Surface Capacitive Touch Panel Clock Switching for Low-Power Standby
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Solution Overview
Problem
Conventional surface capacitive touch panels consume excessive power as they remain operational at all times, which is not suitable for portable devices and contradicts eco-friendly standards.
Innovation Solution
A power-down mode is implemented using a second clock generator to reduce power consumption by switching from an external, energy-consuming clock source to an internal, more power-efficient clock source when the touch panel is not in use, and periodically activating necessary circuits to detect touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface capacitive touch panel circuits remain always functioning to detect touch input, then the touch responsiveness is improved, but the power consumption increases
Solution Approach 1:
The system dynamically adjusts its operational state based on touch input detection. During active mode, all circuits function normally for immediate touch response. During power-down mode, the system transitions to a low-power state with reduced circuit functionality, switching between these states adaptively to balance responsiveness and power consumption
Solution Approach 2:
The system implements periodic touch detection at different intervals depending on the operational mode. In power-down mode, touch detection occurs at extended intervals rather than continuously, allowing the system to maintain basic touch functionality while significantly reducing power consumption compared to continuous monitoring
2Stability of the object's composition
If the external clock generator is used during normal operation, then the clock signal stability is improved, but the power consumption increases
Solution Approach 1:
The system changes the clock source parameter based on operational mode. During normal operation, the external clock generator provides stable clock signals. During power-down mode, the system switches to an internal clock generator with lower power consumption, dynamically adjusting the clock source parameter to match current operational requirements
3Reliability
If the touch panel is placed directly on the display panel, then the touch detection functionality is improved, but the light penetration rate decreases
Solution Approach 1:
The touch panel is segmented into conductive layers (first and second conductive layers) separated by an insulating layer. This segmentation allows the touch detection functionality to be maintained through the conductive layers while the insulating layer and overall structure are optimized to minimize light interference and maximize light penetration to the display panel
Data Source
AI summary
A display device using a surface capacitive touch panel is proposed. Upon a normal mode, an external clock generator supports a clock source; meanwhile, an external clock generator, a signal generator, a current detector, a current-to-voltage converter, an analog-to-digital converter, a filter, an interface controller, a microprocessor, and the touch-position calculators are turned on. But under a power-down mode, the external clock generator, the analog-to-digital converter, filter, the interface controller, the microprocessor, and the touch-position calculators are turned off in order to reduce power consumption. Furthermore, the external clock generator is also turned off to minimize the power consumption.