Capacitive Touch Phase Calibration for Uniform Signal Detection
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Solution Overview
Problem
Capacitive touch sensing devices face challenges due to signal propagation delays and non-uniformity across the touch sensor array, leading to inconsistent touch detection performance and susceptibility to noise.
Innovation Solution
A phase calibration method is employed to determine phase offsets for individual unit cells within the touch sensor array, adjusting phase parameters to compensate for signal delays and non-uniformity, using a calibration unit and touch panel model to optimize touch detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase calibration is performed for each unit cell to improve touch detection uniformity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by determining phase offset parameters for different unit cells based on their specific signal propagation characteristics. The calibration unit measures actual phase differences and adjusts the phase offset parameters accordingly, transforming a uniform phase assumption into location-specific phase compensation, thereby improving touch detection uniformity across the sensor array.
Solution Approach 2:
The patent segments the touch sensor array into multiple unit cells, each with its own phase offset parameter. Instead of treating the entire array uniformly, the system divides it into discrete measurement and calibration units, allowing independent phase calibration for each unit cell or group of unit cells, which improves overall measurement precision while managing complexity through modular calibration.
2Measurement precision
If signal propagation delays are compensated through phase offset adjustment, then touch detection accuracy is improved, but processing time increases
Solution Approach 1:
The patent implements preliminary action by performing phase calibration during the manufacturing or initialization phase. The calibration unit determines and stores phase offset parameters for each unit cell before actual touch detection operations begin. This pre-calibration approach eliminates the need for real-time phase calculation during touch events, thereby improving detection accuracy without adding processing time during operation.
3Reliability
If phase offset parameters are determined for all unit cells, then touch detection consistency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies self-service by enabling the touch sensor array to perform its own phase calibration automatically. The calibration unit utilizes the array's existing transmit and receive lines to measure phase differences and determine offset parameters without requiring external calibration equipment or complex manual procedures. This self-calibration capability improves manufacturing ease while ensuring consistent touch detection across all unit cells.
Data Source
AI summary
In an embodiment of the techniques presented herein, a touch detection system includes a touch sensor array having transmit lines, receive lines, and unit cells defined at intersections of the transmit lines and the receive lines, a transmit sequencer configured to generate a transmit signal on the transmit lines, an analog-to-digital-converter module configured to measure responses of the unit cells to the transmit signal, and a calibration unit configured to determine a first phase offset for a first unit cell of the unit cells based on a first response, of the responses, of the first unit cell, determine a second phase offset for a second unit cell of the unit cells based on a second response, of the responses, of the second unit cell, and set a phase offset parameter of the touch sensor array based on the first phase offset and the second phase offset.