Capacitive Force Touch Sensing via Housing Plate Integration
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Solution Overview
Problem
Existing touch screen devices that sense force touch using piezoresistive materials face limitations such as inability to detect pressures equal to or greater than a threshold value, increased electrode channels leading to longer data processing times, and vulnerability of the touch screen panel to external impacts.
Innovation Solution
An electronic device that senses force touch by detecting capacitance variations between touch electrodes and a conductive housing plate, eliminating the need for a separate force sensing panel and enhancing touch sensitivity through a design that includes a display module with touch electrodes, a conductive housing, and a driving circuit to process capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoresistive sensing electrodes are used to detect force touch, then force touch sensing capability is provided, but the device cannot sense force touch when pressure is equal to or more than a threshold value
Solution Approach 1:
The patent changes the sensing parameter from resistance (piezoresistive) to capacitance. The driving circuit senses force touch by detecting capacitance variation between the touch electrode and housing plate, which occurs due to distance change caused by touch pressure. This capacitance-based sensing method enables continuous detection across the full pressure range without saturation.
2Device complexity
If touch screen panel is disposed on display panel, then integrated design is achieved, but the touch screen panel can be damaged by external impact
Solution Approach 1:
The patent merges the force sensing function into the existing display module structure. The touch electrodes are formed on the rear surface of the display module, and the housing plate serves dual purposes as both structural support and sensing electrode. This integration eliminates the need for a separate force sensing panel while maintaining protection against external impacts.
Solution Approach 2:
The housing plate is designed to serve multiple functions: it acts as the rear cover of the device, provides structural support, and functions as the sensing electrode for force touch detection. This multi-functionality reduces the number of separate components needed while enhancing the overall robustness of the device.
3Measurement precision
If touch screen devices use separate force sensing panel, then force touch detection is enabled, but data processing time increases
Solution Approach 1:
The patent combines the touch sensing and force sensing functions into a single integrated system. The same touch electrodes and driving circuit used for touch detection are utilized for force touch sensing by detecting capacitance variation. This eliminates the need for separate processing channels, thereby reducing data processing time while maintaining full force touch detection capability.
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 accurate detection of force touch pressures without a separate force sensing panel, reduces data processing time, and protects the display panel from external impacts by using a capacitance-based sensing mechanism.
Implementation Method 1
a driving circuit sensing variation in capacitance between one or more of the touch electrodes and the housing plate, caused by a change in distance between said one or more of the touch electrodes and the housing plate
Data Source
AI summary
An electronic device comprises a display module including a plurality of touch electrodes, a cover window covering a front surface of the display module, a housing including an electrically conductive housing plate disposed below a rear surface of the display module and a housing side wall surrounding at least a portion of a side surface of the display module or supporting the display module, and a driving circuit sensing variation in capacitance between one or more of the touch electrodes and the housing plate, caused by a change in distance between said one or more of the touch electrodes and the housing plate.