Stabilizing Sensor Distance with Low Expansion Material
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Solution Overview
Problem
Existing systems for determining relative positions using a transmitter and sensor unit face challenges in maintaining high precision due to environmental influences and aging phenomena, such as thermal expansion of substrates, which can alter the sensor distance and affect measurement accuracy.
Innovation Solution
A system with a sensor unit comprising a first and second sensor spaced apart, utilizing a component made of dimensionally stable and aging-resistant material with a thermal expansion coefficient of 0 to 5×10^-6 K^-1, allowing for precise determination of sensor distance, either through measurement-based methods or pre-determined values stored in the control and evaluation unit, to maintain consistent sensor spacing despite temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensors are attached to a substrate (e.g., printed circuit board), then the sensor unit can be manufactured with standard techniques, but the substrate expands due to thermal effects, changing the sensor distance and reducing measurement precision
Solution Approach 1:
The system separates the sensor mounting function from the measurement reference function. Sensors are mounted on a substrate for ease of manufacture, but the sensor distance is determined independently using a separate component with a scale (ruler) that is not affected by substrate thermal expansion. This segmentation allows standard manufacturing techniques while maintaining measurement precision.
Solution Approach 2:
A component with a scale (ruler) acts as an intermediary between the sensors and the measurement process. This scale provides a stable reference for determining sensor distance that is independent of the substrate's thermal expansion. The scale serves as a mediator that transfers the measurement function from the thermally sensitive substrate to a thermally stable reference.
2Ease of manufacture
If the sensor distance is determined before assembly, then the manufacturing process is simplified, but environmental influences and aging can change the sensor distance during operation, affecting measurement accuracy
Solution Approach 1:
The system transitions from a static pre-determined sensor distance to a dynamic determination process. The sensor distance is not fixed during manufacturing but is continuously or periodically determined during operation using the scale component. This dynamic approach allows the system to adapt to environmental changes and aging effects, maintaining reliability despite operational conditions.
Solution Approach 2:
The system performs self-calibration by using its own sensors to detect the scale and determine the sensor distance autonomously. No external calibration equipment or manual adjustment is needed during operation. The system services itself by continuously monitoring and determining its own geometric parameters, ensuring reliability without additional complexity.
3Measurement precision
If a component with high dimensional stability and low thermal expansion coefficient is used, then the sensor distance remains stable under thermal influences, but the cost and complexity of the system increases
Solution Approach 1:
The system applies high dimensional stability locally only where needed - specifically in the scale component that defines the reference length, not throughout the entire sensor unit. The substrate can remain a standard, thermally sensitive material, while only the critical measurement reference (the scale) uses dimensionally stable material. This local application of quality reduces overall system complexity and cost.
Solution Approach 2:
The system uses a composite structure combining a standard substrate (for ease of manufacture) with a dimensionally stable scale component (for measurement precision). These two components with different material properties work together, with the scale component compensating for the substrate's thermal expansion. This composite approach allows the system to benefit from both standard manufacturing and high precision without requiring the entire structure to be made from expensive, dimensionally stable materials.
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
Enables high-precision relative position determination by stabilizing the sensor distance, reducing the impact of thermal expansion and aging on measurement accuracy, and allowing for precise sensor distance determination at any time during measurement, even in the presence of environmental influences.
Implementation Method 1
Environmental influences and/or aging phenomena can cause a change in the distance between the sensors in such sensor units. Such an environmental influence can be, for example, the effect of heat, which leads to an expansion of the substrate, the extent of which depends on the coefficient of thermal expansion (CTE for short) of the substrate material.
Implementation Method 2
The sensor unit has a first sensor (6a) and at least one additional, second sensor (6b) for detecting sensor elements (3c).
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
System (100) for determining relative positions, comprising a sensor (3) with sensor elements (3c) and a sensor unit (4) with a first sensor (6a) and at least one second sensor (6b,c). The sensor unit (4) and the sensor (3) are movable relative to each other, and their relative positions can be determined by the system (100). The first sensor (6a) and second sensor (6b) are separated by a sensor distance (d). The system (100) further comprises a component (5) made of a dimensionally stable and age-resistant material with a coefficient of thermal expansion ranging in magnitude from 0 to 5 × 10⁻⁶ K⁻¹. The sensor distance (d) can be determined with high precision by the component (5) by using the component (5) to fix the position of the sensors (6a-c) or by the component (5) having a scale (15) on the basis of which the sensor distance (d) can be measured.