Touchscreen Group Filtering for Accurate 3D Position Detection
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Solution Overview
Problem
Conventional touch screens face limitations due to channel coupling effects and body-induced background capacitance, leading to inaccurate finger position detection and multi-touch issues, especially in mobile devices with power and size constraints.
Innovation Solution
A single-layer touch panel with a highly sensitive capacitive sensing circuit and a bootstrapped-oscillator-based correlated double sampling (CDS) circuit, combined with a grouping filter, to reduce noise and accurately detect finger position and gestures remotely, overcoming ghost points and inter-channel coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 2D capacitive touch sensing is used, then multi-touch detection can be supported, but false detection and inaccurate finger position estimation occur due to channel coupling effects and body-induced background capacitance
Solution Approach 1:
The patent transitions from 2D capacitive touch sensing to 3D optical sensing by introducing a camera to capture depth information and finger position in three-dimensional space. This dimensional change allows the system to distinguish between actual touches and false signals caused by channel coupling, as the optical data provides independent verification of finger presence and position.
Solution Approach 2:
The patent introduces an intermediary processing system that combines data from both the 2D capacitive sensors and the 3D optical camera. This intermediary layer fuses the two data streams, using the optical information to filter and validate capacitive signals, thereby eliminating false detections while maintaining accurate multi-touch detection capability.
2Adaptability or versatility
If camera-based 3D touch detection is used, then remote finger position detection capability is achieved, but device power consumption and hardware size increase
Solution Approach 1:
The patent implements partial 3D optical sensing by using the camera only when needed for remote touch detection or gesture recognition, rather than continuously. The system switches between 2D capacitive mode for normal operation and 3D optical mode for enhanced functionality, thereby achieving remote detection capability while minimizing power consumption by activating the camera only during specific gestures or conditions.
3Volume of moving object
If device size is reduced for mobile applications, then portability is improved, but sensing accuracy deteriorates with shrinking device dimensions
Solution Approach 1:
The patent replaces the need for large physical sensing electrodes with optical sensing using a camera. This substitution allows accurate 3D position detection without requiring proportionally larger electrode arrays, enabling mobile devices to maintain high sensing accuracy while keeping the device compact and portable.
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 remote finger position detection and gesture recognition with improved sensitivity and reduced power consumption, addressing the limitations of traditional touch screens in mobile devices.
Implementation Method 1
A filter for background noise reduction and multi-touch position detection for contactless 3D touch sensing
Implementation Method 2
a bootstrapped-oscillator-based correlated double sampling (CDS) circuit
Data Source
AI summary
A low-cost single-layer mobile touch-screen is disclosed, including a highly sensitive capacitive sensing circuit, and a corresponding finger 3D position estimation and gesture recognition algorithms compatible with mobile device platforms and that can be readily programmed into the mobile device's application processor.