JPS6015327Y2 - Feedthrough capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention primarily relates to a feedthrough capacitor suitable for use in an antenna input circuit of a TV receiver.

One of the reception disturbances in a receiver is image disturbances such as ghosts or reflected images caused by the reflection of signal radio waves.

This is because there is a difference in signal strength, time, etc. between the signal coming from the receiving antenna and the signal that directly enters the receiver or the signal that reflects off buildings etc. and enters the antenna. This is caused by overlapping images.

In addition, it is necessary to match the antenna input circuit in order to improve the transmission efficiency as much as possible and prevent round-trip reflection of the signal on the feeder line. In such areas, receiving systems using shared antennas are becoming widespread, and matching of antenna input circuits has become an even more important issue.

Therefore, conventionally, as shown in Figure 1, a coupling capacitor C□ is connected to the center conductor of the coaxial cable, and a bypass capacitor C is used to pass unnecessary frequency signals to the outer conductor.
An antenna input circuit unit with a configuration in which two antennas were connected was used.

However, since the capacitors C1 and C2 of this conventional antenna input circuit unit have lead wires, the inductance of the lead wires acts, deteriorating the frequency characteristics in the VHF1UHF band, increasing the reflection coefficient, and increasing the lead inductance. Because of its large size, it has drawbacks such as difficulty in matching the characteristic impedance of the coaxial cable.

In order to eliminate this conventional drawback, a feedthrough capacitor shown in FIG. 2 has been proposed.

This feedthrough capacitor is the bypass capacitor C2 shown in FIG. A flat ceramic capacitor 7 having electrodes 5 and 6 is fixed so that the electrode 6 is in contact with the bottom 1, and the electrode 5 has a cylindrical interior that is penetrated through the through hole 4 of the ceramic capacitor 7. The terminals 8 were fixed by soldering or other means, and an insulating resin 9 was filled around the ceramic capacitor surrounded by the internal terminals 8 and the external metal fittings 3.

However, with the above structure, when connecting the coaxial cable, it is necessary to use a special connector such as an F-type plug and insert it into the internal terminal 8, which increases the cost. Also, it is necessary to solder the coaxial cable and coupling capacitor to the F type connector.
Assembling the antenna input circuit unit becomes troublesome.

In addition, since the insulating resin 9 has a structure in which the shrinkage ratio is in direct contact with the external metal fitting 3, the ceramic capacitor 7, and the internal terminal 8, which has a small shrinkage ratio of more than one digit, it is possible to prevent the insulating resin 9 from curing and shrinking or during a heat cycle test. Due to the thermal shock caused by the insulating resin 9, the external metal fitting 3, the ceramic capacitor 7, and the internal terminal 8, gaps, cracks, or peeling may occur at the interface between the insulating resin 9, the external metal fitting 3, the ceramic capacitor 7, and the internal terminal 8.
It also had the disadvantage that withstand voltage characteristics, moisture resistance, etc. tend to deteriorate.

The present invention eliminates the above-mentioned drawbacks, allows conductors such as coaxial cables to be connected directly without using special connectors such as F-type connectors, and has extremely high resistance to thermal shock. The purpose is to provide a highly reliable and inexpensive feedthrough capacitor.

In order to achieve the above object, the present invention provides a feed-through type capacitor in which one of the electrodes of a capacitor having a through hole is connected and fixed on an external metal fitting, and an internal terminal passing through the through hole is connected and fixed to the other electrode of the capacitor. In the internal terminal, the small diameter portion passing through the through hole and the large diameter portion constituting the connector portion for the external connector together with the center conductor of the connecting body inserted into the inner diameter portion of the small diameter portion are coaxially connected to each other. It is characterized by a stepped cylindrical structure arranged in a row.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings, which are examples.

FIG. 3A is an exploded perspective view of a feedthrough capacitor according to the present invention, and FIG. 3B is an assembled sectional view thereof.

In the figures, the same reference numerals as in FIG. 2 indicate functionally identical components.

10 is an internal terminal.

The internal terminal 10 is formed by rolling a single metal plate material and subjecting it to a stepped process, and includes a small diameter part 10a passing through the through hole 4 of the capacitor 7, and a larger inner diameter part 10a. It has a cylindrical structure with a slit 11 provided between the edges appearing in the circumferential direction.

This internal terminal 10 is inserted into the through hole 4 of the capacitor 7 so that the end faces of the small diameter part 10a1 and the large diameter part 10b protrude outside the external metal fitting 3 and the insulating resin 9, and are inserted into the through hole 4 of the capacitor 7. The outer surface of the capacitor 7 is brought into contact with the electrode 5 of the capacitor 7 and fixed by soldering or the like.

Further, a projection 12 that projects inward is provided on the inner diameter portion of the small diameter portion 10a1 and the large diameter portion 10b.

13 and 14 are heat-resistant insulating tubes fitted around the outer peripheries of the small-diameter portion 10a and the large-diameter portion 10b, and are made of an insulating material with high elasticity and heat resistance, such as silicone rubber.

