Capacitive Touch Sensing Surface Displacement Load Apportionment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional touch-sensitive input devices struggle to reliably distinguish between objects resting on the surface and those actively applying pressure, especially when multiple touches are involved, as variations in capacitance due to pressure changes are not sufficient to determine which object is intended to input a command.
Innovation Solution
A sensing apparatus comprising a capacitive sensor element mounted relative to a frame, with displacement sensing circuitry and processing circuitry to determine the net displacement load and apportion it to respective objects based on their locations, allowing for accurate identification of input commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensing is used to detect multiple touches, then the spatial positions of multiple simultaneous touches can be resolved, but it cannot reliably distinguish which object the user intended to use for input when too many touches are applied
Solution Approach 1:
The patent changes the measurement parameter from capacitive coupling alone to a combination of capacitive coupling and displacement measurements. By measuring both the capacitive signal and the physical displacement of the sensing surface at each touch location, the system can distinguish between resting fingers (minimal displacement) and active input fingers (significant displacement), thereby resolving the ambiguity in identifying which object the user intends to use for input.
2Ease of operation
If only capacitive coupling measurements are used, then the system can detect multiple touches, but variations in capacitance from pressure changes are not sufficient to reliably distinguish between objects resting on the surface and objects actively applying pressure
Solution Approach 1:
The patent makes the sensing surface multi-functional by integrating both capacitive sensing and displacement sensing capabilities into a single structure. The sensing surface serves simultaneously as a capacitive electrode and as a displacable element whose physical movement can be measured, eliminating the need for separate pressure sensors and providing both touch detection and pressure differentiation functions.
Solution Approach 2:
The system transitions from measuring only electrical parameters (capacitive coupling) to measuring both electrical parameters and mechanical parameters (displacement). This dual-parameter approach allows the system to differentiate between light resting touches and active pressing gestures by detecting the magnitude of physical displacement in addition to capacitive changes.
3Reliability
If the sensing surface is made more sensitive to pressure variations, then differentiation between resting and active fingers may be improved, but the complexity of the sensing system increases
Solution Approach 1:
The patent combines capacitive sensing and displacement sensing into a unified sensing system where both measurements are taken from the same sensing surface structure. This merging approach avoids the complexity of adding entirely separate pressure sensor systems, as the displacement measurement can be implemented using capacitive principles between the sensing surface and a reference electrode, thereby maintaining system simplicity while improving differentiation reliability.
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 precise determination of which object is applying the input command by calculating the centre of press location and apportioning the net displacement load, effectively addressing the ambiguity in multiple touch scenarios.
Implementation Method 1
capacitive sensing circuitry coupled to the capacitive sensor element and configured to determine locations for a plurality of objects capacitively coupled to the sensing surface
Implementation Method 2
displacement sensing circuitry coupled to the displacement sensor element and configured to determine changes in the displacement of the capacitive sensor element relative to the frame at a plurality of different locations due to displacement loads applied by the plurality of objects
Data Source
Figure 1~3
Figure 4~5
Figure 6~7B
AI summary
A sensing apparatus for determining relative amounts of force applied to a sensing surface at a plurality of locations, the sensing apparatus comprising: a capacitive sensor element comprising the sensing surface, wherein the capacitive sensor element is moveably mounted; a displacement sensor element for detecting changes in the displacement of the capacitive sensor element; capacitive sensing circuitry coupled to the capacitive sensor element and configured to determine locations for a plurality of objects capacitively coupled to the sensing surface; displacement sensing circuitry coupled to the displacement sensor element and configured to determine changes in the displacement of the capacitive sensor element at a plurality of different locations; and processing circuitry configured to determine a location at which a net displacement load acts on the sensing surface from the determined changes in displacement of the sensor element, and to establish relative amounts of the net displacement load on the determined locations.