Flexible Dielectric Position Sensor for High-Sensitivity Force Detection
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Solution Overview
Problem
Existing position detecting sensors using the cross-point capacitive sensing system face challenges in detecting indicators with high sensitivity due to small capacitance changes and limited noise margin, and are unable to accurately detect pressing force, especially when users wear gloves or use non-conductive materials.
Innovation Solution
A position detecting sensor with flexible conductors and a dielectric member that changes the abutting area between conductors upon pressing, causing a significant change in capacitance, allowing for sensitive and accurate detection of both position and pressing force, regardless of the indicator's conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cross-point capacitive sensing system is used to detect indicator position, then the sensor can detect position changes, but the capacitance change is small and the noise margin is limited, resulting in low detection sensitivity
Solution Approach 1:
The patent changes the physical state of the dielectric member from rigid to flexible, allowing it to deform under indicator pressure. This parameter change enables the abutting area between the dielectric member and conductors to vary dynamically, producing significant capacitance changes (from 0.01 pF to 0.1 pF or more) that exceed noise margins and achieve high detection sensitivity
Solution Approach 2:
The patent introduces flexibility to the dielectric member, transforming the static capacitor structure into a dynamic one. The flexible dielectric member deforms in response to indicator pressure, continuously changing the abutting area and capacitance value. This dynamic behavior enables the sensor to detect both position and pressing force with high sensitivity, overcoming the limitations of rigid dielectric structures
2Measurement precision
If conventional capacitive sensing is used, then position detection is possible, but pressing force cannot be accurately detected
Solution Approach 1:
The patent makes the flexible dielectric member serve multiple functions: it acts as both the dielectric material and the pressure-sensitive element. The same component that maintains the capacitor structure also deforms under pressure to change the abutting area, enabling simultaneous detection of position and pressing force without adding separate sensing mechanisms
Solution Approach 2:
The patent utilizes the change in physical state of the flexible dielectric member (from relaxed to deformed) to encode pressing force information. The degree of deformation, which varies with pressing force, directly changes the abutting area and capacitance value, enabling accurate pressing force detection through capacitance measurement
3Adaptability or versatility
If rigid dielectric members are used in capacitive sensors, then the sensor structure is stable, but the sensor cannot detect pressing force or work effectively with non-conductive indicators
Solution Approach 1:
The patent changes the dielectric member from rigid to flexible, allowing it to adapt its shape and abutting area in response to various indicator types. This flexibility enables the sensor to work with non-conductive indicators (like gloves or styluses) by detecting the mechanical deformation caused by their pressure, maintaining reliability while expanding adaptability
4Productivity
If the abutting area between dielectric member and conductor is fixed, then the sensor structure is simple, but the capacitance change range is limited
Solution Approach 1:
The patent transforms the fixed abutting area into a dynamic one by making the dielectric member flexible. The abutting area now varies with indicator pressure, enabling the capacitance to change over a wide range (from 0.01 pF to 0.1 pF or more). This dynamic adjustment of the abutting area significantly increases the capacitance change dynamic range without requiring complex additional components
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 sensor achieves high sensitivity and accuracy in detecting positions and pressing forces, even with non-conductive indicators, and operates effectively even when users wear gloves, enhancing the dynamic range of capacitance change.
Implementation Method 1
one surface of the dielectric member having flexibility abuts the plurality of first conductors or the plurality of second conductors... The abutting area between the surface of the dielectric member having flexibility and the plurality of second conductors or the plurality of first conductors is changed when the plurality of first conductors are pressed... causing a change in the capacitance between the plurality of first conductors and the plurality of second conductors
Data Source
AI summary
A position detecting sensor is configured by providing a dielectric member having flexibility between first conductors and second conductors and providing spacers for separating the first conductors or the second conductors from the dielectric member by a determined gap. When a pressing force is applied by an indicator (e.g., a finger or a pen) on the position detecting sensor, the first conductor and the second conductor come to abut each other, with the dielectric member interposed therebetween. Further, an abutting area (contact area) between the dielectric member and the conductor changes (e.g., increases) according to the pressing force applied by the indicator. Thus, capacitance of the capacitor formed between the first conductor and the second conductor is largely changed, to allow detection of a position indicated by the indicator as well as the pressing force applied at the indicated position with high sensitivity and high accuracy.