Optical Proximity Sensor Shield and Lens Layout for Crosstalk Reduction
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Solution Overview
Problem
Existing optical proximity sensors face challenges with excessive crosstalk, poor optical efficiency, and limited detection distance due to complex metal shields that are difficult to align and manufacture, especially in the context of smaller portable electronic devices.
Innovation Solution
The design incorporates spherical lenses over the light emitter and detector, along with a light shield featuring alignment and spacing members, which minimizes crosstalk and maximizes detection distance by optimizing the alignment and configuration of the light emitter, lenses, and shield components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a complex metal shield is used to provide optical isolation, then crosstalk between emitter and detector is reduced, but the shield becomes difficult to fit and align during manufacturing
Solution Approach 1:
The shield is divided into multiple segments or sections that can be independently positioned and aligned. Each segment contains alignment features that facilitate precise positioning relative to the emitter and detector, making the assembly process easier while maintaining optical isolation effectiveness
Solution Approach 2:
Alignment features such as alignment pins, registration marks, or intermediary alignment structures are introduced between the shield and the emitter-detector assembly. These intermediary elements serve as mediators that simplify the alignment process by providing reference points and mechanical guides for proper positioning
2Device complexity
If no collimating lenses are used, then the device structure remains simple, but light emitted by the emitter is unfocused and dissipates, reducing detection distance
Solution Approach 1:
Collimating lenses are pre-positioned over the emitter and detector to prepare and condition the light paths before the light interacts with the external environment. The lenses pre-collimate the emitted light and pre-focus the returning light, ensuring optimal optical performance from the outset
Solution Approach 2:
The introduction of lenses changes the optical parameters of the system by modifying the light divergence angle and intensity distribution. The lenses transform the light from a divergent pattern to a more collimated or focused pattern, thereby extending the effective detection distance without fundamentally redesigning the entire sensor structure
3Manufacturing precision
If the shield is hand-fitted and glued during assembly, then proper alignment can be achieved, but the manufacturing process becomes time-consuming and costly
Solution Approach 1:
The shield and associated components are designed with self-aligning features such as tapered interfaces, snap-fit mechanisms, or gravity-assisted positioning that enable the components to automatically align themselves during assembly. This eliminates the need for manual fitting and gluing while maintaining high alignment accuracy
Solution Approach 2:
Manual mechanical alignment operations (hand-fitting and gluing) are replaced with automated mechanical assembly systems. The shield design incorporates features that work with automated pick-and-place machines or insertion tools, enabling rapid and precise assembly without manual intervention
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 allows for accurate and quick assembly of the shield, reduces crosstalk, increases detection distance, and enhances the overall performance and manufacturability of optical proximity sensors, while also enabling smaller form factors and lower costs.
Implementation Method 1
a first spherical lens disposed over the light emitter and configured to collect and direct light emitted by the light emitter in an upward direction
Implementation Method 2
a second spherical lens disposed over the light detector and configured to collect and direct light incident thereon that has been transmitted upwardly by the first lens and reflected downwardly from the object to be detected towards the light detector
Implementation Method 3
a light barrier projecting downwardly between the first and second top portions to separate the light emitter from the light detector and divide the proximity sensor into light emitting and light detecting portions
Data Source
AI summary
Various embodiments of an optical sensor comprising a novel shield that may be quickly and accurately aligned and positioned with respect to an underlying light emitting and light detecting assembly are disclosed. Also disclosed are novel lens arrangements for efficiently collimating light emitted and received by the optical proximity sensor, and for reducing crosstalk.