JP3201621B2 - Impedance matching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system between a coaxial cable and a twisted pair so that a twisted pair can be used as a transmission medium in a computer digital communication network using a coaxial cable as a transmission medium. The present invention relates to an impedance matching device that performs impedance matching.

[0002]

2. Description of the Related Art Conventionally, digital communication between computers such as a local area network uses a coaxial cable as a transmission medium in many cases.

[0003]

Incidentally, coaxial cables used as transmission media have different impedances depending on the product of each company. For example, 125Ω in Fujitsu K series, 93Ω in Fujitsu M series, IB
In the M5080 series, it is 75Ω or the like. Therefore, there is a problem that PDS cannot be used for signal transmission of these computers. In addition, since the coaxial cable is relatively hard to bend, there is a problem that wiring work is troublesome and expensive compared to twisted pair wire.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems by using a coaxial cable by matching the impedance between a coaxial cable and a twisted pair line and using the twisted pair line as a transmission medium for digital communication. An object of the present invention is to provide an impedance matching device which can be easily and inexpensively constructed as compared with the case.

[0005]

According to the present invention, in order to achieve the above object, a connector connected to a coaxial cable for digital communication of a computer is detachably connected to the coaxial connector and a twisted pair wire. A modular jack to which the modular plug is detachably connected,
An impedance matching circuit provided in a case with an impedance matching circuit for matching impedance between the coaxial connector and the modular jack;
The matching circuit is mounted on the board, and the coaxial connector is
The modular jack is connected to one end of the board.
Is arranged and connected to the other end of the substrate, and
On both sides where the plug is not attached or detached.
A flange piece extending in the vertical direction is provided, and the case is
And a cover attached to the body,
At least one of the cover and the case is
Flange jack is perpendicular to the board surface
That is, the inner side surfaces on both sides have holding structures that are loosely fitted in the opposite directions.

[0006]

According to the above construction, a coaxial connector for electrically connecting a coaxial cable, a modular jack for electrically connecting a twisted pair wire, and an impedance matching circuit for matching impedance between the coaxial connector and the modular jack. By connecting the coaxial cable connected to the computer performing digital communication to the coaxial connector, the impedance can be converted to match the twisted pair wire. This makes it possible to use an inexpensive twisted pair wire as the transmission medium.

[0007]

(Embodiment 1) As shown in FIG. 2, the case 1 has a rectangular parallelepiped shape, and is formed by connecting a body 11 and a cover 12 as shown in FIG. The body 11 and the cover 12 are joined by bonding or heat bonding. Body 11
A plurality of support ribs 13 protrude from a side portion of the inner bottom portion,
A rectangular circuit board 21 is placed on the support rib 13. As the circuit board 21, for example, a glass epoxy board is used. At one end in the longitudinal direction of the circuit board 21, an auxiliary plate 22 whose both sides protrude on both sides in the width direction of the circuit board 21.
The auxiliary plate 22 is provided with a receptacle-type coaxial connector 2 at right angles to the circuit board 21. As the coaxial connector 2, for example, a BNC type connector is used. A modular jack 3 is provided at the other end of the circuit board 21.
Is arranged. As the modular jack 3, for example, an 8-pole, 8-core type is used. Flange pieces 23 project from both sides of the modular jack 3, respectively. The modular jack 3 is mounted on the circuit board 21 so that the front end face of the flange piece 23 does not protrude from both side edges in the width direction of the circuit board 21. Fixed to

Since the coaxial connector 2 has a cylindrical connection portion with a plug-type connector (not shown), a semicircular cutout 14 is formed at the joint between the peripheral walls of the body 11 and the cover 12. The end of the coaxial connector 2 projects from the case 1 through the cutout 14. Further, the body 11 and the cover 12 are provided with holding ribs 15 protruding from both side walls so as to face the inside of the peripheral wall from which the coaxial connector 2 protrudes. Are sandwiched.
On the other hand, the modular jack 3 comprises a body 11 and a cover 12.
Between the rectangular cutouts 16 formed at the joints of the peripheral walls. The cover 12 is provided with holding ribs 18 having holding grooves 17 into which flange pieces 23 projecting from both sides of the modular jack 3 are inserted.

With the above configuration, the auxiliary plate 22 to which the coaxial connector 2 is attached and the modular jack 3 are fixed to the body 11 and the cover 12.
The circuit board 21 is sandwiched between the support ribs 13 and the holding ribs 18 to fix the position in the thickness direction, and is arranged between the holding ribs 15 to fix the position in the width direction.

