JPH08124630A - Coaxial plug - Google Patents

Abstract

PURPOSE: To prevent obstacle occurrence even in the case no terminal is connected. CONSTITUTION: A conductive shell 17 of a plug is connected with an earth wire 3 of a coaxial cable and the center contact 11 is connected with a coated electric wire 1 of the coaxial cable. An electric circuit of a circuit board 23 is electrically connected with the shell at one end and with a switch member 28 at the other end and the electric circuit is provided with an electric resistor 25. A switch operating member 34 is forced toward the connector joining side by an elastic body 33 and at the same time against the forcing force of the elastic body, the switch operating member 34 moves to the coaxial cable connection side by the joining of the connector and thus the switch member and the conter contact are parted from the mutually contacting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial plug used as an output terminal of a coaxial cable for transmitting electric signals such as CATV.

[0002]

2. Description of the Related Art A coaxial connector used for an output terminal of a coaxial cable of this type is connected to a coaxial connector connected to devices such as a TV. Then, when no device is provided at the output terminal of the coaxial cable, the coaxial connector is detached and becomes a so-called empty terminal. TV that is commonly used for home listening and radio interference
In the case of retransmission or the like, since there is almost no signal transmitted to the adjacent channel, even if the empty terminal is left, the occurrence of a trouble or the like to the other TVs provided does not pose a problem.

However, in the case of multi-channel transmission, which has been introduced in recent years, and CATV systems such as bidirectional CATV, since many channels are used, signals are transmitted also to adjacent channels, and an empty terminal is used. If it is left as it is, a problem will occur because a failure or the like will occur in a TV or the like that is deployed for the following reason.

Explaining the mode of failure with reference to FIGS. 9 and 10, when the B side of the two-way divider is an empty terminal as shown in FIG. 9, the VSW in the arrow direction which is the B side terminal direction is shown.
Since R (voltage standing wave ratio) becomes infinite, a phase difference occurs in the signal due to the reflected wave from the B-side terminal, and the signal deteriorates. Then, a ghost is generated in the TV or the like connected to the A terminal. Further, the phase shift also causes an amplitude variation, which deteriorates the frequency characteristic, which causes a failure in some channels.
Also, during BS / CS-IF transmission, the satellite broadcast signal is F
Since it is M-modulated, truncation noise is generated and energy diffusion removal failure occurs. Since the CATV is also FM-modulated, the same trouble occurs.

Further, as shown in FIG. 10, bidirectional CAT
The B side of the V system 2 divider is an empty terminal,
If the coaxial core wire is exposed, external noise will be carried on the coaxial core wire, and the noise carried on the vacant terminals of many terminals will be combined to rise to the center side. This is called ingress noise. Also, noise is not only on the coaxial core wire, but noise is also on the coaxial cable itself, and when noise from many coaxial cables is combined, it becomes ingress noise as well, and in the case of bidirectional communication, Uplink cannot be used due to ingress noise.

FIG. 11 shows the reflection loss characteristics when the output terminal of the series unit is an empty terminal and when it is terminated by a dummy resistor. Although a reflection loss of 20 dB or more can be obtained, when an empty terminal is used, as shown by B, only a reflection loss of about 15 dB is obtained.

FIG. 12 shows the reflection loss characteristics when the tap-off output terminal for branching into four branches is an empty terminal and when it is terminated by a dummy resistor. 20 across the entire band
A reflection loss of dB or more can be obtained, but when one terminal is an empty terminal, it is shown as B, and the reflection loss characteristic deteriorates so as to wavy, and when two terminals are empty terminals, it is shown as C. Thus, only a reflection loss of about 15 dB can be obtained. Further, when three terminals are vacant terminals, a reflection loss of about 12 dB is obtained as shown by D, and when all four terminals are vacant terminals, about 8 dB is shown as E. Only the reflection loss of will be obtained.

[0008] By the way, in order to prevent such an obstacle, a dummy plug is conventionally connected to an empty terminal of a coaxial connector. Such a dummy plug is actually fair 6-1
It is described in Japanese Patent No. 7363, etc., and will be described with reference to FIG. In this figure, 01 is a dummy plug and 02
Is a center contact, 03 is a dummy resistor having the characteristic impedance of a coaxial cable, 04 is a shell, 05 is a soldering portion for connecting the dummy resistor 03 to the shell 04,
Reference numeral 06 is a connection nut. And this dummy plug 0
When 1 is connected to a coaxial connector (not shown), the transmitted electric signal flows into the center contact 02 of the dummy plug 01 through the center contact of the coaxial connector, and the dummy resistor 03, the soldering portion 05, the shell 04, and the connection. It is grounded to the connector body of the coaxial connector via the nut 06. In this way, by terminating the electric signal by the dummy resistor 03 of the dummy plug 01, reflection of the electric signal and intrusion of external noise are prevented.

