JPS6114187Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a branching device that is used, for example, in a community reception facility, to take out a part of the signal being transmitted on a main line to a branch line.

Conventionally, this type of branching device has a structure in which a primary coil is inserted into the signal transmission path, a secondary coil is coupled to this primary coil, and a branch signal can be taken out from this secondary coil. is well known. With such a configuration, since the amount of branching is determined by the amount of coupling between the primary coil and the secondary coil, the amount of signal branching is almost quantifiable. This means that, for example, if the mounting position of the branch with respect to the main line differs, the signal level of the main line at each position will be different, and the amount of signal obtained at the branch terminal will also vary. In particular, when this branch is installed near the main amplifier, the amount of branching to the branch terminal is too large, resulting in excessive input to the TV receiver, which may disrupt the picture quality of the TV receiver. .

In order to solve this problem, for example, as shown in FIG.
It has also been considered to connect the attenuator 62 and send the signal to the television receiver through the attenuator 62, but in this case, there is a drawback that extra cost is required for the attenuator.

Also, in order to solve the above problem, it is possible to change the number of turns of the secondary coil, but doing so is difficult because the coil is thin and is wound around a ferrite core etc. Making it possible to take out a large number of taps and switch between them, and also switch resistors to match impedances, requires very complex and highly accurate technology, making the product significantly more expensive. There is a drawback.

Therefore, the present invention was designed to eliminate the above-mentioned drawbacks.It can be configured with the same number of circuit elements as a normal branch, and can be supplied at low cost.Moreover, the amount of signal taken out from the branch end can be adjusted to the respective signal level at the place of use. The purpose of the present invention is to provide a variable branch output type branching device that can be arbitrarily adjusted according to the situation.

The drawings showing the embodiments of the present application will be described below. In Figures 1 to 3, 1 is a case;
Constructed using metal materials. Reference numerals 2, 3, and 4 indicate an input end, an output end, and a branch end, each of which is constructed using a plug seat. T ₁ indicates a first coupling transformer, in which 5 is a core made of a magnetic material such as ferrite, 6 is a primary coil inserted through the through hole 5a of the core 5, and 7 is a coil wound around the core 5. One end 7a of the turned secondary coil is connected to the branch end 4, and the other end 7b is grounded to the case 1.
The turns ratio of both coils 6 and 7 is determined depending on the amount of signal (branch amount) to be transmitted from the primary side to the secondary side. Next, VR ₁ is a variable resistor exemplified as a variable resistance element for adjusting the branch output, and 8 is a knob for adjusting the variable resistor. T ₂ indicates a second coupling transformer, in which 9 is a core formed integrally with the core 5, 10 is a primary coil wound around the core 9, and one end 10a of the coil is connected to a variable resistor VR _1. It is connected. A secondary coil 11 is inserted through the through hole 9a of the core 9, and is configured in an autotransformer shape with the primary coil 10, and its connection point 12 is connected to the branch end 4. Note that the winding ratio of both coils 10 and 11 is determined according to the amount of signal branching, similarly to the first coupling transformer _T1 . _R1 is a resistor, one end of which is connected to the secondary coil of the second coupling transformer _T2 , and the other end of which is grounded to case 1. This resistor is used to select the voltage standing wave ratio of the branch end 4, and is selected to a value that improves the voltage standing wave ratio. In addition, in the branching switch with the above configuration, the impedance of the input end, output end, and branch end is equal to the impedance of the connected line, for example, 75Ω.
The frequency band used is 530KHz to 1GHz.
selected.

Next, to explain the operation of the branching device with the above configuration, most of the signal that enters the input terminal 2 passes through the primary coil 6 in the first coupling transformer _T1 to the output terminal 3.
while part of the above signal i.e. variable resistor
The amount of signal set by VR ₁ appears at branch end 4.

Next, graphs of FIGS. 4 to 8 showing various characteristics measured for the turnout having the above configuration will be explained. In addition, in FIGS. 4 to 6, the turns ratio of the primary coil and the secondary coil in the first coupling transformer T ₁ is 1t:3t, the variable resistor VR ₁ is 0 to 235Ω, and the second coupling transformer T ₂ For an example in which the turns ratio of the primary coil and secondary coil is 3t:1t, and the resistor _R1 is 56Ω, the seventh
The figure and FIG. 8 show the characteristics of an example in which the resistor R ₁ is further changed to 400Ω.

First, Figure 4 shows the characteristics of the insertion loss, that is, the loss from the input end 2 to the output end 3, and the attenuation amount from the input end 2 to the branch end 4. Both characteristics are approximately equal to each other over a wide frequency band. It is confirmed that the attenuation amount is constant, and the attenuation amount increases as the resistance value of the variable resistor VR ₁ increases (the amount of signal branching decreases). Next, Figure 5 shows the characteristics of the voltage standing wave ratio at input terminal 2 and output terminal 3 when variable resistor VR ₁ is adjusted to 235Ω, and Figure 6 shows the characteristics when it is adjusted to 0Ω. It is confirmed that both values are well within 1.5.

Next, Figure 7 shows the same characteristics as Figure 4 under the above conditions (R ₁ = 400Ω), and in this case, the smaller the value of the variable resistor VR ₁ , the greater the attenuation. This is confirmed.

