JP2001085118A - Differential transmission cable and joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently ensure the quality of a digital signal waveform and substantially reduce radiation noise by mounting a common mode choke coil on a board molded inside a connector, within an interface cable for transmitting a pair or two pairs or more of differential transmission signals. SOLUTION: A differential transmission cable 1 is composed of a cable 3 and connectors 2a, 2b arranged on the opposite ends. Radiation noise is suppressed by a function for selectively reducing only a noise component which is not cancelled each other by imbalance of differential transmission signals of a pair of digital signals and a function for preventing generation of noise caused by acting as an antenna of the cable itself, with a common mode choke coil 4 arranged inside the connector 2a. By mounting the coil 4 on a board, reliability in soldering of a cable and a lead wire with the coil 4 is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the construction of differential transmission cables and joints.

[0002]

2. Description of the Related Art Differential transmission cables are being put to practical use, for example, in the application of digital signals between a computer and its peripheral devices. (UniversalSer
ialBus), IEEE1394, etc., which are used as transmission cables for transmitting such differential transmission signals.

The differential transmission system is a transmission system in which digital signals in mutually opposite directions are added to a pair of lines under no bias or under a bias. Such a pair of lines has a high frequency component when viewed from a distance. This is a digital transmission system that takes noise countermeasures into consideration so that radiation noise is not generated in principle because the noise is canceled out.

[0004] In addition, even with respect to external noise induced in a transmission line by propagating through a hollow space, such noise is equivalently induced in a pair of lines. It is said that there is no principle to disturb the transmission. Therefore, differential transmission cables are generally
It has been assumed that there is no problem in principle regarding the transmission and reception of radiation noise.

However, an actual cable sometimes generates radiation noise. One of the causes of the noise is caused by the imbalance of the differential transmission signal.
Of the pair of digital signals described above, the difference that cannot be completely canceled out becomes a noise current and eventually becomes radiation noise. The other is that conduction noise generated from a personal computer, peripheral equipment, or the like is transmitted to a transmission cable, which becomes radiation noise.

Of these radiated noises, harmful ones need of course countermeasures. A conventional cable countermeasure method (for example, a method disclosed in Japanese Patent Application Laid-Open No. 8-84124) is a countermeasure method for a general transmission method, and specifically includes an inductive element, a capacitive element, This is a method of inserting a common mode choke coil, a low-pass filter (for example, the T-type filter in the disclosed example) and the like into a transmission system.

In addition, as a cable using differential transmission lines, Japanese Patent Laid-Open Publication No. 10-208818 discloses a cable having two or more pairs of differential transmission lines. When ferrite beads are inserted and in-phase signals are transmitted to a pair of transmission lines, the magnetic flux generated due to the signals does not affect other pairs of transmission lines as harmful mutual interference. Things.

[0008]

However, in the prior art, when a differential signal is transmitted to a transmission line, there is no sufficient differential transmission cable using an effective countermeasure against noise.

Therefore, the present invention provides a differential transmission cable which ensures sufficient quality of a digital signal waveform, greatly attenuates radiated noise, is inexpensive and has high reliability, and a joint for connecting the differential transmission cable and a device. Another object of the present invention is to provide a practical structure of the differential transmission cable and the joint.

[0010]

In order to achieve the above object, a differential transmission cable according to the present invention comprises a pair of differential transmission cables.
A differential transmission cable having a common mode choke coil on a pair of signal lines in an interface cable transmitting differential transmission signals of a pair or more, wherein the common mode choke coil is mounted on a board, and the board is A differential transmission cable characterized by being molded inside a connector.