[0009]

However, it is necessary to attach a dummy connector to the empty terminal when the devices are removed from the output terminal arranged at the end of the coaxial cable. Dummy connectors are rarely installed because they are uncommon. Especially in ordinary households, it is rare that a dummy connector is attached even if there is an empty terminal as a conventional practice.

Therefore, an object of the present invention is to provide a coaxial plug which is used as an output terminal of a coaxial cable and which does not cause any trouble even if it is left as an empty terminal.

[0011]

To achieve the above object, a coaxial plug according to the present invention comprises a substantially cylindrical shell, a center contact to which an electric signal is input, and a substantially central axis line of the shell. In a coaxial plug including an insulator for arranging a center contact and a connection nut for connecting to a coaxial connector, a circuit board including a switch member is provided in the shell, and the switch member contacts the middle of the center contact. Is turned on, the center contact is terminated by a dummy resistor provided on the circuit board, and the coaxial connector is connected to the coaxial plug, whereby the switch operating member slides and the switch member turns off. It was made to be done.

Further, the coaxial plug of the present invention comprises a substantially cylindrical shell, a center contact to which an electric signal is input, an insulator for arranging the center contact in a substantially central axis of the shell, and a coaxial connector. In a coaxial plug including a connection nut for connecting, a circuit board having one end of a switch member connected to the central axis of the shell is disposed in the shell, and the other of the switch member is provided in the middle of the center contact. The switch member is biased so that the ends come into contact with each other, and in a state in which the coaxial connector is not connected to the coaxial plug, the center contact is terminated by a dummy resistor provided on the circuit board and is coaxial with the coaxial plug. When the connector is connected, the switch actuating member provided for sliding on the shaft in the shell slides. Enter between the leading edge of the switch member and the center contact, the switch member from the center contact is intended to be turned off disengaged.

Further, a noise shield plate may be formed by using one surface of the circuit board as an entire ground. further,
The ground portion of the circuit board may be connected to the shell by pressing the circuit board against a step formed on the inner surface of the shell.

Further, another coaxial plug of the present invention comprises a substantially cylindrical shell, a center contact to which an electric signal is inputted, an insulator for arranging the center contact in a substantially central axis of the shell, and a coaxial plug. In a coaxial plug including a connection nut for connecting to a connector, a circuit board having one end of a switch member connected to the central axis of the shell is disposed in the shell, and the switch member is provided in the middle of the center contact. The switch member is formed in a dogleg shape in cross section so that the other end of the switch member is pressed, and the center contact is a dummy resistor provided on the circuit board in the state where the coaxial connector is not connected to the coaxial plug. A switch provided to slide on its axis in the shell when a coaxial connector is connected to the coaxial plug by terminating with The moving member slides so that the tapered portion of the switch operating member enters between the center contact and the switch member, and the switch member is disengaged from the center contact and turned off. It is a thing.

Further, in the coaxial plug, when the coaxial connector is detached from the coaxial plug, the taper portion of the switch operating member is pushed back by the elastic force of the switch member so that the switch operating member is in the initial state. It was designed to return to.

In such a coaxial plug of the present invention, when the coaxial connector is not connected to the coaxial plug, the electric signal transmitted from the coaxial cable is transmitted to the center contact, and the electric signal of the circuit board is transmitted through the switch member. Input to the circuit. The electric circuit is provided with a dummy resistor, and the electric signal is transmitted to the shell of the coaxial plug through the dummy resistor and grounded.

