NO971492L - Distribution box for signal outputs from a communications network, in particular a cable television system - Google Patents

Description

This invention relates to a distribution box for signal distribution in a communication network, in particular a network made up of a cable television system (CATV: community antenna television).

Although different connection networks have different architectures and structures, they usually include in their physical design a cable that runs from a transmitter, relay station, etc. and out to receivers, users or subscribers who extract signal from the cable (tap it). Such tapping is often carried out in many places along a cable route. What happens at a tapping point or outlet where the signal is to be distributed is that there must be an incoming signal, part of the power associated with the signal is taken out to the user, and the rest of the signal power is allowed to be passed on to other users who are connected to corresponding tapping points. Instead of pure tapping points, the main cable that carries the signals can also have pure dividing points or branches, and here there will not necessarily be a distinction between such places for the distribution of signals or signal power. The English expression "splitter" can be representative, and in the text below "distribution box" will correspond to this expression, as it is the purely physical embodiment of such a "point" in the network that forms the invention and shall be described in the following.

Furthermore, it is often necessary to transfer electrical power (power/power supply) from the network center or operator and to the individual users or subscribers, and this power in the form of feed current to the consumers' devices can just as easily be sent in the same main cable that runs from one distribution box to the next one. The cable can therefore transmit both supply current, often as low-frequency alternating current, and high-frequency signals, and the distribution boxes must therefore be able to have the additional function of extracting the supply current from the cable.

However, today's distribution boxes have certain disadvantages when it comes to field use or network adaptation. This has led to a number of different constructions being offered, depending on how many subscribers are to be connected to each distribution box, on the attenuation needed and how the supply current is to be taken out etc. In order to avoid these problems, therefore, according to the invention, it is provided a distribution box which can be considered to have a modular construction.

The distribution box of the invention thus has:

an input port to receive an incoming signal,

an output port for an outgoing signal,

a signal tap port,

a physically extractable circuit for extracting a first portion from the incoming signal and transferring it to the tap port and for transferring a second portion of the incoming signal from the input port to the output port, and

a switch to electrically connect the input port to the output port when the circuit is physically removed.

According to the invention, a distribution box is also provided which has an input port for receiving an incoming signal, an output port for an outgoing signal, means for extracting the first power part from the incoming signal and transferring a second power part to the output port, and a removable power distribution module that can receive the first power part and has at least one power output.

These individual features can be combined.

The invention is illustrated in the associated drawings, where fig. 1 in perspective shows a typical distribution box, fig. 2A - D show sections of such a box with an internal switch, fig. 3A and 3B show perspective sections of a distribution box with a port for extracting power for power supply, fig. 4 and 5 show in perspective a distribution box which additionally has a power distribution module for power distribution, fig. 6-8 show the installation of cables for tapping ports, fig. 9-11 show the installation of cables to main ports, fig. 12 shows sealing of blind main gates, and fig. 13 and 14 show removable covers with distribution circuits.

Fig. 1 shows a distribution box 1 which is suitable for a cable system (CATV). The box has a housing 2 and various ports that form openings in the housing, for connection with various cables for signals in and out. The box also has internal electronic circuits, switches etc. to tap signals from a line and/or extract electrical power for power supply, from a line which in combination transmits such power in addition to signals. Furthermore, the distribution box has circuits to provide sufficient damping between the power and signal transmission.

As is known, such a distribution box is used in a facility or network at a location in a main cable line where a signal is to be distributed or branched to subscribers. The distribution box 1 therefore has an input port (which can be in the form of a branch port 3 or a termination port 4) for the introduction of a cable carrying a signal from a CATV transmitter etc, and ports 5, 6 for a continuous line, so that the signal (or rather a remaining part of the signal effect) can be carried on further into the plant or network, e.g. to a next distribution box of the same type.

The distribution box 1 therefore extracts part of the incoming signal and forwards it to tap ports 7 which are connected to subscribers. The number of tap ports can e.g. be two, four, six or eight, possibly more.

The distribution box does not need to have the ability to connect the main cable in a direct line or stub configuration, but instead the box can have only ports 3 or 5, or only ports 4 or 6 (or one of each). Unused ports can be blinded as shown below.

