Patent Grant
10381136
This application claims priority to Chinese patent application No. 201820063702.8, filed on Jan. 16, 2018, the disclosure of which is incorporated herein by reference in its entirety.
The present disclosure relates to a signal transmission cable, and in particular to a signal transmission cable with a metal shielding film.
Two devices transmit signals to each other through a cable disposed between these devices. However, in recent years, since the transmission amount of the signals increases substantially, high-frequency signals are used in the signal transmission. Moreover, two adjacent wires in the cable are quite close, so the transmission of the high-frequency signal is susceptible to an interference problem, producing a crosstalk phenomenon on the high-frequency signal, causing errors in the signal transmission and reducing the quality of transmission.
In order to solve the interference problem generated by the high-frequency signal, the wire for transmitting information coated with a metal shielding structure is designed to solve the high-frequency interference problem. The shielding structure may be fixed to the wire in many ways. When the shielding components coated on the exterior of the wires are fixed in a spiral longitudinal winding manner, gaps are easily formed between the shielding components or the shielding components have different thicknesses across the surface of the wire, which can easily affect the wire and cause inconsistent impedances, resulting in a an increase in insertion loss, and thus reducing the efficiency of signal transmission.
In existing art, with reference to FIG. 9, U.S. Pat. No. 8,653,373 discloses a shielded cable structure A. The cable structure A includes a pair of wires B, a first shielding tape C and a second shielding tape D. Each wire B includes a core wire B1 and an insulator B2. The core wire B1 is coated by the insulator B2. The first shielding tape C includes a plastic tape C1 and a metal foil C2. The plastic tape C1 and the metal foil C2 are attached to each other. The second shielding tape D includes a plastic tape D1 and a metal foil D2. The plastic tape D1 and the metal foil D2 are attached to each other. These wires B are arranged in parallel. The first shielding tape C is secured to the surfaces of these wires B in a spiral winding manner in a direction in which these wires B extend longitudinally. Adjacent parts of the wound first shielding tape C overlap each other to form an overlap portion C3 and a step portion C4. The second shielding tape D is secured to the surface of the first shielding tape C in a spiral winding manner in the direction in which these wires B extend longitudinally, and the winding direction of the first shielding tape C is different from that of the second shielding tape D. Adjacent parts of the wound second shielding tape D overlap each other to form an overlap portion D3 and a step portion D4. By doubly coating the wires B with the first shielding tape C and the second shielding tape D, a better electromagnetic shielding effect is expected.
However, the outer surfaces of the wires B are coated by the first shielding tape C and the second shielding tape D in a multi-layer manner, the spiral winding manner makes these first shielding tapes to form overlapping structures having different layers, which vary constantly in the direction in which these wires B extend longitudinally. The first shielding tape C and the second shielding tape D form an overlapping structure having three layers and an overlapping structure having four layers on the outer surfaces of these wires which alternate. These overlapping structures easily cause the impedance values of the wires B to vary continuously, resulting in an increase of insertion loss, thereby affecting the quality and efficiency of signal transmission in the wires B.
The spiral winding manner of these shielding tapes disclosed by the related art still has a defect of inconsistent impedances, easily causing a loss in the signal transmission, unable to meet various industrial requirements. In order to maintain the quality of signal transmission in the cable, there is a tremendous need for an improved design for the cable.
One or more embodiments of the present disclosure provide a signal transmission cable, which in particular has an arrangement in which the wires are enclosed by metal shielding films. Therefore, the interference noise generated between wires is isolated by the metal shielding films, thereby achieving a better quality of signal transmission.
One or more embodiments of the present disclosure provide a signal transmission cable, which in particular uses an insulation film to secure the metal shielding film. Therefore, the wires can be stably surrounded by the metal shielding film, thereby fixing the metal shielding film better.
Embodiments of the present disclosure provide signal transmission cable, which includes: a pair of signal wires for transmitting a group of differential electronic signals; a first metal shielding film coated on a first part of a surface of the pair of signal wires; a second metal shielding film opposite to the first metal shielding film and coated on a second part of the surface of the pair of signal wires; and a first insulation film for securing the first metal shielding film and the second metal shielding film to the surface of the pair of signal wires. The first metal shielding film and the second metal shielding film are collectively coated on the entire surface of the pair of signal wires, and the second metal shielding film partially overlaps the first metal shielding film.
In the embodiments of the present disclosure, the metal shielding films of the signal transmission cable are made of metal foils and coated on the wires oppositely, significantly alleviating a problem of uneven thickness of the metal shielding films in the longitudinal direction of the wires caused by the overlapping of metal shielding films. Moreover, in combination with the design of insulation film, each metal shielding film is secured to the outer surface of the wires to reduce the interference noise on the wires from outside and between the wires, thereby achieving a better electromagnetic shielding effect.
