle to achieve even surface resistivity in the circumferential direction, leading to deviations in the ideal proportional relation between rotation angle and resistance value in rheostats.
Innovation Solution
A resistance substrate with an arc-shaped resistance part that includes a first part and a second part, where the second part is narrower and thicker than the first part, and the width continuously changes between them, ensuring even surface resistivity by varying the sectional area in the circumferential direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the resistance part is formed by screen printing method, then the manufacturing process is simple, but the thickness uniformity in circumferential direction deteriorates
Solution Approach 1:
The resistance part is designed with varying width along the circumferential direction, creating local quality differences. The width is narrower at positions where the screen printing method tends to produce thicker sections and wider at positions where thinner sections are expected, thereby compensating for the non-uniform thickness and achieving even surface resistivity.
2Ease of manufacture
If the resistance part has uniform width, then the manufacturing is easier, but the surface resistivity uniformity in circumferential direction deteriorates
Solution Approach 1:
Instead of uniform width, the resistance part employs variable width along the circumferential direction. This local variation in geometry compensates for the inherent non-uniformity of the screen printing process, ensuring that the product of width and thickness (sectional area) remains relatively constant, thereby achieving even surface resistivity.
3Manufacturing precision
If the resistance part is formed with even thickness, then the surface resistivity is uniform, but the width must vary which complicates the design
Solution Approach 1:
The design accepts variable width as a deliberate local quality modification to achieve the primary goal of even surface resistivity. The width variation is calculated to compensate for thickness non-uniformity, and this straightforward geometric adjustment does not significantly complicate the overall device design or manufacturing process.
Data Source
AI summary
A resistance substrate contains a substrate and a resistance part that is formed on an upper surface of the substrate by printing. The resistance part is formed into an arc shape (a C shape) so that a width of the resistance part continually changes. The resistance part is formed so that a part having a narrow width becomes thick and a part having a narrow width becomes thin.