Capacitance detection circuit, touch detection apparatus and electronic device
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Solution Overview
Problem
Current capacitance detection circuits face challenges in improving detection performance, particularly in reducing noise interference and enhancing signal-to-noise ratio for accurate capacitance measurement in capacitive sensors used for human-machine interaction.
Innovation Solution
A capacitance detection circuit that includes a first and second charging and discharging circuit, an analog-to-digital conversion circuit, and a digital processing circuit, which continuously samples the voltage difference between a capacitor to be detected and a calibration capacitor, allowing for digital detection of capacitance variations by processing energy values of fundamental frequencies, thereby reducing noise interference and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitance detection methods are used, then the detection circuit is simple, but the detection precision and signal-to-noise ratio are insufficient
Solution Approach 1:
The detection process is segmented into multiple charging and discharging phases with distinct control signals. The first charging and discharging circuit performs charging operations while the second performs discharging operations, allowing separate optimization of each phase for improved precision without requiring a monolithic complex circuit design.
Solution Approach 2:
The circuit employs periodic charging and discharging cycles controlled by first and second control signals. This periodic action enables time-domain separation of measurement phases, allowing precise capacitance detection through repeated sampling while maintaining circuit simplicity through reuse of the same components in different states.
2Measurement precision
If continuous sampling of voltage difference is performed, then noise interference is reduced and signal-to-noise ratio is improved, but energy consumption increases
Solution Approach 1:
Continuous sampling is achieved through periodic charging and discharging cycles rather than continuous operation. The analog-to-digital conversion circuit samples voltage differences at specific intervals during these periodic phases, reducing energy consumption compared to truly continuous sampling while maintaining adequate signal-to-noise ratio through sufficient sampling frequency.
Solution Approach 2:
The circuit maintains continuous useful action by seamlessly transitioning between charging and discharging phases. The first and second charging and discharging circuits operate in coordinated sequences, ensuring that the measurement process continues without interruption while managing energy consumption through efficient phase transitions and component reuse.
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 enhances the signal-to-noise ratio and improves detection performance by allowing for precise capacitance measurement, enabling better user interaction experiences in capacitive sensor applications.
Implementation Method 1
a capacitor is formed between a detection electrode and ground, when a conductor (such as a finger) approaches or touches the detection electrode, a capacitance between the detection electrode and the ground changes
Implementation Method 2
an analog-to-digital conversion circuit, configured to continuously sample a voltage difference between the capacitor to be detected and the calibration capacitor in a charging or discharging process to obtain sampled data
Implementation Method 3
a digital processing circuit, configured to detect a capacitance of the capacitor to be detected according to the sampled data
Data Source
AI summary
Provided is a capacitance detection circuit, which has better detection performance. The capacitance detection circuit includes: a first charging and discharging circuit configured to perform charging or discharging on a capacitor to be detected; a second charging and discharging circuit configured to perform charging or discharging on a calibration capacitor; an analog-to-digital conversion circuit configured to continuously sample a voltage difference between the capacitor to be detected and the calibration capacitor in a charging or discharging process to obtain sampled data; and a digital processing circuit configured to detect a capacitance of the capacitor to be detected according to the sampled data.