Capacitive Voltage Divider Touch Sensor With Self-Referenced Measurement
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Solution Overview
Problem
Existing touch and proximity sensors face challenges in efficiently measuring and detecting changes in capacitance with complex designs and a high number of components, necessitating simplified methods for capacitance measurement in microcontroller applications.
Innovation Solution
A system comprising a measurement circuit with reference capacitors and pads connected to a microcontroller, which applies reference voltages and grounds to nodes, allowing for automated voltage application and measurement across capacitive sensors to determine capacitance values, enabling efficient detection of touch or proximity events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitance measurement methods are used, then capacitance detection is achieved, but device complexity and component quantity increase
Solution Approach 1:
The patent combines the reference capacitor and measurement capacitor into a single capacitive divider circuit. The first capacitor (reference) and second capacitor (sensor) are connected in series between a reference voltage and ground, forming an integrated voltage divider that eliminates the need for separate reference capacitor circuits and reduces overall component count while maintaining measurement accuracy.
Solution Approach 2:
The capacitive divider circuit serves multiple functions simultaneously: it provides reference voltage division, enables capacitance measurement through voltage ratio comparison, and allows for both absolute and relative capacitance sensing. The same circuit topology handles both the reference and measurement functions, reducing device complexity.
2Measurement precision
If traditional capacitance measurement methods are used, then capacitance detection is achieved, but component quantity increases
Solution Approach 1:
The patent merges the reference capacitor and measurement capacitor into a single series-connected capacitive divider. This integration reduces the total component count by eliminating redundant capacitors and associated circuitry found in traditional separate reference and measurement circuits.
Solution Approach 2:
The capacitive divider circuit uses itself as the reference standard. By comparing the voltage division ratio across the two capacitors, the system performs self-referenced measurement, eliminating the need for external reference capacitors or additional calibration components.
3Device complexity
If voltage ratio comparison method is used, then capacitance measurement is simplified, but measurement precision may be affected
Solution Approach 1:
The system incorporates feedback through the capacitive divider configuration where the voltage ratio automatically adjusts based on the capacitance values. The measurement process uses the natural voltage division feedback to determine capacitance ratios, providing both simplicity and precision through the self-regulating nature of the capacitive divider.
Solution Approach 2:
The patent measures capacitance by observing changes in voltage parameters rather than directly measuring capacitance. By applying a known reference voltage and measuring the resulting voltage division ratio across the capacitors, the system translates capacitance values into measurable voltage parameters, simplifying the measurement process while maintaining accuracy through precise voltage ratio comparison.
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 solution simplifies capacitance measurement, reduces component requirements, and effectively detects changes in capacitance, enabling reliable operation of touch and proximity sensors in various applications with reduced complexity and cost.
Implementation Method 1
The first capacitor and the second capacitor form a capacitive divider between the reference voltage and ground
Data Source
AI summary
A system for measuring capacitance has a measurement circuit with a first reference capacitor connected to a first node and to a second node. Each of the nodes is connected to a unit operable to apply a reference voltage or ground to one of the nodes. Each node has a first pad connected to the first node and a unit operable to measure voltage between the first node and second node.