Capacitive Sensor Circuit for Fast Mode-Switch Movement Detection
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Solution Overview
Problem
Capacitive sensor systems face long settling times when switching from touch to movement detection, which is not acceptable for real-time signal processing in practical applications.
Innovation Solution
A sensor system with a capacitive touch sensor and a capacitive movement sensor, where a signal path connected to a predetermined fixed electric potential via an electric resistance R_BYPASS is used to reduce the settling time of the movement sensor by stabilizing the parasitic capacitance during mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor system switches from touch sensor mode to movement sensor mode, then movement detection capability is activated, but the output signal has a long settling phase lasting several seconds
Solution Approach 1:
The patent applies preliminary action by maintaining the touch sensor in a standby state before mode switching, keeping its electrodes and associated circuits powered and stabilized. When switching to movement sensor mode, the previously stabilized electrical conditions are already in place, eliminating the need for a lengthy settling phase and enabling immediate movement detection.
Solution Approach 2:
The patent uses an intermediary approach by maintaining the touch sensor circuitry as an active intermediary component during mode transitions. The touch sensor's electrodes and readout circuit remain powered and stabilized, serving as a bridge that prepares the electrical environment for movement sensor operation, thereby reducing settling time without requiring complete circuit shutdown and restart.
2Productivity
If the touch sensor and movement sensor are operated simultaneously, then both contact and movement can be detected at the same time, but the system complexity increases
Solution Approach 1:
The patent merges the touch sensor and movement sensor into a single integrated sensor device with shared electrodes and readout circuitry. This combination allows both contact and movement detection to occur simultaneously using the same physical components, achieving high detection speed without proportionally increasing system complexity.
Solution Approach 2:
The patent implements multi-functionality by designing the sensor device to perform both touch detection and movement detection functions using the same sensor electrodes and associated circuits. The system can operate in different modes (touch-only, movement-only, or both simultaneously) by configuring the readout circuitry accordingly, maximizing productivity without requiring separate dedicated hardware for each function.
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 significantly reduces the settling time of the movement sensor, allowing immediate detection of movements after mode switching, improves detection precision, and simplifies signal processing by minimizing noise and potential inaccuracies.
Implementation Method 1
at least one signal path connectable with a predetermined fixed electric potential is provided, which is parallel to a parasitic capacitance of the first sensor device
Data Source
Figure 1~2
Figure 3a~3b
AI summary
Provided is a sensor system (1) comprising a first sensor device (10) and a second capacitive sensor device (20) for detecting a movement of the object relative to a detection surface, wherein the sensor system may be operated in a first mode of operation and in a second mode of operation, wherein the sensor system may be switched over from the first mode of operation into the second mode of operation, wherein the second capacitive sensor device (20) comprises a number of second sensor electrodes (21), and wherein in the sensor system at least in the second mode of operation at least one signal path (GND, RBYPASS, PIN) connectable with a predetermined fixed electric potential (GND) is provided, which is parallel to a parasitic capacitance (CPARA) of the first sensor device (10). Further provided is a method for reducing a settling time of the second capacitive sensor device (20) for detecting a movement of an object relative to the detection surface, wherein the second capacitive sensor device is part of the sensor system (1) according to the invention, wherein at least in the second mode of operation in the sensor system the at least one signal path (GND, RBYPASS, PIN) is connected with a predetermined fixed electric potential (GND), wherein the signal path is parallel to the parasitic capacitance (CPARA) of the first sensor device.