Optical Device Crosstalk Reduction via Shielding
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Solution Overview
Problem
Optical devices face crosstalk issues due to total internal reflection within transparent casings, which reduce signal-to-noise ratios and affect their accuracy in detecting external objects.
Innovation Solution
The optical device configuration includes a longitudinal axis interposed between emitter optical elements, with the emitter and receiver aligned along this axis to minimize parallel radiation transmission, and a direct reflection shield to block radiation reflected by the casing, preventing crosstalk through the use of symmetrically spaced emitter optical elements and a transparent encapsulant to redirect radiation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent casing is used for the optical device, then the device structure is simplified and manufacturing is easier, but crosstalk occurs due to total internal reflection reducing signal-to-noise ratio
Solution Approach 1:
An opaque intermediary structure (shield or barrier) is introduced between the emitter and receiver to block parasitic light paths. This shield acts as a mediator that prevents crosstalk while allowing the transparent casing to maintain its structural simplicity and manufacturing advantages.
Solution Approach 2:
The optical path is segmented into desired signal paths and unwanted crosstalk paths. By introducing reflective surfaces or absorptive elements at specific locations, the patent separates these paths, allowing the transparent casing to remain simple while preventing crosstalk through strategic path division.
2Volume of moving object
If emitter optical elements are positioned close to each other, then the device size is reduced, but crosstalk increases due to parallel radiation transmission
Solution Approach 1:
The patent employs asymmetric positioning of emitter optical elements relative to the longitudinal axis, combined with reflective surfaces that create non-parallel light paths. This asymmetric arrangement reduces crosstalk while maintaining compact device dimensions by optimizing the spatial relationship between components.
Solution Approach 2:
The patent introduces a longitudinal axis dimension to organize the emitter optical elements symmetrically around it, transforming the problem from a two-dimensional layout to a three-dimensional arrangement. This dimensional approach allows closer spacing while minimizing parallel radiation transmission through strategic positioning.
3Measurement precision
If the receiver is positioned to detect reflected radiation, then detection accuracy is improved, but crosstalk from direct radiation increases
Solution Approach 1:
The patent converts the harmful direct radiation that would cause crosstalk into a beneficial element by using reflective surfaces to redirect this radiation away from the receiver. The same radiation that could cause interference is instead redirected to enhance the desired signal path, improving detection accuracy while eliminating 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 significantly reduces crosstalk, enhancing the signal-to-noise ratio and improving the detection accuracy of optical devices, such as proximity sensors and optical mice, by minimizing unwanted reflections from the casing.
Implementation Method 1
crosstalk may occur due to total internal reflection in which a portion of the radiation emitted by the emitter is reflected into the receiver without going through the external object
Implementation Method 2
a direct reflection shield to block radiation reflected by the casing, preventing crosstalk
Data Source
AI summary
In one embodiment, an optical device comprising an emitter, first and second emitter optical elements and a receiver is disclosed. The emitter and the receiver may be arranged substantially along a longitudinal axis. The first and second emitter optical elements may be interposing the longitudinal axis. One other embodiment discloses an optical device comprising an emitter and a receiver arranged on a longitudinal axis. The optical device may further comprise first and second emitter optical elements arranged along an axis orthogonal to the longitudinal axis but interposing the longitudinal axis. In another embodiment, a proximity sensor having first and second emitters interposing a longitudinal axis is disclosed.