Alternating Voltage Driving Circuit for Active Stylus Power Reduction
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Solution Overview
Problem
Existing active styluses for capacitive touch screens consume high power for high-voltage driving, which complicates the design of the power supply unit and increases power requirements.
Innovation Solution
A positive and negative voltage driving circuit that alternately outputs positive and negative voltages to the stylus tip, reducing power consumption by using a low DC voltage input and eliminating the need for high-voltage generation, thereby simplifying the power supply unit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional high-voltage generating circuits are used to drive the active stylus, then the driving voltage is sufficient for capacitive touch operation, but the power consumption is high and the power supply unit design becomes complex
Solution Approach 1:
The patent changes the voltage generation approach from direct high-voltage DC output to alternating positive and negative voltage generation from a low DC input. The power supply unit outputs low DC voltage, and the driving circuit converts it to alternating positive and negative voltages through capacitive coupling and switching, fundamentally changing the voltage parameter generation method to reduce power consumption and simplify design
Solution Approach 2:
The patent employs periodic switching of capacitors to generate alternating positive and negative voltage signals. The first and second capacitors are periodically connected to different circuit nodes through switching elements, creating time-varying voltage signals that drive the stylus tip without requiring continuous high-voltage DC generation, thereby reducing average power consumption
2Power
If high DC voltage is generated by the power supply unit, then the stylus can achieve effective driving, but the power supply unit design difficulty increases and the device must withstand high voltages
Solution Approach 1:
The patent introduces capacitors as intermediary elements between the low-voltage power supply output and the stylus driving circuit. These capacitors store and transfer energy, enabling voltage transformation and signal generation without requiring the power supply unit to directly generate high voltages. The capacitors act as mediators that convert low DC voltage into the required alternating voltage signals
Solution Approach 2:
Instead of generating high voltage directly from the power supply, the patent inverts the approach by using low voltage input and generating the required high voltage signals through capacitive switching and energy transfer. The power supply outputs low voltage, and the circuit topology inversion (through capacitor connections) creates the necessary voltage conditions for driving
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 significantly reduces the driving power consumption of the active stylus to a quarter of that of traditional high-voltage generating circuits, allowing for efficient high-voltage driving without the need for high DC voltage generation, thus lowering the design complexity and power requirements.
Implementation Method 1
a first capacitor, a second capacitor and a third capacitor, wherein one end of the first capacitor is connected to a stylus tip, the other end of the first capacitor is connected to a first switching element, one end of the second capacitor is connected to the stylus tip, the other end of the second capacitor is connected to a second switching element, one end of the third capacitor is connected to a system ground, the other end of the third capacitor is connected to a voltage output end
Data Source
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AI summary
Some embodiments of the present disclosure provide a positive and negative voltage driving circuit. The positive and negative voltage driving circuit includes: a positive and negative voltage generating module and a control module. The positive and negative voltage generating module includes a switch module. The control module is configured to control a turn-off state and a turn-on state of the switch module to enable the positive and negative voltage generating module to output a positive voltage and a negative voltage to a stylus tip of an active stylus. The positive and negative voltage driving circuit of the embodiments of the present disclosure can significantly reduce the driving power consumption of the active stylus while ensuring driving effects.