JP3614950B2 - Tap-off with transformer function for CATV - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a CATV tap-off for connecting a distribution line of a CATV system and a service line of a subscriber's house.
[0002]
[Prior art]
In recent years, interactive CATV systems are not only used for transmission of video signals and data but also for telephone services. As an example of a telephone service using a bidirectional CATV system, there is a system as shown in FIG. This is a headend device through a protector K, a tap-off D, and a bidirectional amplifier C using a digital signal from a terminal (VIU: Voice Interface Unit) placed on the subscriber A side using the upstream band of the CATV system. B is transmitted to the telephone center device located in B, and the digital signal is put on the downstream band of the CATV system by the switch of the telephone center device, and the other subscriber side through the bidirectional amplifier C, tap-off D, and protector K. To the other terminals so that the subscribers can talk to each other. Incidentally, tap-off D is branching unit provided between the capacitor C _1, C 2, which is provided in _series, both capacitors C _1, C ₂ between the output terminal B and the input terminal A as shown in FIG. 2 in FIG. 4 G, distributor H, distributor H and capacitors C ₃ and C ₄ provided between branch output terminals I ₁ and I ₂ , choke coils J ₁ and J provided in parallel between input terminal A and output terminal B ₂ and a capacitor C ₅ provided between both choke coils J ₁ and J ₂ . The choke coils J ₁ and J ₂ are provided for transmitting power to an amplifier connected to the input side or output side of the tap-off.
[0003]
[Problems to be solved by the invention]
When the telephone service is realized by the CATV system, in the current CATV system, various terminal-side devices including the telephone terminal (VIU) on the subscriber side are all driven by the power source on the subscriber side. When a power failure occurs on the subscriber side due to a lightning failure or the like, there is a problem that the terminal on the subscriber side does not operate and the telephone cannot be communicated.
[0004]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a CATV system that uses a high-frequency signal sent from a facility side to a subscriber side to a CATV system such as a main line amplifier or a main line branch amplifier connected to the main line or branch main line of the CATV system. Paying attention to the fact that the power source (usually AC60V) for driving the mobile phone is superimposed, the power source is transmitted to the subscriber side to operate the booster, the telephone terminal (VIU), etc. Only the telephone function can be ensured even if the side loses power. When voltage is sent from the facility side to the subscriber's home side using a coaxial cable, power must be transmitted at 30V or less in accordance with regulations (Ministry of International Trade and Industry Ordinance No. 61, Article 249). Therefore, the tap-off with a transform function for CATV according to the present invention, as shown in FIG. 1, uses the tap-off used in the CATV system to supply the power supply voltage transmitted from the facility side of the system superimposed on the high-frequency signal to the CATV in the subscriber premises. A step-down unit 1 is provided for stepping down to a voltage required for driving the equipment.
[0005]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1
An embodiment of a tap-off with a transformation function for CATV of the present invention will be described in detail with reference to FIG. The tap-off with a transformer function for CATV shown in FIG. 1 includes capacitors C ₁ and C ₂ provided in series between an input terminal A and an output terminal B, a branching device G provided between both capacitors C ₁ and C ₂ , and distribution. Capacitor H, distributor H and capacitors C ₃ and C ₄ provided between branch output terminals I ₁ and I ₂ , choke coils J ₁ and J ₂ provided in parallel between input terminal A and output terminal B, The provision of the capacitor C ₅ provided between both choke coils J ₁ and J ₂ is the same as the tap-off in FIG.
[0006]
In the present invention, a step-down unit 1 surrounded by a chain line in FIG. 1 and a power transmission unit 2 for transmitting the stepped-down power to branch output terminals I ₁ and I ₂ are added to the tap-off in FIG. The step-down unit 1 includes a step-down transformer 3 between the choke coils J ₁ and J ₂ and the ground. The step-down transformer 3 may be other transformers.
[0007]
The power transmission unit 2 in FIG. 1 connects choke coils J ₃ and J ₄ between two distribution lines 4 and 5 wired from the distributor H, and turns between the choke coils J ₃ and J ₄ and the winding of the step-down transformer 3. the choke coil J ₅ between the middle line is provided, comprising providing a capacitor ₆ between the choke coil J ₅ and ground.
[0008]
【Example of use】
