Capacitance Detection Method for Touch Panel Controller
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Solution Overview
Problem
The existing capacitance detection methods for touch panels require complex configurations due to increased wiring resistance and the number of sense lines, making it difficult to detect capacitance distribution efficiently as the size of the touch panel increases.
Innovation Solution
A capacitance detection method that uses intersecting first and second signal lines, with switch elements to drive and read linear sum signals based on a code sequence, allowing for inner product computation to detect capacitance or changes in capacitance, thereby simplifying the configuration and improving detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of the touch panel is increased, then the detection area is improved, but the wiring resistance of the sense line increases and the number of channels of the read circuit increases
Solution Approach 1:
The patent divides the touch panel into multiple regions with multiple detection electrodes, where each region can be independently scanned. The read circuit processes signals from multiple sense lines in parallel through sequential scanning, breaking down the complex task of handling all electrodes simultaneously into manageable segments that can be processed in time-division multiplexing fashion.
Solution Approach 2:
The patent employs periodic scanning of sense lines in a sequential manner, where each sense line is activated and read at specific time intervals. This periodic action allows the read circuit to handle multiple channels by time-division multiplexing, reducing the need for simultaneous high-channel-count processing while maintaining comprehensive detection coverage across the entire touch panel.
2Measurement precision
If the number of detection electrodes is increased, then the detection precision is improved, but the number of sense lines and wiring complexity increase
Solution Approach 1:
The patent segments the detection electrodes into multiple groups associated with different sense lines, allowing capacitance detection at multiple spatial locations simultaneously through parallel sense line scanning. This segmentation enables high detection precision across the touch panel while managing wiring complexity by organizing electrodes into structured groups that can be processed sequentially.
Solution Approach 2:
The patent introduces a time dimension to the detection process by sequentially scanning sense lines over time. This transforms the spatial complexity of handling multiple simultaneous channels into a temporal processing scheme, where the same read circuit resources are reused across different time slots, effectively adding a time dimension to resolve the contradiction between detection precision and wiring complexity.
3Device complexity
If sequential scanning of sense lines is performed, then the read circuit complexity is reduced, but the detection time increases
Solution Approach 1:
The patent implements continuous scanning of sense lines without idle periods, where each sense line is immediately processed after the previous one. This continuous operation minimizes detection time while maintaining the simplicity of sequential scanning architecture, ensuring that the read circuit remains actively engaged in useful detection work throughout the scanning process.
Solution Approach 2:
The patent uses periodic scanning with optimized timing intervals, where sense lines are scanned in rapid succession at regular intervals. This periodic action balances the simplicity of sequential processing with time efficiency by establishing a rhythmic scanning pattern that minimizes total detection time while keeping the read circuit configuration simple and manageable.
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 enables efficient detection of capacitance distribution with a simple configuration, reducing the complexity and noise resistance of the touch panel system, and is advantageous for in-cell touch panels by allowing parallel scanning and reducing the initial investment cost.
Implementation Method 1
capacitance detection method for detecting a capacitance or a change in capacitance between each of a plurality of electrodes and a detected subject
Implementation Method 2
distribution of the electrostatic capacity or a change in electrostatic capacity on the touch panel
Data Source
AI summary
Capacitance distribution on a touch panel is detected with a simple configuration. A drive switch element between each of electrodes and a corresponding drive line is made to turn on and the drive line is driven on the basis of a code sequence. A sense switch element between each of the electrodes and a corresponding sense line is made to turn on and a linear sum signal of each of the electrodes is read along the sense line.