Photo-Sensing Display With Angular Filters for Stylus Detection
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Solution Overview
Problem
Existing touch sensing systems struggle with accurately detecting the tilt angle and hover distance of a stylus, leading to degraded performance and tracking accuracy due to reflections and refractions at the boundary between the detection surface and mediums like air or water, which can be misidentified as a finger or stylus.
Innovation Solution
Employing angular filters for light illuminators and detectors within the integrated touch screen to limit illumination and detection angles, and using passive, semi-active, or active styluses with diffusive, retroreflective, or diffractive reflectors to generate consistent or modulated light patterns for precise detection of stylus location, tilt angle, and rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If capacitive touch sensor panels are used for stylus detection, then touch sensitivity and ease of operation are improved, but the ability to accurately detect tilt angle and hover distance deteriorates due to reflections and refractions at boundaries
Solution Approach 1:
The system divides the detection function into separate components: capacitive sensors for basic touch detection and optical sensors for tilt angle and hover distance measurement. This segmentation allows each sensor type to optimize for its specific function while working together to provide comprehensive stylus detection.
Solution Approach 2:
The patent introduces optical sensors as an intermediary measurement system between the capacitive touch surface and the stylus. These optical sensors detect light patterns created by the stylus to determine tilt angle and hover distance, serving as a mediator that provides accurate measurements without requiring direct physical contact or being affected by boundary reflections.
2Measurement precision
If optical sensors are added to detect stylus tilt and hover distance, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The optical sensors serve multiple functions: detecting stylus presence, determining tilt angle, measuring hover distance, and identifying rotation. By making the optical detection system multi-functional, the patent reduces the need for separate dedicated sensors for each measurement type, thereby limiting the increase in device complexity while maintaining high measurement precision.
Solution Approach 2:
The patent combines optical detection capabilities with the existing capacitive touch sensor system, merging the functions of touch detection and optical measurement into an integrated system. This consolidation allows the system to achieve enhanced measurement precision without proportionally increasing device complexity by sharing hardware and processing resources.
3Illumination intensity
If the detection surface boundary is made transparent for display visibility, then display quality is improved, but false detection of water droplets and reflections increases
Solution Approach 1:
The system dynamically analyzes the temporal and spatial characteristics of detected light patterns to distinguish between valid stylus contact and false signals from water droplets or reflections. By monitoring changes in the detection pattern over time and across multiple sensors, the system can reliably filter out false positives while maintaining display visibility through the transparent boundary.
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors detection patterns and compares them against expected stylus interaction characteristics. When anomalies such as water droplet reflections are detected, the system uses feedback to adjust detection thresholds and algorithms, preventing false positives while maintaining the transparent display boundary's visibility.
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
Enhances the accuracy of stylus detection by reducing false positives from reflections and refractions, allowing for precise determination of hover distance, tilt angle, and rotation, enabling additional input modes such as controlling line texture and color in drawing applications.
Implementation Method 1
detecting light transmitted by a stylus
Implementation Method 2
detecting modulated light generated by some of the micro-LEDs and reflected off the object
Implementation Method 3
The micro-LEDs and micro-driver circuitry can be configured in an optical reflective touch mode to detect the presence of an object such as a finger or stylus by detecting modulated light generated by some of the micro-LEDs
Implementation Method 4
passive, semi-active, or active styluses with diffusive, retroreflective, or diffractive reflectors
Implementation Method 5
passive, semi-active, or active styluses with diffusive, retroreflective, or diffractive reflectors
Implementation Method 6
passive, semi-active, or active styluses with diffusive, retroreflective, or diffractive reflectors
Data Source
AI summary
An optical stylus system including an optical stylus and optical sensing system that are together operative to determine one or more of the target or touch location, centroid, hover distance, tilt angle, azimuth, and in some instances the orientation and rotation of the stylus is disclosed. In some examples, light illuminator and detector angular filters are employed to limit the illumination and detection angles of light to minimize false object detection. In other examples, the stylus is a passive stylus with a surface that reflects light with a consistent angular reflection profile or reflected light pattern regardless of stylus tilt. In still other examples, the stylus can detect light at different modulation frequencies emitted from an array of light emitters in the optical sensing system, or the stylus can emit light and detect reflected light with different spectral distributions across the optical sensing system to determine stylus location.