Integrated Capacitive Sensing and NFC Circuit Using Resonant Amplification
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Solution Overview
Problem
Existing communication circuits require additional circuit blocks to implement touch functions and data transmission, leading to increased complexity, size, and weight due to the separation of touch and communication functions.
Innovation Solution
An integrated communication and capacitive sensing circuit using a microprocessor, sensing electrode, and resonant circuit, where the microprocessor determines capacitive variations and enables/disables a high-frequency carrier signal for both capacitive sensing and data transmission using the same sensing electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate circuit blocks are used for touch function and data transmission, then each function can be independently implemented, but the circuit complexity increases and the occupied area becomes greater
Solution Approach 1:
The patent combines touch sensing and data transmission functions into a single integrated circuit block. The same electrode serves dual purposes: detecting touch events through capacitive sensing and transmitting data through NFC communication. This merging eliminates the need for separate circuit blocks, reducing overall circuit complexity while maintaining both functions' reliability through unified control logic in the microprocessor.
Solution Approach 2:
The electrode is designed as a multi-functional element that performs both capacitive touch sensing and NFC data transmission. The microprocessor controls the electrode to switch between sensing mode (detecting capacitance changes) and communication mode (transmitting modulated signals). This universal design allows one component to fulfill multiple roles, reducing the total number of components needed in the system.
2Reliability
If separate circuit blocks are used for touch function and data transmission, then each function can be independently implemented, but the product size and weight become greater
Solution Approach 1:
The patent merges touch sensing and data transmission circuits into a single integrated block, directly reducing the total component count. Fewer discrete components mean less material usage and reduced assembly weight. The unified circuit design eliminates redundant structures while maintaining both functions' operational reliability through shared hardware resources controlled by the microprocessor.
Solution Approach 2:
The electrode serves as a universal component for both touch detection and data transmission, eliminating the need for separate dedicated components for each function. This multi-functionality reduces the total material required in the product, thereby reducing overall product weight while maintaining functional independence through software-controlled mode switching.
3Device complexity
If the same electrode is used for both capacitive sensing and data transmission, then circuit area is reduced, but signal interference may occur
Solution Approach 1:
The microprocessor implements periodic action by alternating between capacitive sensing mode and NFC communication mode in time-division multiplexing. During sensing periods, the electrode is configured for high-impedance capacitance measurement; during communication periods, it switches to signal transmission mode. This periodic switching prevents simultaneous operation of both functions, eliminating signal interference while maintaining circuit integration and reducing area.
Solution Approach 2:
The electrode's electrical characteristics are dynamically adjusted based on the current operation mode. The microprocessor changes the electrode's impedance state and connection configuration in real-time: high-impedance for accurate capacitance sensing, low-impedance for efficient signal transmission. This dynamic reconfiguration allows the same physical electrode to serve both functions without interference by adapting its electrical properties to the current task.
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 reduces circuit complexity and size by integrating capacitive sensing and communication functions, allowing for simultaneous capacitive sensing and data transmission while maintaining effective capacitive variation detection and data decoding.
Implementation Method 1
a high frequency carrier signal of the second input/output pin of the microprocessor is enabled/disabled according to a transmission data, wherein a magnitude of the high frequency carrier signal is amplified by the resonant circuit
Implementation Method 2
the microprocessor determines the capacitive variation of the sensing electrode according to the charging/discharging status of the sensing electrode from the first input/output pin
Data Source
AI summary
An integrated communication and capacitive sensing circuit and an interactive system using the same are provided in the present invention. The integrated communication and capacitive sensing circuit includes a microprocessor, a sensing electrode and a resonant circuit. The microprocessor includes a first input/output (I/O) pin and a second I/O pin. The sensing electrode is coupled to the first I/O pin of the microprocessor. The input terminal of the resonant circuit is coupled to the second I/O pin of the microprocessor, and the output terminal of the resonant circuit is coupled to the sensing electrode. When sensing the capacitance is performed, the first I/O pin of the microprocessor detects the charging/discharging state of the sensing electrode to determine the capacitive variation. When a data output is performed, the first I/O pin of the microprocessor is set to high impedance, and the second I/O pin of the microprocessor outputs or does not output a high frequency carrier according to a transmission data, wherein the resonant circuit amplifies the amplitude of the high frequency carrier.