Optical Navigation Specular Reflection Blocking
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Solution Overview
Problem
Conventional optical navigation systems face difficulties in distinguishing individual features on highly reflective surfaces due to low contrast images caused by high intensity specular reflections, making it challenging to accurately determine movements.
Innovation Solution
Incorporating a lens and a mask that focuses specular light to a focus region and filters it out, while passing scattered light to the image sensor, allowing for the generation of navigation signals based on the scattered light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optical navigation systems collect light reflected at a specular reflection angle from highly reflective surfaces, then the signal intensity of the reflected light is high, but the contrast of the image is low making it difficult to distinguish individual features
Solution Approach 1:
The patent segments the reflected light into two distinct components: specular reflection and scattered light. By using optical elements to separate these components spatially, the system can selectively block the specular portion while preserving the scattered light component, thereby maintaining signal intensity while improving image contrast for feature detection
Solution Approach 2:
The patent extracts and removes the harmful specular reflection component from the total reflected light using a mask or aperture positioned at the specular reflection angle. This extraction eliminates the dominant high-intensity specular component that washes out surface features, allowing the weaker scattered light containing surface information to become detectable
2Loss of information
If a mask is used to filter out specular light, then image contrast improves, but device complexity increases
Solution Approach 1:
The patent merges the specular light blocking function with existing optical navigation components. The mask is integrated into the optical path near the image sensor, and the same optical elements that collect scattered light also define the field of view, combining multiple functions into a unified optical design that minimizes additional complexity
Solution Approach 2:
The patent introduces a simple mask or aperture as an intermediary element in the optical path. This passive optical component selectively blocks specular light without requiring active control mechanisms, electronic processing, or complex mechanical systems, thereby improving contrast while adding minimal complexity to the device
3Volume of moving object
If the device size is reduced, then portability improves, but the ability to accurately track movements on glossy surfaces deteriorates
Solution Approach 1:
The patent replaces traditional mechanical or software-based compensation methods with an optical solution. By using optical elements (lens, mask, aperture) to physically separate and block specular light in the optical path, the system achieves accurate movement tracking on glossy surfaces without requiring larger device dimensions or complex mechanical adjustment mechanisms
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 enhances the ability to track movements on glossy surfaces by reducing the intensity of reflected light at the image sensor, improving signal quality and enabling more accurate navigation signals with a smaller device size.
Implementation Method 1
The lens focuses a specular portion of the reflected light to a focus region
Implementation Method 2
The mask is located at approximately the focus region. The mask filters out substantially all of the specular portion of the reflected light
Implementation Method 3
The light reflects off of the reflective navigation surface 16 at an angle of reflection, which is equal to the angle of incidence, because of the reflective nature of the reflective navigation surface 16
Data Source
AI summary
A system for optical navigation includes a light source and an imaging system. The light source illuminates a navigation surface. The navigation surface reflects light from the light source. The imaging system is located approximately within a path of the reflected light. The imaging system includes a lens, a mask, and an image sensor. The lens receives reflected light from the navigation surface. The lens focuses a specular portion of the reflected light to a focus region. The mask is located at approximately the focus region. The mask filters out substantially all of the specular portion of the reflected light and passes at least some of a scatter portion of the reflected light outside of the focus region. The image sensor generates a navigation signal based on the scattered portion of the light that passes outside the focus region and is incident on the image sensor.