Further, the joint for differential transmission according to the second invention of the present application is a joint for connecting an interface cable for transmitting one or more pairs of differential transmission signals and a device, and a pair of pairs in the joint. The signal line includes a common mode choke coil, and the common mode choke coil is mounted on a substrate, and the substrate is molded inside a male connector. A joint for differential transmission according to the third invention of the present application is a joint for connecting an interface cable and a device for transmitting one or more pairs of differential transmission signals, and a common signal line for a pair of signal lines in the joint. A mode choke coil, wherein the common mode choke coil is mounted on a board, and the board is molded at least inside one of the male and female connectors, and a joint length is within 10 cm. It is a joint. The differential transmission cable according to the fourth invention of the present application is an interface cable for transmitting one or more pairs of differential transmission signals, wherein a pair of signal lines in the interface cable includes a common mode chopping coil. The common mode choke coil is a differential transmission cable arranged in a housing portion of a connector, wherein the housing portion is provided with a land for mounting the common mode choke coil, and the common mode choke coil is provided with a land for mounting the common mode choke coil. A differential transmission cable comprising a positioning holding section. The joint for differential transmission according to the fifth invention of the present application is a joint for connecting an interface cable and a device for transmitting one or more pairs of differential transmission signals, and a common signal line for a pair of signal lines in the joint. A mode choke coil, wherein the common mode choke coil is disposed in a housing portion of the male connector,
The joint is characterized in that the housing section is provided with a land for mounting the common mode choke coil and a holding section for positioning the common mode choke coil. The joint for differential transmission according to the sixth invention of the present application is a joint for connecting an interface cable and a device for transmitting one or more pairs of differential transmission signals, and a common signal line for a pair of signal lines in the joint. A mode choke coil is provided, and the common mode choke coil is disposed in a housing portion of at least one of the male and female connectors, and the housing portion is provided with a land for mounting the common mode choke coil, The joint is provided with a holding portion for positioning the common mode choke coil, and the length of the joint is within 10 cm.

According to a seventh aspect of the present invention, there is provided a differential transmission cable and a joint according to the fourth to sixth aspects of the present invention, wherein a terminal portion of a connector is used in a part of a land on which a common mode choke coil is mounted. is there.

The eighth invention of the present application is the differential transmission cable and the joint according to the first to seventh inventions, characterized in that a constriction is formed in a land on which a common mode choke coil is mounted.

A ninth aspect of the present invention is the differential transmission cable and the joint according to the fourth to eighth aspects of the present invention, wherein the land on the side on which the common mode choke coil is mounted is a contact pin type. .

According to a tenth aspect of the present invention, there is provided the differential transmission cable and the joint according to the fourth to ninth aspects of the present invention, wherein an upper shape of the holding portion for positioning is a key shape. An eleventh invention of the present application is the differential transmission cable and the joint according to the first to tenth inventions, wherein a noise suppression component other than the common mode choke coil is inserted together inside the connector. Dynamic transmission cables and joints.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The first invention of the present application relates to one to two pairs.
Interface cable for transmitting differential transmission signals of more than a pair ←
A common mode choke coil provided in the interface cable, wherein the common mode choke coil is mounted on a board, and the board is molded inside the connector.

According to this structure, the common mode choke coil is arranged in the mold section connecting the terminal section of the connector of the interface cable and the cable, and thereby the balance of the differential transmission signal among the pair of digital signals is improved. Radiation noise can be suppressed by selectively attenuating only noise components (skew) that could not be canceled out by the collapse and by preventing the cable itself from becoming an antenna and becoming a noise source. . Also, in this configuration, when an in-phase signal is transmitted to a pair of transmission lines, the magnetic flux generated due to the signal can be removed by common-mode impedance, and the transmission to another pair of transmission lines can be performed. It does not cause harmful mutual interference.

The common mode choke coil is mounted on a board to ensure reliability in soldering a cable line and a lead wire to the common mode choke coil, and is further mounted with a common mode choke coil. Since the substrate is molded inside the connector, reliability can be improved. Further, when a common mode choke coil is inserted into the connector, it is not necessary to manufacture a special connector because a commercially available housing or the like can be used. Therefore, it is possible to provide a low-cost and highly reliable differential transmission cable that sufficiently secures the quality of the digital signal waveform, greatly attenuates the radiation noise, and provides a low cost. A second invention of the present application is a joint for connecting an interface cable for transmitting one or two or more pairs of differential transmission signals and a device, comprising a common mode choke coil on a pair of signal lines in the joint, and The mode choke coil is mounted on a board, and the board is molded inside the male connector. This configuration is such that when the above-mentioned joint is arranged between a commercially available differential transmission cable and a device, the joint is formed. By disposing the common mode choke coil inside the male connector, the noise suppression effect as described in the first invention of the present application is obtained. In addition, this configuration secures the reliability in soldering the common mode choke coil with the cable or lead wire connecting the male and female connectors by mounting the common mode choke coil on the board, and furthermore, the common mode choke coil is mounted on the board. Since the substrate on which the choke coil is mounted is molded inside the connector, reliability can be improved. Further, when a common mode choke coil is inserted into the connector, it is not necessary to manufacture a special connector because a commercially available housing or the like can be used. Therefore, it is possible to provide a joint for differential transmission that ensures sufficient quality of digital signal waveforms, significantly attenuates radiation noise, and is inexpensive and highly reliable. The third invention of the present application is a joint for connecting an interface cable for transmitting one or two or more pairs of differential transmission signals and a device, comprising a common mode choke coil on a pair of signal lines in the joint, The mode choke coil is mounted on a board, and the board is molded inside at least one of the male and female connectors, and the joint length is within 10 cm. When the above-described joint is disposed between the joint and the device, the common mode choke coil is disposed in at least one of the insides of the male and female connectors of the joint, so that noise suppression as described in the first invention of the present application is achieved. The present invention has the effect and the advantage described in the second invention of the present application. In addition, this configuration, when considering the differential transmission cable and joint as an antenna that is a single noise source,
In order to suppress radiation noise efficiently, the insertion place of the common mode choke coil is preferably arranged as close to the apparatus as possible within 10 cm from the apparatus, and the joint length is desirably manufactured within 10 cm.