Television sets or other equipment that must be supplied with a signal via a distribution box of this type will generally require an additional power supply source, typically for 60 V alternating voltage. Such a power supply can also be provided from the distribution box 1 according to the invention which in turn can receive it from the main cable connected to port 3 or 4, in that this cable in combination carries alternating current to the power supply and utility signals at higher frequencies.

The subscriber can thus be supplied with supply current via the tapping ports 7, but this may be inappropriate if it is not always expected that there is 60 V or another supply voltage at the cable outlet, and therefore the distribution box 1 has a separate supply port 8 for this purpose. Some of the power supply power is thus taken out via this port 8, and the rest is sent on via port 5 or 6 for distribution in the next box on the line. The distribution box 1 will also normally contain a low-pass filter to prevent the high-frequency signals from coming out on the power supply line.

Furthermore, the distribution box can have slits 9 or depressions, possibly projections, rings etc. on the ports to keep covers, covers, seals etc. in place. to provide a good transition for the connected cables or installation of blind plugs.

Fig. 2 shows a section through a distribution box which corresponds to the one shown in fig. 1 (since the cut is taken approximately parallel to the paper sheet and seen from the back). Fig. 2B shows a section indicated by the arrows in fig. 2A, and fig. 2C and 2D show normal sections of this.

In fig. 2A - 2D one sees the housing 2, the input ports 3 and 4, the through ports 5 and 6 and the tapping ports 7. The ports are arranged for connection with their respective coaxial cable (although other cable connection ports can also be arranged), and they are particularly in the form of contact sockets to receive cable contact plugs mounted on the cable ends, or for the direct connection of cables that have stripped ends. Contact parts 10 for a coaxial cable's inner conductor, and contact parts 11 for its outer conductor are shown in the drawings.

The distribution box 1 also has a switch 12 with displaceable contacts 12A and 12B which, when connected together, provide an electrical connection between the input ports 3 and 4 and the output ports 5 and 6. So when the switch is closed, incoming signals will be routed directly from one or more input ports and to a or several output ports without any branching out to the tap ports taking place.

The switch 12 is, however, arranged to be open when suitable distribution circuits have been brought into place. Thereby, the direct connection between the input ports and the output ports is broken, and the distribution circuits will form an intermediate connection and convey some of the effect that the signals represent to the tapping ports 7. These distribution circuits are not shown in fig. 2A - 2D, and in these drawings the switch 12 is therefore closed. The circuits can be arranged on a removable cover which in place would lie in a plane just above the plane of fig. 2A, and the switch contacts 12A and 12B would then be kept apart.

A lower metal surface of the housing 2, e.g. the right wall shown in fig. 2B can form a ground plane. It is preferred that any moving parts in the switch have their movement approximately parallel to the ground plane so that the high-frequency characteristics do not change particularly in the distribution box when they move.

The switch 12 is desired because service will be able to be provided down the line relative to the distribution box when distribution circuits are not present, and it may be desirable to remove such circuits in order to replace them with other circuits (e.g. to provide more or fewer outlets, for repair, upgrade etc). It is preferred that the removal of the circuits does not cause any momentary interruption of the service offer, and therefore the physical removal of such circuits should involve: 1. electrical connection between the input port and the output port (via the switch), and then 2. electrical disconnection of the circuits from the input and the exit.

A subsequent replacement of the circuits should, however, provide contact between the input and output ports (via these circuits) before the direct contact is broken by opening the switch 12.

In order to avoid that the circuits are partially connected (ie if a connection has been established between the input and output ports both via the switch and the circuits) it is preferred that the circuits pass a position where the connection (1) has been made, but where the disconnection (2) has not been made , as this position is unstable.

Preferably, a single movement (e.g. a movement 1 in a straight line from the housing) will cause the connection (1) and the disconnection (2). It is also preferred that the physical removal itself causes arming/disarming, instead of first removing a lock or releasing a locking mechanism.

The switch 12 is preferably mechanical, but can also be electronic, and it is preferably activated mechanically by direct mechanical or physical movement of the circuits or by a lid, cover etc. to which it is attached (including some "prong" or other protruding part from the lid).

