Touch Screen Controller Floating Mode Entry Logic
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Solution Overview
Problem
Conventional touch screen devices struggle to accurately differentiate single touches from multiple touches in floating touch sensing mode, often falsely reporting multiple touches when only one finger is touching the screen, due to differences in ground levels between the device and the user's finger.
Innovation Solution
A touch screen controller with input and processing circuitry that acquires and normalizes mutual and self touch data, calculates differences, and switches between floating and non-floating touch data processing modes based on threshold conditions to accurately determine the number of touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional finger separation algorithms are used in floating touch sensing mode, then the device can detect multiple touches, but it falsely reports multiple touches when only one finger is touching the screen
Solution Approach 1:
The system dynamically switches between normal touch sensing mode and floating touch sensing mode based on detected ground level differences. The finger separation algorithm is selectively applied only in normal mode, while floating mode uses a different processing approach that accounts for ground potential differences, preventing false multiple touch detections
Solution Approach 2:
The system changes the touch data processing parameters based on the operating mode. In floating mode, the algorithm modifies how touch data is interpreted and processed compared to normal mode, adapting to the different electrical conditions caused by ground level differences between the device and user finger
2Measurement precision
If the system enters floating mode based on touch data differences, then it improves touch detection accuracy, but it requires complex threshold comparisons and mode switching logic
Solution Approach 1:
The system performs preliminary analysis of touch data by comparing self touch data with mutual touch data before fully committing to floating mode processing. Threshold comparisons are used to determine whether ground level differences exist, allowing the system to prepare and switch modes proactively rather than reactively
Solution Approach 2:
The system uses an intermediate determination step that compares touch data from two different sensing approaches (self and mutual capacitance) to decide whether floating mode conditions exist. This intermediary comparison acts as a mediator that translates raw touch data into a mode selection decision, simplifying the overall control logic
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 solution effectively differentiates single from multiple touches in floating conditions, preventing false touch registrations and improving touch screen accuracy by exploiting differences in touch strength values between mutual and self touch data.
Implementation Method 1
Touch screens typically operate based on capacitive touch sensing, and include a patterned array of conductive features. The conductive features form capacitive nodes at various points. By evaluating changes in capacitance at each capacitive node, a user touch or hover, such as by a finger or, can be detected.
Implementation Method 2
The processing circuitry cooperates with the input circuitry to acquire mutual touch data from the touch screen, sum values of the mutual touch data to produce mutual sums, acquire self touch data from the touch screen, normalize the mutual sums and the self touch data, and calculate differences between the normalized self touch data and the normalized mutual sums.
Data Source
AI summary
Disclosed herein is a touch screen controller including input circuitry operating a touch screen, and processing circuitry cooperating with the input circuitry to acquire mutual touch data and self touch data from the touch screen, sum values of the mutual touch data to produce mutual sums, normalize the mutual sums and the self touch data, and calculate differences between the normalized self touch data and the normalized mutual sums. The touch screen controller enters into a floating mode if a largest difference that is positive is greater than a positive difference threshold and if a smallest difference value that is negative is less than a negative difference threshold, but enters a non-floating mode if the largest difference that is positive is less than the positive difference threshold or if the smallest difference value that is negative is less than the negative difference threshold.