When a coaxial connector is connected to the coaxial plug which is the empty terminal, the switch operating member moves to the coaxial cable connecting side against the urging force of the elastic body to bring the switch member into contact with the center contact. To leave. Therefore, the circuit for grounding the electrical signal is cut off. Further, since the center contact of the coaxial plug is connected to the center contact of the coaxial connector, the electric signal transmitted from the coaxial cable is input to the coaxial connector via the center contact of the coaxial plug and the center contact of the coaxial connector. Further, when the coaxial connector is detached from the coaxial plug, the switch actuating member is pushed back to the initial position by the elasticity of the switch member, and the switch member is again brought into contact with the center contact.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the coaxial plug of the present invention will be described with reference to FIGS. 1 is a sectional view of a coaxial plug according to a first embodiment of the present invention, FIG. 2 is a sectional view when a coaxial connector is connected to the coaxial plug of FIG. 1, and FIG. 3 is an exploded perspective view of the coaxial plug. It is a figure.

In these figures, D is a coaxial cable for transmitting CATV signals, P is a coaxial plug to which the coaxial cable D is connected, and in the case of the first embodiment, it is an F-type plug. Has been done. C is a coaxial connector connected to the coaxial plug P. Further, 1 is a conductive core wire of the coaxial cable D, 2 is an insulator covering the core wire 1 of the coaxial cable D, 3 is a conductive ground mesh wire of the coaxial cable D, and 4 is an insulating outer side of the coaxial cable D. 5 is a crimp ring for fixing the coaxial cable D to the coaxial plug P.

Further, 11 is a center contact of the coaxial plug P made of a conductive metal, and 12 is this center contact 1.
A slot is provided so that the core wire 1 of the coaxial cable D can be inserted and held at the connection portion 1. 14 is a holder made of insulating synthetic resin for holding the center contact 11,
Is a guide portion of the holding body 14 which is an insulator, and guides the core wire 1 when the core wire 1 of the coaxial cable D is inserted into the connecting portion 12 of the center contact 11. Reference numeral 17 denotes a shell forming a cylindrical shell on the outside of the coaxial plug P, which is made of a conductive metal, and 18 is a caulking claw portion of the shell 17 formed at the tip on the side to which the coaxial cable D is connected. It prevents the coaxial cable D from coming off from the coaxial plug P together with the crimp ring 5. Reference numeral 19 denotes a taper clamp portion formed in a taper shape in which the outer diameter is gradually reduced toward the tip where the caulking claw portion 18 is formed. When,
The distance between the crimp ring 5 and the taper clamp portion 19 gradually decreases, and the crimp ring 5 is crimped to the ground mesh wire 3 and the coating 4 of the coaxial cable D and fixed to the shell 17. Reference numeral 20 denotes a holding body locking step portion that locks the holding body 14, and 21 denotes a substrate locking step portion.

Reference numeral 23 denotes a donut plate-shaped circuit board which is arranged substantially perpendicularly to the center contact 11. The circuit board 23 is arranged so as to close the inside of the shell 17, and the surface on the coaxial connector connection side is entirely grounded to cause noise jump. Is being prevented. 24 is in contact with the shell 17 at one end of the electric circuit of the circuit board 23. Further, 25 is a small chip resistor that is disposed in the middle of the electric circuit of the circuit board 23, for example, a small chip resistor of 75 ohms, and 26 is a small chip resistor that is similarly disposed in the middle of the electric circuit of the circuit board 23. It is a chip capacitor. 27 is the other end of the electric circuit of the circuit board 23. Reference numeral 28 denotes a switch member made of conductive elastic metal, one end of which is connected to the other end 27 of the electric circuit of the circuit board 23 and the other end of which is in contact with the center contact 11.

Reference numeral 29 denotes a cylindrical connecting body made of a conductive metal, which is press-fitted into the shell 17 and the tip of the shell 17 is caulked after the press-fitting so that the body of the connecting body 29 is fixed to the inner surface of the shell 17. . In addition, one end of the connecting body 29 is connected to the circuit board 2
The surface of No. 3 is in contact with and pressed. By this pressing, one end portion 24 of the electric circuit of the circuit board 23 and the shell 17 are brought into pressure contact with each other to electrically secure the connection. On the other hand, at the other end of the connector 29, a step portion 30 for locking the switch operating member 34 is formed on the inner surface thereof, and a step portion 31 for locking the connection nut 38 rotatably is formed on the outer surface thereof. There is.

