Patent Application
20190393645
The present invention relates generally to connectors deployed for radio frequency (RF) cables. More specifically, the present invention is a solution to strain relief provided when cables get attached to other cables or to hardware apparatus. Due to long lengths and several degrees of freedom of movement, without strain relief, the entire torque or strain of the tendency to move shall fall on the connection points. Strain relief is therefore provided to restrict degrees of freedom and movement from around the connection points to clamp points which are designed to absorb shocks due to movements. A new strain relief method and apparatus is presented for RF cabling, saving costs on replacements, providing compactness and providing better alignment on concentric connections.
Electronic systems comprise, among other things, a plurality of printed circuit boards with electronic components. Such components may be application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), dynamic random access memories (DRAMs), flash memories, central processing units (CPUs), read only memories (ROMs), capacitors, inductors, resistors and wires. The design of boards is targeted to various interfaces that differ in form factor, protocol, speed and power consumption. The electronic systems in communications employ radio frequency receive and transmit interfaces. The signals are carried to and from an antenna on cables that collect received signals and also serves as the transmit point for signals from the electronic system to the antenna. In general, either the cables terminate on the electronic system hardware or they are connected through coupler to connect to a similar cable to effectively increase the length of the cable.
At the joint point, electrical connections are made between the wires assembled from the cables and the hardware apparatus which could be a radio capable of receiving and transmitting RF signals. The cables are long and either during the connection or much after that, the cables may move for various reasons. This causes the torque of stress to directly impact the connection joint between the connector and cable. If no support is provided, the electrical connection can break, leading to functional failures. Such failures are costly, may involve entire cable replacement because the end connector is no longer working. In another embodiment, such torque of movement may be passed on to a cable to cable connector. Again failure at connection point even in this case is costly. Entire cable may have to be discarded and failures may lead to substantial down times. The shock of movement or torque passed to the connection points are stopped from reaching the critical connection points through the use of strain relief mechanisms. The cable may go through metallic or nylon casing, may go through clamp points that restrict the movements around the connection points and directional turns may also be provided through the strain relief mechanisms and apparatus.
For the RF cabling, the signals are carried on concentric cables. Alignment of the center wire poses peculiar problems. Further this problem becomes worse due to the connector attach points. Connectors are designed to have a strain relief, and in most cases strain relief is indispensable. In general, connectors are designed so that when the two connectors are mated, the contact should self-align. When working with RF contacts, this becomes more complicated, due to the inherent design of RF contacts. In theory they should align as the connectors are mated. This does not always happen, especially when strain reliefs are used. That is the reason that engineers prefer to have one of the connectors contact fixed.
When providing strain relief for Mil-specification connector, the current strain relief products do not allow for RF contacts used in Mil-inch specification connectors to stay concentric within the cavity hole they are installed into. Once the clamp is tightened, which is part of the strain relief; it causes the RF Cables to lean towards one side of the other of the cavity. Also, current strain relief mechanisms are too large for small space applications. A costly solution is to design a custom strain relief back shell, install all RF Cables, and then fill with an epoxy to secure the contacts so there is no movement at all. The epoxy process has a major flaw in its design. If there is a failure to one or more of the cables within the connector housing, after the epoxy process is completed, the cable assembly must be scrapped and cannot be reworked.
The present invention overcomes this problem, by providing a new and compact strain relief mechanism for strain relief for RF cabling. To a connector providing a plurality of connection points for RF cables, a back shell is attached in one embodiment and using a clamp with shrink tubing, the cables are clamped using screws and washers to attach clamp with the back shell. In another embodiment, the clamp or cover is extended in all four directions, providing a four directional possibility to direct the cables outwards from the connection point. This embodiment is used where the cables need to turn in all four directions from the connection point. The clamp or cover is only in one dimension where cables need to turn only in one direction. No potted or epoxy material is used to restrict the degrees freedom, so that a single cable replacement is possible rather than discarding the entire set of cables.
All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention.
