KR830000256Y1 - Turnout for TV public facilities - Google Patents

Abstract

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Description

Turnout for TV public facilities

1 is a circuit diagram showing a conventional example using a resistor for preventing the return of a signal between output terminals in a general distributor.

FIG. 2 is a circuit diagram showing a conventional example in which a balance core transformer is used to prevent a signal from being returned between output terminals in a tap-off.

Figure 3 is a circuit diagram of the TV commercial equipment branch according to the embodiment of the present invention.

4 is a perspective view of a diverter which is the embodiment of FIG.

The present invention relates to a branch for a TV public hearing facility for branching a TV signal to a branch line in a transmission line of a CATV system.

In the CATV system, the TV signals received by the public antenna are sent to the transmission trunks, the TV signals are branched to the plurality of branch lines from the transmission trunks, and input to the TV receivers. For this reason, several branches are provided in the middle of a transmission trunk, and as a branching machine, the thing which generally used the simple divider has been used a lot. That is, the two middle taps are connected to each other by inputting one end of the winding of the mating transformer with the intermediate tap and the other end being grounded, and one end of each of the windings of the distribution transformer with the intermediate tap. Therefore, although it has been known to have been used as a divider for distributing a signal given to an input terminal to two output terminals at the same level, it is possible to change the number of turns of windings on both sides of a tap of the distribution transformer. Since the signal level ratio of the output terminal is changed, it is possible to use it as a diverter by appropriately determining the number of turns.

When the branching device using the above-mentioned divider is used for branching of the TV signal in the trunk line of the CATV system, the leakage of the local oscillation signal of the TV receiver connected to one output terminal is different from the other output terminal. Returning to the output terminal of, there is a time when mutual interference with TV signal in the transmission system occurs.

Conventionally, various measures have been taken to eliminate such unnecessary signals, but both satisfactory results are obtained in both the UHF band and the VHF band. In other words, it is difficult to remove sufficiently unnecessary signals along a wide band. A balance with separate taps was required as a balancesa trans, and neither could achieve satisfactory performance and construction.

An object of the present invention is to add a resistor in a TV commercial equipment splitter using a divider to obtain a flat frequency characteristic in a wide band ranging from a UHF band to a VHF band, and to output an unnecessary signal Effectively preventing the return of the liver, preventing mutual interference, and simplifying the circuit and structure.

In other words, in the television public hearing facility tap-off apparatus of the present invention, one winding terminal and two output terminals are provided, and one winding terminal of a mating transformer having a tab is connected to the input terminal, and the other winding terminal is grounded. Each of the output terminals is connected to the two winding ends of the distribution transformer with a tab, and the tabs of the two transformers are connected to each other, and the winding number of the winding between the one winding end and the tap is bounded by the tab of the separation transformer. The ratio between the windings and the number of turns between the other winding means and the tap is to divide the TV signal given to the tap into a desired ratio and output it to each output terminal. The connection is made via a resistor for power absorption between the terminal and the tap of the distribution transformer.

In this case, the output terminal on the side that outputs a relatively high current level TV signal is usually used as the trunk output terminal connected to the transmission trunk in the terminal, and the output terminal on the side of the other side that outputs the TV signal of relatively low current level is output. It is used as a branch line output terminal connected to a TV receiver via a branch line.

Unnecessary signal current flows from the output terminal side to one of the windings bounded by the tap of the distribution transformer, and the voltage drop generated in the one winding and the reverse voltage are induced to the other winding by this unnecessary signal current. If the voltage drop and the induced voltage are equal in magnitude, they do not face each other, and no return of unnecessary signals between the output terminals occurs. Therefore, in the present invention, any voltage drop generated when the same current flows, power is absorbed by parallel connection of the resistor to the winding of the large side, and the tap is equivalent to the unnecessary signal flowing from the output terminal side. (等價 的) middle tap. Specifically, since the windings with a large number of turns on the side of the tab are on the branch line output terminal side, and the windings with a small number of turns are on the main line output terminal side, power is absorbed in parallel with the windings on the side of the number of turns, that is, between the tap and the branch line output terminals. Connect the resistor for.

