Thermistor Element Resistance Stability via Electrode Distance Ratio
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Solution Overview
Problem
Conventional thermistor elements experience variability in resistance due to variations in the length of external electrodes, leading to inconsistent performance across different products.
Innovation Solution
The thermistor element design ensures that the ratio of the first distance between the outermost internal electrode and the external electrode to the second distance between adjacent internal electrodes satisfies 4≤(d/ed)≤10, maintaining a consistent resistance by adjusting the distance and overlap area between internal and external electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the first distance d between the external electrode and the outermost internal electrode is reduced to achieve compact size, then the overall dimensions are improved, but the resistance varies from one product to another due to manufacturing variations
Solution Approach 1:
The patent changes the critical parameter from the first distance d to the ratio d/ed, where ed is the distance between adjacent internal electrodes. By controlling this ratio within 0.05≤d/ed≤0.50, the invention ensures that even when d varies due to manufacturing tolerances, the resistance remains consistent because the variation is compensated by corresponding variations in ed. This parameter transformation resolves the contradiction by making the design less sensitive to absolute dimensional variations.
Solution Approach 2:
The patent establishes predetermined relationships between multiple distances (d, ed, and the number of internal electrodes) before manufacturing. By designing the structure such that d/ed falls within a specific range, the invention pre-compensates for expected manufacturing variations. This preliminary design constraint ensures that resistance consistency is maintained even when absolute dimensions vary, preventing the harmful effect of resistance variation before it occurs.
2Reliability
If the first distance d is made short to reduce the contribution ratio of resistance between external electrode and internal electrode, then the resistance stability is improved, but the distance becomes too short causing selective discharge at high voltage
Solution Approach 1:
The patent introduces a new dimensional relationship by considering the ratio d/ed instead of just the absolute distance d. This dimensional transformation allows the design to simultaneously satisfy both conditions: d can be kept small for compact size and reduced resistance contribution, while ed is adjusted proportionally to maintain adequate insulation distance and prevent discharge. The ratio-based approach adds a degree of freedom that resolves the apparent contradiction.
Solution Approach 2:
By transforming from controlling absolute distance d to controlling the ratio d/ed, the patent enables a new design space where both compact dimensions and high voltage reliability can be achieved. The ratio constraint ensures that d remains sufficiently small for low resistance contribution while ed scales accordingly to prevent selective discharge, thus resolving the contradiction between resistance stability and discharge prevention.
3Volume of moving object
If the length of external electrodes is reduced to achieve smaller size, then the volume is improved, but the resistance varies due to variations in the first distance d
Solution Approach 1:
The patent transforms the design parameter from absolute distance d to the ratio d/ed. This allows the thermistor element to be miniimized by reducing d while maintaining resistance consistency through the ratio constraint. The number of internal electrodes is also used as a可调 parameter to further control the resistance contribution from the external electrode connection, providing additional freedom to reduce size without sacrificing reliability.
Solution Approach 2:
The patent segments the resistance path into multiple components: resistance between external electrode and outermost internal electrode, resistance between adjacent internal electrodes, and resistance through the body. By controlling the ratio d/ed and the number of internal electrodes, the invention segments and balances these resistance contributions, ensuring that the external electrode connection resistance remains a small, controlled portion of the total resistance, thus maintaining consistency even in miniaturized designs.
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 design stabilizes the resistance across different products, preventing variations caused by dimensional changes in external electrodes and ensuring reliable performance, even in small-size and low-profile thermistor elements.
Implementation Method 1
the resistance between the outermost internal electrode and the other external electrode varies from one product to another, and as a result, the thermistor element resistance varies from one product to another
Data Source
AI summary
A thermistor element satisfies 4≤(d/ed) when a first distance is d, which is a shortest distance between a first internal electrode and a second external electrode, whereas a second distance is referred to as ed, which is a shortest distance between the first internal electrode and a fifth internal electrode, in a cross section of a body including an L direction and a T direction thereof.