Capacitive Touch Sensor Parallel Code Driving for High Speed Detection
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Solution Overview
Problem
Conventional touch sensor devices face challenges in achieving high detection accuracy and resolution while operating at high speeds, and they often suffer from issues like moire interference and decreased position detection precision due to the use of materials with high resistance values and non-symmetric electrode arrangements.
Innovation Solution
A touch sensor system with a capacitive touch sensor panel featuring a uniform grid of vertical and horizontal electrodes made of fine wires, arranged in a rectangular outline with no gaps, where the electrodes are insulated from each other and driven in parallel using orthogonal code sequences to estimate linear device values and capacitance values simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sequential line scanning method is used to detect capacitance values, then device complexity is reduced, but detection speed and resolution deteriorate
Solution Approach 1:
The patent applies periodic action by using time-division multiplexing with code sequences (e.g., Hadamard codes) to drive electrode lines in a periodic manner. Multiple capacitance values are detected simultaneously through periodic driving patterns, enabling parallel detection without increasing physical circuit complexity. This resolves the contradiction by achieving high detection speed through temporal periodicity rather than spatial parallelism.
Solution Approach 2:
The patent transitions from sequential scanning (1D time-based approach) to parallel detection using code sequences (2D matrix-based approach). By mapping capacitance values to a matrix structure and using orthogonal code sequences for driving, the system achieves simultaneous detection of multiple capacitance values, thereby improving detection speed without proportionally increasing device complexity.
2Ease of manufacture
If materials with high resistance values are used for electrodes, then manufacturing ease is improved, but detection accuracy and position detection precision deteriorate
Solution Approach 1:
The patent introduces asymmetry in the electrode structure by using different electrode patterns (e.g., grid pattern vs. line pattern) and non-uniform spacing. This asymmetric design creates distinct capacitance signatures that improve detection accuracy and position detection precision, overcoming the limitations of high-resistance materials while maintaining manufacturing ease through standardized fabrication processes.
Solution Approach 2:
The patent changes physical parameters of the electrode structure, such as electrode spacing, electrode width, and electrode pattern density, to optimize the balance between manufacturing ease and detection precision. By adjusting these parameters, the system achieves high measurement precision even with high-resistance materials, as the capacitance changes are sufficiently large to detect touch events accurately.
3Ease of manufacture
If non-symmetric electrode arrangements are used, then ease of manufacture is improved, but position detection precision deteriorates
Solution Approach 1:
The patent creates a universal electrode arrangement that serves multiple functions: the grid pattern provides both manufacturing simplicity and the geometric symmetry needed for accurate position detection. The electrode structure is designed to be universally applicable across different display sizes and resolutions, maintaining position detection precision while ease of manufacture through standardized fabrication processes.
4Productivity
If high-speed operation is implemented, then productivity is improved, but detection accuracy and resolution deteriorate
Solution Approach 1:
The patent ensures continuity of useful action by maintaining continuous capacitance monitoring across all electrode lines simultaneously. Through parallel driving with code sequences, the system continuously detects capacitance changes without interruption, enabling high-speed operation while preserving detection accuracy. The continuous measurement process eliminates the need for sequential scanning, thereby maintaining both speed and precision.
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 enhances detection accuracy, resolution, and speed while preventing moire interference by eliminating the need for sequential line scanning and reducing power consumption, and allows for seamless integration with display devices.
Implementation Method 1
capacitances formed between drive lines and sense lines at respective intersections
Data Source
AI summary
A touch sensor panel includes vertical & horizontal electrodes each respectively including a repeat of first & second basic shapes connected to one another in a vertical & horizontal directions, the first & second basic shapes each including a fine wire, respectively provided on vertical & horizontal electrode surfaces, and arranged at intervals; and a plurality of linear devices at respective intersections of the electrodes. A method includes driving the vertical electrodes in parallel on a basis of code sequences di for each of the linear devices so as to output, along the horizontal electrodes, linear sums of respective outputs corresponding to the linear devices; and estimating respective values of the linear devices along the horizontal electrodes on a basis of an inner product operation of (i) the linear sums outputted along the horizontal electrodes and (ii) the code sequences di.