Touch Sensor Pressure Detection via Capacitance Change
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Solution Overview
Problem
Current touch sensor panels can only detect touch and position on a surface but not the magnitude of pressure applied, limiting their functionality in computing systems.
Innovation Solution
A touch sensor panel design incorporating a first electrode, a second electrode, and a spacer layer, where the electrodes are spaced apart to detect changes in capacitance caused by external pressure, allowing for the measurement of pressure magnitude through changes in distance between the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional touch sensor panel is used, then the touch and position can be detected, but the magnitude of pressure cannot be detected
Solution Approach 1:
The patent combines the touch detection function and pressure magnitude detection function into a single integrated sensor structure. The first and second electrodes form a capacitive sensing element that simultaneously detects both touch presence/position and pressure magnitude through capacitance changes, eliminating the need for separate pressure sensing mechanisms.
Solution Approach 2:
The patent utilizes changes in capacitance parameter in response to varying pressure magnitudes. As pressure increases, the distance between the first and second electrodes changes, causing measurable capacitance variations that directly correlate with pressure magnitude, enabling quantitative pressure detection without additional components.
2Measurement precision
If the electrodes are placed close together to detect pressure, then pressure sensitivity increases, but the risk of short circuit increases
Solution Approach 1:
The patent introduces a spacer layer as an intermediary component positioned between the first and second electrodes. This spacer maintains a controlled distance between the electrodes, preventing direct contact and short circuits while still allowing capacitance changes to occur in response to pressure, thus balancing sensitivity and reliability.
Solution Approach 2:
The spacer layer functions as a thin film structure that provides mechanical separation between the electrodes. This thin film maintains the necessary gap to prevent short circuits while being sufficiently compliant to allow electrode deformation under pressure, enabling capacitance-based pressure detection without electrical failure.
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 the detection of touch, position, and pressure magnitude on a touch sensor panel, enhancing the functionality of touch input devices by utilizing capacitance changes to quantify pressure applied.
Implementation Method 1
The mutual capacitance between the first electrode and the second electrode changes according to a distance between the first electrode and the second electrode
Data Source
AI summary
In one embodiment, a touch sensor includes a first electrode, a second electrode, and a spacer layer located between the first electrode and the second electrode. One of the first electrode and the second electrode is a drive electrode to which a drive signal is applied. The other one of the first electrode and the second electrode is a receiving electrode that receives the drive signal by a mutual capacitance between the first electrode and the second electrode. When an external pressure is applied to the first electrode through a display, the first electrode is concavely bent toward the second electrode. The mutual capacitance between the first electrode and the second electrode changes according to a distance between the first electrode and the second electrode. The magnitude of the external pressure according to the change of the capacitance between the first electrode and the second electrode is detected.