As in the conventional example of the present invention, referring to the drawings, FIG. 1 shows a conventional example of preventing the return of a signal between output terminals in a splitter which distributes the input signal to two output terminals at the same level. Where 1 is the input terminal. 2 and 3 are output terminals, 4a is a mating transformer and 4b is a distribution transformer, and these transformers 4a and 4b are windings wound around a common core. One end of the winding of the mating trans 4a is connected to the input terminal, the other end is grounded, and the winding has an intermediate tap 5a. On the other hand, one end of the winding of the distribution transformer 4b is connected to one output terminal 2, the other end is connected to the other output terminal 3, and this winding also has an intermediate tap 5b. Both intermediate tabs 5a and 5b of the two transverses 4a and 4b are connected to each other, and condensate 6 is connected between the intermediate tabs and the ground. In distribution transformer 4b, resistor 7 is connected between both ends of the winding.

In such a splitter, the signal applied to the input terminal 1 is transmitted to the middle tap 5b of the distribution transformer 4b via the matching transformer 4a, and is distributed to two output terminals in the distribution transformer 4b and output. In this case, since the turns ratio of the windings on both sides of the middle tap 5b of the distribution transformer 4b is 1: 1, the signals appearing at the output terminals 2, 3 are at the same current level. When the winding ratio is changed, a signal of a large current level appears on the side where the winding is small, and a signal of a small current level appears on the side where the winding is large. Therefore, it is used as a so-called diverter which makes a desired level ratio signal appear at both output terminals by appropriately setting the turn ratio.

Resistor 7 is to prevent unwanted signals such as noise between output terminals 2 and 3 from returning to each other and to prevent mutual interference. For example, when a noise signal flows from output terminal 2, in-phase flowing through resistor 7 The phase component and the reverse phase component trying to flow to the output terminal 3 through the winding of the distribution transformer 4 face each other and disappear. The output terminal 3 prevents the noise signal from appearing. However, this resistance 7 does not maintain the impedance value of the high frequency signal as the UHF and VHF bands due to the influence of the stray capacitance of its own. Therefore, the resistance 7 has a constant power consumption for the entire TV reception frequency band. Absorption function is not sufficiently exerted. As a result, with the connection method as described above, the use of the resistor 7 cannot completely prevent the return of unnecessary signals between the output terminals, and when used as a TV hearing tapper, the desired function cannot be exhibited. .

On the other hand, in order to prevent mutual interference and to ensure flat frequency characteristics for a wide band, it is proposed to use the balance antenna 18 as shown in FIG. In Fig. 2, reference numeral 11 denotes an input terminal, 12 and 13 respectively an output terminal, 14a a matching transformer with a tab 15a, and 14b a distribution transformer with a tab 15b. (16) is a condensate yarn, and (17) is a resistor connected to the tap of the belensa atlanth 18. That is, in the tap-off of FIG. 2, the tabs 15a and 15b are provided with tabs so that the turns ratio of each of the two sides becomes a predetermined ratio, so that the trunk output terminal 12 of the distribution transformer 4b has a relatively large current level. The signal is transmitted, and a relatively small level signal is transmitted to the branch line output terminal 13, and the balanced saatance 18 with a tap is connected between the winding end of the distribution transformer 4b to the trunk output terminal 12 and the ground. The resistor 17 is connected between the tap of the bellensa atrence 18 and the winding end to the branch line output terminal 12 of the distribution transformer 4b.

In the diverter of FIG. 2, since the balancing transformer 14 having a tab is added to the matching transformer 14a and the distribution transformer 14b, a trans configuration is used when the windings are formed on a common core. In particular, the winding method of each winding becomes complicated, and the winding to the branch line output terminal 13 of the tab of the distribution transformer 14b and the distribution transformer 14b in response to the turn ratio of the windings on both sides of the tap of the distribution transformer 14b. If the potential between the stages, i.e., the potentials at both ends of the resistor 17 are the same, the mutual interference cannot be reliably prevented unless the tap installation of the bellows atlant 18 and the resistance of the resistor 17 are determined. There is a problem with adjustment.

The breaker for TV systems of the present invention solves all of the disadvantages of the conventional examples shown in FIGS. 1 and 2, and is simple by connecting only resistors without adding structural coil parts.

That is, Figure 3 shows an embodiment of the present invention, where (21) is an input terminal, (22) and (23) are output terminals, respectively, and one output terminal 22 is used as the trunk output terminal. The other output terminal 23 can be used as the branch line output terminal. 24a is a mating transformer with a tab 25a, one end of which is connected to the input terminal 21, and the other end is grounded. 24b is a distribution transformer with a tab 25b, one end of the winding is connected to the trunk line output terminal 22, the other end to the branch line output terminal 23, and the tab 25b is the output terminal 22. The tab is provided so that the turn ratio between the winding 28a of the root and the winding 28b of the output terminal 23 becomes a predetermined value.