According to a fourth aspect of the present invention, there is provided an interface cable for transmitting one or more pairs of differential transmission signals, wherein the interface cable includes a common mode choke coil, and the common mode choke coil comprises: The connector is arranged in a housing portion of the connector, and the housing portion is provided with a land for mounting a common mode choke coil, and a positioning holding portion is provided at a place where the common mode choke coil is inserted.

According to this configuration, the common mode choke coil disposed in the housing of the connector has a noise suppressing effect as described in the first invention of the present application.

In this configuration, by providing a land for mounting the common mode choke coil on the housing of the connector, reliability of the adhesive strength between the cable wire and the land of the housing and the common mode choke coil at the time of soldering is improved. By providing a holding portion for positioning at a place where the common mode choke coil is mounted, it is possible to reduce defects due to misalignment when the common mode choke coil is mounted. In other words, an object of the present invention is to provide an inexpensive and highly reliable differential transmission cable that sufficiently secures the quality of a digital signal waveform, greatly attenuates radiation noise, and has a high reliability.

According to a fifth aspect of the present invention, there is provided a joint for connecting an apparatus and an interface cable for transmitting one or more pairs of differential transmission signals, and a common mode choke coil is provided on a pair of signal lines in the joint. The common mode choke coil is disposed in a housing portion of the male connector, and the housing portion is provided with a land for mounting the common mode choke coil and a holding portion for positioning the common mode choke coil. This is the configuration of This configuration is described in the first invention of the present application by disposing the common mode choke coil inside the male connector of the joint when the above-mentioned joint is arranged between the commercially available differential transmission cable and the device. There is a noise suppression effect as described.
In this configuration, a land for mounting the common mode choke coil is provided in the housing of the connector, so that the reliability of the adhesive strength between the cable or lead wire and the land of the housing and the common mode choke coil during soldering is improved. By providing a holding portion for positioning at a place where the common mode choke coil is mounted, it is possible to reduce a defect due to a positional shift when the common mode choke coil is mounted. In other words, an object of the present invention is to provide an inexpensive and highly reliable joint for differential transmission that ensures sufficient quality of a digital signal waveform, significantly attenuates radiation noise, and is inexpensive. A sixth invention of the present application is a joint for connecting an interface cable for transmitting one or two or more pairs of differential transmission signals and a device, comprising a common mode choke coil on a pair of signal lines in the joint, The mode choke coil is arranged at least in a housing portion of one of the male and female connectors, and the housing portion is provided with a land for mounting the common mode choke coil, and the positioning portion for positioning the common mode choke coil. There is a holding part,
The joint length is within 10 cm. According to this configuration, when the above-described joint is arranged in the question of a commercially available differential transmission cable and a device, a common mode choke coil is arranged in at least one of the insides of the male and female connectors of the joint. This joint has both the noise suppression effect as described in the first and third aspects of the invention and the advantage described in the fifth aspect of the present invention. According to a seventh aspect of the present invention, a differential transmission cable and a joint according to the fourth to sixth aspects are provided.
By using the terminal part of the connector on a part of the land,
An object of the present invention is to provide a differential transmission cable and a joint which can reduce the number of components and are inexpensive.

