Stray Light Redirection Structures for Optical Sensor Noise
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Solution Overview
Problem
Electronic devices with optical sensors face interference from stray light that is internally reflected within transparent layers, leading to noise and reduced performance of the sensors.
Innovation Solution
Incorporation of stray light redirecting structures such as protrusions, recesses, gaps, textured regions, micro-bubbles, and index-matched coatings in the transparent layer to redirect and absorb stray light, reducing its impact on optical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent layer is used to cover the front of the head-mounted device, then the user can see real-world images and displayed images can be overlaid, but stray light is internally reflected within the transparent layer causing noise and reduced sensor performance
Solution Approach 1:
The patent converts the harmful effect of total internal reflection into a beneficial one by strategically placing opaque masking layers and light-absorbing materials at specific locations where reflected light would otherwise cause noise. The masking layers are positioned to absorb stray light while maintaining visibility of real-world images and displayed overlays, thus transforming the problematic reflection into a controlled light management system that improves sensor performance without sacrificing the transparent layer's optical functionality
Solution Approach 2:
The patent introduces opaque masking layers and light-absorbing materials as intermediary elements between the transparent layer and the optical sensor. These intermediaries intercept and absorb stray light that would otherwise reflect within the transparent layer and reach the sensor, thereby reducing noise. The masking layers are strategically positioned to block harmful reflected light while allowing necessary light transmission for imaging and display functions
2Strength
If the transparent layer is made thicker to improve structural integrity, then the device becomes more durable, but total internal reflection of stray light increases
Solution Approach 1:
The patent acknowledges that thicker transparent layers increase structural integrity but also increase stray light reflection. To convert this harm into a benefit, the patent incorporates opaque masking layers and light-absorbing materials within the thicker layer structure. These elements are positioned to absorb the increased amount of stray light generated by the greater thickness, thereby maintaining the structural advantages while compensating for the increased reflection through strategic light management
3Adaptability or versatility
If optical sensors are added to detect reflected light from external objects, then environmental tracking capability is improved, but the sensors receive noise from internally reflected stray light
Solution Approach 1:
The patent introduces opaque masking layers and light-absorbing materials as intermediary elements positioned between the transparent layer and the optical sensors. These intermediaries selectively absorb stray light that would otherwise reach the sensors and create noise, while allowing the sensors to continue detecting reflected light from external objects for environmental tracking. The masking layers are strategically positioned to block harmful internal reflections without interfering with the sensors' ability to perform their primary function of environmental detection
Solution Approach 2:
The patent converts the harmful effect of stray light reaching the optical sensors into a beneficial outcome by using opaque masking layers to absorb the stray light. This allows the optical sensors to maintain their environmental tracking capability while experiencing reduced noise levels. The masking layers transform the problematic stray light into absorbed energy, improving the signal-to-noise ratio and measurement accuracy of the 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
Significantly reduces stray light reaching optical sensors, enhancing their signal-to-noise ratio and improving performance by redirecting and absorbing stray light within the transparent layer.
Implementation Method 1
The stray light redirecting structure may be configured to redirect stray light that is reflecting within the transparent layer. For example, the stray light redirecting structure may defeat the total internal reflection of the stray light within the transparent structure.
Implementation Method 2
The stray light redirecting structure may formed from protrusions, recesses, gaps in the transparent layer, textured regions, micro-bubbles, and/or index-matched coatings.
Data Source
AI summary
An electronic device such as a head-mounted device may have a transparent layer supported by head-mounted support structures. A light source may emit light through the transparent layer, and an optical sensor may detect light that has reflected from an external object, such as to track the external object. A stray light redirecting structure may be formed in the transparent layer. The stray light redirecting structure may be configured to block stray light that is reflecting within the transparent layer. This reduces the amount of stray light received by the optical sensor. The stray light redirecting structure may formed from protrusions, recesses, gaps in the transparent layer, textured regions, micro-bubbles, and/or index-matched coatings. An opaque masking layer may be coupled to the transparent layer to absorb the stray light and further reduce the amount of stray light that reaches the optical sensor.