Compact Optical Branching Device for FTTH Junction Boxes
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Solution Overview
Problem
Existing optical branching devices are too bulky to be installed in the small, space-constrained junction boxes of FTTP/FTTH optical access networks, which further complicates the already tight space due to the presence of other cables.
Innovation Solution
A compact optical branching device design that separates the branching function from the protection of the access window, concentrating the branching function in a central channel with obliquely diverging lateral channels and a non-projecting fixing member housing, allowing for a reduced longitudinal dimension of 4 or 5 cm, enabling easy installation in junction boxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional optical branching device is used, then the branching function is provided, but the device is too bulky to be installed in the small junction boxes
Solution Approach 1:
The device is segmented into two distinct functional parts: a protection cap that covers and protects the access window in the cable sheath, and a branching body that provides the lateral channels for fiber extraction. This segmentation allows each component to be optimized independently, with the branching body being compact enough for junction box installation while the protection cap handles the cable protection function externally.
Solution Approach 2:
The protection function is extracted from the main branching device and implemented separately through the protection cap that covers the access window. This extraction allows the branching device itself to be minimized in size, containing only the essential branching channels and fixing mechanism, while the protection cap handles the cable sheath protection externally.
2Volume of moving object
If the branching device is made compact, then it can be installed in junction boxes, but the fixing member housing must not project beyond the lateral channels
Solution Approach 1:
The housing for the fixing member is positioned asymmetrically within the branching device structure, specifically configured to not project beyond the maximum extension of the lateral channels in the longitudinal direction. This asymmetric placement optimizes space utilization and ensures the compact form factor required for junction box installation while maintaining the necessary fixing functionality.
3Device complexity
If the access window is protected outside the branching device, then the branching function is concentrated, but the integration of protection and branching is reduced
Solution Approach 1:
The protection cap and branching body are designed to be assembled together, with the protection cap covering the access window and the branching body providing the fiber extraction channels. This merging of separate functional components into a single assembled unit maintains functional concentration while achieving practical integration for installation and operation.
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
What is described is an optical branching device suitable for branching optical fibres extracted through an access window cut in a sheath of an optical cable. The optical branching device comprises a central channel configured to house a portion of the optical cable, at least one lateral channel which branches from the central channel and which is configured to house at least one of the optical fibres, and a housing suitable for receiving a fixing member for fixing the device to the optical cable. The housing is in a non-projecting position relative to the lateral channel along a longitudinal direction of the central channel.