Optical Navigation Lens Structure for Stray Light Suppression
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Solution Overview
Problem
Conventional optical navigation devices suffer from reduced detection accuracy due to stray and scattered light beams, which interfere with the optical detector and decrease navigation precision.
Innovation Solution
The optical navigation device incorporates first and second optical elements, such as front prism blocks or opaque layers, to deflect, refract, or diffuse stray and scattered light beams away from the detector's field of view, preventing them from reaching the navigation surface and eliminating undesired secondary signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical navigation device is lifted relative to the navigation surface at a certain height, then the illumination beam can cover a larger area, but stray light beams are generated that interfere with the optical detector and reduce detection accuracy
Solution Approach 1:
The patent extracts and removes the harmful stray light beams from the optical path by introducing a baffle structure that selectively blocks stray light while allowing the useful illumination beam and reflection beam to pass through. This separates the harmful stray light from the useful optical signals, resolving the contradiction between illumination area and detection accuracy.
Solution Approach 2:
The baffle acts as an intermediary element positioned between the illumination lens and the navigation surface. It mediates the interaction between the illumination beam and the optical detector by selectively blocking stray light paths while permitting the desired optical signals to reach the detector, thus improving detection accuracy without reducing illumination coverage.
2Productivity
If the optical detector receives the stray light beam, then the illumination beam can be projected onto the navigation surface, but an undesired secondary signal is generated that decreases navigation accuracy
Solution Approach 1:
The patent converts the harmful effect of stray light into a beneficial outcome by using the baffle to redirect stray light away from the optical detector. The baffle structure is designed to block stray light paths while maintaining the integrity of the useful optical signals, thus eliminating the harmful secondary signals without compromising illumination efficiency.
3Measurement precision
If a baffle structure is added to block stray light beams, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The baffle structure is designed to perform multiple functions simultaneously: it blocks stray light beams, maintains the optical path for useful signals, and can be integrated with existing optical components. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved detection accuracy.
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 design significantly enhances detection accuracy by effectively blocking stray and scattered light beams, thereby improving navigation precision and protecting the illumination lens from damage.
Implementation Method 1
The first surface has a function of total internal reflection, an included angle formed between a planar normal vector of the first surface and a planar normal vector of the navigation surface is substantially equal to forty-five degrees, and the first surface is adapted to totally reflect the stray light beam sideway to the second surface
Implementation Method 2
The second surface is adapted to refract the stray light beam in a preset direction away from the navigation surface
Implementation Method 3
The first optical element is an opaque layer adapted to absorb the stray light beam to prevent the stray light beam from being projected onto the navigation surface
Implementation Method 4
The first optical element is an optical deflection layer adapted to reflect or refract the stray light beam away from the navigation surface
Implementation Method 5
The first optical element is an optical deflection layer adapted to reflect or refract the stray light beam away from the navigation surface
Implementation Method 6
The first optical element is an optical diffusion layer adapted to diffuse the stray light beam away from the navigation surface
Data Source
AI summary
An optical navigation device includes a case, an illumination light source, an illumination lens, an optical detector and a first optical element. The case is movably located above a navigation surface. The illumination light source is disposed inside the case and adapted to emit an illumination beam. The illumination lens is disposed under the illumination light source and has an output surface. The illumination beam passes through the output surface to project onto the navigation surface. The optical detector is disposed inside the case and adapted to detect a reflection beam from the navigation surface. The first optical element is disposed adjacent to the output surface of the illumination lens and extended to an outer edge of the illumination lens, and adapted to eliminate a stray light beam generated by the illumination beam propagated between the illumination lens and the navigation surface from reaching the navigation surface.