JP5583081B2 - Common mode impedance stabilization jig for communication cables - Google Patents

Description

  The present invention relates to EMI (Electro Magnetic Interference) measurement for detecting and measuring an interference wave from an electronic device, and more particularly to a common mode impedance stabilization jig for a communication cable having a shield.

  Conventionally, as an EMC test for evaluating the electromagnetic compatibility (EMC) of an electronic device or an electronic component, the magnitude of an interference wave radiated or conducted from the test object (electronic device or electronic component) itself Emission measurement (EMI measurement) and immunity test (EMS test) for evaluating the tolerance of a device when receiving an external interference wave.

  Among these, for EMI measurement, radiated EMI measurement that measures radiation noise from the EUT to the space, and cables (power line, signal line, control line) connected from the EUT to the EUT. There is a conducted EMI measurement that measures the common mode noise conducted.

  In the conducted EMI measurement, the measurement method differs between the power port (power line) and the communication port (signal line, control line). Furthermore, the communication port conducted EMI measurement method is roughly divided into cases with and without a cable shield. It is divided roughly into.

  As a measurement method when the communication cable has a shield, a method using an ISN (Impedance Stabilization Network) is a general measurement method.

  The ISN is a unit that uses a 150Ω termination resistor and ferrite as a jig. The common mode impedance of the communication cable is kept constant, and the common mode voltage / current induced in the communication cable is set to 150Ω. Has the effect of keeping. Using this ISN, the common mode impedance is maintained at 150Ω, and the voltage or current of the common mode noise induced in the shield of the communication cable is measured.

  However, when ISN is used, it is necessary to cut the communication cable in order to insert the ISN between the communication cables, and to process the connector so that the ISN can be connected. Moreover, although ISN is prepared mainly for a coaxial line and a shielded twisted pair line (STP), it is not prepared for all shielded cables.

  If the ISN cannot be prepared, the measurement system shown in FIG. 6 is assembled, and the EUT and the opposing device (AE) are connected by a shielded cable equipped with a ferrite tube. Further, as shown in FIG. 7, the insulation sheath of the shielded cable is broken, and a terminal resistance of 150Ω is connected between the shield surface of the shielded cable and the ground.

  By connecting in this way, the common mode impedance of the shielded cable is maintained at 150Ω, and the voltage or current of the common mode noise induced in the shield of the communication cable is measured using a voltage or current probe (the following non-patent patent) Reference 1).

  However, when a 150Ω resistor as shown in FIGS. 6 and 7 is connected to the shield surface, a simple connection method such as an alligator clip is implemented as a method of connecting the termination resistor to the shield surface. Therefore, it is not possible to stably connect a termination resistor of 150Ω to the shield surface.

VCCI Technical Standard Annex IV “Disposition and Measurement Method for Communication Port Conducted Interference Measurement” 2011.04.01, revised 4th edition

  Since the conventional communication port conduction EMI measurement method for communication cables is configured as described above, when using ISN, cut the communication cable to insert the ISN between the communication cables, It is necessary to process the connector so that the ISN can be connected. Further, the ISN connector does not support all communication cables, and there is a problem that it is limited to a cable with a specific connector.

  In addition, when connecting a 150Ω termination resistor to the shield surface, a simple connection method such as an alligator clip has been implemented as a method for connecting the termination resistor to the shield surface. A terminal resistor of 150Ω cannot be connected. As a result, a floating inductance and a stray capacitance are generated in the terminal resistor, and a desired common mode impedance cannot be obtained.

  The present invention has been made in order to solve the above-described problems, and can flexibly cope with the thickness of a communication cable, reduce the stray inductance and stray capacitance of a termination resistor, and achieve a desired common. The present invention provides a common mode impedance stabilization jig for a communication cable that stably obtains a mode impedance.

  A common mode impedance stabilization jig for a communication cable according to the present invention includes a first sandwiching member on which the communication cable is placed, a second sandwiching member provided so as to face the first sandwiching member, An interval adjusting member that adjusts an interval between the first sandwiching member and the second sandwiching member is provided, and the first sandwiching member is in contact with the shield of the communication cable and faces the contact surface. The back surface is composed of a conductor, the contact surface and the back surface are composed of a resistor having a desired resistance value, and the back surface composed of the conductor is set to a reference potential.

