Touch Screen Timing Accuracy via Sensor Signal Windowing
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Solution Overview
Problem
Conventional touch screens in electronic devices, such as smartphones and tablets, suffer from inaccuracies in timing measurements due to low sampling frequencies and position-dependent response times, making them unsuitable for precise reaction time-based tasks like the Psychomotor Vigilance Test (PVT) and Finger Tapping Task (FTT).
Innovation Solution
A method that utilizes a sensor signal, such as a microphone or accelerometer, to derive more accurate touch timings by identifying a time window in the sensor signal corresponding to touch events, which can then be processed to determine the precise timing of touches, thereby improving the accuracy of reaction time measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a touch screen is used to register user responses in reaction time tests, then the need for dedicated hardware is reduced and ease of operation is improved, but the measurement precision of touch timing deteriorates due to low sampling frequency and position dependency
Solution Approach 1:
The patent combines multiple sensing modalities (touch screen contact detection, accelerometer motion detection, and audio recording) into a unified measurement system. The processor integrates data from all three sources to determine reaction time, leveraging the strengths of each sensor type to overcome the limitations of the touch screen alone.
Solution Approach 2:
The accelerometer acts as an intermediary sensor that detects the mechanical motion of the user's finger during the tapping action. This intermediate measurement provides timing information that is independent of the touch screen's scanning limitations, thereby improving overall measurement precision.
2Device complexity
If touch screen scanning is used to detect touch timing, then device complexity is reduced by using existing components, but the reliability of timing measurements deteriorates due to jitter and position dependency
Solution Approach 1:
The system uses feedback from multiple sensors (accelerometer and audio recorder) to verify and correct timing measurements from the touch screen. The processor compares timing data across different modalities and uses this feedback to compensate for jitter and position-dependent errors in the touch screen measurements.
Solution Approach 2:
The patent creates a composite sensing system that combines data from heterogeneous sources (touch screen, accelerometer, audio). This composite approach leverages the complementary strengths of each sensor type to produce more reliable timing measurements than any single sensor could provide alone.
3Use of energy by moving object
If the sampling frequency of the touch screen is kept low to save energy and reduce processing load, then use of energy is improved, but the measurement precision of touch timing deteriorates
Solution Approach 1:
The system uses partial sampling from the accelerometer and audio recorder at higher frequencies than the touch screen, but only processes these high-frequency measurements when needed for timing determination. This selective high-frequency sampling provides improved measurement precision without continuously consuming high energy.
Solution Approach 2:
The accelerometer and audio recorder serve multiple functions: they provide timing information, verify touch screen measurements, and compensate for positioning errors. This multi-functionality justifies their higher energy consumption by providing superior measurement capabilities that benefit the overall system performance.
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 enhances the accuracy of touch timing measurements, allowing for more reliable implementation of reaction time-based tasks on electronic devices, providing better precision in assessing user alertness and psychomotor performance.
Implementation Method 1
A method that utilizes a sensor signal, such as a microphone or accelerometer, to derive more accurate touch timings
Implementation Method 2
A method that utilizes a sensor signal, such as a microphone or accelerometer, to derive more accurate touch timings
Data Source
AI summary
The invention relates to a method and apparatus for improving the measurement of the timing of touches of a touch screen. In an embodiment a method of determining a time at which a user touched a touch screen of an electronic device comprises obtaining (101) a touch signal generated by the touch screen for a first time period, the touch signal indicating when the user touched the touch screen during the first time period; obtaining (103) a sensor signal generated by a first sensor for at least the first time period, the sensor signal comprising a first signal component corresponding to a measurement by the first sensor of the user making contact with the touch screen; using (105) the touch signal to identify a time window in the sensor signal containing the first signal component; and processing (107) the windowed sensor signal to determine the timing of the first signal component in the sensor signal.