According to an eighth aspect of the present invention, there is provided a differential transmission cable and a joint according to the first to seventh aspects,
By placing a constriction in the land, after mounting the common mode choke coil, when soldering a cable wire or a lead wire, it is difficult to conduct heat to the land portion on which the common mode choke coil is mounted, Another object of the present invention is to provide a differential transmission cable and a joint with higher reliability by preventing the solder at the portion where the common mode choke coil is soldered from melting and causing a contact failure.

The ninth invention of the present application is directed to a differential transmission cable and a joint according to the fourth to eighth inventions,
Since the land on the side on which the common mode choke coil is mounted is a contact pink eve, a soldering step when mounting the common mode choke coil can be omitted, and a more inexpensive differential transmission cable and joint are provided. It is in.

According to a tenth aspect of the present invention, in the differential transmission cable and the joint according to the fourth to ninth aspects, the upper portion of the holding portion for mounting the common mode choke coil has a key shape. An object of the present invention is to provide a more inexpensive and highly reliable differential transmission cable and joint, which can further drastically reduce defects due to positional deviation when mounting a transformer. The eleventh invention of the present application is the first invention.
In the cables and joints according to the tenth to tenth aspects of the present invention, noise suppression components other than the common mode choke coil are inserted together inside the connector, so that the noise and the noise as described in the first and third aspects of the present invention are obtained. In addition to the suppression effect, for example, when chip beads are inserted in the power supply line, defensive mode noise flowing in the power supply line can be suppressed. Also U
Connecting a device that is turned on by a hot plug function such as SB or IEEE 1394 causes a problem such as breakage of the device due to the flow of overcurrent. However, inserting a polymer PTC thermistor to protect the device from above Can also. When a chip varistor or a chip surge absorber is inserted, the device can be protected from overvoltage such as static electricity.

[0026]

Embodiment 1 FIG. 1 is a schematic view of a differential transmission cable according to one embodiment of the present invention. FIG. 1 is drawn schematically to ensure the visibility, so the scale of each part is not accurate, and one common mode choke coil 4 is connected to a pair of differential transmission lines 5.
This is an embodiment in the case where only the number is used. Further, as shown in FIG. 1, the configuration of this embodiment is as follows. The differential transmission cable 1 includes a cable 3 and connectors 2a and 2b disposed at both ends of the cable 3, and a common mode choke coil 4 is disposed inside the connector 2a. The cable 3 has a pair of differential transmission lines 5, and the connectors 2a and 2b have terminal portions 6a and 6
b, and are electrically connected between the terminal portions 6a and 6b of the connector.

In this configuration, the common mode choke coil 4 disposed inside the connector 2a allows only a noise component (skew) of a pair of digital signals, which cannot be canceled out due to the imbalance of the differential transmission signal to each other. Radiated noise can be suppressed by the function of selectively attenuating the noise and the function of preventing the cable itself from becoming an antenna and becoming a noise source. In general, a differential transmission cable such as a USB which is commercially available has a differential transmission line 5 made of a stranded wire, and is provided with a power supply line and a shield. Is not listed.

Next, a method for manufacturing the differential transmission cable 1 will be described. First, the differential common mode choke coil 4 is manufactured in the following manner. A Ni-Cu-Zn ferrite material is kneaded with a solvent or the like to form a paste, which is formed into a sheet by a doctor blade to produce a green sheet. A conductive paste mainly composed of Ag is formed on the green sheet by screen printing, appropriately laminated, and integrally fired to produce a laminated common mode choke coil. Usually, two or more are simultaneously printed and laminated,
Divided and fired. In addition, after printing and baking electrodes as external terminals, nickel, solder plating or the like is applied.

The common mode choke coil 4 desirably has a coupling coefficient at 100 MHz of 0.65 to 0.98 in order to sufficiently secure the quality of the digital signal waveform and greatly attenuate the radiation noise. , 0.75-
More preferably, it is 0.95. Further, as the common mode choke coil 4, an integrally fired laminated common mode choke coil in which the coupling coefficient is easily adjusted relatively easily by changing the thickness of the green sheet and the like was used. Although this laminated common mode choke coil is preferable, it may be composed of a winding or a thin film. Also, the material used for the common mode choke coil 4 is not limited to the above-mentioned material, and the shape is desirably 3216 size or less in consideration of being mounted on a cable such as a USB.

