Capacitive Detection Circuit Phase Timing Control
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Solution Overview
Problem
Capacitive sensing circuits in touch screens lack information about the phase of transmission signals from active styluses, leading to inappropriate mixing operations and signal distortion due to exceeding the dynamic range of internal output circuits.
Innovation Solution
A capacitive detection circuit that includes a phase detection circuit to determine the phase of reception signals and generate a time signal, which instructs the mixing module to start the mixing operation only after a specific time point, ensuring the output signal remains within the dynamic range of the internal output circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixing module performs mixing operation on the reception signal without phase information, then the mixing operation can be executed, but the output signal exceeds the dynamic range of the internal output circuit causing signal distortion
Solution Approach 1:
The phase detection circuit performs preliminary detection of the reception signal phase before the mixing operation is executed. This preliminary action provides the necessary phase information in advance, allowing the mixing module to adjust its operation timing and avoid output signal distortion while maintaining productive mixing operations.
2Manufacturing precision
If the mixing module waits for phase detection before performing mixing operation, then signal distortion is prevented, but the response time is increased
Solution Approach 1:
The phase detection circuit continuously monitors and detects the phase of the reception signal in advance, so that when the mixing operation is needed, the phase information is already available. This eliminates the time delay that would occur if phase detection were performed only when mixing was required.
Solution Approach 2:
The phase detection circuit operates continuously to maintain up-to-date phase information of the reception signal. This continuous detection ensures that the mixing module can immediately perform mixing operations without waiting for phase detection to complete, thus maintaining continuous useful action without time loss.
3Manufacturing precision
If the output circuit is designed with larger dynamic range to accommodate all signal conditions, then signal distortion is avoided, but the production cost increases
Solution Approach 1:
Instead of designing the output circuit with a universally large dynamic range, the invention changes the operational parameters by introducing phase-based timing control. The mixing module adjusts its operation based on detected phase information, allowing the use of a smaller, more cost-effective output circuit dynamic range while still avoiding signal distortion through intelligent timing control.
Data Source
AI summary
A capacitive detection circuit is provided according to the disclosure. The capacitive detection circuit is applied to an electronic device. The electronic device includes a touch screen, and the touch screen comprises a plurality of receiving electrodes. The capacitive detection circuit includes: a phase detection circuit for detecting a phase of a reception signal and generating a time signal, wherein the receiving electrode receives a transmission signal and generates the reception signal; a mixing module for performing a mixing operation on the reception signal according to the time signal so as to generate an output signal; and a back-end processing module for determining a capacitance corresponding to the receiving electrode according to the output signal. The time signal instructs the mixing module to perform the mixing operation on the reception signal after a first time point.