Reference numeral 33 denotes a resin spring made of synthetic rubber, which is a cylindrical elastic body, disposed inside the connecting body 29, and 34 denotes a switch operating member made of an insulating synthetic resin material. 35
Is a switch cam portion formed on the switch operating member 34, the inner surface of which has a cylindrical shape with a circular cross section, and is slidably supported by the center contact 11. Further, the outer surface of the switch cam portion 35 has a truncated cone-shaped cam surface. Reference numeral 36 denotes an engaging portion of the switch operating member 34, which abuts the step portion 30 of the connecting body 29 for the switch operating member to prevent the switch operating member 34 from coming off the connecting body 29 to the outside. The switch actuating member 34 is constantly urged toward the coaxial connector C coupling side by the insulating resin spring 33, but when pressed against the coaxial cable D coupling side, the central contact is resisted against the urging force of the resin spring 33. While being guided by 11, it moves to the coaxial cable D coupling side.

Reference numeral 38 denotes a connecting nut made of a conductive metal, which is rotatably supported by the connecting body 29. Reference numeral 39 denotes a retaining step portion that can come into contact with the connecting nut step portion 31 of the connecting body 29, and prevents the connecting nut 38 from coming off the connecting body 29. Reference numeral 40 denotes a female screw portion formed on the inner surface of the connection nut 38. Reference numeral 51 denotes a male screw portion formed on the outer surface of the coaxial connector C.

In FIG. 3, the center contact 11 is inserted into the holder 14, and then the circuit board 23 fitted with the switch member 28 is fitted into the holder 14. The holder 14 thus assembled is inserted into the shell 17. On the other hand, the connected body 2
The switch actuating member 34 and the resin spring 33 are inserted in 9, and the connecting nut 38 is fitted on the outside of the connecting body 29. Then, the connecting body 29 is fitted into the shell 17 in which the holding body 14 is inserted, and is pushed and the tip of the shell 17 on the connecting body 29 side is caulked to fix and connect the shell 17 and the connecting body 29.

When connecting the coaxial plug P to the coaxial cable D, as shown in FIG. 1, the core wire 1 of the coaxial cable D is connected to the connecting portion 12 of the center contact 11 provided on the coaxial plug P. Insert and connect. Further, the taper clamp portion 19 of the shell 17 of the coaxial plug P is inserted between the insulator 2 and the ground mesh wire 3 of the coaxial cable D, and the taper clamp portion 19 and the ground mesh wire 3 are inserted.
Contact with. Then, the crimp ring 5 previously fitted to the coaxial cable D is crimped by pliers or the like. Then, the ground mesh wire 3 and the coating 4 are sandwiched by the crimp ring 5 and the taper clamp portion 19, and the coaxial cable D is fixed to the coaxial plug P. Then, even if the coaxial cable D is pulled in the direction in which it is separated from the coaxial plug P, the coaxial cable D is removed by the caulking claw portion 18.
The relative displacement between the coaxial plug P and the coaxial plug P is prevented.

Further, when the coaxial connector C is not connected to the coaxial plug P and is an empty terminal shown in FIG. The signal is input to the center contact 11.
In the case of the conventional coaxial plug, since nothing is in electrical contact with the center contact 11, it is reflected and returns the core wire 1 of the original coaxial cable D. However, in the case of the coaxial plug of the present invention, since the switch member 28 is in contact, an electric signal flows to the electric circuit of the circuit board 23 via the switch member 28, and the small chip arranged in the electric circuit. Resistor 25 and small chip capacitor 2
It flows through the series circuit of 6 into the shell 17 from the end 24 of the electric circuit. Then, the ground mesh wire 3 of the coaxial cable D is passed through the taper clamp portion 19 of the shell 17.
To be grounded. With such a configuration, even if the coaxial plug P becomes an empty terminal, it is possible to prevent the electric signal from the coaxial cable D from being reflected and also prevent the center contact 11 from picking up external noise. .

When the coaxial connector C is connected to the coaxial plug P which is such an empty terminal, as shown in FIG.
The male screw portion 51 of the coaxial connector C is screwed into the female screw portion 40 of the connection nut 38 of the coaxial plug P. Then, the center contact 11 of the coaxial plug P is inserted and connected to the center contact (not shown) of the coaxial connector C. Also,
The tip portion of the coaxial connector C presses the switch operating member 34, and the switch operating member 34 is displaced toward the coaxial cable connecting side against the elastic force of the resin spring 33, that is, the biasing force. Then, the switch cam portion 35 of the insulative switch actuating member 34 enters between the switch member 28 and the center contact 11 of the coaxial plug P to release the contact between the center contact 11 and the switch member 28, and an electric signal Transmission to the small chip resistor 25 is cut off. Therefore, an electric signal can be input from the center contact 11 of the coaxial plug P to the center contact of the coaxial connector C as in the conventional case.