Figs. 2A, 2C and 2D also show a component 13 for transferring power from the input ports 3 or 4 and to the output ports 5 or 6, and preferably this component 13 can serve as a low-pass filter or otherwise transfer power to the power supply mainly alone , i.e. without simultaneously transmitting energy at a higher frequency, in the form of signals coming in to the input port. This is desirable if the component 13 can work as a power divider or a tapping point for transferring power supply power to subscribers. Power supply power can e.g. is taken from the center point of the coil and fed to a supply port such as port 8 in fig. 1. Instead of filtering within the housing 2 of the distribution box by means of the component 13, further filtering may be desirable. Such additional filtering can be provided within an additional module for supply power distribution, described below.

Fig. 3A and 3B show how to remove a cover that closes the supply port 8. The cover can be removed by pulling it straight out or unscrewing it, as illustrated in fig.

3A, or it can be cut off as indicated in fig. 3B if it is more firmly mounted.

Fig. 4 shows the distribution box with a cover removed from the outside of the supply port 8, this being on an outer surface of the distribution box's housing 2. A gel mass or other internal sealing material 15 is shown in the port 8. A power distributor 16 is about to be mounted on side of distribution box 1, and electrical contact between this and the box, e.g. with an inner conductor 17 and an outer conductor 18 in a plug-type coaxial contact on the module 16, corresponding to a socket contact in the port 8.

The module 16 can be attached to the housing 2 with insertion hooks 19A or with a bolt in an insertion hole 19B, possibly in another way.

Fig. 5 shows the module 6 installed on the housing 2. It is preferred that a removable module in itself is not primarily responsible for removing supply power from an incoming power supply line, from a high-frequency signal, but that means for such separation and removal are instead arranged in the distribution box itself.

Several functions can be handled in the module. E.g. can here be distributed the power supply from a single port 8 and to at least two power outlets 20 and/or to another type of outlet, from port 8, e.g. to an outlet suitable for connecting a pair of lines 21. The outlets may comprise contact elements which retract the insulation or other means to handle the termination of a line. Preferably, each outlet can have means for connecting two conductors in the line pair 21 shown, and each outlet in a row can additionally have a gel mass or other means for sealing and sealing. The number of outlets will usually be equal to the number of signal ports, since each subscriber usually maintains a separate power supply.

A further or alternative functional aspect of the module 16 is filtering. The distribution box itself does not need to be equipped with any filter to remove high-frequency signals from the power take-off, or such filtering may be insufficient. Additional low-pass filtering or other suitable filtering can thereby be arranged in the module 16.

Electrical protection can be provided additionally or alternatively. Overcurrent or overvoltage protection may be provided in the module 16 to prevent current or voltage applied or induced in one of the outlets (over the ports) from being able to destroy the circuit components in the distribution box or reach transmitter or receiver equipment at the end of the lines, if necessary destroy subscriber equipment. Such protective devices can also protect the users' equipment from overcurrents or overvoltages on the main lines between the individual distribution boxes. The devices are preferably of the resettable type, preferably automatically resettable. Examples of suitable overcurrent devices include those based on conductive polymers, such as commercially available components, e.g. manufactured by Raychem under the brand name Polyswitch.

Figs. 6-8 show different ways of sealing cables 22 to ports 7. Fig. 6 shows cables 22 terminated in connectors 23 which are screwed on or otherwise attached to ports 7. The connectors, a part of the cables 22 near these and the ports 7 themselves are sealed against the surroundings by being enclosed in sleeves 24 and so on. The sleeves 24 preferably comprise flexible plastic material, preferably with a gel mass 15 or another sealing material, and optionally they can have a holding device 26 which is designed to engage in a corresponding holding mechanism, such as the slot 9 mentioned earlier, inside the port 7. The sleeves 24 may have a bellows or corrugated area to facilitate bending and/or stretching/compression. A sleeve is shown before insertion into a port, together with a plug 25, at the far left of fig. 6, the stopper 25 being arranged to close the cable entry in the sleeve and allow this to be used instead as a blanking cap to seal off a free port. A section through this separate sleeve 24 shows how it is constructed internally.

