Reduction of capacitance and forcing of different voltages for capacitor
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Solution Overview
Problem
Conventional capacitive detection devices face challenges in enhancing detection sensitivity and signal reliability due to noise interference and limited resolution, particularly in capacitive input devices for mobile terminals, where the detection of added capacitance is difficult with existing technologies.
Innovation Solution
The solution involves reconfiguring internal parasitic capacitors to apply driving voltages, using multiple capacitive detection areas with different driving voltages from separate power supplies, and incorporating shielding capacitors to stabilize the operational amplifier's operation point, thereby improving signal-to-noise ratio and reducing consumption current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple capacitors are connected to a single sensing signal line, then the detection sensitivity of added capacitance is improved, but the inrush current based on capacitive load increases
Solution Approach 1:
The patent applies different sizes of driving voltages generated at different locations for each capacitance, dynamically adjusting the voltage applied to each capacitor based on its position and capacitance value. This dynamic voltage adjustment limits the inrush current while maintaining the ability to detect capacitance changes with high sensitivity.
Solution Approach 2:
The patent changes the driving voltage parameter by applying different voltage levels to different capacitors. By varying the voltage magnitude according to the capacitor's location and capacitance, the system optimizes both detection sensitivity and current consumption, preventing excessive inrush current while preserving measurement precision.
2Device complexity
If a single power supply is used for the operational amplifier, then the device complexity is reduced, but the output defect phenomenon occurs due to unstable operation point
Solution Approach 1:
The patent introduces an intermediary mechanism by using capacitors connected to the sensing signal line that are driven by different voltages from separate power supplies. These capacitors act as intermediaries to stabilize the operation point of the operational amplifier, allowing the use of a single power supply while maintaining operational stability and preventing output defects.
3Adaptability or versatility
If the operation point of ADC or DAC is not fixed, then the system adaptability is improved, but the detection resolution and signal reliability deteriorate due to noise interference
Solution Approach 1:
The patent applies preliminary action by pre-stabilizing the operation point of the ADC or DAC to a desired position using the capacitance network. This preliminary stabilization ensures that subsequent measurements are performed with high resolution and reliability, while the system maintains adaptability through the configurable capacitor arrangement and voltage selection.
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 detection sensitivity and reliability by stabilizing the operational amplifier's operation point, reduces noise interference, and improves the signal-to-noise ratio, making it suitable for capacitive input devices in mobile terminals and laptops.
Implementation Method 1
Multiple capacitors, parallelly connected to a sensing signal line, for detecting the added capacitance by applying driving voltages of different sizes to two capacitors among the multiple capacitors
Data Source
AI summary
The present invention involves driving multiple capacitors, including a shielding capacitance (Cin_sd), to minimize voltage fluctuations detected on the CDA signal line (200), thereby enhancing the resolution of the ADC. The additional capacitance (Cobj) generated between the CDA (100) and the object (20) due to the appearance of the object (20) is detected in the form of voltage. By analyzing with an ADC of improved resolution, it is possible to detect the presence of the object (20) more reliably.