In the following description specific details are set forth describing certain embodiments. It will be apparent, however, to one skilled in the art that the disclosed embodiments may be practiced without some or entire specific details mentioned herein. The specific embodiments presented are meant to be illustrative, but not limiting. One skilled in the art may realize other material that, although not specifically described herein, is within the scope and spirit of this disclosure.
In one embodiment of the apparatus, in the design of electrical and mechanical systems, one important component among a plurality of the components is a printed circuit board (PCB). The printed circuit board could be a single instantiation in the electrical system or it may exists in multiple instantiations of the same printed circuit board. In another embodiment, the electrical system may comprise of multiple printed circuit boards that the functionally and physically different, communication with each other through a backplane connector or through cables carrying network or communication signals. In one embodiment, such signals may be RF signals. In another embodiment, this communication could be through ribbon or other cables or wires secured or otherwise used within the system. In another embodiment, a printed circuit board may connect to one or more daughter cards which are typically smaller in size than the printed circuit board (also sometimes referred as a mother board). For remote electrical signals, the cables are attached to hardware assembly, including printed circuit boards through connectors. In another apparatus, a certain length of cables may attach to another cable through a connector. For RF signals, the cable may involve concentric wires, with the connector ensuring alignment.
In a typical electrical system, a printed circuit board provides a platform or space where electronic components are placed and populated. These components include but are not restricted to Application Specific Integrated Circuits (ASIC), Field Programmable Gate Array (FPGA), a plurality of memory chips or modules, capacitors, resistors, connectors and interconnect among others. Connectors are used where remote signals are brought to this apparatus through cables of various kinds. For a printed circuit board used in a set top box for dish TV reception, a set of RF cables are brought from the dish antenna to the set top box's printed circuit board and connected to the radio on the printed circuit board through connectors. While connection is made or after that, it is natural that the long distance cables shall move for various reasons. Without any strain relief, the movement of the long distance cable will generate a strain or torque, which tends to disrupt the connection between the cable and the radio on the PCB. A strain relief apparatus is used to isolate the cable movement and the actual electrical joint between the connector and the cable. Various kings of strain relief solutions are available. The strain relief apparatus for RF cabling involving mil-specifications provides special challenges and requires advanced solutions.
An embodiment of the present invention provides a solution that does a couple of things different than current products. It solves the centering of the contacts within the cavity and allows minimum movement of the contact in case the cables are moved or routed to one side to the other. It also reduces the amount of space verse the standard strain relief products. In another embodiment of this solution, an improvement is achieved in the capability of reworking a failed cable assembly. There is no more requirement to scrap the completed cable assembly. In one embodiment of the present invention, one has to just remove the failed cable and replace it with a new one. This design also is much smaller and can be adapted for smaller spaces. It also utilizes the existing mounting hole of the connector. In one embodiment, there is no need to screw on a strain relief back shell.
In order to restrict the movement around the points of joining of the connector and the cable, or where connector joins a cable to another cable, the traditional solution is a “potted” version. The strain relief apparatus is potted or joined through epoxy materials which includes the multi cable apparatus. If there is a failure, there is no way to remove the “potting” materials. The materials setups to a very solid state, that requires a “grinder” to remove, ensuring again that there is no way to replace a failed cable. The present embodiment does not not use any type of “potting” process. Therefore, having to rework a failed cable is just a matter of removing, sliding the strain relief back to allow an insertion/extraction tool to be used. The method merely involves removing the failed cable and replacing it with a new one. The sliding clamp (strain relief) is part of the new invention. It replaces the standard strain relief (back shell) that is used for the “potting” process.
In one embodiment, in order to accommodate small spaces, it's a matter of changing the “thickness” of the new invention. In one application, one embodiment of the invention involves thickness of approximately 1.75 inches, which is the smallest to date. In other embodiments of the invention, the thickness ranges from 1.75 to 3.00 inches. In one latest embodiment, the invention has a cable clamp, which allows the cables to be secured to one of four directions.