According to the present invention, the shield of the communication cable and the contact surface of the first sandwiching member can be brought into electrical stable contact with the first and second sandwiching members and the interval adjusting member. By configuring the first sandwiching member with a resistor having a desired resistance value between the contact surface and the back surface, the stray inductance and stray capacitance of the termination resistor are reduced, and a desired common mode impedance is stably obtained. be able to.
In addition, since the interval adjusting member is configured to adjust the interval between the first and second sandwiching members, there is an effect that the thickness of the communication cable can be flexibly handled.

It is a front view which shows the common mode impedance stabilization jig | tool of the cable for communication in the shielded cable by Embodiment 1 of this invention. It is a front view which shows the common mode impedance stabilization jig | tool of the cable for communication in the shielded cable by Embodiment 2 of this invention. It is a front view which shows the common mode impedance stabilization jig | tool of the cable for communication in the shielded cable by Embodiment 3 of this invention. It is a front view which shows the common mode impedance stabilization jig | tool of the cable for communication in the shielded cable by Embodiment 4 of this invention. FIG. 5 is a top view of FIG. 4. It is a schematic diagram which shows a measurement system when ISN cannot be prepared in the communication port conduction EMI measurement system in a shielded cable. It is a schematic diagram which shows the connection method in the case of connecting terminal resistance to the shield surface of a shielded cable.

Embodiment 1 FIG.
1 is a front view showing a common mode impedance stabilization jig for a communication cable in a shielded cable according to Embodiment 1 of the present invention.
In FIG. 1, the sandwiching member 1 is disposed on the reference surface 2 set to the ground potential, and the shielded cable 3 with the shield surface 3 a exposed is placed.
In addition, as for the pinching member 1, the back surface 1b which opposes the contact surface 1a which contacts the shield surface 3a of the shielded cable 3, and the contact surface 1a is comprised with a conductor. Further, the member 1c between the contact surface 1a and the back surface 1b is formed of a resistor having a desired resistance value (150Ω) as a termination resistor. Further, a back surface 1b made of a conductor is disposed on the reference surface 2.

The sandwiching member 4 is provided so as to face the sandwiching member 1 with the shield cable 3 interposed therebetween. The sandwiching member 4 is made of an insulator.
One end of the bolt 5a is inserted into the sandwiching member 1 and fixed. The other end is inserted into a hole (not shown) larger than the diameter of the bolt 5 a provided in the sandwiching member 4, and is tightened with a nut 5 b from the back side of the sandwiching member 4. It is pressed so as to be pressed.
In addition, a space | interval adjustment member is comprised with the volt | bolt 5a and the nut 5b.
With such a configuration, a termination resistor having a desired resistance value (150Ω) can be connected between the shield surface 3a of the shielded cable 3 and the reference surface 2 set to the ground potential.

Next, the operation will be described.
The communication port conduction EMI measurement procedure in the shielded cable includes the measurement system shown in FIG. 6 and connects the EUT and the opposing device (AE) with the shielded cable 3 fitted with a ferrite tube. Further, as shown in FIG. 7, the insulating sheath of the shield cable 3 is broken, and the shield surface 3A of the shield cable 3 is placed on the sandwiching member 1 of the jig shown in FIG. 1, and the sandwiching member 4 and the bolt 5a are placed. And the nut 5b.
By connecting in this way, the common mode impedance of the shielded cable 3 is kept at 150Ω, and the voltage or current of the common mode noise induced in the shield of the shielded cable 3 is measured using a voltage or current probe.

According to the first embodiment, the shielding surface 3a can be appropriately pressed by the contact surface 1a of the sandwiching member 1 by the sandwiching members 1 and 4, the bolt 5a and the nut 5b. 1a can be brought into electrical stable contact, and the sandwiching member 1 is formed of a resistor having a desired resistance value (150Ω) between the contact surface 1a and the back surface 1b. Therefore, the desired common mode impedance can be stably obtained.
Further, since the interval between the sandwiching members 1 and 4 is adjustable by the bolt 5a and the nut 5b, the thickness of the shield cable 3 can be flexibly dealt with.

  In the first embodiment, the shielded cable 3 is applied as the communication cable. However, a coaxial cable or a multi-core cable may be applied as the communication cable, and the same effect can be obtained.

