Inductive-Capacitive Touch Force Sensing With Shared Resonance
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Solution Overview
Problem
Conventional touch force sensors face challenges in accurately detecting touch location and force due to low precision and increased hardware costs, particularly when using inductive sensors alone or in combination with other sensors, and struggle with rapid detection and power consumption in multi-channel configurations.
Innovation Solution
A touch force sensor system that independently operates capacitive and inductive sensors to detect touch location and force, using a shared reference resonant circuit to reduce hardware costs and power consumption, and enables simultaneous detection without varying frequency components, allowing for precise and rapid recognition of touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an inductive sensor is used alone to detect touch force, then the sensor structure is simple, but the precision of sensing touch location and touch force is low
Solution Approach 1:
The patent combines capacitive sensing and inductive sensing into a single integrated sensor structure. The capacitive sensor detects touch location through capacitance changes, while the inductive sensor detects touch force through inductance changes. This merging of two sensing mechanisms resolves the contradiction by achieving high precision in both touch location and touch force detection without requiring separate sensor systems.
2Measurement precision
If an inductive sensor is combined with another sensor to separately detect touch force and touch location, then the precision of sensing is improved, but hardware cost increases
Solution Approach 1:
The patent integrates capacitive and inductive sensing functions within a single sensor module structure. The capacitive electrode and inductive coil are positioned in overlapping regions, allowing both sensing mechanisms to share the same physical space and structural components. This merging approach achieves high precision sensing while avoiding the need for separate sensor systems, thereby controlling hardware costs.
Solution Approach 2:
The sensor module is designed to perform multiple sensing functions simultaneously - capacitive sensing for touch location detection and inductive sensing for touch force detection. This multi-functionality is achieved within a single integrated structure, eliminating the need for multiple separate sensors and reducing overall hardware cost while maintaining high measurement precision.
3Measurement precision
If touch sensors are densely arranged to recognize touch force for each minute area, then the detection coverage and precision are improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines capacitive and inductive sensing channels into a single integrated sensor unit that can detect both touch location and touch force simultaneously. This merging allows dense arrangement of sensor units without proportionally increasing overall system complexity, as each unit is self-contained and handles multiple sensing functions independently.
4Ease of manufacture
If a shared reference resonant circuit is used to reduce hardware costs, then manufacturing cost is reduced, but signal interference may increase
Solution Approach 1:
The patent uses a shared reference resonant circuit for both capacitive and inductive sensing channels. This shared reference circuit provides a common baseline for sensing operations, reducing hardware complexity and manufacturing cost. The design ensures that the shared reference does not cause significant signal interference through proper circuit isolation and timing management.
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 system enhances precision and reliability of touch detection, reduces hardware costs, and minimizes power consumption, enabling efficient recognition of touch forces and gestures across multiple channels with reduced sensing time.
Implementation Method 1
an inductive coil disposed on a substrate that is spaced apart from the first part; a first inductive channel resonant circuit coupled to the inductive coil, and configured to have a first inductive resonant frequency attributable to a first inductance formed in the inductive coil based on the displacement of the first part relative to the inductive coil
Implementation Method 2
a first capacitive channel resonant circuit connected to a touch electrode disposed in a contact portion with which a finger comes into contact
Implementation Method 3
a first oscillator configured to apply a first alternating current (AC) signal to the first capacitive channel resonant circuit; a second oscillator configured to apply a second AC signal to the first inductive channel resonant circuit
Implementation Method 4
a first capacitive channel resonant circuit connected to a touch electrode disposed in a contact portion with which a finger comes into contact; a first inductive channel resonant circuit coupled to the inductive coil, and configured to have a first inductive resonant frequency
Data Source
AI summary
A touch force sensor includes a reference resonant circuit, a first resonant circuit coupled to an inductive coil, a second resonant circuit connected to a touch electrode, and further includes a determination circuit configured to obtain a first resonant frequency attributable to a first inductance formed in an inductive coil and a first resonant circuit based on a displacement between a target and the inductive coil formed by an external force input in a Z-axis direction, the second resonant frequency of a second resonant circuit attributable to a capacitance varying depending on whether a finger comes into contact with the touch electrode, and information about a reference resonant frequency.