Next, a specific structure will be described. FIG.
FIG. 3 is a diagram illustrating a structure of an embodiment according to the present invention, in which a common mode choke coil is mounted inside a series A connector of a USB cable. FIG. 3 is a plan view of a substrate used in this embodiment. The common mode choke coil 4 is mounted on the land 21 of the substrate 11a and connected. The signal wires 5 and the lead wires 12 of the USB cable 3 are soldered to the lands 21 of the board 11a. This allows
The reliability in soldering the signal line 5, the lead wire 12 and the common mode choke coil 4 is ensured. The substrate 11a is not particularly limited as long as it is a material that can withstand soldering and molding. The shape (dimensions) of the land on the side on which the common mode choke coil 4 is mounted
It is desirable to use a general pattern size recommended by each company for mounting the component of the chip component.

Subsequently, the substrate 11a on which the cable 3 and the common mode choke coil 4 are mounted is molded together with the power supply line 14 and the leading end of the lead wire 12 as shown in FIG. 2, thereby further improving the reliability. be able to. Further, since the substrate 11a on which the common mode choke coil 4 is mounted is inserted into the mold portion 13, the housing portion 7a of a commercially available connector can be used as it is, so that the common mode choke coil is installed in the differential transmission cable 1. There is no need to fabricate a special connector for mounting 4.

Subsequently, after the terminal portions 15 and 6a of the connector are soldered to the power supply line 14 and the lead wire 12, the connector 2a is assembled using components such as a shield plate.

Incidentally, a method other than that described above, for example, the substrate 11a
After the common mode choke coil 4 is mounted on the land portion 21, the signal wire 5 and the lead wire 12 are soldered to the land 21 of the substrate 11 a, and the terminal portions 15 and 6 a of the connector, the power supply wire 14, and the lead wire 12 are soldered. After attaching, the substrate 11a on which the cable 3 and the common mode choke coil 4 are mounted and the housing 7 are molded together as long as the final configuration is the same. Further, the board to be inserted into the connector is not limited to the shape shown in FIG.
For example, as shown in FIG. 4, a substrate 11b that can be soldered to the power supply line 14 may be used.

Table 1 shows the results of comparing the performance of the differential transmission cable 1 manufactured as described above with a commercially available USB cable. Table 2 shows the characteristics of the common mode choke coil 4 used in the embodiment shown in Table 1.

In evaluating the performance of the cable, an evaluation circuit shown in FIG. 5 is used. The evaluation circuit connects the differential transmission cable 1 to the personal computer 31 and the USB hub 32, connects the USB hub 32 and the buffer 33 with a commercially available USB cable 36 that can convert one side into parallel, and connects the buffer 33 and the printer. 34 is connected by a parallel cable 37, and a high frequency current transformer 35 is attached to the differential transmission cable 1 so that a noise level radiated from the cable can be observed by a spectrum analyzer. A voltage probe is attached to the input pin, and the quality of the waveform can be confirmed by the signal observed by the sampling oscilloscope. Usually, the quality of a waveform is evaluated by the rise time of a digital wave, and the rise time is determined by a predetermined standard.

Therefore, in this evaluation, the radiation noise was set to 0 dB based on the radiation noise level measured using a commercially available USB cable, and the radiation noise level was measured using the differential transmission cable 1 of the present invention. Relative comparison is evaluated by the difference. The radiation noise evaluated by the relative comparison is due to harmful conduction noise from a personal computer observed at 145 MHz.

As for the quality of the waveform, the time delay of the rise time is used as an index, and the rise time delay is set to 0 second based on the rise time of a commercially available USB cable. The time when the rise time when used is delayed at the time of Min and at the time of Max is relatively compared and evaluated. The measurement point of the rise time is the time from when the voltage waveform of the digital wave observed by the sampling oscilloscope reaches the position at 10% of the wave height to the position at 90% of the wave height.

[0038]

[Table 1]

[0039]

[Table 2]

Therefore, as can be seen from Table 1, the differential transmission cable constructed according to the present invention can sufficiently secure the quality of the digital signal waveform and can greatly reduce the radiation noise.

