Touch Screen Controller Parallel Sampling Rate Noise Analysis
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Solution Overview
Problem
Thinner touch sensitive displays in handheld electronic devices suffer from increased noise coupling, degrading the accuracy of touch sensing due to parasitic capacitances, making existing frequency scanning methods time-consuming and resource-intensive.
Innovation Solution
A touch screen controller that generates digital touch voltage samples at a base sampling rate and analyzes subsets of samples at different investigated sampling rates to determine a preferred sampling rate with lower noise content, using filters and registers to evaluate noise and select optimal sampling and filtering configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the touch sensitive display is made thinner to meet consumer desires, then the device thickness is reduced, but noise coupling increases due to greater parasitic capacitances
Solution Approach 1:
The patent changes the sampling frequency parameter to optimize touch sensing accuracy. By scanning through multiple sampling frequencies and identifying the frequency that minimizes noise impact, the system adapts to the increased noise coupling caused by thinner display construction without requiring structural modifications
Solution Approach 2:
The patent performs preliminary frequency scanning and noise analysis before actual touch sensing operations. By pre-determining the optimal sampling frequency that minimizes noise coupling effects, the system prepares in advance to compensate for the inherent noise problems introduced by thinner display designs
2Measurement precision
If frequency scanning is performed by acquiring separate full sets of samples at different sampling frequencies, then noise analysis accuracy is improved, but time consumption and resource usage increase
Solution Approach 1:
The patent merges multiple sampling frequency analyses into a single unified sampling process. By collecting one complete set of samples at a base sampling frequency and then digitally re-sampling this single dataset at multiple different frequencies, the system combines what would otherwise require multiple separate acquisition processes into one efficient operation
Solution Approach 2:
The patent creates digital copies of the sampled signal at different sampling frequencies from a single original dataset. Instead of physically re-acquiring samples at each frequency, the system generates synthetic sample sets by interpolating or re-sampling the original high-frequency data, significantly reducing measurement time while maintaining analysis accuracy
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 improves the accuracy of touch sensing by efficiently selecting a sampling rate that minimizes noise, enhancing the performance of touch screen technology while reducing resource consumption.
Implementation Method 1
The capacitance between the sense lines and the driven drive line is sensed at the point where they intersect. Presence of a human finger or a conductive object alters the expected capacitance at the intersection point
Implementation Method 2
as the thinner designs result in greater parasitic capacitances coupling the noise from the display layer through to the sensing layer
Data Source
AI summary
A touch screen controller disclosed herein includes a circuit configured to generate a digital touch voltage comprises of samples, at a base sampling rate. The touch screen controller also includes a digital processing unit configured to analyze a first subset of samples of the digital touch voltage samples to determine noise content thereof, the first subset of samples corresponding to samples at a first investigated sampling rate that is a first function of the base sampling rate. The digital processing unit is also configured to analyze a second subset of samples of the digital touch voltage to determine noise content thereof, with the second subset of samples corresponding to samples at a second investigated sampling rate that is a second function of the base sampling rate, and determine a preferred sampling rate from among the first and second investigated sampling rates as a function of determined noise content thereof.