Proximity Sensor Optical Routing Module Blind Zone Elimination
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Solution Overview
Problem
Proximity sensors face challenges such as blind zones and crosstalk noise, which can lead to failure in detecting targets due to non-overlapping emitter and detector fields of view and internal light reflections, especially when targets are close or have low reflectance materials.
Innovation Solution
Incorporating an optical routing module with a transmissive-reflective surface oriented at 45° ± 10° within an air gap between the proximity module and lens, allowing emitted light to exit and target-reflected light to be detected by aligning the detector field of view with the emitter field of view, and using a smaller transmissive portion on the lens to reduce crosstalk and aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the emitter and detector are positioned close together in a standard proximity sensor configuration, then the device structure is simple and compact, but a blind zone is created where the emitter FOV and detector FOV do not overlap, preventing detection of close targets
Solution Approach 1:
The patent introduces a beam splitter positioned at 45 degrees to redirect light paths in a third dimension. The emitter FOV and detector FOV are separated spatially and redirected through the beam splitter to overlap in the external space, eliminating the blind zone while maintaining compact internal structure. This dimensional reconfiguration allows both FOVs to cover the same external region without requiring the emitter and detector to be in direct alignment.
2Area of stationary object
If the detector FOV is made larger to increase target detection area, then more targets can be detected, but crosstalk increases as more internal reflections are captured
Solution Approach 1:
The patent segments the optical paths by using a beam splitter to separate the emitter and detector FOVs internally while maintaining external overlap. The beam splitter divides the light paths such that emitted light and reflected light follow distinct routes, reducing internal reflections and crosstalk while preserving a large effective detection area.
Solution Approach 2:
The beam splitter acts as an intermediary optical element that mediates between the emitter and detector. It redirects light paths to achieve FOV overlap externally while preventing direct internal reflections from reaching the detector, thus reducing crosstalk noise while maintaining large detector FOV area.
3Use of energy by moving object
If the transmissive portion of the lens is made larger to improve light transmission, then more light reaches the target and returns to the detector, but crosstalk increases and aesthetic appearance deteriorates
Solution Approach 1:
The beam splitter redirects light paths in a third dimension, allowing a smaller transmissive lens area to achieve the same effective light transmission by utilizing angular separation. This reduces the physical transmissive area needed while maintaining light transmission efficiency and reducing crosstalk.
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 eliminates blind zones, reduces crosstalk noise, and enhances the detection of targets close to the sensor, improving the signal-to-noise ratio and allowing for more aesthetically pleasing device designs without compromising performance.
Implementation Method 1
The optical routing module is configured to guide the emitted light transmitted by the transmissive-reflective surface through the transmissive portion of the lens to the exterior of the mobile telephone device
Implementation Method 2
The optical routing module is further configured to guide target-reflected light collected by the transmissive portion of the lens to the detector by reflecting the target-reflected light using the transmissive-reflective surface
Implementation Method 3
a lens separated from the proximity module by an air gap, where the lens has (i) a transmissive portion in alignment with the emitter FOV and with the detector FOV
Data Source
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AI summary
A proximity sensor for an electronic device (300,500,600,700) comprises a proximity module (302,702), a lens (310) and an optical module (330,530,630,730) secured in an air gap (312) therebetween. The proximity module has an emitter (304) and a detector (306) and is configured to generate a signal that is a function of light emitted by the emitter, and light detected by the detector, some portion of the detected light having been reflected by a target (101) external to the electronic device. A transmissive-reflective surface (322,522,622,722) of the optical module is aligned with the emitter field of view 'FOV' (305) and the detector FOV. The optical module guides emitted light through a transmissive portion of the lens to the exterior of the electronic device, and guides target-reflected light collected by the transmissive portion to the detector. The emitter FOV and the detector FOV are substantially aligned with one another.