Touchscreen Integrator Gain Calibration for Noise and Offset Reduction
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Solution Overview
Problem
Capacitive touchscreens face issues with linearity and accuracy due to deviations in integration circuits and panel touch nodes, leading to offset and noise in capacitance measurements.
Innovation Solution
A touchscreen device with a panel unit, driving circuit, sensing circuit, and control unit that calibrates gains of converter circuit units and panel deviation calibration units to equalize voltage levels and adjust capacitance values, using a switching circuit to sequentially apply driving signals and calibrate output signals from converter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If capacitance values are converted into electrical signals using integrators, then noise is reduced, but deviations among integration circuits cause offset and deterioration of linearity and accuracy
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gain of each integrator circuit based on calibration data. During calibration, the system measures the actual output voltage of each integrator and calculates a correction gain value. This gain parameter is then applied to compensate for deviations, allowing the system to maintain both low noise and high measurement precision simultaneously.
Solution Approach 2:
The patent implements feedback through a calibration process where the actual output signals from integrators are measured and used to generate correction factors. These correction factors are stored and applied during normal operation to compensate for integrator deviations, creating a closed-loop system that maintains accuracy while preserving the noise-reduction benefits of integration.
2Measurement precision
If multiple converter circuit units are used to sense capacitance changes, then measurement capability is improved, but deviations among converter circuits and panel touch nodes cause offset and reduce accuracy
Solution Approach 1:
The patent applies local quality by implementing individual calibration for each converter circuit unit and panel touch node. Instead of treating all circuits uniformly, the system performs separate calibration measurements for each converter circuit and applies node-specific correction values. This localized approach allows each circuit to be optimized independently, compensating for manufacturing variations and ensuring high reliability across the entire touchscreen.
Solution Approach 2:
The patent segments the calibration process into distinct stages: first calibrating integrator circuits individually, then calibrating converter circuit units separately, and finally adjusting for panel touch node variations. This segmented approach allows systematic correction of deviations at each level, improving overall measurement precision while maintaining reliability through methodical error compensation.
3Measurement precision
If calibration is performed to correct deviations, then linearity and accuracy are improved, but additional circuit units and calibration operations increase device complexity
Solution Approach 1:
The patent merges the calibration functionality into the existing touchscreen controller by integrating calibration circuits within the same IC that handles normal touch sensing. The calibration operations are combined with regular touch processing, allowing the system to perform both functions using shared hardware resources. This reduces overall device complexity while still providing comprehensive calibration capabilities.
Solution Approach 2:
The patent implements self-service calibration where the touchscreen system automatically performs calibration operations without requiring external intervention or additional complex equipment. The calibration process uses the touchscreen's own hardware resources and can be executed during manufacturing or in-field, reducing the need for external calibration devices and simplifying the overall system architecture.
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
Significantly improves linearity and accuracy of touch input by calibrating deviations among integration circuits and panel touch nodes, reducing noise and offset, thereby enhancing the reliability of touch data.
Implementation Method 1
capacitance values of capacitors provided on a touch panel are changed by a user's finger or stylus, the changed capacitance values are converted into electrical signals
Implementation Method 2
a method of using integrators is frequently used because it includes several operations of the conversion of capacitance of capacitors into voltage to be output
Data Source
AI summary
A touchscreen device may include: a panel unit, a driving circuit unit, a sensing circuit unit and a control unit. The control unit may apply a driving signal to a first node capacitor formed at an intersection between a first and a first one of the plurality of sensing electrodes and calibrate gains of the plurality of converter circuit units. Each of the plurality of panel deviation calibration units may calibrate an output signal from the respective one of the plurality of converter circuit units by using a capacitance value of a first capacitor included in the respective one of the plurality of panel deviation calibration units when a driving signal is applied to the first one of the driving electrodes.