When such insulating tubes 13 and 14 are provided, the insulating resin 9, the ceramic capacitor 7, and the external fitting 3 made of metal material can be
Since the heat shock that occurs due to the difference in shrinkage ratio between the insulating resin 9 and the internal terminal 10 is alleviated by the elasticity of the insulating tube 13, 14, the insulating resin 9 and the capacitor 7,
No gaps, cracks, or peeling occur at the interface between the external metal fitting 3 and the internal terminal 10, and the temperature resistance, moisture resistance, etc. are significantly improved.

The effect of alleviating heat shock is further enhanced by providing the internal terminal 10 with the slit 11 to give it elasticity.

Further, it is desirable that the tips of the insulating tubes 13 and 14 protrude above the surface of the insulating resin 9.

The creepage distance between the external metal fitting 3 and the internal terminal 10 increases,
This is because the insulation voltage characteristics are improved.

FIG. 4 is a cross-sectional view of a feedthrough capacitor unit for an antenna input circuit constructed by incorporating a feedthrough capacitor according to the present invention.

In the figure, 15 is a feedthrough capacitor according to the present invention;
6 is a shield case, and 17 is an antenna terminal plate.

The feedthrough capacitor 15 is constructed by inserting the external metal fitting 3 into one side plate of the shield case 16 by, for example, soldering, and attaching the large diameter portion 10b of the internal terminal 10 to the antenna terminal plate 1.
It is fitted into the mounting portion 17a of No.7.

18 is a coupling capacitor, for example, an RC with a discharge gear
Composed of composite parts.

Reference numeral 19 denotes a connector attached to the side plate of the shield case 16, to which a coaxial cable on the tuner side is connected.

20 is a connecting body inserted into the small diameter portion 10a of the internal terminal.

This connecting body 20 is pressed and supported within the small diameter portion 10a by the elastic force of the slit 11 and the locking force of the protrusion 12.

In this case, since the small diameter portion 10a and the large diameter portion 10b are in a coaxial relationship, the center conductor 20a of the connecting body 20 is also coaxial with the large diameter portion 10b, and the center conductor 20a and the large diameter portion 10b are in a coaxial relationship. This constitutes a connector portion for an external connector (not shown) connected to the coaxial cable on the antenna side.

Therefore, when the feedthrough capacitor according to the present invention is used, the connector led from the antenna can be directly connected to the capacitor, making it extremely easy to connect external circuits such as the antenna.

Moreover, since the internal terminal 10 can be constructed inexpensively from a metal plate material or the like, it is also advantageous in terms of cost.

Further, as shown in the embodiment, since the large diameter portion tab is provided with the slit 11, the large diameter portion 10b has elasticity.
External connectors can be supported elastically and stably.

As described above, the present invention provides a feedthrough capacitor in which one of the electrodes of the capacitor having a through hole is connected and fixed on an external metal fitting, and an internal terminal passing through the through hole is connected and fixed to the other electrode. The internal terminal coaxially connects a small diameter portion that passes through the through hole and a large diameter portion that constitutes a connector portion for the external connector together with a center conductor of a connecting body inserted into the inner diameter portion of the small diameter portion. Because it has a stepped cylindrical structure, for example, when it is incorporated into a feed-through capacitor unit for an antenna input circuit, the external connector on the antenna side can be directly connected as is, making it easier to connect the external circuit. It is possible to provide a feedthrough capacitor that is very easy to use.

Further, since the internal terminal itself functions as a connector, an independent connector is not required, and a feedthrough capacitor with low component cost can be provided.

In addition, as shown in the examples, the internal terminals can be constructed at low cost by using metal plate materials, etc. In this case, by making slits to give them elasticity, the stability of insertion of the internal terminals into the capacitor can be improved. It is possible to provide a feedthrough capacitor with highly stable coupling between an external connector and an internal terminal.

Furthermore, as shown in the example, by covering the internal terminal with an insulating tube, heat shock during curing and shrinkage of the filled insulating resin or during heat cycle tests is alleviated, resulting in high reliability with excellent temperature resistance and moisture resistance. It is possible to provide a feedthrough capacitor of 100%.

[Brief explanation of the drawing]

Fig. 1 is a TV antenna input circuit diagram, Fig. 2 is a sectional view of a conventional feedthrough capacitor, Fig. 3A is an exploded perspective view of a feedthrough capacitor according to the present invention, and Fig. 3B is an assembled sectional view thereof. 4 is a sectional view of a feedthrough capacitor unit for an antenna input circuit incorporating a feedthrough capacitor according to the present invention. 3...External metal fitting, 4...Through hole, 5,
6... Electrode, 7... Capacitor, 10
...Internal terminal, 10a...Small diameter part, 1
0b...Large diameter part.

Claims (2)

[Scope of utility model registration request] (1) In a feed-through capacitor in which one of the electrodes of the capacitor having a through hole is connected and fixed on an external metal fitting, and an internal terminal penetrating through the through hole is connected and fixed to the other electrode, the internal terminal is connected to the A stepped tube in which a small diameter portion passing through the through hole and a large diameter portion forming a connector portion for an external connector together with the center conductor of the connecting body inserted into the inner diameter portion of the small diameter portion are coaxially connected. A feed-through capacitor characterized by having a structure like the following. (2) The feedthrough capacitor according to claim 1, wherein the inner terminal has an outer periphery of the small diameter portion and the large diameter portion covered with an insulating tube.