Embodiment 2 FIG. 6 is a schematic diagram of another embodiment according to the present invention. FIG.
Are drawn schematically in order to ensure visibility, the scale of each part is not accurate, and the common mode choke coil 4 is connected to two pairs of differential transmission lines 5A and 5B by one.
This is an embodiment in the case of mounting one by one. As shown in FIG. 6, the configuration of this embodiment is as follows. The differential transmission cable 1 includes a cable 3 and connectors 2a and 2b disposed at both ends of the cable 3, and two common mode choke coils 4 are disposed inside the connector 2a. The cable 3 has two pairs of differential transmission lines 5A and 5B, and the connectors 2a and 2b are provided with terminal portions 6a, 6b, 6c and 6d of the connectors, respectively.
It is electrically connected between the terminal portions 6a and 6b and 6c and 6d of the connector. In addition, generally commercially available IEEE
A differential transmission cable such as 1394 is a differential transmission line 5A,
5B is a pair of stranded wires, and a power supply line and a shield are provided, but are not shown in FIG. 6 for simplicity of description.

In addition to the features described in the first embodiment, when a signal having the same phase is transmitted to the pair of transmission lines 5A, this configuration causes the magnetic flux generated due to the signal to be transmitted to the common mode in-between. Since it can be removed by dance, harmful mutual interference does not occur in the other set of transmission lines 5B.

Note that the common mode choke coil 4 has
Individual ones may be used, or multiple common mode choke coils may be used. More preferably, it is a multiple common mode choke coil, which is provided with a countermeasure against crosstalk and has a shape of 3216 size or less.
As in the first embodiment, the connection structure includes a common mode choke coil mounted on a substrate, connected, and molded inside the connector.

Embodiment 3 FIG. 7 shows another embodiment of the differential transmission cable according to the present invention. FIG. 7 shows a housing part of a series A connector of a USB cable. A common mode choke coil is mounted on the housing. The housing part 7b of this embodiment has a positioning holding part 25a at a place 24 where the common mode choke coil is mounted.
By providing the protrusions, it is possible to reduce defects due to misalignment when the common mode choke coil is mounted. The holding portion 25a for determining the position may have any configuration as long as the insertion position of the common mode choke coil can be determined, but a key-shaped upper portion 25b as shown in FIG. 10 is used. By
Defects due to misalignment when the common mode choke coil 4 is mounted can be further drastically reduced. The holding unit 25
It is preferable that a and 25b are manufactured together when the housing part is manufactured. The terminal 15 of the connector is
After the 6a is attached, a common mode choke coil is mounted, and a signal line of a USB cable is connected to form a differential transmission cable.

Further, by providing the land 23 for mounting the common mode choke coil on the housing portion 7b, the reliability of the adhesive strength between the signal line and the common mode choke coil at the time of soldering can be improved. Can,
By using the terminal 6a of the connector as a land for mounting the common mode choke coil, it is possible to secure the adhesive strength between the terminal 6a of the connector and the common mode choke coil and to reduce the number of constituent members. The unit price can be reduced. Further, by inserting a constriction 26 into the land 23 as shown in FIG. 8, after the common mode choke coil is mounted, when the signal line is soldered, the land 23 on the side on which the common mode choke coil is mounted is mounted. To provide a highly reliable differential transmission cable that makes it difficult to conduct heat and prevents problems such as melting of the solder where the land and the common mode choke coil are soldered, resulting in poor contact. Can be. The land 23 is preferably molded together with a metal piece having excellent solderability (eg, plated with tin) at the time of manufacturing the housing portion 7b. . Further, the land 23 does not necessarily have to be formed of a metal piece, but may be formed by a plating method or the like. It is desirable that the shape (dimension) of the land portion on the side on which the common mode choke coil is mounted is a general pattern size recommended by each company for mounting the chip component.

Further, by using a contact pin type land 28 having a land portion on the side on which the common mode choke coil is mounted as shown in FIG. 9, a soldering process for mounting the common mode choke coil 4 is performed. Can be omitted, so that a more inexpensive differential transmission cable can be provided. The shape of the land portion 28 may be any shape as long as the land portion 28 can be in contact with the external terminal 27 of the common mode choke coil 4. Also,
Since the land 28 is a place for transmitting and receiving electric signals, the land 28 must have a small time change and a low contact resistance. For this reason, it is desirable to use the one plated with gold.

