Battery Charging Interrupt for Capacitive Touch Noise
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Solution Overview
Problem
Capacitive touch interfaces in electronic devices are susceptible to common mode noise from aftermarket AC/DC power supplies, leading to erratic operation and false touch inputs, especially when these devices are charged or powered by non-manufacturer-approved power sources.
Innovation Solution
Implementing a battery charging interrupt mechanism that detects excessive common mode noise and temporarily isolates the charging circuit from the power source when a user contacts the capacitive touch interface, thereby reducing noise interference and maintaining reliable touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an AC/DC power supply is used to charge the battery, then the battery charging function is enabled, but common mode noise is introduced that causes display jitter and false touch inputs
Solution Approach 1:
A noise detection circuit is introduced as an intermediary between the power supply and the capacitive touch interface. This circuit monitors the common mode noise level and triggers an interrupt when noise exceeds a threshold, effectively mediating the harmful interaction between the power supply and the touch interface by detecting and responding to the noise condition.
Solution Approach 2:
The noise detection and interrupt generation functionality is extracted as a separate circuit module from the main capacitive touch interface. This allows the noise detection operation to be performed independently, enabling the system to identify and respond to noise conditions without interfering with the normal touch sensing operations.
2Adaptability or versatility
If a capacitive touch interface is implemented, then user interaction capability is enhanced, but the interface becomes susceptible to electrical noise causing erratic operation
Solution Approach 1:
A feedback mechanism is implemented where the noise detection circuit continuously monitors the capacitive touch interface for noise conditions and feeds back this information by generating interrupts when noise thresholds are exceeded. This feedback loop enables the system to dynamically respond to noise conditions and maintain reliable operation by interrupting noisy periods.
Solution Approach 2:
The noise detection circuit performs preliminary detection of common mode noise before it can significantly degrade touch interface performance. By detecting noise conditions in advance and generating interrupts proactively, the system takes preliminary anti-action to prevent erratic operation and false touch inputs before they occur.
Data Source
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AI summary
In embodiments of battery charging interrupt, a device (102) includes a capacitive touch interface (104), a battery (110), and a charging circuit (108) that charges the battery when the device is coupled to a power supply (114). A touch detection system (106) detects a conductive contact on the capacitive touch interface of the device, and the touch detection system determines a level of noise on the capacitive touch interface. The level of noise may increase due to the conductive contact on the touch interface while charging the battery. A device controller (126) determines a charge level of the battery. The device controller can then interrupt charging the battery when the level of the noise exceeds a noise level threshold (128) and when the charge level of the battery exceeds a minimum charge level.