Capacitive Touch Panel Power Reduction via Multi-Supply and Energy Recovery
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Solution Overview
Problem
Touch screens in mobile devices face challenges in reducing power consumption while maintaining sensitivity and operational frequency, as the power required to drive capacitive touch panels increases with thinner designs and higher capacitance, leading to higher power dissipation in both the panel and the touch controller.
Innovation Solution
A multi-supply drive approach combined with an energy recovery method, where the touch panel uses multiple voltage sources to charge and discharge capacitors, and energy is exchanged between capacitors and inductors to reduce power consumption, enhancing overall efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single voltage source is used to charge the capacitor directly to the final voltage, then the circuit design is simple, but the power consumption is high
Solution Approach 1:
The voltage charging process is segmented into multiple stages using different voltage sources. Instead of using a single voltage source to charge the capacitor directly to the final voltage, the patent employs a first voltage source to charge to an intermediate voltage level, then a second voltage source to complete the charging to the final voltage. This segmentation of the charging process reduces overall power consumption while managing circuit complexity.
Solution Approach 2:
The patent changes the voltage parameter dynamically during the charging process. By switching between different voltage sources (first voltage source with lower voltage, second voltage source with higher voltage) and adjusting the charging voltage levels (intermediate vs. final voltage), the system optimizes power consumption. This parameter change approach allows efficient power management in touch screen driving.
2Illumination intensity
If the touch panel becomes thinner to improve display quality, then the display quality improves, but the capacitance increases and power consumption increases
Solution Approach 1:
The patent segments the power delivery system into multiple voltage sources with different voltage levels. This allows the system to handle the increased capacitance of ultra-thin touch panels more efficiently by charging in stages, reducing the peak power demand that would otherwise be required to charge the larger capacitance values.
Solution Approach 2:
The patent implements dynamic voltage switching based on the charging state of the capacitor. The system transitions from using the first voltage source to the second voltage source as the capacitor charges, creating a dynamic power management system that adapts to the real-time state of the touch panel, thereby reducing overall power consumption.
3Speed
If the operating frequency is increased to transmit signals faster, then the signal transmission speed improves, but the power consumption increases
Solution Approach 1:
The patent employs periodic switching between different voltage sources synchronized with the operating frequency of the touch panel. By aligning the voltage source switching with the periodic signal transmission cycles, the system maintains high-speed operation while reducing average power consumption through efficient use of available power during each cycle.
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 dramatically improves power efficiency by up to 80% in capacitive touch panels, making them suitable for ultra-thin touch screens in mobile devices and flexible displays.
Implementation Method 1
Energy recovery operates by exchanging stored energy between a capacitor and an inductor
Data Source
AI summary
Dual power supply and energy recovery techniques are used in a capacitive touch panel that employs a concurrent drive scheme. A dual supply output buffer boosts a capacitor from an intermediate voltage level to a high voltage level. Energy recovery exchanges stored energy between a capacitor and an inductor. When both techniques are used together, power consumption of a capacitive touch panel drive circuit can be reduced dramatically, by as much as about 80%. Such high efficiency touch panels have wide application to ultra-thin touch screens, including those suitable for use in mobile devices and flexible displays.