With reference to
As disclosed in a first embodiment of the present disclosure with reference to
The insulation layer 22 is made of non-conductive plastic material, and the insulation layer 22 is coated on an exterior surface of the conductor 21, and the insulation layer 22 and the conductor 21 may have a same axis. The material of the insulation layer 22 includes polyester, e.g., polyvinyl chloride (PVC) or polyethylene (PE), and has a good insulating effect. The insulation layer 22 may be a tape made from polyester, and the tape made from polyester is fixed to the conductor 21 in a spiral winding manner using adhesive. The insulation layer 22 may also be formed on the exterior surface of the conductors 21 by coating to achieve the insulation effect.
As disclosed in the embodiment of the present disclosure, these wires 2 include at least one pair of signal wires 23. When the high-frequency signal is transmitted, the problem of high-frequency interference easily occurs. To solve this problem, the differential electronic signals are transmitted through the pair of signal wires 23 in a differential signal pair manner. The differential signals of the differential signal pair respectively are simultaneously transmitted in the pair of adjacent signal conductors 23. Two signals in the differential signal pair have the same amplitude and are opposite in phase. Due to this characteristic, the interferences to signals transmitted by the pair of adjacent signal conductors 23 may offset with each other, thereby having advantages of strong anti-interference ability, effective suppressing electromagnetic interference (EMI) ability and accurate timing positioning, and greatly improving the quality and efficiency of the signal transmission. As disclosed in the embodiment of the present disclosure, these metal shielding films 3 are thin sheets made from metal material. The metal shielding films 3 are made of one or more of materials consisting of Al, Cu, Pb, Sn, and a laminated film formed by polyester is added, such that these metal shielding films 3 have characteristics of electromagnetic interference isolation and better thermal conduction.
These metal shielding films 3 include a first metal shielding film 31 and a second metal shielding film 32 outside the first metal shielding film 31. Two ends of the first metal shielding film 31 each have a first edge 33. The first metal shielding film 31 covers a part of a surface of the insulation layers 22 of this pair of signal wires 23. A gap between the first edges 33 exposes the other part of the surface of this pair of signal wires 23. The axes of the pair of signal wires 23 are connected to each other to form a horizontal axis line, and two perpendicular axis lines each pass through a respective one of the axes of the pair of signal wires 23 and is perpendicular to the horizontal axis line. The angle between one of the horizontal axis line and the perpendicular axis line and a line, which connects a first edge to the axis of the signal wire adjacent to the first edge, is about 45 degrees.
As disclosed in an embodiment of the present disclosure, the insulation films 4 include a first insulation film 41 and a second insulation film 42. The first insulation film 41 covers the first metal shielding film 31 and a part of the second insulation film 42, such that the first metal shielding film 31 is secured between the pair of signal wires 23 and the second insulation film 42. The first metal shielding film 31 may be secured by gluing or clamping. The second insulation film 42 is attached to the each of the pair of signal wires 23 exposed between the first edges 33, and the first edges 33 of the first metal shielding film 31 is clamped between the second insulation layer 42 and the pair of signal wires 23. The first edge 33 of the first metal shielding film 31 does not exceed contacting points of the second insulation film 42 and the pair of signal wires 23, such that the first metal shielding film 31 can be smoothly secured by the second insulation film 42, thereby preventing the first edge 33 of the first metal shielding film 31 from being warped or sliding.
As disclosed in an embodiment of the present disclosure, the second metal shielding film 32 has second edges 34. There is a gap between the second edges 34. The second metal shielding film 32 is coated on the surface of the second insulation film 42, such that the second metal shielding film 32 is coated on a part of the surface of the pair of signal wires 23 with the second insulation film 42 disposed between the second shielding film 32 and the pair of signal wires 23, and the second metal shielding film 32 is coated on the gap between the first edges 33 between the first metal shielding film 32. The gap between the second edges 34 exposes the second insulation film 42, such that the second insulation film 42 is partially disposed between the first metal shielding film 31 and the second metal shielding film 32. An angle between each of the horizontal axis line and the perpendicular axis lines and a line connecting a terminal of each second edge 34 and the axis of the signal wire adjacent to the each second edge 34 is about 45 degrees. The second edges 34 of the second metal shielding film 32 respectively overlap the first edges 33 of the first metal shielding film 31 with the second insulation layer 42 disposed between the first edges 33 and the second edges 34, such that the periphery of the pair of signal wires 23 are completely enclosed by the first metal shielding film 31 and the second metal shielding film 32. Positions where the first metal shielding film 31 and the second metal shielding film 32 overlap each other are respectively located a surface of an end of one of the pair of signal wires 23 and a surface of an end the other one of the pair of signal wires 23 away from the surfaces of the end of the one of the pair of signal wires 23, and are symmetrical to each other. Positions where the first metal shielding film 31 and the second metal shielding film 32 overlap each other are located at side edges of the pair of signal wires 23 which are symmetrical to each other, such that the generated electromagnetic effects can be mutually balanced. The first metal shielding film 31 and the second metal shielding film 32 are longitudinally arranged in an extending direction of the pair of signal wires 23 and face each other, and then enclose the pair of signal lines oppositely. The pair of signal wires 23 is isolated from outside through the metal shielding films 3, such that the pair of signal wires 23 is enabled to not be interfered by outside signals, thereby achieving a better shielding effect.
