Touch Sensor Compensation Circuit for Parasitic Capacitance Uniformity
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Solution Overview
Problem
Conventional touch panels suffer from inaccurate touch position calculations due to parasitic capacitances formed between touch sensors and conductive structures in display devices, leading to unwanted electrical activity that complicates signal interpretation.
Innovation Solution
A signal compensation circuit with a dual compensation mechanism, comprising first and second compensation circuits that generate charging and discharging currents in a time-division manner to adjust initial signals on touch electrodes, ensuring accurate touch position calculation without increasing the circuit's size by avoiding the multiplication of circuit units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a compensation circuit is added to compensate for unwanted electrical activity on touch sensors, then the uniformity of signal values is improved, but the circuit size increases and occupies more space
Solution Approach 1:
The compensation circuit is divided into multiple independent compensation units, each corresponding to a specific touch sensor. This segmentation allows each unit to handle compensation for its associated sensor independently, improving measurement precision while keeping individual unit sizes small and manageable.
Solution Approach 2:
The patent integrates compensation functionality into the existing touch sensor array structure by adding compensation units at the same spatial level rather than as separate external components. This dimensional integration reduces the overall area occupied while maintaining compensation effectiveness.
2Measurement precision
If circuit units are added to increase resolution for signal compensation, then the compensation accuracy is improved, but the circuit complexity and size increase
Solution Approach 1:
Each compensation unit is designed with specific local characteristics tailored to its associated touch sensor's parasitic capacitance properties. This localized optimization allows each unit to achieve high compensation accuracy for its specific sensor without requiring all units to be complex, thereby reducing overall circuit complexity while maintaining high precision.
Solution Approach 2:
The compensation units perform preliminary compensation of unwanted electrical activity before the main signal processing occurs. By pre-compensating the signals from touch sensors, the subsequent processing stages deal with already-corrected data, improving overall compensation accuracy without requiring complex processing in later stages.
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
The dual compensation mechanism effectively reduces signal differences across touch electrodes, enhancing the accuracy and uniformity of touch position calculations by applying 'coarse' and 'fine' adjustments, thereby improving the resolution without expanding the circuit's footprint.
Implementation Method 1
parasitic capacitances are formed between the touch sensors and conductive structures (such as scanning lines and data lines) in the electrical device
Data Source
AI summary
A circuit to cancel the effect of parasitic capacitances (“initial signals”) in calculations as to precise touch locations on a touch display screen (signal compensation circuit) includes first and second compensation circuits connected to a charge-discharge node. The first compensation circuit receives initial signals, generates first charging currents to charge, and first discharging currents to discharge, the charging-discharging node. The second compensation circuit generates second charging currents to charge, and second discharging currents to discharge, the charging-discharging node. Values of the first charging currents, the second charging currents, the first discharging currents, and the second discharging currents are of different magnitudes and are applied in order to amount to a more precise match for the exact compensation value required. The charging-discharging node outputs target signals according to the initial signals as compensated by the compensation values to achieve uniformity of initial signals across the entire touch display screen.