Next, the coaxial connector C is connected to the coaxial plug P.
2, the switch actuating member 34 returns from the state of FIG. 2 to the state of FIG. 1 by the urging force of the resin spring 33, and the switch member 28 contacts the center contact 11 and is grounded via the small chip resistor 25. . Then, it returns to the above-mentioned state of the empty terminal.

Next, a second embodiment of the present invention will be described with reference to FIG. In the description of the second embodiment, the same components as those in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 4, 4
Reference numeral 1 denotes a conductive earth spring for the circuit board 23, one end of which is in contact with the end 24 of the electric circuit of the circuit board 23 and the other end of which is in contact with the shell 17. 42 is the connection case body,
Reference numeral 43 is a connection spring spring provided in place of the female screw. The coaxial plug P of the second embodiment is a one-touch type plug.

Unlike the first embodiment, the second embodiment differs from the first embodiment in that the electric circuit of the circuit board 23 is grounded by using a ground spring 41. Further, the connecting body 29 of the first embodiment is not arranged, and the connection case body 42 is provided instead of the connection nut 38.
The tip of the connection case body 42 is press-fitted into the shell 17 and caulked and fixed. The connection with the coaxial connector C (not shown) is not made by screwing, but by the connection spring 43 provided in the connection case body 42, as in the conventional one-touch type plug. The operation when the coaxial connector C is connected to the coaxial plug P is the same as that of the first embodiment, and will be omitted.

Next, the detailed structure of the circuit board 23 is shown in FIG. As shown in this figure, in the circuit board 23 on the disk, a ground surface 23-1 is formed of copper foil on one surface of the insulating plate 23-2 as shown in FIG. The printed line 23-3 is formed as shown in FIG.
6 are arranged so as to face each other, and the chip resistor 25 and the chip capacitor 26 are connected to the printed line 2
They are connected in series by 3-3.

Then, the circuit board 23 is fitted into the ground spring 41 as shown in FIG. 3D, and the ground surface 23-1 formed on one surface of the circuit board 23 is grounded via the ground spring 41. There is. Furthermore, the printed line 23-3 to which the chip resistor 25 on the side not connected to the chip capacitor 26 is also connected to the ground spring 4
It comes to be grounded through 1. Note that e and f in FIG.
As shown in, the switch member 28 is electrically connected to the ring-shaped copper foil portion around the central square hole by soldering or the like. This switch member extends in the direction opposite to the earth spring 41 and acts as a switch for the center contact 8 as described above. Note that FIG.
The circuit board 23 shown in e and f is applied to the second embodiment, and the circuit board 2 shown in FIGS.
When the switch member 28 is attached to the switch 3, the circuit board 23 applicable to the first embodiment can be obtained.

Next, the configuration of the third embodiment of the coaxial plug of the present invention is shown in FIG. In the description of the third embodiment, the same components as those in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted. The structure of the third embodiment different from the first embodiment will be described. In the third embodiment, the structure of the switch member 28 'and the switch actuating member 3 will be described.
The configuration of the switch cam portion 35 'of 4'is made different, and the resin spring 33 is omitted.

As will be described later, the switch member 28 'has a spring-shaped cross section with a dogleg-shaped cross-section to increase the moment of inertia of area. Therefore, the spring pressure of the switch member 28 'is about twice that of the first and second embodiments. Further, the taper of the switch cam portion 35 'is tightly inclined. In the first and second embodiments, the taper angle is about 20 °, but in this example, the taper angle is about 30 ° to 45 °. As described above, when the taper angle of the switch cam portion 35 'is tight, the switch cam portion 35' is pushed back by the spring force of the switch member 28 'when the coaxial connector connected from the coaxial plug is detached. Resin spring 3
Even if 3 is omitted, the switch actuating member 34 'can be returned to the initial position.

This will be described in more detail with reference to FIG. 7. When the coaxial connector is connected to the coaxial plug, the switch operating member 34 'slides into the connecting body 29 as shown in FIG. It is pushed in. At this time, the tip of the switch cam portion 35 'of the switch actuating member 34' enters into the switch member 28 'so as to push open the switch member 28', and the state shown by the solid line in FIG. 7 is obtained. At this time, the tip of the switch member 28 'comes into pressure contact with the taper portion of the switch cam portion 35', but the axial force component W1 of the pressure contact force W causes the switch cam portion 35 '.
Will be pushed back. This component force W1 becomes larger as the taper portion of the switch cam portion 35 'becomes tighter and becomes larger as the spring force of the switch member 28' becomes larger.

