Inducing Capacitance Detector Circuit for High-Sensitivity Position Tracking
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Solution Overview
Problem
Capacitive position detectors require high-resolution A/D conversions, increasing complexity and manufacturing costs, and are limited in sensitivity due to large detector loads compared to human finger capacitance, making them unsuitable for large-sized human-machine interfaces.
Innovation Solution
The inducing capacitance detector employs a capacitive sensor array with sensor and reference resistors, operational amplifiers, and feedback capacitors to produce output signals that are independent of individual capacitor values, enhancing sensitivity and reducing the need for high-resolution conversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution A/D conversions are used in capacitive position detectors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the conventional A/D conversion-based detection method with an inducing capacitance measurement method. Instead of using high-resolution A/D converters to measure small capacitance changes, the invention uses an operational amplifier to amplify the inducing capacitance signal directly, substituting complex digital conversion circuitry with a simpler analog amplification approach that achieves the same measurement precision.
Solution Approach 2:
The patent introduces an operational amplifier as an intermediary element between the capacitive sensor and the output. This intermediary amplifies the inducing capacitance signal before it reaches the output stage, allowing for precise position detection without requiring high-resolution A/D conversion circuitry, thus reducing overall device complexity while maintaining measurement precision.
2Stability of the object's composition
If detector load is made much larger than induced capacitance of human finger, then stability is improved, but sensitivity deteriorates
Solution Approach 1:
The patent employs feedback through the operational amplifier circuit to dynamically adjust the detection sensitivity. The feedback mechanism allows the system to maintain stability while being highly responsive to small inducing capacitance changes from human finger contact, effectively decoupling the stability-sensitivity trade-off that plagues conventional designs with fixed detector loads.
Solution Approach 2:
The patent transitions from a static detector load configuration to a dynamic detection system using operational amplifiers. The amplifier gain can be adjusted to optimize sensitivity for different operating conditions, allowing the system to maintain both stability and high sensitivity to inducing capacitance changes, unlike fixed load configurations where increasing stability necessarily reduces sensitivity.
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 configuration improves sensitivity and reduces complexity, enabling effective position detection in large-sized human-machine interfaces by amplifying the output signal based on inducing capacitance rather than individual sensor capacitances.
Implementation Method 1
The capacitive position detector integrates the detector load and the capacitance of human finger as a compound variable to perform hierarchical signal triggering. The location of the contact point is detectable by a controller that measures a change in a capacitively coupled electrical signal at the touch location.
Implementation Method 2
A finger touch to the sensor provides a capacitive couple from the conductive layer to the body.
Data Source
AI summary
One aspect of the present invention relates to an inducing capacitance detector. In one embodiment, the inducing capacitance detector has an input terminal for receiving a supply voltage; a capacitive sensor array with a first output terminal and a second output terminal; an operational amplifier having an inventing input terminal electrically connected to the first output terminal of the capacitive sensor array, a non-inventing input terminal electrically connected to the second output terminal of the capacitive sensor array and the input terminal, and an output terminal for outputting an output signal, a feedback capacitor electrically connected between the inventing input terminal and the output terminal of the operational amplifier.