The tabs 25a and 25b of the two transformers 24a and 24b are connected to each other, and a condensate 26 is also connected between the tabs and the grounds of the tabs 25b and the windings 28b of the windings 28b. A resistance 27 for power absorption is connected between the pre-winding end to (23).

As described above, in the tap-off according to the present invention, the input signal applied to the input terminal 21 is transmitted to the tab 25b of the distribution transformer 24b via the matching transformer 24a. When the ratio of the number of turns Na of the windings 28a and the number of turns Nb of the windings 28b is Nb / Na = N, the ratio of the impedance Zb of the windings 28a is Zb / Za = √N as in the case of a general transpooma. When √N = n, n / (1 + n) in the input signal is distributed to the trunk line output terminal 22 and 1 / (1 + n) is distributed to the branch line output terminal 23, respectively. The input signals are distributed to both output terminals 22 and 23 at a current level ratio determined by winding turns 28a and 28b on both sides of the tab 25b of the distribution transformer 24b.

Normally, a TV receiver is connected to the branch line output terminal 23, so that the branch line output terminal 23 may introduce a missing portion of the local oscillation signal from the tuner of the TV receiver. This missing signal returns to the output terminals 23 to 22 if no countermeasures are taken, and as a result, an interference noise signal is generated in the transmission system. It is prevented to go back.

That is, in Fig. 3, unnecessary signals, such as missing local oscillation signals inputted to the branch line output terminal 23, pass through the winding 28b of the distribution transformer 24b and enter the input terminal 21 at the tab 25b. Flows from the path to reach. At this time, the voltage corresponding to the winding 28a is diminished by the unnecessary signal current flowing through the winding 28b, and in the direction of the induced voltage, the voltage corresponding to the winding 28a is diminished by the unnecessary signal current. The direction of this induced voltage is opposite to the voltage drop of the winding 28 caused by the unnecessary signal current. When the resistance value of the parallel resistance 27 of the winding 28b is selected so that the induced voltage and the voltage value of the reverse voltage drop in the opposite direction are equal to each other, both of them face each other and as a result are lost in the winding 28a due to an unnecessary signal. The induced voltage is absorbed by the resistor 27 and no unnecessary signal is returned to the trunk line output terminal 22.

In addition, even for a separate unnecessary signal that tries to return from the trunk output terminal 22 to the branch line output terminal 23, the winding 28b is connected to the winding 28b by the mutual induction of unnecessary signal current flowing through the winding 28a. The voltage drop due to the unnecessary signal current of the winding 28a and the induced voltage in the reverse direction are generated, and since this is absorbed by the resistor 27, no unnecessary signal is returned.

In this way, the return of signals between the trunk line output terminal 22 and the branch line output terminal 23 is prevented, and the function of the balance saatance used as a conventional branch is only distributed by the connection of the resistor 27. It is to be combined with (24b).

Therefore, in the configuration of the double transits 24a and 24b, as shown in FIG. 4, the tabing matching transverses 24a are separated from the common cores 29, respectively, as shown in FIG. By winding the winding with the transformer 24b and only connecting the resistor 27 between the tap 25b of the distribution transformer 24b and the winding end to the branch line output terminal 23, a simple structure is achieved. It is over.

As described above, the branching device for a television system is a simple configuration in which a resistor is connected only between the tap of the distribution transformer and the winding of the branch line output terminal, and the output terminal is connected to each other only by connecting the resistor. Unnecessary return of the signal is canceled in the distribution transformer, and since the addition of the constant is good, the frequency characteristic is flat even in a wide band, and the transmission quality can be improved at a low price.

Claims (1)

An input terminal and a pair of output terminals, one end of which is connected to the input terminal, the other end is a mating transformer made of a winding with a tap, and the other end is a branch transformer made of a tap with a winding connected to both output terminals. And a tap of the mating transformer is connected to the tap of the distribution transformer, and a predetermined number of turns between one end of the winding of the distribution transformer and each of the tap and the other end of the tap and the tap are made differently. A turnout for equipment as described above, wherein the resistance for power absorption is connected to both ends of the winding on the side with the greatest number of turns among the windings on both sides of the tap of the distribution transformer.