Light Blocking Vias Reduce Optical Cross-Talk in Sensor Modules
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Solution Overview
Problem
Optical cross-talk in optical sensor modules, such as those integrated into smartphones, occurs due to light emitted by emitters being coupled through substrates like printed circuit boards to light sensors, leading to interference and reduced accuracy.
Innovation Solution
Incorporating light blocking vias in the substrate, such as copper through-holes, blind vias, or buried vias, to prevent light from traveling through the substrate and reaching the light receiver, determined through computer simulations to identify paths of potential cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light blocking vias are added to the substrate to prevent optical cross-talk, then measurement precision of the light receiver is improved, but device complexity increases
Solution Approach 1:
The patent combines light blocking vias with existing electrical vias in the substrate. By merging the optical blocking function with the electrical connection function in the same structural elements, the design prevents optical cross-talk without adding separate components, thereby improving measurement precision while minimizing increases in device complexity
Solution Approach 2:
The vias in the substrate are designed to serve multiple functions: providing electrical connections between layers and simultaneously blocking optical paths to prevent cross-talk. This multi-functionality approach allows a single structural element to address both electrical and optical requirements, resolving the contradiction between improved precision and increased complexity
2Reliability
If light blocking vias are incorporated into the substrate to prevent optical cross-talk, then reliability of the optical sensor module is improved, but manufacturing precision requirements increase
Solution Approach 1:
The light blocking vias are integrated into the existing via fabrication process used for electrical connections. By combining the optical blocking function with the established electrical via manufacturing process, the design improves reliability by preventing cross-talk while avoiding the need for separate manufacturing steps, thereby not significantly increasing manufacturing precision requirements
Solution Approach 2:
The via structures are designed and positioned in advance during the substrate design phase to simultaneously satisfy both electrical connection and optical blocking requirements. This preliminary planning allows the manufacturing process to use standard via fabrication techniques without requiring additional precision beyond what is already needed for electrical via formation
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
Effectively reduces internal optical cross-talk, enhancing the accuracy and reliability of optical sensor modules by blocking light paths between emitters and receivers, without requiring additional manufacturing steps and potentially overlapping with electrical vias.
Implementation Method 1
The substrate includes one or more light blocking vias arranged to prevent at least some light produced by the light emitter from traveling through the substrate and thereby generating optical cross-talk in the light receiver
Data Source
AI summary
An apparatus includes a substrate, a light emitter mounted on the substrate, and a light receiver, including a light sensitive region, mounted on the substrate. The substrate includes one or more light blocking vias arranged to prevent at least some light produced by the light emitter from traveling through the substrate and thereby generating optical cross-talk in the light receiver.