The results of comparing the performance of the differential transmission cable manufactured as described above with a commercially available USB cable were the same as those in Table 1 described in Example 1. Fourth Embodiment FIG. 11 is a view showing the structure of an embodiment according to the present invention, which is a case of a joint used when connecting a USB cable to a personal computer. First, common mode choke coil 4
Is mounted on the substrate 11a. Next, the terminal portions 6a and 15 of the male connector of the series A, the terminal portions 6b and 16 of the female connector, and the substrate 11a are soldered with the lead wires 17. Thereby, the reliability in soldering the lead wire 17 and the common mode choke coil 4 is secured. Subsequently, the male connector, the female connector, and the board 11a are molded together,
Assemble the joint using parts such as shield plates.
Since the substrate 11a on which the common mode choke coil 4 is mounted is inserted into the molded portion 13, the reliability can be further improved. Further, since the housing portions 7a and 7c of commercially available connectors can be used as they are, there is no need to manufacture a special connector for mounting the common mode choke coil 4 in the joint. The performance of the joint manufactured as described above was measured using a commercially available USB
A comparison was made between the case where the cable was inserted between the cable 1 and the personal computer 31 and the case where only the commercially available USB cable 1 was used. The results were the same as Table 1 described in Example 1. In addition to the above, for example, the same effect can be obtained by changing the connector 2b of the differential transmission cable described in the first embodiment to a female connector and using it as a joint. Also, when inserting a board with a common mode choke coil into the female connector 2b without inserting a board with a common mode choke coil into the male connector 2a of the joint, the joint length should be 10 cm or less. Similar effects can be obtained. Fifth Embodiment FIG. 12 is a view showing the structure of another embodiment according to the present invention, which is a joint used when connecting a USB cable to a personal computer. In the housing portion 7b of this embodiment, a positioning holding portion 25a (projection-shaped member) is provided at the place 24 where the common mode choke coil is mounted, thereby reducing defects due to misalignment when the common mode choke coil is mounted. Can be done. The position determining holding portion 25a may have any configuration as long as the position where the common mode choke coil is inserted can be determined. After mounting the common mode choke coil on the housing part 7b, the housing parts 7b and 7c are connected together by a lead wire 17, molded together, and a joint is assembled using parts such as a shield plate. The performance of the joint prepared as described above is inserted between the commercially available USB cable 1 and the personal computer 31 and between the commercially available USB cable 1 and the personal computer 31.
The comparison is made with the case where only the cable 1 is used. The results were the same as Table 1 described in Example 1. In addition to the above, the same effect can be obtained by changing the connector 2b of the differential transmission cable described in the third embodiment to a female connector and using it as a joint. Also, a commercially available housing is used for the male connector 2a of the joint, and the housing of the female connector 2b is changed to a shape in which a common mode choke coil can be mounted. 10c
If it is less than m, the same effect can be obtained. Sixth Embodiment FIG. 13 is a view showing the structure of another embodiment according to the present invention, and shows a differential transmission cable and a board inserted into a connector of a joint. This substrate 11c has a common mode choke coil 4 mounted on a land 21 for a differential transmission line and a chip bead 9 mounted on a land 29 for a power supply line. When this is inserted inside the connector instead of the substrate 11a described in the drawings 2 and 11 described in the first embodiment or the fourth embodiment, not only the noise suppression effect described in the above-described embodiment but also the defensive current flowing in the power supply line is obtained. It is possible to suppress the shear mode noise. This embodiment is an embodiment of the present invention, and the present invention is not limited to this embodiment. For example, chip beads may be mounted on the housing of the connector. As another example, a polymer PTC thermistor may be inserted into the connector together with the common mode choke coil. This product may be inserted by inserting a common mode choke coil on the front surface of the substrate and a polymer-based PTC thermistor on the rear surface into the inside of the connector instead of the substrate 11a of the first or fourth embodiment. Alternatively, as in the third and fifth embodiments, the housing portion 7b on which the common mode choke coil 4 is mounted may be used and inserted into the connector together with the substrate on which only the polymer PTC thermistor is mounted. An advantage of inserting this component is that the device can be protected from the problem that the device is broken because an overcurrent flows when the device is powered on by a hot plug function such as USB or IEEE1394. Also,
As another example, when a chip varistor or a chip surge absorber is inserted, the device can be protected from overvoltage such as static electricity. By inserting the common mode choke coil and other noise suppression components together inside the connector as described above, in addition to the advantages of inserting the common mode choke coil, the advantages of other noise suppression components are also obtained at the same time. Can be. Therefore, there is no problem in inserting the connector inside the connector by any method that does not hinder the above advantages.

[0048]

According to the present invention, the quality of the digital signal waveform can be sufficiently ensured, the radiation noise can be greatly attenuated, and an inexpensive and highly reliable differential transmission cable and joint can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a differential transmission cable according to one embodiment of the present invention.

