Force Sensing Transducer Wakeup Circuit for Portable Devices
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Solution Overview
Problem
Portable electronic devices with touch-sensitive displays face significant power consumption issues due to periodic scanning required to detect touch events, especially in sleep modes, which reduces battery life.
Innovation Solution
A low power wakeup detection circuit that uses a combination of an accelerometer and force sensing transducers to detect inertial events and applied forces, allowing the touch-sensitive display to be activated only when a predetermined wake force threshold is exceeded, thereby reducing unnecessary power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the touch-sensitive display performs periodic scanning to detect touch events, then touch event detection capability is maintained, but power consumption increases significantly
Solution Approach 1:
The patent segments the detection function into two independent parts: a low-power force sensing transducer that continuously monitors for wake forces, and the full touch-sensitive display scanning system that activates only when needed. This segmentation allows the system to maintain touch detection capability while dramatically reducing power consumption during sleep mode by eliminating continuous full-display scanning.
Solution Approach 2:
The force sensing transducer performs preliminary detection of applied forces before the full touch-sensitive display scanning system is activated. When the transducer detects a force exceeding the wake threshold, it triggers the display to wake from sleep mode. This preliminary action eliminates the need for continuous scanning while ensuring rapid response to actual touch events.
2Ease of operation
If the touch-sensitive display remains active to detect touch events, then user interaction responsiveness is maintained, but battery life is reduced
Solution Approach 1:
The patent implements periodic action by placing the touch-sensitive display in sleep mode during idle periods and activating it only when a wake force is detected. The force sensing transducer operates periodically at low power to monitor for activation forces, while the main display scanning operates periodically at full power only when needed, thereby extending battery life while maintaining responsiveness.
Solution Approach 2:
The patent extracts the wake detection function from the main touch-sensitive display system and implements it through a separate force sensing transducer. This extraction allows the display to remain in low-power sleep mode while the transducer continuously monitors for activation forces, separating the always-on monitoring function from the power-intensive display scanning function.
3Use of energy by moving object
If the device enters sleep mode to conserve power, then power consumption is reduced, but the ability to detect touch events is compromised
Solution Approach 1:
The force sensing transducer serves as an intermediary between the user's touch input and the main touch-sensitive display system. When a user applies force to the display, the transducer detects this force and acts as a mediator to trigger the display's wake-up sequence, ensuring that touch event detection capability is maintained even when the display is in sleep mode.
Solution Approach 2:
The force sensing transducer performs preliminary detection of applied forces before the full touch-sensitive display scanning system is activated. When the transducer detects a force exceeding the wake threshold, it triggers the display to wake from sleep mode. This preliminary action eliminates the need for continuous scanning while ensuring rapid response to actual touch events.
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 solution conserves power by eliminating the need for periodic scanning of the touch-sensitive display, extending battery life while maintaining the ability to detect touch events and provide tactile feedback.
Implementation Method 1
a force sensing transducer, both located below the touch-sensitive display on an opposite side to the touch-sensitive overlay
Implementation Method 2
The plurality of piezoelectric elements comprise four piezoelectric disks, each piezoelectric disk being located near a respective corner of the touch-sensitive display
Data Source
AI summary
Methods of waking a portable electronic device are disclosed. In one embodiment, the method comprises: causing the portable electronic device to enter a sleep mode in which a touch-sensitive display is deactivated a force sensing transducer measures forces applied to the touch-sensitive display at a reduced rate relative to a rate of a full power mode when in the sleep mode; causing a force sensing transducer to measure forces applied to the touch-sensitive display at the rate of the full power mode in response to detection of an inertial event; causing the touch-sensitive display to be reactivated in response to detection of a force which is greater than a predetermined wake force threshold; and causing the portable electronic device to wake in response to detection of a touch event within a first predetermined duration of the detection of the force which is greater than a predetermined wake force threshold.