Optical Touch Calibration via Intensity Curve Analysis
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Solution Overview
Problem
Optical-touch panels face issues with deformation of the touch-sensing area, leading to noise and misalignment due to external forces affecting the optical sensor's position, which existing area optical sensors attempt to address but at the cost of higher complexity, power consumption, and longer capture times.
Innovation Solution
An optical-touch calibration method using a line optical sensor to measure reflected intensity curves and adjust the emitting power of a projective light source based on calculated intensity differences between actual and reference curves, thereby calibrating deformations without the need for complex area sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an area optical sensor is used to sense toward different angles, then the touch-sensing accuracy is improved under deformation, but the device complexity, manufacturing cost, power consumption, and image capture time increase
Solution Approach 1:
The patent divides the optical sensing function into two separate components: a projective light source that emits structured light patterns and a line optical sensor that detects reflected light along a linear axis. This segmentation allows each component to be optimized independently, avoiding the need for a complex area optical sensor while maintaining the capability to detect deformations through intensity curve analysis
Solution Approach 2:
The patent transitions from using a two-dimensional area optical sensor to a one-dimensional line optical sensor combined with a projective light source. By projecting structured light patterns and analyzing the reflected intensity curves along a linear axis, the system achieves deformation detection in a different dimensional approach, reducing sensor complexity while preserving measurement precision
2Measurement precision
If an area optical sensor is used to reselect optimal sensing angle, then the touch-sensing accuracy is improved, but the power consumption increases
Solution Approach 1:
The system performs preliminary calibration by capturing intensity curves at different emitting powers of the projective light source and storing reference intensity curves in advance. During normal operation, the line optical sensor only needs to compare current readings against these pre-stored references, significantly reducing power consumption while maintaining accurate deformation detection capability
3Measurement precision
If an area optical sensor is used with extra step for selecting optimal sensing angle, then the touch-sensing accuracy is improved, but the image capture time increases
Solution Approach 1:
The calibration process performs preliminary measurements at different light source emitting powers and stores reference intensity curves in advance. During actual touch sensing, the system directly compares current intensity curves against these pre-computed references, eliminating the need for real-time angle selection and significantly reducing image capture time while maintaining measurement precision
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 reduces noise and misalignment by efficiently calibrating deformations, maintaining touch-sensing accuracy while minimizing cost, size, and power consumption, and enabling faster operation compared to traditional area optical sensors.
Implementation Method 1
A projective beam is generated by the projective light source. The projective beam is reflected to the line optical sensor.
Implementation Method 2
The line optical sensor is utilized to measure the reflected projective beam for obtaining a reflected intensity curve relative to a linear coordinate axis.
Data Source
AI summary
An optical-touch calibration method and an optical-touch panel are disclosed herein. The optical-touch calibration method is suitable for the optical-touch panel including a projective light source and a line optical sensor. The optical-touch calibration method includes steps of: generating a projective beam by the projective light source, and the projective beam being reflected to the line optical sensor; utilizing the line optical sensor to measure the reflected projective beam for obtaining a reflected intensity curve relative to a linear coordinate axis; calculating an intensity difference between the reflected intensity curve and a reference intensity curve; and, adjusting an emitting power of the projective light source if the intensity difference exceeds a threshold value.