Capacitance Detection Using Time Division Oscillation Frequencies
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Solution Overview
Problem
Conventional capacitance detection systems are prone to errors due to external noise interference, which causes oscillation frequency variations that are not accurately attributed to changes in the capacitance of the detection plate.
Innovation Solution
The method involves generating a plurality of time division oscillation frequencies and counting them over a predetermined period to offset noise-induced frequency deviations, ensuring a uniform count value and minimizing noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single oscillation frequency is used for capacitance detection, then the detection system is simple, but the measurement precision deteriorates due to noise interference
Solution Approach 1:
The patent divides the single oscillation frequency into multiple time-division oscillation frequencies (first, second, and third frequencies). Each frequency is measured separately during different time periods, and the results are combined to obtain the final capacitance value. This segmentation allows noise at any single frequency to affect only one measurement, while the other measurements remain relatively unaffected, thereby improving measurement precision without significantly increasing overall system complexity.
Solution Approach 2:
The patent employs periodic switching between multiple oscillation frequencies in a time-division manner. The oscillator alternates between first, second, and third frequencies in sequential time periods, with each frequency being measured for a predetermined duration. This periodic action ensures that noise interference is distributed across different time periods and frequencies, allowing the system to average out the noise effects and achieve more accurate capacitance detection.
2Measurement precision
If multiple time division frequencies are used for detection, then the measurement precision improves by offsetting noise effects, but the device complexity increases
Solution Approach 1:
The oscillator is designed to automatically switch between multiple frequencies using internal control logic without requiring complex external intervention. The system self-manages the time-division multiplexing of frequencies, with each frequency period being self-contained and independently measurable. This self-service approach minimizes the need for additional complex control circuitry while still achieving the benefits of multi-frequency measurement.
3Loss of time
If a single frequency measurement is performed, then the detection time is short, but the reliability deteriorates due to noise susceptibility
Solution Approach 1:
The patent maintains continuous detection by seamlessly transitioning between multiple frequency measurements in a time-division manner. Rather than performing separate independent measurements, the system continuously switches between frequencies during the detection process, ensuring that the overall detection action is uninterrupted. This continuous multi-frequency measurement approach provides both timely detection results and improved reliability through noise averaging.
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 effectively reduces errors in capacitance detection by isolating frequency variations caused by the capacitance plate from those caused by external noise, maintaining accuracy even under noisy conditions.
Implementation Method 1
an oscillator to output a plurality of time division oscillation frequencies according to the capacitance detected by a capacitance detection plate
Implementation Method 2
the plurality of time division oscillation frequencies are counted by a frequency counter
Data Source
AI summary
Disclosed herein is a method for detecting capacitance including: allowing an oscillator to output a plurality of time division oscillation frequencies according to the capacitance detected by a capacitance detection plate; counting the plurality of time division oscillation frequencies during a predetermined time period; and offsetting increasing and decreasing of the oscillation frequencies due to noise such that a count value becomes uniform over the predetermined time period. Even when external noise is applied, distortion of the oscillation frequency due to the external noise is minimized and the oscillation frequency varies depending on only the capacitance of the capacitance detection plate. Accordingly, it is possible to prevent an error due to the noise at the time of the detection of the capacitance.