As disclosed in an embodiment of the present disclosure, the first insulation film 41 covers the second metal shielding film 32 and the surface of the second insulation layer 42 exposed between the second edges 34. The second metal shielding film 32 is fixed between the first insulation film 41 and the second insulation film 42, and the second insulation film 42 exposed between the second edges 34 is fixed between the first metal shielding film 31 and the first insulation film 41. The fixing may be achieved by gluing or clamping. The second edges 34 of the second metal shielding film 32 are smoothly fitted to surface of the second insulation film 42 by the first insulation film 41 so as to prevent the second edges 34 from being uneven. Each of the first metal shielding film 31 and the second metal shielding film 32 is one or more layers of plastic tape spirally wound to the exterior of the pair of signal wires 23, or one or more layers of plastic extruded and secured to the exterior of the pair of signal wires 23. The first insulation film 41 and the second insulation film 42 are made of a transparent or translucent material so as to facilitate the detection of the status that the inner first metal shielding film 31 and second metal shielding film 32 are coated on the pair of signal wires 23.
In an embodiment of the present disclosure, the ground wire 5 has an elongated cylindrical metal structure. In an embodiment, the ground wire 5 may be a bare twisted metal wire. The ground wire 5 is not coated by any insulation material, and is arranged in the gap between the pair of signal wires 23 in a bare state. The ground wire 5 is in contact with the first metal shielding film 31 and is electrically connected to the first metal shielding film 31. The ground wire 5 is mainly used for absorbing the electromagnetic interference generated by the pair of signal wires 23 and grounding the electromagnetic noise received by the first metal shielding film 31 quickly. Therefore, the ground wire 5 is continuously arranged between the pair of signal wires 23 and has characteristics such as low resistance for achieving the effects of quickly grounding and reducing electromagnetic interference.
In a second embodiment of the present disclosure, with reference to
In a third embodiment of the present disclosure, with reference to
An angle between one of the horizontal axis line and the vertical axis lines and a line connecting a terminal of the first edge 33 or the terminal of the second edge 34 and the axis of the signal wire adjacent to the first edge 33 or the second edge 34 is about 45 degrees. The arrangement in which the angle is about 45 degrees has a better fixing effect, such that the first edges 33 of the first metal shielding film 31 are secured to surface of the pair of signal wires 23 by the second metal shielding film 32, and the second edges 34 of the second metal shielding film 32 are secured to surface of the first metal shielding film 31 by the first insulation film 41, thereby preventing the first edges 33 or the second edges 34 from being uneven or warped due to a too long or too short design of the first edges 33 and the second edges 34. The above securing manner may adopt gluing or clamping. The two ground wires 5 are arranged in gaps adjacent to the pair of signal wires 23. The ground wires 5 are symmetrically arranged with respect to the horizontal axis line. The pair of signal wires 23 and the ground wires 5 are arranged inside the space formed by the first metal shielding film 31 and the second metal shielding film 32, and the ground wires 5 are in contact with the metal shielding films 3 respectively, such that the metal shielding films 3 are electrically connected to the ground wires 5 so as to provide a better electromagnetic shielding characteristic for the pair of signal wires 23.
In a fourth embodiment of the present disclosure, with reference to
In a fifth embodiment of the present disclosure, with reference to
In a sixth embodiment of the present disclosure, with reference to
In a seventh embodiment of the present disclosure, with reference to
In an eighth embodiment of the present disclosure, with reference to
In the related art, the metal shielding films are usually designed to be longitudinally spirally wound. However, the metal shielding films may have overlapping or gaps during the longitudinal winding process. Since the overlapping area actually has deviations, or the overlapping area is likely changed after the cable is bent, the wires have unpredictable impedance variations. Compared with the related art, these wires in the embodiments of the present disclosure are oppositely coated by the metal shielding films made from metal thin sheets, which greatly alleviates the problem that the longitudinal thickness of the wire is not uniform due to the overlapping of the metal shielding films. Moreover, in combination with the design of insulation films, the metal shielding films are fixed to the outer surface of the wires so as to reduce the interference noise on the wires from the outside or from the space between the wires and to achieve a better electromagnetic shielding effect.
The above descriptions are merely embodiments of the present disclosure, and are not intended to limit the scope of the present disclosure. Therefore, any simple equivalent change and modification according to the scope of disclosure and contents of the specification of the present disclosure should still be within the scope of the present disclosure.
Although the embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will note that various changes, modifications and substitutions may be made without departing from the spirit and scope disclosed in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018 2 0063702 U | Jan 2018 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4327246 | Kincaid | Apr 1982 | A |
| 20120267159 | Gundel | Oct 2012 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20190221332 A1 | Jul 2019 | US |