Next, Figure 8 shows the voltage standing wave ratio characteristics at the input end, output end, and branch end when the amount of attenuation is maximum and minimum, and it was confirmed that all of them were within a good value of 1.5 or less. be done.

Note that FIGS. 9 and 10 show an example of a method for measuring the characteristics as described above.
5, Detector 16, 17, Oscilloscope 18, 1
9, 20, VSWR auto tester 21, terminator 2
2, 23 and the branch A with the above configuration are connected as shown in the figure, the oscilloscope 18 measures the insertion loss, the oscilloscope 19 measures the attenuation to the branch end, and the oscilloscope 20 measures the input terminal (connection). (The output end and branch end are also measured in the same way) by changing the voltage standing wave ratio.

Next, FIG. 11 shows a variable resistance element for adjusting the branched output having a different configuration, in which the amount of branching can be adjusted stepwise by a switch 25.

Next, Fig. 12 shows the state in which the splitter having the above-mentioned structure is used in a common receiving facility. In the figure, 27 is an antenna, 28 is a trunk line, 29 is a trunk amplifier, 30 is a branch line, 31 is an extension amplifier, 3
Reference numeral 2 denotes the distributor, and 33 denotes the terminals of each subscriber's home. In this state of installation, even if the terminals 33 of the subscriber's home are located directly below the extension amplifier 31, it is possible to send signals of an appropriate level to the terminals 33 of those subscriber's homes by narrowing down the amount of branching in this branch A.

Next, FIG. 13 shows, as a block, the trunk branch widening device 35 incorporating the branching device of the above configuration, and also shows the relationship between this and the common reception circuit. It should be noted that the members indicated by reference numerals 36 to 45 are well-known, respectively.
6 is an input terminal, 37 is a BON circuit, 38 is a main amplifier section, 39 is a branch circuit, 40 is an output terminal, 41 is a distribution amplifier, 42 is a distributor, 43 is a distribution output terminal, 44 is a power supply separation filter, 45 is the power supply device. In the amplifier 35 having such a configuration, a signal is sent from the distribution output terminal 43 to the terminal 33e at the subscriber's premises located a little distance from the amplifier 35, and the signal is sent from the distribution output terminal 43 to the terminal 33e at the subscriber's premises located just below the amplifier 35.
A signal is sent from a branch output terminal 46 connected to the branch Ae, so that a signal of an equal level is sent to the terminals of every subscriber's home.

It should be noted that the same reference numerals as those in the previous figure are appended with an alphanumeric letter "e" for parts that are functionally the same or equivalent to those in the previous figure, and redundant explanations are omitted.
(Also, in the following figure, the same idea is given, and the redundant explanation is omitted by adding an alphanumeric character f.) Next, FIG. 14 shows a circuit of a branching switch equipped with a medium wave broadcast output terminal 48. It is something. In the figure,
49 is a distribution transformer, and 50 is a capacitor, which together with the coil of the distribution transformer 49 constitutes a low-pass filter capable of passing signals in the medium wave broadcast band. The above-mentioned coil is, for example, 16 μH, and the capacitor is 200 pF. 51 is a transformer for impedance matching,
For example, one that converts 75Ω to 600Ω is used. Note that 52 is a capacitor designed to pass broadcast signals and block the passage of power for operating the amplifier, and 53 is a capacitor selected to have a value that allows FM broadcast and television broadcast signals to pass.

As described above, this invention is equipped with a variable resistance element for adjusting the branch output so that the amount of signal taken out to the branch end 4 can be changed, so a large number of units are all manufactured to a single standard. However, when it is used in the field, the amount of signals taken out from the branch ends 4 can be adjusted freely, that is, it is convenient that a desired level of branch signals can be taken out at each location. Moreover, even if it is possible to take out a signal of any level, its internal structure has the advantage that it can be composed of approximately the same number of circuit elements as compared to conventional branching switches. This has a great effect in providing an inexpensive branch output variable type branch switch.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and Fig. 1 is a circuit diagram, Fig. 2 is a perspective view showing the external appearance, Fig. 3 is a perspective view showing the internal structure, and Figs. 4 to 8 show characteristics. Graphs, Figures 9 and 10 are wiring diagrams showing the measurement status of characteristics, Figure 11 is a diagram showing branch output adjustment elements with different configurations, Figure 12 is a system diagram showing part of the communal reception facility, FIG. 13 is a block diagram showing the configuration of a main branch amplifier, FIG. 14 is a circuit diagram showing a different embodiment, and FIG. 15 is a circuit diagram showing a conventional example. 2...Input end, 3...Output end, 4...Branch end,
T ₁ , T ₂ ... coupling transformer, VR ₁ , 25 ... branch output adjustment element.

Claims (1)

[Scope of utility model registration request] It has an input end, an output end, and a branch end, a primary coil of a first coupling transformer is connected between the input end and the output end, and a second coil of the first coupling transformer is connected to the primary coil. A secondary coil is coupled, one end of the secondary coil is connected to the branch end, and the other end is connected to ground, and between the output end side end of the primary coil and ground,
A variable resistance element for branching output adjustment sequentially from the end, a second coupling transformer in which a primary coil and a secondary coil are configured in an autotransformer shape, and a resistor are connected in series, and furthermore, a resistor is connected in series. A variable branch output type branching device characterized in that a connection point between the primary coil and the secondary coil in the second coupling transformer is connected to the branch end.