Multi-Core Plastic Optical Fiber Cable for Repeated Bending
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Solution Overview
Problem
Existing plastic optical fiber cables fail to withstand repeated bending with a bend radius of 2 mm without experiencing significant optical loss or breaking, due to limitations in flexure resistance and connectivity issues with thin strands.
Innovation Solution
A multi-core plastic optical fiber cable is developed with a cladding layer or sea part formed from a soft resin and a coating layer made of a thermoplastic resin with a high flexural modulus, using specific transparent resins for the cores and cladding, and a thermoplastic coating like nylon 12, which enhances flexibility and resistance to bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic optical fiber strands with outside diameter of 0.7 mm are used, then the cable structure is simple and easy to manufacture, but the cable breaks after 100,000 or less repeated bending cycles with bend radius of 2 mm
Solution Approach 1:
The invention divides the optical fiber cable into multiple thin strands (each 0.1-0.5 mm diameter) bundled together, rather than using a single thick strand. This segmentation allows the cable to flex more easily and withstand repeated bending while maintaining optical performance through the collective bundle structure.
Solution Approach 2:
The invention uses a composite coating structure with multiple layers: a soft resin coating layer (Shore A 20-40) for flexibility and a hard resin coating layer (Shore D 60-80) for protection. This composite material approach resolves the contradiction between flexibility and durability in the cable construction.
2Reliability
If thin plastic optical fiber strands (0.265 mm diameter) are bundled to improve flexure resistance, then the repeated bending performance improves, but the coating layer must be removed during connection and the thin strands become apart causing large optical loss
Solution Approach 1:
The invention applies a preliminary protective coating structure before connection is needed. The soft resin coating layer is applied first to protect the thin strands, and this coating is designed to be removable only when connection is required. This preliminary protection enables easy handling and connection while maintaining strand integrity during normal use.
Solution Approach 2:
The soft resin coating layer acts as an intermediary that holds the thin optical fiber strands together during handling and installation, preventing them from separating. This intermediary coating can be selectively removed at connection points without affecting the bundled structure elsewhere, facilitating easy connection while maintaining flexure resistance.
3Loss of energy
If multiple thin plastic optical fiber strands are bundled, then the optical signal transmission is maintained through compensation, but the cable becomes difficult to connect due to coating removal requirements and strand separation
Solution Approach 1:
The invention uses multiple thin optical fiber strands as copies of the original thicker fiber, each capable of carrying optical signals. By bundling these copies together, the cable maintains optical transmission capability while gaining flexibility. The standardized coating structure on each strand simplifies the connection process by providing a uniform interface for joining.
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 cable maintains low optical loss and exhibits excellent resistance to repeated bending, withstanding 100,000 cycles without breaking or significant optical attenuation, and facilitates easy connection through hinge structures in portable electronic devices.
Implementation Method 1
applying to the optical fiber strand a coating layer formed of a thermoplastic resin with a high flexural modulus
Implementation Method 2
the resin forming at least one of the cladding layer and the sea part is a resin having a Shore D hardness of 25 or more and 55 or less
Data Source
AI summary
A plastic optical fiber cable that is strong in repeated flexure, ensuring low light loss at bending with a bend radius of 2 mm. The plastic optical fiber cable is one composed of a multicore plastic optical fiber strand including 7 to 10,000 cores of transparent resin, island portions each consisting of at least one core-surrounding sheath layer of transparent resin with a refractive index lower than that of the transparent resin constituting the cores and sea portion of resin surrounding the island portions and, enclosing the multicore plastic optical fiber strand, a coating layer, characterized in that the resin constituting at least either the sheath layer or sea layer is one of 25 to 55 Shore D hardness while the resin constituting the coating layer consists of a thermoplastic resin of 500 to 2000 MP flexural modulus.