Linear Projected Single-Layer Capacitance Sensor Design
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Solution Overview
Problem
Traditional touch sensor technologies, such as projected capacitance sensors, require multiple conductive planes which are expensive to manufacture, and existing touchpad systems rely on complex electrode configurations and multiple measurements to determine object position, limiting cost-effectiveness and sensitivity.
Innovation Solution
A touch sensor system using a single plane of parallel drive electrodes driven at one or both ends, with adjacent electrodes connected to a sense amplifier and ADC to determine object position through self-capacitance and mutual capacitance methods, measuring current or voltage changes to calculate finger position using ratiometric equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional projected capacitance sensors use multiple conductive planes, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the second conductive plane from the traditional two-plane capacitance sensor structure, retaining only the single top conductive plane. This reduction in structural complexity directly lowers manufacturing costs while the patent compensates for the lost plane through innovative signal processing methods that analyze capacitance changes along the length of individual electrodes, maintaining position detection precision without requiring multiple conductive layers.
Solution Approach 2:
The patent makes the single conductive plane perform multiple functions: it serves as both the drive electrode and the sense electrode. By driving electrodes from one or both ends and sensing on the same electrodes, the system achieves position detection capability that traditionally required separate drive and sense planes, thereby reducing manufacturing complexity while preserving measurement precision.
2Measurement precision
If traditional touchpad systems use complex electrode configurations with multiple measurements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the electrode array into multiple independent drive electrodes that can be driven individually from one or both ends. Each electrode or group of electrodes is independently controlled and sensed, allowing the system to determine object position by analyzing the capacitance changes across multiple segmented electrodes. This segmentation enables precise position determination while simplifying the control architecture compared to traditional grid-based systems requiring multiple complete measurement cycles.
Solution Approach 2:
Instead of using a traditional grid of orthogonal X and Y electrodes requiring four measurement cycles to determine position, the patent inverts the approach by using linear electrode arrays that can be driven from both ends. This inversion allows position to be determined through simpler single-end or dual-end driving schemes, reducing the number of measurement cycles and overall system complexity while maintaining or improving position determination accuracy.
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
This approach reduces manufacturing costs, enhances sensitivity, and improves resolution by eliminating the need for multiple conductive planes while maintaining high precision in determining object position, suitable for both single and multi-finger detection.
Implementation Method 1
The touch sensor system uses self-capacitance and mutual capacitance methods to determine object position
Implementation Method 2
The touch sensor system uses self-capacitance and mutual capacitance methods to determine object position
Data Source
AI summary
A touch sensor having a plurality of parallel drive electrodes that are being electrically driven, providing stimulus on one end or simultaneously on both ends, thus creating a linear or varying electric field across the length of the drive electrodes, wherein adjacent sensor electrodes are connected to a sense amplifier and analog-to-digital (ADC) converter to determine the position of an object that comes near to the drive and/or sense electrodes, wherein the system uses self-capacitance and measures the amount of current driven by each driver, wherein the system uses a mutual capacitance current divider in a first method by driving an electrode with a time varying voltage and measuring induced currents at each end of an adjacent sense electrode and using ratiometric equations to determine finger position, and using a mutual capacitance voltage divider in a second method.