Optical Sensor Light Barrier Reduces Specular Reflections
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Solution Overview
Problem
Current optical proximity sensors are complex, costly, and prone to specular reflections when used with light transmissive cover plates, which reduces their ability to sense distance accurately due to noise from direct light leakage and reflections.
Innovation Solution
The implementation of a dual opaque light barrier system within the sensor device, comprising a first barrier to block direct light transmission and a second barrier extending towards the light source to minimize specular reflections, along with an optional third barrier to further reduce detected reflections, is proposed. This system includes a light source and detector separated by opaque materials to prevent light leakage and reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light transmissive cover plate is placed over the optical sensor, then the sensor is protected and can be integrated into devices, but specular reflections occur that reduce sensing accuracy
Solution Approach 1:
A light barrier is introduced as an intermediary element between the light source and light detector. This barrier selectively blocks specular reflections from the cover plate while allowing direct light transmission, thus mediating between the protective cover plate and the sensing function to eliminate harmful reflections without compromising sensor protection
Solution Approach 2:
The optical path is segmented into direct light transmission paths and reflection paths. By placing the light barrier at a specific position and orientation, the design separates useful direct light from harmful specular reflections, allowing both the cover plate protection and accurate sensing to coexist
2Measurement precision
If a light barrier is used to block direct light transmission from source to detector, then light leakage is reduced, but the device complexity and manufacturing cost increase
Solution Approach 1:
The light barrier is merged with the cover plate assembly, where the barrier can be integrated into the cover plate structure itself or positioned as a unified component. This combining approach reduces the number of separate parts and simplifies manufacturing while maintaining the light-blocking function
Solution Approach 2:
The cover plate assembly is designed to serve multiple functions: providing physical protection, enabling light transmission for sensing, and blocking specular reflections. By making the cover plate assembly multi-functional, separate dedicated components are eliminated, reducing overall device 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 configuration results in a cost-effective, reduced form factor optical sensor with enhanced sensitivity by minimizing noise from direct light leakage and specular reflections, allowing for more accurate proximity sensing.
Implementation Method 1
A light barrier is often used to isolate the light source from the light detector
Implementation Method 2
a second opaque light barrier portion extending from the first opaque light barrier portion in a direction towards the light source is configured to reduce an amount of specular reflections
Data Source
AI summary
An optical sensor device, according to an embodiment of the present invention, includes a light source and a light detector. The light source includes one or more light emitting elements, and the light detector includes one or more light detecting elements. A first opaque light barrier portion, between the light source and the light detector, is configured to block light from being transmitted directly from the light source to the light detector. A second opaque light barrier portion, extending from the first opaque light barrier portion in a direction towards the light source, is configured to reduce an amount of specular reflections that would occur if a light transmissive cover plate were placed over the optical sensor device. A third opaque light barrier portion, extending from the first light barrier portion in a direction towards to the light detector, is configured to reduce an amount of specular reflections that would be detected by the light detector, if a light transmissive cover plate were placed over the optical sensor device.