Center-Point Capacitive Sensing with Reset Voltage Precharge
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Solution Overview
Problem
Conventional capacitive detection devices struggle to accurately detect changes in voltage due to charge sharing phenomena, leading to low signal-to-noise ratios and high power consumption, making it difficult to discern real signals amidst noise.
Innovation Solution
The device applies a first driving voltage to a capacitance connected to a sensing signal line, fixes the charge quantity, and then applies a second driving voltage to induce charge sharing, using an operational amplifier to detect the change in voltage size, while shielding noise with a shielding capacitor and reducing driving voltage to minimize current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional capacitive detection device is used to detect charge sharing phenomenon, then the detection function is provided, but the signal-to-noise ratio is low and power consumption is high
Solution Approach 1:
The patent applies a first driving voltage to the sensing signal line before the actual detection to pre-charge the line and stabilize the charge distribution. This preliminary action ensures that when the second driving voltage is applied to induce charge sharing, the baseline charge state is known and stable, improving signal-to-noise ratio while allowing for optimized voltage application timing that reduces overall power consumption
Solution Approach 2:
The patent employs periodic application of driving voltages with specific timing sequences. The first driving voltage is applied for a predetermined period to establish stable charge, then the second driving voltage is applied to induce charge sharing. This periodic action with optimized duty cycles improves detection precision while minimizing the duration of high-power voltage application, thereby reducing overall power consumption
2Measurement precision
If driving voltage is applied to induce charge sharing phenomenon, then capacitive detection is enabled, but current consumption increases
Solution Approach 1:
The patent segments the driving voltage application into two distinct phases: a first driving voltage phase for pre-charging and stabilizing the sensing signal line, and a second driving voltage phase for inducing charge sharing. This segmentation allows each phase to be optimized independently - the first phase uses lower voltage for longer duration with lower current draw, while the second phase uses higher voltage for shorter duration, reducing overall energy loss compared to continuous high-voltage application
Solution Approach 2:
The patent changes the voltage parameters dynamically - applying a first driving voltage with specific amplitude and duration to establish stable charge distribution, then switching to a second driving voltage with different parameters to induce charge sharing. By optimizing the amplitude, duration, and timing of each voltage phase, the patent achieves accurate capacitive detection while minimizing the integral of power over time, thereby reducing total current consumption and energy loss
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 approach enhances signal-to-noise ratio and reduces power consumption, enabling precise capacitive detection suitable for mobile terminals and laptops.
Implementation Method 1
maintains the charge quantity that induces charge sharing phenomenon at a constant value, and induces charge sharing phenomenon in the added capacitance by charge supply
Implementation Method 2
shielding noise with a shielding capacitor
Data Source
AI summary
The present invention applies a reset voltage to the center point prior to the progression of an event to ensure uniformity of the charge amount at the center point. It is possible to observe changes in the environment by supplying charge to the center point and detecting changes in the amount of charge. By varying the magnitude of the reset voltage for each object being measured, the observation range of the observation device is narrowed, thereby enhancing the observation resolution.