Touch Sensor Channel Calibration for Parasitic Capacitance Mismatch
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Solution Overview
Problem
The development of electronic devices with capacitance touch sensors is hindered by the need for individual sensitivity measurement and threshold setting for each channel due to varying parasitic capacitance values caused by differences in wiring lengths, leading to prolonged development times and inconvenient methods.
Innovation Solution
An apparatus and method for automatically calibrating capacitance per channel by measuring parasitic capacitances and adding unique calibration capacitance values to equalize all channels to a preset reference capacitance, using a capacitance measurement and calibration device with a calibration controller and capacitance calibration modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual sensitivity measurement and threshold setting is performed for each channel, then measurement precision is improved, but development time increases and operation becomes inconvenient
Solution Approach 1:
The system performs automatic self-calibration by measuring parasitic capacitance values of each channel and automatically adding compensation capacitance values without requiring manual intervention. The calibration controller autonomously identifies channels with lower sensitivity and adds appropriate capacitance compensation, enabling the system to correct its own inconsistencies without external assistance during the development phase.
Solution Approach 2:
The invention changes the capacitance parameter by adding compensation capacitance values to channels with lower sensitivity. By dynamically adjusting the total capacitance value of each channel (original parasitic capacitance plus compensation capacitance), the system equalizes sensitivity across all channels, transforming the parameter distribution from unequal to equal.
2Measurement precision
If individual sensitivity measurement and threshold setting is performed for each channel, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The calibration system operates autonomously by automatically measuring parasitic capacitance, identifying channels requiring compensation, and adding appropriate capacitance values without requiring operator intervention. This self-service mechanism eliminates the need for manual sensitivity tuning and threshold setting for each channel, significantly improving ease of operation.
Solution Approach 2:
The calibration controller acts as an intermediary that mediates between the capacitance measurement device and the capacitance calibration modules. It processes measurement data, determines compensation requirements, and controls the addition of calibration capacitance, thereby automating the entire calibration process and improving operational convenience.
3Adaptability or versatility
If wiring length differences are maintained for channel arrangement, then device layout flexibility is improved, but manufacturing precision deteriorates due to varying parasitic capacitance
Solution Approach 1:
The invention applies local quality by providing individualized capacitance compensation to each channel based on its specific parasitic capacitance characteristics. Instead of requiring uniform wiring lengths across all channels, the system measures and compensates each channel's unique capacitance value locally, allowing flexible layout while maintaining consistent sensitivity performance.
Solution Approach 2:
The system changes the capacitance parameter by adding compensation capacitance values to channels with lower sensitivity caused by shorter wiring lengths. This parameter adjustment equalizes the total capacitance across all channels regardless of their wiring length differences, maintaining manufacturing precision while preserving layout flexibility.
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 simplifies the sensitivity tuning development procedure by ensuring all channels have the same sensitivity value and threshold level, reducing development time and complexity.
Implementation Method 1
a capacitance value with a surrounding ground (GND) pattern is formed in an electric wiring (trace or route), which is referred to as a parasitic capacitance Cp
Implementation Method 2
add a unique calibration capacitance value of each channel such that all channels have the same reference capacitance value that is preset
Data Source
AI summary
Disclosed herein are an apparatus and method for automatically calibrating capacitance per channel, for measuring parasitic capacitance values of respective channels due to a difference in a length of a wiring of each capacitance sensing channel when a circuit is designed and adding a unique calibration capacitance value of each channel such that all channels have the same reference capacitance value that is preset, and in detail, the apparatus for automatically calibrating a capacitance per channel includes a touch sensing device including a plurality of touch sensing regions, and a capacitance measurement and calibration device configured to measure parasitic capacitances of channels connected to the plurality of touch sensing regions, respectively, and to add a unique calibration capacitance of each channel to a corresponding channel to acquire a preset reference capacitance when each channel is connected to the parasitic capacitance.