Adaptive Touch Sensor Frequency Control for Charger Noise
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Solution Overview
Problem
Capacitive touch sensors in rechargeable devices are susceptible to noise interference from external battery chargers, which complicates design and reduces sensitivity due to varying noise spectra produced by different chargers.
Innovation Solution
A rechargeable touch screen device that identifies external battery chargers through interface information, wireless signal processing, and location inference, and adjusts its operating frequency to minimize noise interference by selecting a suitable frequency based on the charger and charge state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If switched mode power supply is used for external battery charger, then the charger becomes lighter and less expensive, but high frequency noise is produced that interferes with capacitive touch sensor operation
Solution Approach 1:
The patent applies dynamics by making the touch sensor's operating frequency adjustable rather than fixed. The system dynamically changes the operating frequency based on the detected charger type and battery charge state, allowing the touch sensor to adapt to varying noise spectra from different chargers and charging phases.
Solution Approach 2:
The patent changes the operating parameter (frequency) of the touch sensor based on external conditions. By detecting the charger's noise spectrum characteristics and the battery charge state, the system selects from multiple available frequencies to operate the touch sensor at a frequency that minimizes noise interference while maintaining functionality.
2Device complexity
If the touch sensor operates at a fixed high frequency, then the sensor design is simplified, but the noise spectrum from the charger overlaps with the sensor frequency reducing sensitivity
Solution Approach 1:
The system transitions from a static fixed-frequency design to a dynamic multi-frequency system. The touch sensor can switch between multiple operating frequencies based on the detected noise environment, maintaining simplified sensor hardware while improving measurement precision through adaptive frequency selection.
Solution Approach 2:
The operating frequency parameter of the touch sensor is made variable rather than fixed. The system selects from multiple available frequencies based on the charger's noise spectrum and battery charge state, thereby maintaining design simplicity while enhancing sensitivity by avoiding noisy frequency ranges.
3Adaptability or versatility
If the external battery charger varies switching frequency or pulse width to provide variable current, then different charge states are supported, but the noise spectrum changes making it unpredictable and harder to design noise-immune touch sensor
Solution Approach 1:
The system implements feedback by detecting the actual noise spectrum produced by the charger and the battery charge state, then using this information to select the appropriate operating frequency for the touch sensor. This closed-loop approach allows the system to adapt to variable noise conditions caused by different charging phases and charger configurations.
Solution Approach 2:
The touch sensor's operating frequency is dynamically adjusted in response to changing charging conditions. As the charger varies its switching frequency or pulse width to provide different current levels, the system detects these changes and switches the touch sensor to a frequency that avoids the current noise spectrum.
4Adaptability or versatility
If multiple different external chargers from different companies are used, then device compatibility is improved, but each charger produces a different noise spectrum that varies with battery charge state
Solution Approach 1:
The system achieves universality by being compatible with multiple different charger types while maintaining consistent performance. Through multi-frequency operation and adaptive frequency selection based on detected noise characteristics, the touch sensor can work effectively with any charger regardless of its specific noise spectrum, making the system universally compatible.
Solution Approach 2:
The system changes the operating frequency parameter to accommodate different charger noise spectra. By detecting the specific noise characteristics of each charger and selecting an appropriate frequency from available options, the system maintains compatibility with various chargers while avoiding their respective noise interference patterns.
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 device effectively reduces noise sensitivity by determining the specific noise spectrum of the connected charger and adjusting its operating frequency, enhancing touch sensor performance and reliability across different charging scenarios.
Implementation Method 1
In a capacitive touch sensor, a high frequency signal is successively applied to each of a set of conductive areas of the touch sensor. Contact or proximity of a person's finger to one of the conductive areas establishes or enhances a capacitive circuit which affects the amplitude of the high frequency signal applied to the conductive area.
Implementation Method 2
In a switched mode power supply, a circuit through a primary side of a transformer is interrupted by a switch operated at high frequency thereby inducing a current in the secondary side of the transformer.
Data Source
AI summary
A rechargeable touch sensor equipped device (102) is adapted to identify (1008) each of multiple external charging devices (118, 120, 122, 602) by an ID or other information received through an interface (230, 630) or to infer the identity (1020) based on location information derived from received wireless signals, the time and/or day. The rechargeable touch sensor equipped device (102) determines (1026) and records (1028) a touch screen operating frequency to be used when coupled to each external charging device (118, 120, 122, 602) at each battery charge state (or other indication of power draw) and in this way mitigates the adverse effect of variable charger generated noise on the operation of the touch screen.