An alternative construction of a sealing sleeve is shown in fig. 7. The sleeve 27 is in this case of the slip-on type and can therefore be slipped around a cable 22 even if this is connected to a port 7. A replacement seal can therefore be carried out without interrupting the signal transmission to a subscriber. The sleeve 27 has two parts which are mounted together with a folding hinge 28, and it also has hooks for insertion into the ports in the closed position. A tool 30 shown at the bottom right of fig. 7 can follow to connect the connector 23 with the port 7, especially if the connector is short and does not protrude from the port, as shown at the top right of the four ports. The sleeve 27 can be slipped into place in the gate using devices such as the holding device 26 and the slot 9, in such a way that the sleeve cannot be opened again without damaging it, whereby accidental handling can be prevented for e.g. illegal tapping of signals from the distribution box.

The sleeves shown in fig. 6 and 7, especially those shown in fig. 6, can be used over a wide range of cable and port sizes and

-types.

Figs. 8A-C show how a port can be sealed without a separate outer sleeve of the type shown in Figs. 6 and 7. A port 7 (especially with a connector 7A) is accessible via a hole 32 (here defined in an upright cylindrical wall enclosing the screw-type connector 7A) in an outer surface of the distribution box. The port 7 is enclosed by a sleeve 33 which in this case is forced into contact with the edges of the hole when a contact 23 is screwed in or otherwise attached to the port, so that a kind of seal is formed between the contact and the outer surface. Fig. 9 and 10 show the installation of an applied seal and/or safety sleeve 27 for main cables 35 when they are connected to the input and output ports. The sleeve may contain a gel mass or another sealing material and may generally be similar to the sleeves shown in fig. 7, but preferably with larger dimensions. Fig. 11 shows a sleeve 24 of the bellows type, but otherwise corresponding to the sleeves shown in fig. 6. It is used in this case on a larger main cable 35, intended for continuous signal routing. Fig. 12 shows a sealing cap 36 which contains a gel or other sealing material and is intended to be placed on a protruding cylindrical part of a port 4. to the right of the figure the cap is shown mounted in place.

The cap 36, the sleeve 24 and the sleeve 27 and other devices for sealing against the surroundings can be equipped with means to keep a sealing compound such as a gel under pressure, embedded or for use together with these mentioned elements. It is desirable that such a sealing material is kept under pressure because it will then be in contact with the surfaces to be sealed. The pressure can be achieved by spring action of the elements and/or the housing of the distribution box. Alternatively or in addition, other compliant retention mechanisms may be used.

The sealing material is preferably a gel. In particular, it may comprise an oil-expanded polymer material, and it may be an advantage that the hardness is such that the cone penetration ranges from 80 - 400, in particular from 200 - 400 (10"<1>mm), according to the measurement ASTM D217-68, and that the material has an ultimate elongation of at least 100% (according to ASTM D638-80), especially at least 200%. Other preferred properties include an ultimate tensile strength according to ASTM D412 of less than 1 MPa, a dynamic storage modulus of less than 50 kPa, and essentially no creep effect (slump) up to temperatures of 100, preferably 120° C. An advantage of a material type in the gel class is that such material can be self-repairing, and as a result of this, an enclosing seal will automatically be able remain fully intact even after removing a cable, connector, module, circuit board etc.

Fig. 13 and 14 show distribution boxes 1 with a housing 2 and a lid 37 in the first case and a cover on the underside in the second case. In fig. 13, a physically removable circuit with components 38 that can barely be seen is mounted on the inside of the lid 37, and the circuit serves to separate out a first effect part from an incoming signal that enters port 3. The extracted signals are transferred to ports 7. Furthermore, the circuit serves to transfer a second power part from the signal to an output port (not shown in Fig. 13 or 14). Removal of cover 37 provides access to the housing from above and may allow removal of the circuit. It is preferred that removal of the circuit nevertheless leaves the means for taking out supply power, undisturbed in the distribution box.

In fig. 14 shows a distribution box 1 where the ports 7 out to the subscribers are mounted through a surface 39 on the underside of a bottom cover, so that removal and replacement of this breaks or terminates electrical contact connections between the ports and the circuit 38 with the components on the inside of the cover. Certain contacts (not shown) can be arranged inside the distribution box at each port 7 and the main ports (input and output port) and at corresponding places in the circuit which in the form of a circuit board with components are laid on top.