100 illustrates as one embodiment, the strain relief apparatus. The connector 105 is attached to a back shell 104 using the mounting holes on the connector. A set for the purpose of illustration of three cables 103 are shown traversing the aligned holes of the back shell and the connector. The cables are then turned in one of the four directions and pressed or clamped using a clamp with a shrink tubing 102 using screws and washers 101. The clamp provides the strain relief. No potted material is involved and any bad cable can be replaced individually by disassembly of clamp 102 and back shell 103.
200 shows an isometric view of the assembly from another angle. The connector 201 is shown with holes for the cables 204. The back shell 202 is attached to the connector 201. A clamp with shrink tubing is 203 is attached to the back shell 202 through screws which are hidden in this view. The illustration shows how the connector 201 attaches to the back shell 202. The actual RF cables are not shown in this illustration.
300 is an illustrative embodiment of the apparatus from another isometric view. Connector 304 is attached to back shell 303 and the cables 305 are shown to traverse the back shell 303 and the connector 304. The cables 305 are pressed or clamped using clamp 302 attached to the back shell 303 through screw set 301. There is no potted or epoxy material involved. The strain relief is provided by the clamp 302.
400 is another embodiment that shows piece wise components 401402403404405406 and their corresponding place in the apparatus 400. The connector in this embodiment, as an illustration is size 25406. The connector 406 is attached to back shell 404 and cables traverse 405. The clamp 403 is shown to attach the back shell 404 through screws 401 and 402. The strain relief is provided by clamp 403. No epoxy or potted material is involved and each individual cable can be replaced.
500 represents another embodiment where the one directional clamp or cover is replaced with a single clamp 505 or cover 505 providing for the ability to turn the cables 504502506501 in each direction through single assembly 500. The clamp or cover 505 is attached to back shell 507 using four screws 503. The back shell 507 is designed to have cavities in each dimension, to be covered using the clamps in each direction. The cables are turned 504502506501 and sent outwards through these cavities from the connector 508.
600 represents the apparatus of
700 is the isometric view of the cover of clamp front embodiment of the apparatus, showing the screws 702 connecting the cover or clamp 703705 to the back shell 706 with a connector 707 and with cables 701703704 going outwards in each direction through predesigned cavities between the back shell 706 and the cover 705. Through the turns effectuated, the stress point is not the electrical or physical connection point, which relives stress at the same points.
800 shows the assembly in one embodiment, where four screws 801 are used to attach a clamp or cover 802 to the back shell 804, which in turn attaches to a connector 805. The cables 803, going through connector 805 are shown to be turned in each direction, with no or little stress at the connection point.
900 shows an isometric view of the assembly with cover or clamp removed. The connector 905 is attached to back shell 904 and the cables 904902901906 are shown to be bent towards and outwards from the connection points. The holes are shown on the back shell so that the cover of clamp may be used to attach to it through screws not shown.
1000 shows an isometric view of the apparatus, showing further the assembly. The connector 1007 attaches to back shell 1005, which in turn is attached to a cover or clamp 1003 through screws (not shown), with cables 1006100410081001 coming outwards in each direction. In this embodiment, the coaxial cables 1006100410081001 are shown to be going through the connector and making the electrical connection with mates, with stress relieved form those points due to the use of the assembly.
This invention makes the RF cabling strain relief, as some embodiments, much more compact and flexible. The key differentiator is that no potted or epoxy materials are used and this allows for a single cable replacement on failures rather than discarding the entire mesh of cables. It is stated that while for illustrative purpose, an RF cable connector is chosen for strain relief, it can be used for any such or other cables or wires. It is also apparent to those skilled in the art, that is, to those who have knowledge and experience in this area of technology that the description above explains just one to two of many possible design variations. The examples provided above are exemplary only and are not intended to be limiting. One skilled in the art may readily devise other systems consistent with the disclosed embodiments which are intended to be within the scope of this disclosure.
This non-provisional patent application claims benefit of priority date through specific reference to provisional patent application No. 62/689,127 filed on Jun. 23, 2018 under 35 U.S.C. 119 (e) (1). See also 37 C.F.R. 1.78.
| Number | Date | Country | |
|---|---|---|---|
| 62689127 | Jun 2018 | US |
