JPS6033621Y2 - Noise interference preventer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise interference preventer for wired communication facilities such as wired television.

In the TV community reception system, the TV radio waves received by the community antenna are appropriately amplified and transmitted via coaxial cable to the TV receiver in each subscriber's home. Measures are required to prevent noise and electric shock due to high voltage pulses caused by electricity and high voltage intrusion caused by contact with power transmission and distribution lines.

The present invention proposes a noise interference preventer suitable for installation at the bottom of a subscriber's eaves of a drop-in line that connects a branch from a cable television trunk system to each subscriber's house.

This will now be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows the external appearance of the preventer of the present invention, where 10 is the lid of the casing and 12 is the base plate.

These are all made of metal plates, and have a shielding effect as well as preventing the intrusion of rain, snow, and dust.

The lid part 10 has a hollow trapezoidal shape, and its bottom open end fits into the board part 12 to seal the electric circuit components attached to the board part.

The board part 12 has a square plate shape and has a mounting part 14 on one edge,
This mounting portion has a hole 16.18 into which a mounting screw is inserted.

22 and 24 are one of the coaxial cable connectors (male member in this example), the former 22 being the input side and the latter 24 being the output side.

Figures 2a, b, and C are a plan view of the base plate 12 of the preventer of the present invention excluding the lid 10, and a side view with the lid partially broken;
and a bottom view of the substrate section 12.

As shown in a, coils 26, 28, 30, capacitors 32, 34, 36,
40, 44, and an arrester 42, and their connection state is as shown in FIG.

As shown in FIG. 3, the coil 26.28.degree. 30 and the capacitors 32, 34, 36, and 38 constitute a bypass filter, which passes signals in the television signal frequency band and blocks other low frequency signals.

Note that the capacitors 34 and 38 are minute capacitances on the order of lpF, and are used for input/output matching.

Further, the capacitor 40 is a coupling capacitor, and is 32
It has a larger capacity compared to ゜36.

44 is a capacitor connected between the external conductor side of the connector 24 and the ground G, that is, the housing 10°12,
As shown in FIG. 5, it consists of a dish-shaped metal plate 44a, a disc-shaped metal plate 44b, and four small disc-shaped dielectrics 50 sandwiched and soldered between them.

In other words, the metal plates 44a and 44b serve as electrode plates, and 50 serves as a dielectric to constitute four capacitors 01 to C4.

54 and 56 are insulators, 58 are screws that penetrate the metal plates 44a and 44b and fix them together, and 60 is a nut.

Since the preventer of the present invention is constructed as described above, the television signal transmitted through the coaxial cable of the wired television system is transmitted through the connector 22 on the input side, the capacitors 32, 36 and 40 on the output side as shown in FIG. is transmitted to the television receiver at the subscriber's home through the connector 24 of the subscriber.

Various noises trying to be transmitted on the same route are removed by a bypass filter made up of capacitors 32, 34, 36, 38 and coils 26, 28, 30, and high voltage pulses caused by lightning or other causes are removed by discharge of the arrester 42. be done.

Furthermore, in the present invention, the external conductor side of the output side connector is galvanically insulated from the casing, and a capacitor 44 is inserted between them, and as described above, the dish-shaped metal plate 44a, which is closely attached to the casing,
It has a structure consisting of a disk-shaped metal plate 44b electrically connected to the external conductor side 24a of the connector 24 via a nut 60, etc., and a plurality of small disk-shaped dielectrics sandwiched between these. Therefore, the inductance is extremely low, and for this reason, the noise that has entered the outer conductor of the coaxial cable between this preventer and the television receiver can be completely dropped to the ground, and the outer conductor is isolated from the ground in terms of direct current. Therefore, no direct current flows.

In other words, the outer conductor of the coaxial cable in this part may have a DC potential, for example because the television receiver is a transformerless type and the chassis has a DC potential, but the outer conductor side of the connector 24 is connected directly to the ground. In other words, when connected to the housing, the current due to this DC potential will flow out of the outer conductor of the coaxial cable of the wired television system through the connector 24, the housing of the preventer, and the connector 22, which is desirable. isn't it.

In order to block this, if a normal capacitor with two lead wires coming out from the main body is connected between the external conductor side of the connector 24 and the housing, the inductance will be large and the external conductor of the coaxial cable on the TV receiver side will be connected. The noise that has entered the TV receiver is not sufficiently grounded, and as a result, the noise tends to enter the television receiver through the coaxial cable core.

In this respect, by using the capacitor 44 having the structure of the present invention, such noise invasion can be completely suppressed.

FIG. 4 shows a modification of FIG. 3, in which a fuse 46 is used in place of the arrester 42.

This blows out when overvoltage current enters, preventing it from entering the television set.

This arrester 42 and fuse 46 may be used together.

As explained in detail above, according to the present invention, noise intrusion can be sufficiently prevented, and direct current will not flow through the outer conductor of the coaxial cable connected to the television receiver.

A noise interference preventer is obtained.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the appearance of the preventer of the present invention, Figure 2a,
b and C are a plan view of the circuit board of the preventer, a side view with a part of the lid removed, and a plan view of the circuit board, FIGS. 3 and 4 are electric circuit diagrams of the preventer, and FIG. FIG. 2 is a detailed view of a part of the diagram. In the drawing, 10 is the lid part of the case, 12 is the first part of the board, 22
is the input side connector, 24 is the output side connector, 32, 34
, 36.38 are bypass filter capacitors, 26.
28.30 is the same coil, 42.46 is the overvoltage protector, 4
4 is a capacitor, 44a is a plate-shaped metal plate thereof, 44b is a disc-shaped metal plate, and 50 is a dielectric.

Claims (1)

[Scope of utility model registration request] A metal casing consisting of a board part and a lid part, an input side connector and an output side connector attached to the board part, a bypass filter consisting of a capacitor and a coil connected between these connectors, and an input side connector. an overvoltage protector connected to the core side of the output connector, a dish-shaped metal plate connected between the output-side connector and the housing and in close contact with the housing, and a disk-shaped metal plate connected to the external conductor side of the output-side connector. A noise interference preventer comprising: a plate; and a capacitor made of a plurality of dielectrics sandwiched between these metal plates.