The ports 7 in fig. 14 can have a permanent connection with the components of the electrical circuit, but the construction has the disadvantage that access to the interior of the junction box or replacement of the lid with the circuit components requires that the signal path via the ports 7 is disturbed.

Claims (21)

1. Distribution box for signal outlets, CHARACTERIZED BY: an input port to receive an incoming signal, an output port for an outgoing signal, a signal tap port, a physically extractable circuit for extracting a first portion from the incoming signal and transferring it to the tap port and for transferring a second portion of the incoming signal from the input port to the output port, and a switch to electrically connect the input port to the output port when the circuit is physically removed. 2. Distribution box according to claim 1, CHARACTERIZED BY being arranged so that physical removal of the circuits leads to: 1. electrical connection of the input port (3) and the output port (5), and then 2. electrical disconnection of the circuits from the input port (3) and the output port (5). 3. Distribution box according to claim 1 or 2, CHARACTERIZED BY being arranged so that physical removal of the circuits causes both the connection (1) and the disconnection (2). 4. Distribution box according to claim 3, CHARACTERIZED IN THAT a simple movement of the circuits causes the connection and disconnection. 5. Distribution box according to claim 3 or 4, CHARACTERIZED BY the fact that the circuits during removal are led via a position which causes the connection without the disconnection being carried out, as this position is unstable. 6. Distribution box according to one of the preceding claims, CHARACTERIZED IN THAT the circuits are mounted on a removable lid (37) which forms part of the housing (2) so that the lid provides access to the interior of the housing for removal of the circuits (38). 7. Distribution box according to claim 6, CHARACTERIZED IN THAT the ports (7) for signal outlets to subscribers are arranged on the lid (37). 8. Distribution box according to claim 6, CHARACTERIZED IN THAT the ports (7) for signal outlets to subscribers are arranged on the underside of the lid (37), so that removal and replacement of this breaks/establishes electrical contact between one or more ports (7) and the circuits (38). 9. Distribution box according to one of the preceding claims, CHARACTERIZED BY at least two ports (7) for the withdrawal of signals to subscribers. 10. Distribution box according to one of the preceding claims and with a ground plane, CHARACTERIZED IN THAT the movable parts in the switch (12) are arranged to be guided mainly parallel to the ground plane. 11. Distribution box according to one of the preceding claims, CHARACTERIZED BY means for separating a first power part for power supply to devices, from a combined transmission of supply power and high-frequency signals via the input port (3), and for transmission of a second power part for continuation out through the output port (5 ). 12. Distribution box according to claim 11, CHARACTERIZED IN THAT the means are physically separated from the removable circuits (38). 13. Distribution box according to claim 11 or 12, CHARACTERIZED IN THAT the means are essentially blocked for the transmission of high-frequency signals. 14. Distribution box according to one of claims 11, 12 or 13, CHARACTERIZED BY the fact that the first power part is transferred to a special supply port (8) for power supply to devices. 15. Distribution box according to claim 14, CHARACTERIZED IN THAT the first power part is transferred to several supply ports (8), and that several signal outlet ports (7) are arranged, the number of which corresponds to the number of supply ports (8). 16. Distribution box according to claim 14 or 15, CHARACTERIZED BY a detachable power distribution module (16) which receives supply power for power supply to devices from the supply ports (8), and that the module (16) has several power outlets (20) for electrical power to power supply devices. 17. Distribution box according to one of claims 14 - 16, CHARACTERIZED IN THAT each supply port (8) and/or each power take-off (20) comprises an insulation-displacing contact. 18. Distribution box according to claim 16, CHARACTERIZED IN THAT the module (16) has protective devices for overcurrent and/or overvoltage. 19. Distribution box according to claim 16, CHARACTERIZED IN THAT the module (16) comprises a low-pass filter. 20. Distribution box according to one of the preceding claims, CHARACTERIZED BY one or more ports which are sealed against the surroundings by means of a seal comprising a gel mass. 21. Distribution box according to one of the preceding claims, CHARACTERIZED BY one or more ports to which a cable (22) can be mounted and which is accessible via a hole in an outer surface of the box and enclosed by a sleeve (24, 27), so that when the connector (23) is fitted to the port (7), the sleeve is forced into contact with an edge of the hole so that a seal is formed between the connector and the surface (39).