Embodiment 2. FIG.
FIG. 2 is a front view showing a common mode impedance stabilization jig for a communication cable in a shielded cable according to Embodiment 2 of the present invention.
In FIG. 2, the sandwiching member 4 has a contact surface 4 a that contacts the shield surface 3 a of the shield cable 3 made of a conductor.
The conductor spring 6 is composed of a stretchable conductor, and electrically connects the contact surface 1a of the sandwiching member 1 and the contact surface 1a of the sandwiching member 4.
The conductor spring 6 constitutes a first conductor member.
Other configurations are the same as those in FIG.

  According to the second embodiment, in addition to the contact surface 1a of the sandwiching member 1, the contact surface 4a of the sandwiching member 4 is made of a conductor, so that the shield surface 3a and the contact surfaces 1a and 4a of the sandwiching members 1 and 4 Can be electrically contacted more stably, the stray inductance and stray capacitance of the termination resistor can be reduced, and a desired common mode impedance can be obtained more stably.

Embodiment 3 FIG.
FIG. 3 is a front view showing a common mode impedance stabilization jig for a communication cable in a shielded cable according to Embodiment 3 of the present invention.
In FIG. 3, as in the case of the sandwiching member 1, the sandwiching member 4 includes a contact surface 4 a that contacts the shield surface 3 a of the shielded cable 3 and a back surface 4 b that faces the contact surface 4 a made of a conductor. Moreover, the member 4c between the contact surface 4a and the back surface 4b is comprised with a resistor.

  1 and 2, the member 1c of the sandwiching member 1 has been described as being composed of a resistor having a desired resistance value (150Ω) as a terminal resistance. However, in FIG. 3, the member 1c of the sandwiching member 1 is used. Each of the members 4c of the sandwiching member 4 is configured by a resistor having a resistance value (300Ω), and is set to have a desired resistance value (150Ω) by a parallel resistance by the two resistors.

In FIGS. 1 and 2, the bolt 5a and the nut 5b may be made of either a conductor or an insulator. However, in FIG. 3, the bolt 5a and the nut 5b are made of a conductor, and the sandwiching members 1 and 4 The back surfaces 1b and 4b are electrically connected to each other via a bolt 5a and a nut 5b.
Other configurations are the same as those in FIGS. 1 and 2.

  According to the third embodiment, since the sandwiching members 1 and 4 are configured to be symmetrical with respect to the shield surface 3a, the shield surface 3a and the contact surfaces 1a and 4a of the sandwiching members 1 and 4 are electrically connected. Since the resistance applied to the shield surface 3a is also symmetric, the stray inductance and stray capacitance of the termination resistor can be reduced, and a desired common mode impedance can be obtained more stably.

  In Embodiment 3 described above, both the member 1c of the sandwiching member 1 and the member 4c of the sandwiching member 4 are configured by resistors having resistance values (300Ω). However, the resistance values of both may be different. What is necessary is just to set so that it may have a desired resistance value (150 (ohm)) by the parallel resistance by one resistor.

In the third embodiment, the bolt 5a and the nut 5b are made of conductors. However, the bolt 5a and the member 1c of the sandwiching member 1 are mechanically fixed, and the bolt 5a and the member 1c of the sandwiching members 1 and 4 are fixed. , 4c may be electrically disconnected.
In this case, the setting accuracy of the resistance value of the termination resistor can be increased.
When the bolt 5a is not electrically connected to the member 1c of the sandwiching member 1, the bolt 5a and the member 1c of the sandwiching member 1 are mechanically fixed using an insulating adhesive or the like.
When the bolt 5a and the member 4c of the sandwiching member 4 are electrically disconnected, the hole provided in the member 4c of the sandwiching member 4 is made considerably larger than the diameter of the bolt 5a, and the bolt 5a and the member 4c and the like are made non-contact.

