JPS598424Y2 - safety device - Google Patents

Description

[Detailed description of the invention] This invention is designed to prevent induced lightning that is superimposed on the cable by interposing it between the coaxial cable that transmits incoming signals in cable television broadcasting, etc., and the signal intake part of the television receiver. This protector is used to prevent faults such as electrical leakage, and its purpose is to be able to effectively interrupt abnormal voltages and currents, to transmit television signals with little loss, and to prevent direct waves. It is an object of the present invention to provide a safety device having a large ability to eliminate interference.

The drawings showing the embodiments of the present application will be described below.

In Figures 1 to 4, S indicates a shield case, which is composed of a metal shield board 1 and a metal shield lid 2, and forms the outer box of the protector. It is grounded to.

Reference numeral 3 denotes an input side plug attached to the shield board 1, and its external conductor 4 is grounded to the shield board 1.

5 is an internal conductor of the input side plug, 6 is a through hole drilled in the shield board 1, and 7 is a retaining plate that closes the through hole 6, which is made of a well-known insulating material and protrudes from the shield board 1. It is fixed to the shield board 1 with fixed claws 1'.

8 is an output side plug fixed to the holding plate 7.

The input side plug 3 and the output side plug 8 are both connected to a coaxial cable so that the TV signal is received from the input side plug 3 and sent from the output side plug 8.

9 is an outer conductor of the output side plug 8, and 10 is an inner conductor of the output side plug 8.

11 is an electrically insulating bushing, which has a through hole 6 and an outer conductor 9.
It is interposed in the space between.

Reference numeral 12 denotes a cover mounting member provided at the mounting portion of the output side plug 8, and is used to attach a cover provided to prevent rainwater from entering through the connection portion between the output side plug 8 and the cable.

15 is a plug hole drilled in the center of the retaining plate, and this plug hole 1
The outer conductor 9 of the output side plug is fitted into and fixed to 5.

Reference numeral 16 denotes a ring-shaped conductor portion formed of a printed conductor around the plug hole 15 of the holding plate, and its inner circumferential portion is in close contact with the outer circumferential portion of the outer conductor 9 and is electrically conductive.

Note that the annular conductor portion 16 only needs to be electrically substantially annular together with the outer conductor 9 in the assembled state by taking into consideration the nut 9', and does not necessarily have to be annular by itself.

Reference numeral 17 denotes a radial conductor portion formed continuously around the annular conductor portion 16.

These may be arranged radially at substantially equal angular intervals, and some of them may be continuous in the circumferential direction.

The annular conductor portion 16 and the radial conductor portions 17 are collectively referred to as a first conductor plate 18.

Reference numeral 19 denotes a second conductor plate which is attached by a printing method to a portion of the holding plate 7 other than the first conductor plate 18, and is electrically grounded to the shield substrate 1 through the fixing claw 1'.

Reference numeral 20 denotes an insulating gap formed between the first conductor plate 18 and the second conductor plate 19, and the gaps are approximately equally spaced.

21 is a third conductor plate 22 provided on the holding plate 7 insulated from both the first conductor plate 18 and the second conductor plate 19;
is a V-shaped discharge gap, in which one of the first conductor plates 18 and the second conductor plate 19 bulges at an obtuse angle, and the other is concave at an obtuse angle opposite to this, and the interval between them is almost constant.

This shape is called a V-shape. Note that this shape in which the V shapes are arranged in succession should also be called a parallel zigzag shape, and this can also be considered as an application of the V shape.

Reference numeral 23 denotes a ■-shaped discharge gap provided in the insulation gap between the third conductor plate 21 and the second conductor plate 19.

24 is a capacitor interposed between the radial conductor portion 17 and the shield board 1; 25 is a fuse whose one end 25' is connected to the internal conductor 5 of the input side plug 3; 26 is a coil; It is connected between the other end 25'' and the shield board 1, and is grounded in terms of induced lightning and commercial power frequency.

Reference numeral 27 denotes a lightning arrester consisting of a fuse 25 and a coil 26, one end 25' of the fuse 25 forming its input terminal, and the other end 25'' of the fuse 25 forming its output terminal.

28 is a DC blocking capacitor connected between the output terminal 25'' of the lightning arrester 27 and the third conductor portion 21, and 29 is a conductor connecting the third conductor plate 21 and the internal conductor 10 of the output side plug 8. It is.

In the above structure, the incoming TV signal is sent to the internal conductor 5 of the human-powered side plug 3, passes through the fuse 25 and the DC blocking capacitor 28, and then passes through the internal conductor 1 of the output side plug 8.
sent to 0.

On the other hand, the external conductor 4 of the input side plug 3 and the external conductor 9 of the output side plug 8 are electrically connected by a capacitor 24 in terms of television signals.

When a high voltage current due to induced lightning or earth leakage is applied to the internal conductor 5 of the manual plug 3, it is short-circuited by the coil 26 and disappears, while being blocked by the DC blocking capacitor 28 and applied to the output side plug. is not transmitted.

When this current is extremely large, the fuse 25 burns out to protect the cable.

Furthermore, even if a high voltage is applied to the external conductor of the input side plug 3,
Since the external conductor 9 of the output side plug 8 is DC isolated by the capacitor 24, this high voltage is transferred to the external conductor 9.
to protect the television receiver connected to it.

Furthermore, due to lightning, a high voltage may be applied between the outer conductor 9 of the output side plug 8 and the ground, or between the inner conductor 10 and the ground.

In this case, the ■-shaped discharge gap 22. A discharge occurs in the capacitor 23 to eliminate this high voltage, and the capacitor 24
and prevents destruction of the DC blocking capacitor 28.

