TOF Sensor Light Baffle Layout for Crosstalk Reduction
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Solution Overview
Problem
Time of flight sensors in machine-readable symbol readers face challenges due to cross-talk induced by the transparent covering window and surrounding mechanics, limiting their design flexibility and increasing sensitivity to spurious reflections, which reduces their maximum working distance.
Innovation Solution
Incorporating opaque walls with light baffles that extend between the time of flight sensor layer and the covering window layer, these baffles reduce backscatter of emission and reception signals, shape the signal angles, and provide mechanical tolerance by spacing the exit and entrance windows, thereby reducing cross-talk and allowing for greater design freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the exit window is positioned close to the TOF sensor, then crosstalk is reduced, but the working distance is limited
Solution Approach 1:
The patent introduces an opaque wall as an intermediary element positioned between the TOF sensor and the covering window. This opaque wall acts as a mediator that blocks spurious reflections and crosstalk paths while allowing the useful optical signal to pass through designated openings, thereby resolving the contradiction between reducing crosstalk and maintaining working distance
2Adaptability or versatility
If the TOF sensor is placed far from the exit surface, then mechanical design freedom is increased, but spurious reflections increase
Solution Approach 1:
The opaque wall serves as a protective intermediary that extends into the optical path, creating a controlled environment that shields the TOF sensor from spurious reflections originating from surrounding mechanics. This allows the sensor to be positioned farther from the exit surface without compromising performance
3Object-affected harmful factors
If opaque walls are positioned close to the TOF sensor layer, then crosstalk reduction is improved, but mechanical tolerance issues arise
Solution Approach 1:
The patent extends the opaque wall in the vertical dimension (z-direction) between the TOF sensor layer and the covering window, rather than relying solely on lateral positioning. This vertical extension provides effective crosstalk reduction while maintaining larger lateral tolerances, thereby resolving the mechanical tolerance issue
4Adaptability or versatility
If the covering window is positioned far from the TOF sensor, then design flexibility is increased, but dust particle impact increases
Solution Approach 1:
The opaque wall acts as a protective barrier that extends between the TOF sensor and the covering window, creating a shielded environment that prevents dust particles on the covering window from directly impacting the sensor. This allows the covering window to be positioned farther away for design flexibility while maintaining protection
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
The solution effectively reduces cross-talk and increases the working distance of time of flight sensors by insulating and shaping the signal paths, enhancing mechanical tolerance and reducing the impact of dust particles, thus improving the sensor's performance and design flexibility.
Implementation Method 1
The light baffles in the one or more opaque walls reduce backscatter of emission signals and reception signals
Data Source
AI summary
A time of flight sensor system having a time of flight sensor layer is disclosed. The system includes a covering window layer spaced apart from the time of flight sensor layer, with an exit window and an entrance window, an emitting element in the time of flight sensor layer that transmits an emission signal, a receiving element in the time of flight sensor layer that receives a reception signal, one or more opaque walls, and light baffles incorporated into the one or more opaque walls. The one or more opaque walls extend at least a portion of the distance from the time of flight sensor layer to the covering window layer. The one or more opaque walls reduce the reflection backscatter of emission signals and reception signals. The light baffles in the one or more opaque walls reduce backscatter of emission signals and reception signals.