FIG. 2 is a drawing of a connector part of one embodiment according to the present invention.

FIG. 3 is a plan view of a substrate according to an embodiment of the present invention.

FIG. 4 is a plan view of a substrate according to another embodiment of the present invention.

FIG. 5 is a diagram showing a performance evaluation method according to one embodiment of the present invention.

FIG. 6 is a schematic diagram of a differential transmission cable according to another embodiment of the present invention.

FIG. 7 is a drawing of a connector section of another embodiment according to the present invention.

FIG. 8 is a drawing of a land portion of another embodiment according to the present invention.

FIG. 9 is a drawing of a land portion of another embodiment according to the present invention.

FIG. 10 is a drawing of a holding unit according to an embodiment of the present invention.

FIG. 11 is a drawing of a joint according to an embodiment of the present invention.

FIG. 12 is a drawing of a joint according to another embodiment of the present invention.

FIG. 13 is a plan view of a substrate according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Differential transmission cable 2a, 2b connector 3 Cable 4 Common mode choke coil 5, 5A, 5B, differential transmission line (signal line) 6a, 6b, 6c, 6d, 15, 16 Terminal part 7a, 7b, 7c of connector Connector housing 9 Chip beads 11a, 11b, 11c Substrate 12, 17 Lead wire 13 Molded portion 14 Power supply line 21, 23, 29 Land 24 CMC insertion position 25a, 25b Holding portion 26 Neck 27 External terminal of common mode choke coil 28 Land part of contact pin type

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirokazu Araki 5200 Mikajiri, Kumagaya-shi, Saitama Magnetic Materials Research Laboratory, Hitachi Metals, Ltd.

Claims (11)

[Claims] 1. An interface cable for transmitting one or more pairs of differential transmission signals, comprising a common mode choke coil on a pair of signal lines in the interface cable, wherein the common mode choke coil comprises a substrate. A differential transmission cable mounted on the substrate, wherein the substrate is molded inside the connector. 2. A joint for connecting an interface cable for transmitting one or two or more pairs of differential transmission signals and a device, comprising a common mode choke coil on a pair of signal lines in the joint, wherein the common mode choke is provided. A joint, wherein the coil is mounted on a substrate, the substrate being molded inside the male connector. 3. A joint for connecting an interface cable for transmitting one or more pairs of differential transmission signals to a device, comprising a common mode choke coil in a pair of signal lines in the joint, wherein the common mode choke is provided. A joint, wherein the coil is mounted on a substrate, wherein the substrate is molded inside at least one of the male and female connectors, and the length of the joint is within 10 cm. 4. An interface cable for transmitting one or more pairs of differential transmission signals, wherein a pair of signal lines in the interface cable includes a common mode choke coil, and the common mode choke coil is a connector. Wherein the housing portion is provided with a land for mounting the common mode choke coil and a holding portion for positioning the common mode choke coil is provided. Transmission cable. 5. A joint for connecting an interface cable for transmitting one or more pairs of differential transmission signals to a device, comprising a common mode choke coil on a pair of signal lines in the joint, wherein the common mode choke is provided. The coil is disposed in a housing portion of the male connector, and the housing portion is provided with a land for mounting the common mode choke coil and a holding portion for positioning the common mode choke coil. Features joints. 6. A joint for connecting an interface cable for transmitting one or more pairs of differential transmission signals and a device, wherein a common mode choke coil is provided in a pair of signal lines in the joint, and the common mode choke is provided. The coil is arranged at least in a housing portion of one of the male and female connectors. The housing portion is provided with a land for mounting the common mode choke coil, and a holding portion for positioning the common mode choke coil. A joint having a length of 10 cm or less. 7. The differential transmission cable and joint according to claim 4, wherein a terminal portion of a connector is used in a part of a land on which the common mode choke coil is mounted. 8. The differential transmission cable and joint according to claim 1, wherein a constriction is formed in a land on which the common mode choke coil is mounted. 9. The differential transmission cable and joint according to claim 4, wherein the land on the side on which the common mode choke coil is mounted is a contact pink eve. 10. The differential transmission cable and the joint according to claim 4, wherein an upper portion of the positioning holding portion has a key shape. 11. The differential transmission cable and the joint according to claim 1, wherein a noise suppression component other than a common mode choke coil is inserted together inside the connector. Joint.