Overmold Proximity Sensor with Bleed Groove Lens
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Solution Overview
Problem
Existing proximity sensor technologies face challenges with complex mounting steps, external electrical connection difficulties, and large dimensions due to the need for separate chambers and opaque covers, which also require a flat surface for molding and risk lens contamination.
Innovation Solution
An electronic device with a substrate, optical sensor, and optical emitter, featuring a lens with a curved upper surface and an encapsulation bleed stop groove, and encapsulation material with aligned openings to facilitate overmolding and prevent resin overflow, while maintaining optical isolation and a flush appearance for easy handling and surface mount technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate with separate chambers and opaque cover is used for optical isolation, then optical isolation between optical detector and optical emitter is improved, but device complexity and mounting difficulty increase
Solution Approach 1:
The patent combines the optical isolation function and lens protection function into a single integrated lens structure. The lens itself serves as the optical isolation element, eliminating the need for separate opaque covers and multiple mounting steps. This merging of functions directly reduces device complexity while maintaining optical isolation between the optical detector and optical emitter.
2Ease of manufacture
If molding process is used for fabrication, then manufacturing cost is reduced, but lens contamination risk increases due to black molding parts
Solution Approach 1:
The patent incorporates a bleed groove structure into the lens design before the molding process. This preliminary structural preparation allows the molding material to escape through designated channels during injection, preventing contamination of the lens surface. The bleed groove is pre-formed as part of the mold cavity, enabling the molding process to proceed without compromising lens cleanliness.
Solution Approach 2:
The patent extracts the harmful molding material from the final product by providing escape routes (bleed grooves) during the molding process. The excess or potentially contaminating molding material is directed into the bleed groove and removed from the functional area, leaving only the clean lens and necessary encapsulation material in the final product.
3Reliability
If lens dome shape is required for protection, then lens protection is improved, but molding process difficulty increases due to flat surface requirement
Solution Approach 1:
The patent employs a curved dome-shaped lens structure that provides mechanical protection while being directly formable through injection molding. The curvature is integrated into the mold cavity design, allowing the lens to be formed in a single molding step without requiring subsequent flattening or additional processing. This resolves the conflict between protective dome shape and molding feasibility.
4Ease of manufacture
If overmolding process is used with curved lens, then manufacturing simplicity is improved, but resin overflow may occur without proper control
Solution Approach 1:
The patent introduces a bleed groove as an intermediary structure that mediates between the overmolding process and the lens. This groove acts as a controlled escape route for excess resin, allowing the overmolding process to proceed simply while maintaining precision through the structured management of resin flow. The bleed groove captures and contains the overflow, preventing it from contaminating the lens or final product.
Data Source
AI summary
An electronic device includes a substrate, an optical sensor coupled to the substrate, and an optical emitter coupled to the substrate. A lens is aligned with the optical emitter and includes an upper surface and an encapsulation bleed stop groove around the upper surface. An encapsulation material is coupled to the substrate and includes first and second encapsulation openings therethrough aligned with the optical sensor and the lens, respectively.