Wave transmission lines and networks – Plural channel systems – Having branched circuits
Patent
1997-04-10
1999-04-06
Gensler, Paul
Wave transmission lines and networks
Plural channel systems
Having branched circuits
333136, 361106, H04B 350
Patent
active
058924132
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The present invention relates to a multi-tap distribution apparatus. More particularly, the present invention relates to a multi-tap distribution apparatus which is suitable for use with CATV cables.
BACKGROUND ART
Generally, CATV transmission cables are connected to subscribers via multi-tap distribution apparatuses. CATV stations transmit through the cables not only television signals and control signals but also currents for operating main line amplifiers. Therefore, some distribution apparatuses are designed for passing electrical currents therethrough.
Handling instructions and precautions for equipment connected to the transmission cable are not often followed at subscribers' homes. For example, equipment may be inappropriately installed or tampered with by children, which often causes a short circuit. If a short circuit occurs in a secondary line branching out of a terminal of a branch circuit of a distribution apparatus or in terminal equipment connected to the secondary line, it can cause damage not only to the distribution apparatus to which the concerned secondary line is connected but also to the circuits of the equipment installed in the main line.
A fuse or bimetal device is sometimes interposed in the current transmission circuit of a distribution box to block the transmission of a large current. However, replacing a fuse to restore the flow of currents is a time-consuming task as it requires opening the distribution apparatus. On the other hand, the problem with the bimetal device is that, having a high calorific value, this device tends to raise the temperature in the distribution apparatus and hence change the characteristics of the ferrite components inside.
DISCLOSURE OF THE INVENTION
The present invention provides for a distribution apparatus the current transmitting function of which is immediately lost upon occurrence of a short circuit at a terminal of the transmission cable, but is automatically restored when the cause of the short circuit is removed. The distribution apparatus is characterized in that its branch output terminals and the transmission cable can be connected to each other by a current passage network which has positive thermistors interposed therein.
Preferably, one positive thermistor is provided for each of the output branch terminals in the current passage network.
Also, the connection state of said current passage network can be selected by switching operation.
In one aspect of the invention, the positive thermistors may be connected to the current passage network via connectors by being detachably coupled to the connectors. In this way, the connection state of said current passage network can be selected by detaching or attaching the thermistors.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a multi-tap distribution apparatus of an embodiment of the present invention.
FIG. 2 shows a plan view of the components of the multi-tap distribution apparatus.
FIG. 3 shows the circuit diagram of the components of the multi-tap distribution apparatus.
FIGS. 4A, 4B and 4C show different pairs of cable connecting portions to serve as the input and output terminals for the transmission cables.
FIG. 5 shows the circuit diagram of a modified distribution apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
A multi-tap distribution apparatus embodying the present invention will be explained with reference to the attached drawings. The multi-tap distribution apparatus of the embodiment can be used as either an aerial type or pedestal type device. Also, the number of taps can be changed in the distribution apparatus of this embodiment.
Referring to FIGS. 1 to 3, numeral 1 designates a box-shaped housing with one side open. The housing 1 is provided with one cable connecting portion 2 on one end surface and two other cable connecting portions 3 and 4 on the opposite end surface. Each of the cable connecting portions 2, 3, and 4 is disposed on a corner of the housing 1. Connector insertion holes 2a, 3a, and 4a are provided i
REFERENCES:
patent: 5379022 (1995-01-01), Bacon et al.
patent: 5645746 (1997-07-01), Walsh
Gensler Paul
Maspro Denkoh Co., Ltd.
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