Optical Touch Detection Multiplexing Instruments and Fingers
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Solution Overview
Problem
Current touch-sensitive technologies face challenges in scaling to larger screen sizes, handling multitouch events efficiently, and meeting increasing resolution demands, often resulting in high costs, low yields, and ambiguity in signal processing.
Innovation Solution
An optical touch-sensitive device with multiple emitters and detectors that use multiplexed optical beams to distinguish between instrument and finger touch events, employing features like contact area, attenuation rates, temporal behavior, and wavelength to differentiate instruments, and incorporating active instruments with additional optical communication channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional touch-sensitive technologies are scaled to larger screen sizes, then screen area increases, but manufacturing cost increases and yield decreases
Solution Approach 1:
The touch-sensitive device is divided into multiple independent sensing regions with discrete emitters and detectors. Each region can be manufactured and tested separately, allowing modular assembly for large screens without requiring entire large-area surfaces to be perfectly processed in one go, thereby improving yield and reducing cost.
Solution Approach 2:
The optical components (emitters and detectors) serve multiple functions: they detect finger touches, distinguish instrument touches through temporal analysis, and can identify different instruments through their unique temporal signatures. This multi-functionality reduces the need for additional specialized components, lowering overall manufacturing complexity and cost.
2Adaptability or versatility
If traditional touch technologies handle multitouch events, then touch capability increases, but signal processing complexity and computational load increase
Solution Approach 1:
The system pre-establishes temporal response profiles for different touch types (finger vs. instrument) and different instruments during calibration. During operation, incoming touch signals are compared against these pre-stored profiles using template matching, avoiding the need for complex real-time analysis and reducing computational burden during multitouch events.
Solution Approach 2:
The system uses periodic temporal sampling of optical beam interruptions to capture touch events. By analyzing the periodic temporal patterns of beam interruption and using correlation techniques with pre-stored templates, the system can efficiently distinguish multiple simultaneous touches and their types without requiring excessively complex continuous processing.
3Measurement precision
If touch resolution is increased to meet higher accuracy demands, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The system adds the temporal dimension to the spatial detection of touch events. Instead of relying solely on spatial resolution of optical beams, the system measures the temporal characteristics (duration, rate of change) of beam interruptions. This temporal information provides an additional degree of freedom for determining touch properties, effectively increasing measurement precision without proportionally increasing spatial complexity.
Solution Approach 2:
The system changes from static spatial measurement to dynamic temporal measurement. By analyzing how optical beam interruption parameters change over time (temporal derivatives, acceleration profiles), the system can distinguish touch location and type with higher precision. This parameter transformation allows achieving better resolution without linearly increasing the number of spatial sensors.
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
The solution enables efficient detection and differentiation of touch events on larger screens with improved accuracy and reduced costs, effectively handling multitouch events and increasing resolution demands while maintaining computational efficiency.
Implementation Method 1
The optical beams preferably are multiplexed in a manner so that many optical beams can be received by a detector simultaneously. Touch events disturb the optical beams, for example due to frustrated total internal reflection.
Data Source
AI summary
An optical touch-sensitive device detects touch events caused by instruments (e.g., pens, styluses) and distinguishes these events from touch events caused by fingers. In some embodiments, different instruments can also be distinguished. The optical touch-sensitive device includes multiple emitters and detectors. Each emitter produces optical beams which are received by the detectors. The optical beams preferably are multiplexed in a manner so that many optical beams can be received by a detector simultaneously. Touch events disturb the optical beams, for example due to frustrated total internal reflection. Information indicating which optical beams have been disturbed is analyzed to detect one or more touch events. The analysis also distinguishes instrument touch events from finger touch events.