Capacitive Hover Detection Circuit With Adaptive Drive Amplitude
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing capacitive detection devices face challenges in achieving accurate hover and touch detection without a touch panel, as they require high drive voltages and large electrodes, leading to potential signal saturation and capacitive coupling issues that degrade detection accuracy.
Innovation Solution
A detection device with a sensor circuit, peripheral and shield electrodes, and a control circuit that dynamically adjusts the amplitude of drive signals based on sensing data, using a drive signal generation circuit to generate sinusoidal waveforms and a control circuit to manage the amplitude, thereby improving hover and touch detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high drive voltage and large electrode size are used to improve hover detection sensitivity, then hover detection accuracy is improved, but signal saturation occurs during touch detection
Solution Approach 1:
The drive signal amplitude is dynamically adjusted based on the detected state. During hover detection, a larger amplitude is used to capture minute capacitance changes, while during touch detection, the amplitude is reduced to prevent signal saturation. This dynamic adaptation allows the system to optimize performance for each detection mode without compromising reliability.
Solution Approach 2:
The patent changes the amplitude parameter of the drive signal according to the detection mode. By varying this electrical parameter, the system achieves high sensitivity for hover detection while avoiding saturation during touch detection, thus resolving the contradiction between measurement precision and reliability.
2Measurement precision
If high drive voltage is used to improve hover detection sensitivity, then capacitive coupling between adjacent electrodes deteriorates detection accuracy
Solution Approach 1:
The drive signal amplitude is dynamically controlled to be larger during hover detection to enhance sensitivity, and reduced during touch detection to minimize capacitive coupling interference. This temporal separation of amplitude levels allows the system to achieve high sensitivity when needed while suppressing harmful effects when they would otherwise degrade performance.
Solution Approach 2:
The system periodically switches between hover detection mode and touch detection mode, adjusting the drive signal amplitude accordingly. This periodic modulation of the drive signal characteristics allows the system to alternate between high sensitivity operation and low interference operation, effectively managing the capacitive coupling issue.
3Adaptability or versatility
If a touch panel is added to achieve both touch detection and hover detection, then detection functionality is improved, but device complexity and cost increase
Solution Approach 1:
The sensor electrodes serve dual purposes: they detect both hover states and touch states using the same physical structure. By making the detection system multi-functional, the patent eliminates the need for separate touch panel and hover detection panel structures, thereby reducing device complexity while maintaining versatile detection capabilities.
Solution Approach 2:
The patent merges the touch detection function and hover detection function into a single integrated sensor circuit. Instead of stacking separate panels, the same sensor electrodes perform both functions by dynamically adjusting detection parameters, thus simplifying the overall device structure while achieving comprehensive detection functionality.
4Measurement precision
If electrode size is increased to improve hover detection sensitivity, then capacitive coupling between adjacent electrodes increases
Solution Approach 1:
The drive signal amplitude is dynamically adjusted based on detection mode. During hover detection, the larger amplitude compensates for the capacitive coupling effect, allowing the use of larger electrodes to enhance sensitivity without being overly constrained by the coupling interference. During touch detection, the reduced amplitude minimizes the coupling effect.
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
The solution enhances detection accuracy by reducing signal saturation and capacitive coupling, allowing for precise hover and touch detection without a touch panel, while maintaining detection sensitivity and reducing errors.
Implementation Method 1
a capacitive detection device that detects proximity of an object by detecting changes in capacitance
Implementation Method 2
a drive signal generation circuit configured to generate a drive signal with a substantially sinusoidal waveform
Data Source
AI summary
According to an aspect, a detection device includes: a sensor circuit including a plurality of sensor electrodes provided to a substrate, a peripheral electrode provided around a detection region provided with the sensor electrodes, and a shield electrode provided to a surface opposite to a surface provided with the sensor electrodes and the peripheral electrode; an AFE circuit configured to generate sensing data corresponding to a distance between the sensor electrodes and a proximity object, based on a detection signal acquired from the sensor electrodes; a drive signal generation circuit configured to generate a drive signal with a substantially sinusoidal waveform and supply the drive signal to the peripheral electrode and the shield electrode; and a control circuit configured to control the AFE circuit and the drive signal generation circuit. The control circuit controls an amplitude value of the drive signal based on the sensing data.