Embodiment 4 FIG.
FIG. 4 is a front view showing a common mode impedance stabilization jig for a communication cable in a shielded cable according to Embodiment 3 of the present invention. FIG. 5 is a top view thereof.
4 and 5, the conductor rod 7a is arranged on the reference plane 2 and in parallel with the bolt 5a.
The conductor plate 7 b is fixed to the back surface 4 b of the sandwiching member 4. Further, the contact plate 7c provided on the conductor plate 7b is slidable on the conductor bar 7a.
The conductor rod 7a, the conductor plate 7b, and the contact plate 7c constitute a second conductor member.
3 shows that the bolt 5a and the nut 5b are made of a conductor, but in FIG. 4, the bolt 5a and the nut 5b may be made of a conductor or an insulator.
Other configurations are the same as those in FIG.

According to the fourth embodiment, the same effect as in the third embodiment can be obtained.
Moreover, in the said Embodiment 3, since the volt | bolt 5a and the nut 5b were comprised with the conductor, you have to consider about the electrical property of the volt | bolt 5a and the member 1c of the clamping member 1. FIG.
In the fourth embodiment, the back surfaces 1b and 4b of the sandwiching members 1 and 4 are electrically connected to each other via the external conductor rod 7a, conductor plate 7b and contact plate 7c. Without consideration, the setting accuracy of the resistance value of the termination resistor can be increased.

  In the present invention, within the scope of the invention, any combination of each embodiment, any modification of any component of each embodiment, or omission of any component in each embodiment is possible. .

  1, 4 sandwiching member, 1a, 4a contact surface, 1b, 4b back surface, 1c, 4c member, 2 reference surface, 3 shield cable, 3a shield surface, 5a bolt, 5b nut, 6 conductor spring, 7a conductor rod, 7b conductor Plate, 7c Contact plate.

Claims (4)

A first sandwiching member for placing the communication cable with the shield exposed;
A second sandwiching member provided to face the first sandwiching member across the communication cable;
An interval adjusting member that makes the interval between the first sandwiching member and the second sandwiching member adjustable;
The first sandwiching member is
The contact surface in contact with the shield of the communication cable and the back surface facing the contact surface are made of a conductor, and the contact surface and the back surface are made of a resistor having a desired resistance value. A common mode impedance stabilization jig for a communication cable, wherein a configured rear surface is set to a reference potential. The second sandwiching member is
The contact surface that contacts the shield of the communication cable is made of a conductor, and the other is made of an insulator.
2. The common mode impedance of a communication cable according to claim 1, wherein the contact surface of the first sandwiching member and the contact surface of the second sandwiching member are connected by a stretchable first conductor member. Stabilization jig. A first sandwiching member for placing the communication cable with the shield exposed;
A second sandwiching member provided to face the first sandwiching member across the communication cable;
An interval adjusting member that makes the interval between the first sandwiching member and the second sandwiching member adjustable;
The first sandwiching member is
The contact surface that contacts the shield of the communication cable and the back surface facing the contact surface are made of a conductor, and the contact surface and the back surface are made of a resistor, and the back surface made of the conductor is a reference. Set to potential,
The second sandwiching member is
The contact surface that contacts the shield of the communication cable and the back surface that faces the contact surface are configured with a conductor, and the contact surface and the back surface are configured with a resistor,
The spacing adjusting member is
A conductor that electrically connects the back surface of the first sandwiching member and the back surface of the second sandwiching member;
The resistor of the first sandwiching member and the resistor of the second sandwiching member are:
A common mode impedance stabilization jig for a communication cable, which is set to have a desired resistance value by a parallel resistance formed by these two resistors. A first sandwiching member for placing the communication cable with the shield exposed;
A second sandwiching member provided to face the first sandwiching member across the communication cable;
An interval adjusting member that makes the interval between the first sandwiching member and the second sandwiching member adjustable;
The first sandwiching member is
The contact surface that contacts the shield of the communication cable and the back surface facing the contact surface are made of a conductor, and the contact surface and the back surface are made of a resistor, and the back surface made of the conductor is a reference. Set to potential,
The second sandwiching member is
The contact surface that contacts the shield of the communication cable and the back surface that faces the contact surface are configured with a conductor, and the contact surface and the back surface are configured with a resistor,
The back surface of the first sandwiching member and the back surface of the second sandwiching member are connected by a second conductive member that can expand and contract,
The resistor of the first sandwiching member and the resistor of the second sandwiching member are:
A common mode impedance stabilization jig for a communication cable, which is set to have a desired resistance value by a parallel resistance formed by these two resistors.

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