Optical Touch Sensing Using Angle Sensors for Large Displays
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Solution Overview
Problem
Existing touch sensing technologies, particularly in large format displays, face challenges with capacitive touch sensing being technically difficult and expensive to implement, necessitating an alternative method for determining the position of a light-emitting stylus or pointer on a screen.
Innovation Solution
The implementation of optical sensing technology using an optical stylus that emits light and spatially distributed optical sensors to determine the position of the light on a screen, processing measurements from multiple angle sensors to calculate the position in both two-dimensional and three-dimensional spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive touch sensing is implemented on large format displays, then touch sensing capability is provided, but implementation becomes technically difficult and expensive
Solution Approach 1:
The patent replaces capacitive touch sensing with optical sensing. Instead of using capacitive sensors that require complex electrode patterns and signal processing, the invention uses optical angle sensors to detect the position of a light-emitting stylus by measuring the angle of incident light. This substitution of mechanical/electrical sensing with optical sensing simplifies the overall system implementation on large format displays.
Solution Approach 2:
The patent introduces light as an intermediary between the stylus and the sensor system. The light-emitting stylus emits light that travels through space and is detected by optical angle sensors positioned around the display perimeter. This intermediary approach allows for contactless sensing and simplifies the sensor integration compared to direct capacitive coupling.
2Measurement precision
If optical angle sensors are positioned at multiple locations on the screen, then position determination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the sensing function across multiple optical angle sensors positioned at different locations around the display perimeter (e.g., four corners or edges). Each sensor independently measures the angle of incident light from the stylus, and the system processes these segmented measurements to calculate the two-dimensional or three-dimensional position. This segmentation improves accuracy while keeping each individual sensor simple.
Solution Approach 2:
The patent transitions from two-dimensional position sensing to three-dimensional position sensing by adding depth information through multiple angle measurements. By positioning sensors at different locations and measuring angles from multiple perspectives, the system can determine not only the x-y position but also the z-distance to the stylus, providing enhanced spatial awareness without significantly increasing complexity.
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 accurate and cost-effective touch sensing on various display formats, including large screens, by determining the position of a light-emitting stylus or pointer without the need for direct contact, enhancing user interaction capabilities.
Implementation Method 1
a first optical angle sensor positioned on the screen to measure the angle of light from the optical stylus by detecting the direction of incident light from the optical stylus
Data Source
AI summary
Touch sensing based on optical sensing as disclosed herein can be implemented by using an optical stylus or pointer that emits probe light for optical sensing, and spatially distributed optical sensors at different spatial locations for sensing. The measurements from the different optical sensors can be processed to determine the position of the light from the optical stylus at the screen. Optical sensing of a position on a two-dimensional surface and a position in a three-dimensional space can be achieved for various optical touch sensing applications. In one implementation, an apparatus can include a screen or display, an optical stylus or optical pointer, and two or more optical angle sensors which determine, respectively, a first angle between the first optical angle sensor and a position of light at the screen and a second angle between the second optical angle sensor and the position of light at the screen.