Therefore, in the third embodiment, the taper portion of the switch cam portion 35 'is tight and the spring force of the switch member 28' is increased. As a result, when the coaxial connector is detached from the coaxial plug, the component force W1 causes the switch operating member 34 'to be pushed back to the initial position without requiring a resin spring or the like.

Next, the detailed structure of the switch member 28 'is shown in FIG. In this figure, (a) is a front view, (b) is a side view, (c) is a sectional view of a spring portion, and (d) is a sectional view of a base portion. The switch member 28 ′ is formed by pressing the central contact 11 into contact with the spring portion 28-1, a base portion 28-4 from which the spring portion 28-1 extends, and a portion of the base portion 28-4 cut and raised. Cut and raised piece 28-2 and base 28-4
And a flange portion 28-3 formed at the end of the.

The cross section of the spring portion 28-1 has a dogleg shape as shown in the sectional view taken along the line AA shown in FIG. As a result, it is possible to generate a pressure contact force that sufficiently pushes back the switch cam portion 35 '. The cut-and-raised piece 28-2 is a switch member 28 '.
When the switch member 28 'is inserted into the mounting hole of the circuit board 23, the switch member 28' passes through the mounting hole and engages with the mounting hole.
It is provided so that it does not deviate from 3.

The electrical characteristics of the coaxial plugs of the first, second, and third embodiments of the present invention described above are as follows:
It seems that the characteristics such as VSWR are deteriorated because 3 and the metal parts are stored, but when the reflection characteristics of the coaxial plug of the present invention are actually measured, it is shown as A in FIG. 8 described above. The characteristics are almost the same as the characteristics, and it is possible to obtain a good reflection characteristic equivalent to the case where a separate dummy plug 01 is connected to a coaxial connector and terminated as in the conventional case.
In particular, in the third embodiment, the resin spring can be omitted, so that the electrical characteristics are further improved. As described above, in the present invention, it is possible to improve the transmission quality without terminating the empty terminal of the coaxial plug by some means.

The above-mentioned third embodiment is shown in FIG.
Although the coaxial plug shown in FIG. 4 is premised, it can be applied to the second embodiment shown in FIG. 4 and the resin spring can be omitted. In the above description, the small chip resistor 25 is set to 75 ohms, but since this resistance value is a value that matches the characteristic impedance of the coaxial cable D, 75 ohms or 50 ohms is common. Further, a small chip capacitor 26 is provided on the circuit board 23, but this small chip capacitor 26 is for cutting a DC voltage for transmitting a coaxial cable, and can be omitted as appropriate when a DC voltage is not transmitted.

The resin spring 33 can be appropriately replaced with another elastic body such as a coil spring, but it is preferable that the elastic body has an insulating property in terms of impedance matching. Further, the resin spring 33 also has an action of elastically pressing the circuit board 23, and in the case of the first embodiment, the resin spring 33 interacts with the connecting body 29 to electrically stabilize the circuit board 23. Can be brought into contact with the stepped portion 21.

[0043]

Since the present invention is constructed as described above, when the coaxial connector is not connected to the coaxial plug, the electric signal transmitted from the coaxial cable is transmitted to the center contact, and is transmitted via the switch member. Input to the electric circuit of the circuit board. A resistor is provided in the electric circuit, and an electric signal is transmitted to the shell of the coaxial plug through the resistor and is grounded. Therefore, even if the coaxial plug becomes an empty terminal, it is possible to prevent the electric signal from the coaxial cable from being reflected and also prevent the center contact from picking up external noise.

Further, when the coaxial plug of the present invention is connected to the coaxial connector, the coaxial plug accommodates a circuit board provided with a dummy resistor and the like, and a structure for turning on / off the dummy resistor. Nevertheless, it is possible to maintain the same electrical characteristics as the conventional coaxial plug. Furthermore, since the shell has a tubular shape and a step is formed inside the shell, and one end of the electric circuit of the circuit board inserted and arranged inside the shell is in direct contact with the step of the shell, A member such as a ground spring is not required for grounding the electric circuit of the circuit board and the shell, and the number of assembly steps and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a coaxial plug according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view when a coaxial connector is connected to the coaxial plug of FIG.