On the circuit board 21, components constituting the impedance matching circuit 4 are mounted. The impedance matching circuit 4 is designed according to the type of computer to be connected. That is, in the Fujitsu K series, a 125Ω coaxial cable is used as the transmission medium,
If a twisted pair wire of 00Ω is used, the circuit configuration is as shown in FIG. The coaxial connector 2 connected to the unbalanced terminal T _1, to connect the modular jack 3 to the balanced terminals T _2. The turns ratio of each winding n ₁ , n ₂ is 20:20, and each resistance R ₁ , R ₂ , R ₃ is set to 15Ω, 15Ω, 56Ω, respectively.
It may be set to 0Ω. In the Fujitsu M series,
Since a 93Ω coaxial cable is used, the same windings n ₁ , n
_The resistances R ₁ , R ₂ , and R ₃ are set to 10Ω, 2
What is necessary is just to set it as 7 ohms and 270 ohms. Here, winding n ₁ ,
n ₂ is an annular toroidal core 2 as shown in FIG.
4 On the other hand, in the IBM 5080 series,
Because by using a 75Ω coaxial cable, in order to use the twisted pair 100 [Omega, as shown in FIG. 4, using the one having a center tap on winding n ₂ of the balanced side terminal T _2, the winding n _1, the winding ratio of n ₂ may be set to 12:14.

At the time of assembly, the coaxial connector 2
And the impedance matching circuit 4 on the circuit board 21.
After mounting the components and the modular jack 3, the auxiliary plate 22 and the circuit board 21 are mounted on the body 11, the leads of the coaxial connector 2 are soldered to the circuit board 21, and finally the cover 12 is attached to the body 11. if fixed to the well, at that time, mode
Flange pieces 23 projecting from both sides of the DURAJACK 3
Into the holding grooves 17 provided on the inner surfaces on both sides of the cover 12.
And position the cover 12 and the modular jack 3
By doing so, assembling work of the cover 12 and the body 11
Can be performed easily, reducing assembly man-hours and improving quality.
Improvement can be achieved. As shown in FIG. 5, if two impedance matching devices A having the above configuration are used, coaxial cables X ₁ and X drawn from a computer C ₁ such as a host computer and a computer C ₂ such as a terminal device, respectively.
A twisted pair wire P can be connected to ₂ via an impedance matching device A. That is, the twisted pair wire P can be shared as a transmission medium between the two computers C ₁ and C ₂ , which makes wiring construction easier and less expensive than when all the transmission media are coaxial cables. It can be applied to Also, by using the impedance matching device A designed for each model, the reflection, loss, and waveform of the signal caused by the impedance mismatch at the connection portion between the coaxial cables X ₁ and X ₂ and the twisted pair wire P are obtained. This can prevent the occurrence of distortion and the like.

In the above embodiment, two computers C ₁ and C ₂ are connected as the simplest configuration example.
Needless to say, the impedance matching device A can be used in a star connection or a bus connection. (Embodiment 2) In this embodiment, as shown in FIG. 6, the coaxial connector 3 is formed integrally with the body 12 at the same time, and the auxiliary plate 22 and the holding rib 15 are omitted. . The other configuration is the same as that of the first embodiment, and the description is omitted.

The coaxial connector 3 includes a case 1
It is also possible to use a connector having a flange so as to be fixed with screws or the like. Further, instead of a receptacle-type coaxial connector, a plug-type coaxial connector may be provided in the case 1.

[0014]

According to the present invention, as described above, a coaxial connector for electrically connecting a coaxial cable, a modular jack for electrically connecting a twisted pair wire, and impedance matching between the coaxial connector and the modular jack. Since an impedance matching circuit is provided, by connecting a coaxial cable connected to a computer performing digital communication to a coaxial connector, the impedance can be converted to match the twisted pair wire. There is an advantage that an easy and inexpensive twisted pair wire can be used as a transmission medium for digital communication between them.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment.

FIG. 2 is a perspective view showing an embodiment.

FIG. 3 is a circuit diagram of an impedance matching circuit used in the embodiment.

FIG. 4 is a circuit diagram showing another example of the impedance matching circuit used in the embodiment.

FIG. 5 is a schematic configuration diagram showing a usage pattern of the embodiment.

FIG. 6 is an exploded side view showing the second embodiment.

[Explanation of symbols]

 1 case 2 coaxial connector 3 modular jack 4 impedance matching circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03H 7/42 H01R 13/719 H01R 13/73 H01R 31/02

Claims (1)

(57) [Claims] 1. A coaxial connector to which a connector connected to a coaxial cable for digital communication of a computer is detachably connected, a modular jack to which a modular plug connected to a twisted pair wire is detachably connected, and a coaxial connector. and in the impedance matching device is provided and an impedance matching circuit to match the impedance to the case with the modular jack, said impedance
The matching circuit is mounted on a substrate, and the coaxial connector is
Connected to one end of the board, said modular jack is
The other end of the substrate is connected and connected to the modular
Perpendicular to the board surface on both sides where plugs are not attached
The case is provided with a flange piece that extends in the
And a cover attached to the body,
At least one of the cover and the case is
Lajac flange piece perpendicular to the board surface
An impedance matching device characterized in that a holding structure that loosely fits on the inner surface of both sides is provided.