Use the CATV tap-off of the present invention instead of the conventional tap-off, and join the high-frequency signal sent from the CATV system facility to the coaxial cable by superimposing a power supply (usually 60V) from the facility uninterruptible power supply. When sent to the user side, the high-frequency signal input to the CATV tap-off input terminal A of the present invention passes through the power cut capacitors C ₁ and C ₂ and is output to the output terminal B. On the other hand, the power source (low frequency) superimposed on the high-frequency signal is cut by the capacitors C ₁ and C ₂ and does not flow to the high-frequency transmission path 6, but is output to the output terminal B of the protector through the choke coils J ₁ and J _2. Is done. At this time, the power source also flows into the step-down transformer 3, and is taken out from the middle of the winding of the transformer 3 and stepped down to a voltage (usually 30V) corresponding to the winding ratio. The power is output together with the choke coil _J 3, _{J 4} each branch output terminals _I 1 through, _{I 2} to the high-frequency signal, the branch output terminals _I 1, protector, which is connected to the _{I 2} (K in FIG. 4) Supplied. At this time, if the protector K shown in FIG. 3 having a power passing function is used for the protector K (the protector filed by the applicant on the same date as the present application), the branch output terminals I ₁ and I ₂ shown in FIG. The power input to the protector passes through the protector and is supplied to the terminal equipment connected to the subscriber side coaxial cable to operate them. In this case, since the power supplied to the subscriber side is supplied from an uninterruptible power supply on the facility side, even if the subscriber side fails, those terminal devices continue to operate without stopping.
[0009]
The protector with a power passing function shown in FIG. 3 includes a safety path 11 and a power passing section 12, and the safety path 11 is for power cut provided in series between the input terminal A and the output terminal B of the protector. Capacitors C ₁ and C ₂ , an arrester (ARR) 15 having one end connected between the center conductor of the input end A and the capacitor C ₁ and the other end grounded to the ground E, and one end of both capacitors C ₁ and C ₂ . A choke coil 16 connected between C ₂ and having the other end grounded to the ground E, and a capacitor C ₃ having one end connected to the external conductor of the output end B and the other end grounded to the ground E. . The power passing section 2 includes an insulating transformer 13 having a primary to secondary winding ratio of 1: 1, a primary choke coil 17 connected to the primary side, and a secondary side connected to the secondary side. The choke coil 18 and the posistor 19 are connected in parallel to the security system 11.
[0010]
When the CATV tap-off of the present invention is used in combination with the protector with a power passing function shown in FIG. 3, since the protector has a safety system 11, the facility side and the subscriber of the CATV system are provided as in the conventional protector. The equipment on the side can be protected from lightning damage and high-pressure contact. Further, the high-frequency signal input from the branch output terminals I ₁ and I ₂ of the CATV tap-off of the present invention to the input terminal A of the protector passes through the capacitors C ₁ and C ₂ for power supply cut and is output to the output terminal B. Is done. The power source superimposed on the high frequency signal is cut by the capacitor C ₂ and does not flow into the safety system 11 but flows to the primary side of the insulated transformer 13 through the primary side choke coil 17, which is the winding ratio of the transformer 13. In accordance with (one to one), it is output as it is to the secondary side of the transformer, and is output to the output terminal B of the protector through the secondary side choke coil 18. As a result, power is supplied from the facility side to the subscriber side, and the terminal device connected to the coaxial cable on the subscriber side can be operated at all times by this power source.
[0011]
【The invention's effect】
If the CATV tap-off of the present invention is used in a CATV system, a part of the amplifier power supply on the facility side of the CATV system can be stepped down to a voltage suitable for supplying to the subscriber side. For this reason, the terminal equipment on the subscriber side connected to the coaxial cable, in particular, the telephone terminal can be driven at all times, and the operation of the telephone terminal of the CATV system can be ensured even if the subscriber side loses power. Yes, even if the subscriber side loses power, only the phone can talk.
[Brief description of the drawings]
FIG. 1 is a connection diagram showing an embodiment of a CATV tap-off according to the present invention.
FIG. 2 is an explanatory diagram of a conventional CATV tap-off.
FIG. 3 is a connection diagram of a protector with a power passing function filed on the same day as the present application by the applicant.
FIG. 4 is an explanatory diagram of telephone communication using a CATV system.
[Explanation of symbols]
1 is a step-down unit

Claims (1)

The tap-off used in the CATV system is provided with a step-down unit that steps down the power supply voltage transmitted from the facility side of the system superimposed on the high-frequency signal to a voltage necessary for driving the CATV terminal device in the subscriber's house. A tap-off with a transformation function for CATV.

Images