Capacitive Touch Wake Circuit for Low-Power Button Sensing
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Solution Overview
Problem
Electronic devices with small and finite power sources, such as batteries, quickly consume power budgets and become non-functional due to high power consumption in existing power saving techniques.
Innovation Solution
A low-power touch button sensing system that uses a capacitance sensing circuit to detect the presence of a touch object and control a switch circuit to connect or disconnect the power supply to a processing device, minimizing power consumption by operating in idle states and activating only when a touch event is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processing device operates continuously to handle user interactions, then the device functionality is maintained, but the power consumption increases rapidly
Solution Approach 1:
The system dynamically transitions the processing device between active and idle states based on touch detection. The capacitance sensing circuit continuously monitors for touch events while the processing device remains in a low-power idle state, then activates the processing device only when a touch event is detected, optimizing the balance between functionality and power consumption
Solution Approach 2:
The capacitance sensing circuit periodically samples the capacitive electrodes to detect touch events. This periodic monitoring allows the system to maintain functionality by detecting user interactions while keeping the processing device in idle state between sampling periods, thereby reducing overall power consumption
2Use of energy by moving object
If the processing device enters idle state to save power, then power consumption is reduced, but the device cannot respond to touch events
Solution Approach 1:
The capacitance sensing circuit acts as an intermediary between the touch interface and the processing device. It continuously monitors for touch events in a low-power state and serves as a mediator that triggers the processing device to wake up only when necessary, ensuring both power savings and reliable touch event response
Solution Approach 2:
The capacitance sensing circuit performs preliminary monitoring of touch events before activating the processing device. By detecting touch events in advance while in idle state, the system prepares for upcoming processing needs, ensuring immediate response to user interactions while maintaining low power consumption during idle periods
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 system significantly reduces power consumption, allowing electronic devices to conserve energy and remain functional for longer periods by only powering the processing device when necessary, thus extending the battery life.
Implementation Method 1
The capacitance detected of the capacitive sense electrodes by a processing device may change as a function of the proximity of a touch object to the capacitive sense array
Data Source
AI summary
Systems, apparatus, and methods measure a signal provided by a capacitance sensor, the signal indicative of a presence of an object proximate to the capacitance sensor. Responsive to measuring the signal, embodiments access control information in a memory to determine whether the signal is associated with a first qualifying event of the control information. Responsive to determining that the signal is associated with the first qualifying event, embodiments control a power consumption of a communication device.