■Type discharge gap 22. When a high voltage is applied at 23, a discharge occurs at the tip of the V-shape, and if the discharge is repeated many times, the tip will wear out and become rounded, but since the tip is obtuse and the intervals are almost constant, the discharge will not occur. The starting voltage hardly changes and is durable.

Furthermore, since the discharge current per one can be reduced by using a large number of ■-type gaps, the device is durable in this respect as well.

Next, FIGS. 5 to 8 show cases in which two to five capacitors 24 are connected between the shield board 1 and positions where the outer peripheral portion of the conductive plate 18 is divided into approximately equal parts in the above structure. This figure shows the results (solid line) of actual measurements of various characteristics of the .

In these figures, the characteristics when a similar number of capacitors are connected together or only one capacitor is connected between a part of the conductive plate 18 and the shield substrate 1 are also shown by broken lines for comparison.

First, FIG. 5 shows the insertion loss characteristics, and it is understood that the insertion loss of the above structure is very small.

Next, Figures 6 and 7 show the ability to eliminate direct wave interference in the VHF television signal band and UHF television signal band, respectively, and it can be seen that the ability of the above-mentioned system is excellent. .

Next, FIG. 8 shows the VSWR characteristics of the output side plug, and it can be seen that the characteristics of the above-mentioned valve are good.

As described above, in this invention, a retainer formed of an insulating material is provided between the external conductor 9 of the output side plug 8 and the shield board 1 to which the external conductor 4 of the input side plug 3 is connected. Board 7
Furthermore, since a DC blocking capacitor 28 is interposed between the internal conductor 10 of the output side plug 8 and the internal conductor 5 of the input side plug 3, the output side plug 8 and the input side plug 3 have the feature that both their outer conductors and inner conductors can be electrically disconnected from each other.

This may occur if, for example, an abnormal voltage such as voltage caused by a reverse flash circuit during a lightning strike is applied to the output side plug 8 from a coaxial cable connected to the output side plug 8, or Even if the television receiver breaks down and abnormal current (leakage current) flows from the receiver into the output side plug 8, it is prevented from being transmitted to the input side plug 3.
There is safety in that the circuit connected to the input side plug 3 (for example, a circuit for cable television broadcasting) can be protected.

Moreover, as mentioned above, the outer conductor 9 of the output side plug 8 and the board 1
Even if an insulating material type or holding plate 7 is interposed between the outer conductor 9 and the outer conductor 9, the outer conductor 9 is connected to an annular conductor plate 18 disposed around the outer conductor plate 18 in an inserted manner. The conductor plate 18 has two or more capacitors 2 each capable of passing a television signal.
4. Since it is connected to the board 1 through the connector 24, when a TV signal enters the input connector 3, the signal is transferred to the output connector 9 with less loss and good passing characteristics as described above.
It has the feature of being able to output high-quality images to television receivers.

Furthermore, even if the annular conductor plate 18 is floating from the substrate 1 in a direct current manner, the two or more capacitors 24 that connect it to the substrate 1 are connected to the conductor plate 1 around the external conductor 9.
8, the conductor plate 18 is connected to a position where the entire circumference is divided into approximately equal parts and the base plate 1, so that, for example, in an area where a television signal has a strong electric field, a direct wave of a television signal may jump into the conductive plate 18. Even if there is a direct wave, the direct wave is transferred to the capacitor 24. Board 1 immediately at 24
It has the advantage of greatly increasing direct wave interference rejection capability.

This has the practical effect of preventing front ghosts from occurring on the screen when receiving television as described above, and ensuring a good television screen.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and FIG. 1 is a longitudinal cross-sectional view of the protector, FIG. 2 is an enlarged plan view of the retaining plate, FIG. 3 is an enlarged longitudinal cross-sectional view of the output side plug mounting part, and FIG. Figure 4 is the electrical wiring diagram of the protector, Figure 5 is a graph showing the insertion loss characteristics, and Figure 6 is the V
FIG. 7 is a graph showing interference wave rejection ability in the HF band, FIG. 7 is a graph showing interference wave rejection ability in the UHF band, and FIG. 8 is a graph showing VSWR characteristics. DESCRIPTION OF SYMBOLS 1... Board, 3... Input side connector, 4... External conductor, 5... Internal conductor, 8... Output side connector, 9... External conductor, 10... Internal Conductor, 17... Holding plate, 18
...Conductor plate, 28...DC blocking capacitor, 24
...Capacitor.

Claims (1)

[Scope of utility model registration request] It has a shield case that is separated from the shield board and the shield lid, and the shield board in the shield case is equipped with an input side connector and an output side connector. In a protector that is connected between external conductors and between internal conductors to prevent the passage of direct current but allow television signals to pass, the output side plug is connected to the through hole drilled in the shield board. On the other hand, the outer conductor has an outer conductor that is inserted through the outer conductor in an insulated state, and an inner conductor that is insulated from the outer conductor at the axis of the outer conductor. A retaining plate is fixedly placed around the external conductor in an inserted manner, and the retaining plate is fixed to the shield substrate with one side of the retaining plate aligned with the inner surface of the shield substrate. An annular conductor plate is inserted around the outer conductor, and the inner circumference of the conductor plate is electrically connected to the outer circumference of the outer conductor. The retaining plate is attached to the surface opposite to the surface attached to the shield board, and the outer periphery of the conductor plate is provided with two or more pieces, each of which blocks direct current but allows television signals to pass through. These capacitors are connected to the shield board through capacitors, and these capacitors are connected between the shield board and positions that divide the entire circumference of the conductor plate into approximately equal parts, while the input side The outer conductor of the connector is connected to the shield board, and the inner conductor of the input connector and the output connector are connected via a capacitor that blocks direct current but allows television signals to pass through. A safety device characterized by being wired.