FIG. 3 is an exploded perspective view of a coaxial plug.

FIG. 4 is a sectional view of a coaxial plug according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a detailed configuration of a circuit board.

FIG. 6 is a sectional view of a coaxial plug according to a third embodiment of the present invention.

FIG. 7 is a diagram for explaining a relationship between a switch member and a switch cam portion in the third embodiment example.

FIG. 8 is a diagram showing a detailed configuration of a switch member.

FIG. 9 is a diagram for explaining connection of devices in a home in the CATV system.

FIG. 10 is a diagram for explaining connection of devices in a home in a bidirectional CATV system.

FIG. 11 is a characteristic diagram when an output terminal of the series unit is an empty terminal and when terminated by a dummy resistor.

FIG. 12 is a characteristic diagram of reflection loss characteristics when a tap-off output terminal that branches into four branches is an empty terminal and when it is terminated by a dummy resistor.

FIG. 13 is a partially cutaway sectional view of a dummy plug.

[Explanation of symbols]

 C coaxial connector D coaxial cable P coaxial plug 11 center contact 14 holder (insulator) 17 shell 21 board locking step 23 circuit board 25 chip resistor (dummy resistor) 28 switch member 34 switch actuating member 38 connection nut

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshihiro Nichikawa 4-83-3 Shibaura, Minato-ku, Tokyo Kandenko Co., Ltd. (72) Inventor Tadao Makita 4-83-3 Shibaura, Minato-ku, Tokyo Stocks Company Kandenko

Claims (6)

[Claims] 1. A substantially cylindrical shell, a center contact to which an electric signal is input, an insulator for arranging the center contact in a substantially central axis of the shell, and a connection nut for connecting to a coaxial connector. In the coaxial plug provided with, a circuit board provided with a switch member is provided in the shell, and the switch is turned on by contacting the switch member in the middle of the center contact, and the center contact is provided on the circuit board. A coaxial plug characterized in that the switch actuating member is slid so that the switch member is turned off by terminating with a dummy resistor and connecting a coaxial connector to the coaxial plug. 2. A substantially cylindrical shell, a center contact to which an electric signal is input, an insulator for arranging the center contact in a substantially central axis of the shell, and a connection nut for connecting to a coaxial connector. In the coaxial plug provided, a circuit board having one end of a switch member connected substantially perpendicular to a central axis of the shell is disposed in the shell, and the switch is arranged so that the other end of the switch member comes into contact with the middle of the center contact. When the member is biased and the coaxial connector is not connected to the coaxial plug, the center contact is terminated by a dummy resistor provided on the circuit board, and when the coaxial connector is connected to the coaxial plug, A switch operating member, which is provided so as to slide on the shaft thereof in the shell, slides so that the tip thereof is the center contact. It enters between the bets and the switch member, coaxial plug characterized in that the switch member from the center contact is turned off disengaged. 3. The coaxial plug according to claim 2, wherein one surface of the circuit board is entirely grounded to form a noise shield plate. 4. The stepped portion formed on the inner surface of the shell,
The coaxial plug according to claim 2 or 3, wherein the ground portion of the circuit board is connected to the shell by press-contacting the circuit board. 5. A substantially cylindrical shell, a center contact to which an electric signal is input, an insulator for arranging the center contact in a substantially central axis of the shell, and a connection nut for connecting to a coaxial connector. In the coaxial plug provided with, a circuit board, to which one end of a switch member is connected substantially perpendicular to a central axis of the shell, is arranged in the shell, and the other end of the switch member is pressed into the middle of the center contact. When the switch member has a V-shaped cross section, and the coaxial connector is not connected to the coaxial plug, the center contact is terminated by a dummy resistor provided on the circuit board, and the coaxial plug is connected to the coaxial connector. When the switch is connected, a switch actuating member provided in the shell so as to slide on its axis slides to move the switch. Coaxial plug tapered portion which is tapered Ji actuating member enters between the switch member and the center contact, the switch member from the central contact, characterized in that it is turned off disengaged. 6. When the coaxial connector is detached from the coaxial plug, the elastic force of the switch member pushes the tapered portion of the switch operating member back so that the switch operating member returns to an initial state. The coaxial plug according to claim 5, wherein the coaxial plug is formed.