JPS5840284B2 - Transmission cable - Google Patents

Description

[Detailed description of the invention] This invention relates to transmission cables.

As described in German Patent No. 935 014, it consists of a flexible flat substrate of electrically insulating material having a longitudinally extending signal conductor on one side and a longitudinally extending ground conductor on the other side; A cable in which the above-mentioned two sides are bent so that some of the sides face each other is well known.

According to the present invention, in such a known cable, when the substrate is in a state before being bent, the signal conductor is shifted laterally from the longitudinal centerline of the substrate, and the ground conductor is buttoned A bending path is formed along the other surface of the substrate, and as a result of the substrate being bent along the longitudinal centerline, the signal conductor is formed when the substrate has one ground conductor. is present between the portions of the one earth conductor, or between the two earth conductors if the residual substrate has two earth conductors.

According to the invention, the signal conductor is substantially surrounded by a ground conductor, so that the electrical cable has the advantage of closely resembling a real coaxial cable.

Furthermore, the electrical cable of the present invention is particularly suitable as a transmission cable, and the flap portion can be easily manufactured to any desired length.

This cable includes electrical shields on both sides of the flat signal conductor, thereby virtually eliminating problems caused by alignment of the signal and ground conductors.

Next, three embodiments of the present invention will be described with reference to the drawings.

In the first embodiment shown in FIGS. 1-3, a flexible flat insulating substrate 10 has a signal conductor 1 extending vertically on one surface thereof.
2, and a ground conductor 14 extending vertically on the other surface.

Both conductors 12, 14 can be formed by printing or etching techniques.

The signal conductor 12 is located laterally offset from the longitudinal axis of the substrate 10, and the ground conductor 14 has a generally zigzag-shaped meandering path;
It traverses the surface of the board almost to the extent of the gold mine.

A series of enlarged ground terminal pads 20 and enlarged signal terminal pads 18 are formed at equal intervals along the ground and signal conductors.

Corresponding signal terminal pads and ground terminal pads are located laterally spaced from each other and aligned.

The cable (at location d'16, is cut transversely near the ends of terminal pads 18, 20 of signal conductor 12 and ground conductor 14 and folded back as shown in FIGS. 2 and 3, respectively). and can be held in the folded position with adhesive.

Suitable examples of connectors in which the terminals 22, 24 are then crimped to both pads from the same direction as the transmitting cable or from opposite directions as shown are U.S. Pat.
No. 53836, No. 3663992, and No. 369
Seen in No. 7925.

Although soldering or other forms of connection may be used to connect the terminals, crimp connections are preferred.

The cable of this embodiment is intended for use in high density wiring where it is desired to provide a controlled characteristic impedance with adequate electrical shielding and signal rise times in the nanosecond range.

The characteristic impedance of a cable is determined not only by the thickness and insulation properties of the substrate but also by the wavelength shift or pitch of the ground wire.

This folded construction transmission cable may also be used with multiple conductors, as will be discussed with respect to the second and third embodiments below.

This is because it eliminates a serious problem that could arise from alignment if the ground wire were parallel to the signal wire.

A second embodiment FIGS. 4 and 5 show that a substrate 54 has a plurality of parallel signal conductors 56 formed on its negative side and positioned laterally offset from the longitudinal stop line of the substrate; two separate ground conductors 58, 60 formed on opposite faces, the ground conductors being laterally offset from the longitudinal centerline of the substrate and symmetrical to each other on either side of the centerline; It differs from the first embodiment in that it is bent in a zigzag shape.

This cable can be bent and used in the same way as in the first embodiment.

The ground conductors may be coupled together by terminals (not shown).

In this embodiment, the ground conductor is in phase when the substrate is folded, but other shapes of ground conductors that produce different phase relationships may also be used.

A third embodiment, shown in FIG. 6, shows a flexible insulating substrate having a plurality of signal conductors 64 on one side and two zigzag-shaped ground conductors 66, 68 on the other side when not bent. 62 is shown in a folded position.

Every other signal conductor is coupled to both ground conductors by conducting means 70 to form a series of transmission lines similar in many respects to a coaxial cable.

The connection of the conductors can be done by point gluing, stapling, sewing with metal wire, or other methods.

The cable of the present invention was tested and found to have improved electrical transmission characteristics.

The cable exhibits improved crosstalk characteristics between cables and between channels, while reducing high frequency attenuation and providing stable characteristic impedance.

The cable requires relatively little technical work and when the cables are used individually (C) the cables are relatively easy to manufacture as no special cable treatment is required.

In all embodiments, depending on the shape of the earth conductor,
The problem of alignment of the ground conductor and signal conductor is eliminated, and better crosstalk characteristics between the cables are obtained than with prior art cables having solid ground conductors and transmit conductors.

The alignment between the ground conductor and the signal conductor is no longer so important since the characteristic impedance of the cable can be controlled by adjusting the pitch of the ground conductor and determined by the shape of the ground conductor itself.

Further, with the above-described structure, most of the shielding is provided directly above and below the signal conductor where shielding is strongly desired, rather than near the side edges of the signal conductor where relatively little radiation is generated.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a first embodiment of the transmission cable of the present invention before cutting and bending to form a shield wire, and FIG. 2 shows the first embodiment after cutting and bending to form a shield wire. A plan view of the cable of the example, FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a plan view of the cable of the second embodiment before being bent to form a shield wire, and FIG. 5 is 5 in Figure 4.
6 is a sectional view taken along the line -5, showing the cable after it has been bent, and FIG.

Claims (1)

[Claims] an elongated flexible flat substrate of electrically insulating material having at least one longitudinally extending signal conductor on one side and at least one longitudinally extending ground conductor on the other side; The signal conductors 12, 56, 64 are connected to the substrates 10, 54, 62 before the substrate is bent. The ground conductor is deviated laterally from the longitudinal center line of the substrate, and the ground conductor forms a meandering path along the other surface of the substrate, so that the substrate is bent along the longitudinal center line. As a result, the signal conductor is located between the parts of the ground conductor 14 if the board has one ground conductor 14, or between the parts of the ground conductor 5 if the board has two ground conductors 5.
8, 60, 66°68, the transmission cable is located between the two ground conductors.