Multi-touch Post Processing for Low Latency Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-touch sensors face challenges in achieving low latency and high update rates for detecting touch events, particularly in transparent display surfaces, while also being susceptible to interference and requiring costly manufacturing processes.
Innovation Solution
The development of a fast multi-touch sensor system utilizing projected capacitive methods with orthogonal signal transmission and reception, combined with sinusoid-based signal processing and modulation techniques, such as frequency modulation and direct sequence spread spectrum modulation, to enhance interference resistance and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional multi-touch sensor methods are used, then manufacturing cost is reduced, but latency increases and update rates decrease
Solution Approach 1:
The sensor surface is divided into multiple independent sensor elements arranged in a grid pattern, with each element capable of independent capacitive sensing. This segmentation allows parallel processing of touch events across multiple zones simultaneously, reducing overall system latency while maintaining high update rates.
Solution Approach 2:
The system employs periodic scanning of capacitive values across sensor elements at high frequency intervals. By implementing periodic measurement cycles with optimized timing, the system achieves high update rates while minimizing the time between touch detection and processing.
2Illumination intensity
If transparent display surfaces are used, then visual clarity is improved, but interference susceptibility increases
Solution Approach 1:
The system continuously monitors capacitive values from sensor elements and employs dynamic threshold adjustment based on environmental conditions. By implementing feedback mechanisms that adapt to changing electromagnetic environments, the system maintains high visual clarity of transparent displays while compensating for and reducing susceptibility to external interference.
Solution Approach 2:
The system dynamically adjusts measurement parameters such as excitation frequency and capacitive threshold levels based on detected environmental conditions. By changing operational parameters in response to interference levels, the system maintains optimal performance on transparent displays while resisting electromagnetic and optical interference.
3Object-affected harmful factors
If complex signal processing methods are used, then interference resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The system extracts and processes only the essential capacitive signal components from each sensor element, separating useful touch information from noise and interference. By taking out only the critical measurement data and processing it through simplified algorithms, the system achieves good interference resistance without requiring complex manufacturing processes.
Solution Approach 2:
The system uses simple, cost-effective capacitive sensor elements that can be manufactured using standard transparent conductor techniques. Rather than employing complex persistent interference cancellation systems, the approach uses inexpensive, easily replaceable sensor elements with straightforward signal processing that provides adequate interference resistance for practical applications.
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 enables low-latency detection and processing of touch events with high update rates, reduces interference, and allows for cost-effective manufacturing, particularly suitable for transparent display surfaces.
Implementation Method 1
a fast multi-touch sensor which utilizes post processing techniques to convert capacitive values into touch events
Implementation Method 2
sinusoid-based signal processing and modulation techniques, such as frequency modulation and direct sequence spread spectrum modulation
Implementation Method 3
direct sequence spread spectrum modulation
Data Source
AI summary
In a low-latency touch-sensitive device, post-processing is performed to convert a two-dimensional map of signal strengths into usable touch events. Four such post-processing procedures are disclosed: field flattening, touch point detection, interpolation and touch point matching between frames. The field flattening procedure subtracts an offset to remove crosstalk between rows and columns, and compensates for differences in amplitude between particular row/column combinations due to attenuation. The touch point detection procedure computes coarse touch points by finding local maxima in the flattened signal. The interpolation procedure computes fine touch points from the coarse touch points. In an embodiment, such interpolation is done by fitting the coarse touch points to a paraboloid. The frame matching procedure matches the calculated touch points to each other across frames.