The present invention relates generally to the field of optical devices, and particularly a fiber routing tray mounted on a PCB.
In telecommunications equipment, optical modules and electronic circuits for signal monitoring, signal processing, temperature control, and motion control are typically assembled on a Printed Circuit Board (PCB) module which is then inserted into a modular network system. Depending on the requirement, specific fore-mentioned components are selected and assembled on a PCB for a particular application. A fiber routing tray mounted on a same PCB is utilized to help route incoming fiber cables to each of the optical modules, optical devices, and electronic circuitry on the PCB. The assembled PCB, also known as a daughter board, is inserted into a motherboard used in a telecommunication equipment.
The purpose of a fiber routing tray is to hold excess fiber cable length, provide a strain relief, and guide fiber cables onto other optical modules and optical devices mounted on the PCB. Inside the fiber tray, a retention clamp is used to hold a fiber cable in place to provide strain relief which prevents incoming fiber cables from being pulled out of position excessively. Conventional designs use a retention bar with a flat shaped clamp. Principle shortcomings of the flat shaped clamp include uneven clamping force of the fiber cables and excessive localized clamping pressure on the topside of the buffered fiber cable, which alters the fiber performance. The flat clamp creates non-uniform clamping pressure around a fiber cable especially on the topside, which results in insertion losses and return losses. Other prior art used epoxy to hold the fiber cable in place for the purpose of a strain relief, however the epoxy did not provide adequate clamping force to hold both the inner fiber cable, and the outer fiber jacket tubing in place. Since the fiber jacket tubing and fiber cable are loosely assembled together, the inner fiber cable can move even though the external fiber jacket tubing is weakly clamped by adhesive. Addition glue adhesive is used to increase clamping effectiveness resulting in messy manufacturing assembly. Repairing or repositioning fiber cables held in place with epoxy is also difficult. Accordingly, the present invention addresses these needs by using a retention bar with a fiber clamp that is contoured to the shape of the fiber cable, to distribute uniform clamping pressure all around the fiber cable. In addition to providing a strain relief, the fiber routing tray guides and route fiber cables onto other optical modules and optical devices mounted on the PCB. The fiber routing tray also provides protection for fusion splices, which connect external fiber cables with internal fiber cables inside the fiber routing tray.
The present invention discloses a fiber routing tray with an internal spool to hold excess fiber cable length, a fiber clamping slot to seat fiber cables for clamping, a retention bar with contoured fiber clamps to provide uniform and sufficient clamping force to a fiber cable for strain relief, a precision dimensioned curve slot to allow assembly slack for connecting fiber cables via fiber connectors, and a fiber entry block to provide adequate spacing of fiber cables and proper entry angles. Advantageously, the present invention significantly improves the clamping force to the fiber cable while reducing insertion and return losses.
Other structures and methods are disclosed in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.