Capacitive Sensor Electrode Multiplexing for Multi-Object Detection
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Solution Overview
Problem
Capacitive sensor devices face challenges in accurately detecting the positions and distances of multiple objects due to complex field distortions, leading to systematic measurement errors and unreliable detection, especially when objects are close or far from the sensor surface.
Innovation Solution
The implementation of a sensor device with multiple electrode configurations and a time-multiplexing method, where only one transmitter electrode is active at a time, and auxiliary electrodes are used to reduce interference between electrode configurations, allowing for precise detection of object positions and distances by minimizing the influence of adjacent objects on active electrode configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmitter electrodes are active simultaneously, then the sensor can detect multiple objects in parallel, but measurement errors increase due to field distortion from multiple objects
Solution Approach 1:
The patent applies time multiplexing by activating transmitter electrodes sequentially in periodic cycles rather than simultaneously. Each transmitter electrode is activated for a specific time slot, allowing the system to detect multiple objects by alternating between them. This periodic activation eliminates mutual field distortion while maintaining the ability to detect multiple objects, resolving the contradiction between detection speed and measurement precision.
2Area of stationary object
If a large number of sensor electrodes are provided at short distances, then the sensor can detect objects at various positions, but the influence of other objects on measurement values increases
Solution Approach 1:
The patent divides the sensor surface into multiple electrode configurations, each with its own transmitter electrode. This segmentation allows the sensor to cover a large area while maintaining measurement reliability by isolating the electromagnetic fields of different regions. Each segmented electrode configuration can be activated independently through time multiplexing, reducing mutual interference and improving measurement reliability across the entire sensor surface.
3Reliability
If spatial separation of sensor devices is increased, then interference between objects is reduced, but the device complexity and space requirements increase
Solution Approach 1:
The patent merges multiple electrode configurations into a single integrated sensor device, with each configuration sharing common structural elements and control circuitry. By combining multiple electrode sets that can be independently activated through time multiplexing, the patent achieves reliable detection without requiring large spatial separations. This merging approach reduces device complexity while maintaining detection reliability through temporal rather than spatial isolation.
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 enables robust and precise determination of multiple object positions and distances, reducing interference and measurement errors, and can be applied in handheld devices like mobile phones and game controllers, simplifying the sensor design and production.
Implementation Method 1
applying an alternating electrical signal to one of the transmitter electrodes... generating an alternating electrical field extending from the one transmitter electrode into a detecting range of the sensor device
Implementation Method 2
capacitive sensor devices, capacitive conditions between a sensor surface and an object present in the detecting range of the sensor device are measured or detected. The object present in the detecting range distorts the alternating electrical field in the detecting range.
Data Source
AI summary
A sensor device for detecting a number of objects, has a number of electrode configurations forming a sensor surface, each electrode configuration having a number of measurement electrodes and each electrode configuration being associated with at least one transmitter electrode, and an evaluation device coupled to the measurement electrodes and the transmitter electrodes, which is adapted for using a time multiplexing method for applying an alternating signal to one of the transmitter electrodes, and to apply a predetermined constant electrical potential to the remaining transmitter electrodes, and tapping an electrical signal indicating the position of the object relative to the sensor surface at the measurement electrodes associated with the transmitter electrode having the electrical alternating signal applied.