This application claims priority/priorities from Japanese Patent Application No. 2012-199218 filed on Sep. 11, 2012, the entire contents of which are incorporated herein by reference.
The present invention relates to a multi-core cable, and to a multi-core cable used in wiring of, for example, a Charge Coupled Device (CCD) camera, an endoscope or an ultrasonograph for medical use.
There has been conventionally known a multi-core cable having multiple ultrathin insulated electric wires or coaxial cables (coaxial electric wires). For example, as shown in
The multi-core cable is constructed by collecting the plural coaxial cables 40 and covering the outside of the coaxial cables 40 with a sheath member. This sheath member includes a wrapping, a shielding member and a sheath. The wrapping is formed in the inside. The shielding member is formed on the outside of the wrapping and has electromagnetic shielding characteristics. The sheath is provided as a tubular resin material formed on the outside of the shielding member.
For example, JP-2006-196289-A discloses a multi-core cable having high bendability, that is, high mechanical reliability on repeated bending stress. As shown in
The central part 60 is constructed by arranging a bundle 51 of high-tensile fibers (tension members) in the center (center of the multi-core cable 50) P0 of the central part 60, arranging plural first coaxial cables 61 on the periphery of the bundle 51 into a layer, and winding a marker wrapping 62 on the outsides of the first coaxial cables 61. The marker wrapping 62 has a function of indicating a kind etc. of first coaxial cables. Also, the marker wrapping 62 is wrapped in a direction opposite to a strand direction of the first coaxial cables 61 and is wound to thereby prevent disarray of the first coaxial cables 61.
The peripheral part 70 is formed by arranging plural electric wire units 71 around the central part 60. Plural second coaxial cables (not shown) are included in each of the electric wire units 71.
In the central part 60, the plural first coaxial cables 61 are arranged into plural layers so as to be concentric with respect to the center P0, and are stranded every layer. Also in the peripheral part 70, the plural electric wire units 71 are arranged so as to be concentric with respect to the center P0.
In JP-2006-196289-A, when the number of electric wire units is large, their electric wire units are divided into plural layers (for example, a central layer, a second layer and a third layer), and a collective pitch (strand pitch) of each layer is differentiated. For example, the collective pitches of the central layer, the second layer and the third layer are respectively set at 37.5 mm, 50 mm and 100 mm. The “collective pitch (strand pitch)” corresponds to a distance in a length direction of the multi-core cable through which the electric wire unit rotates 360 degrees. In JP-2006-196289-A, unevenness in appearance is reduced by differentiating the collective pitches of the layers
As shown in JP-2006-196289-A, when the collective pitch every layer differs, arrangement of the electric wire units varies depending on a cut position of the multi-core cable. As a result, in a wire alignment step of connecting each electric wire to a substrate, the mutual electric wires are respectively arranged so as to be crossed. Then, when the electric wires are crossed, wire alignment workability becomes worse. Also, when movement such as bending is applied at the time of use of a product, the electric wire in the crossing place may be strained to cause a break in the wire.
One object of the invention is to equalize arrangement of electric wire units regardless of a cut position of a multi-core cable in the multi-core cable including plural electric wire units obtained by bundling plural coaxial electric wires or insulated electric wires and collectively covering the electric wire units with a sheath.
One aspect of the present invention provides a multi-core cable including:
plural electric wire units in each of which plural coaxial electric wires or insulated electric wires are bundled; and
a sheath collectively covering the electric wire units,
wherein the electric wire units are arranged so as to form plural layers around a center of the multi-core cable, and each of the layers is stranded in the same direction at an equal pitch.
There may also be provide the multi-core cable,
wherein the plural electric wire units are collectively covered with a shielding layer, and the shielding layer is further covered with the sheath.
There may also be provide the multi-core cable,
wherein a gap is formed between the sheath and an inside layer nearest to the sheath.
There may also be provide the multi-core cable,
wherein the plural electric wire units include plural kinds of electric wire units.
There may also be provide the multi-core cable,
wherein the number of electric wire units of each kind is an even number.
There may also be provide the multi-core cable,
wherein electric wire units of each kind are point symmetrically arranged when viewed from a length direction of the multi-core cable.
In a harness product, the distal end of a cable is generally exposed slightly, and attachment work with respect to a substrate is done. Since it is difficult to perform the attachment work when the exposed place is short, it is necessary to select a proper work method according to an electric wire structure. For example, when the number of substrates for connecting a probe is an even number, for example, two, four or six and the number of electric wire units in a multi-core electric wire is also an even number, good workability can be obtained by doing attachment work so as to divide the electric wire units into two groups.
According to the invention, in the multi-core cable including plural electric wire units obtained by bundling plural coaxial electric wires or insulated electric wires and collectively covering the electric wire units with a sheath, the electric wire units are arranged so as to form plural layers around the center of the multi-core cable and also each of the layers is stranded in the same direction at an equal pitch. Therefore, arrangement of the electric wire units can be equalized regardless of a cut position of the multi-core cable.
A multi-core cable of the embodiment will hereinafter be described with reference to the drawings.
As shown in
While plural coaxial cables (coaxial electric wires as shown in
The electric wire units 11, 12, 13 are arranged so as to form plural layers around the center P0 of the multi-core cable 10. In the multi-core cable 10, the electric wire units 11, 12, 13 are arranged into plural layers which are concentric with respect to the center P0, and the sheath 30 functions as the outermost layer.
In this example, the electric wire units 11, 12, 13 are arranged so as to form a total of two layers of an internal layer L1 and an external layer L2. In the internal layer L1, the four electric wire units 11 are arranged, and the four electric wire units 13 are respectively arranged between the electric wire units 11. The external layer L2 is arranged on the periphery of the internal layer L1. In the external layer L2, the eight electric wire units 11 are arranged, and the two electric wire units 12 are arranged so as to partition the electric wire units 11 every four units. The electric wire units of each of the layers L1 and L2 are respectively arranged concentrically with respect to the center P0, and are stranded every layer. In addition, a wrapping may be formed on the periphery of the internal layer L1.
The number of electric wire units of each kind in the multi-core cable is determined according to the number of substrates attached. Since connection to the even-numbered substrates is often made generally, the number of electric wire units of each kind is also preferably an even number.
As can be seen from one symmetric line S shown in
In the multi-core cable 10, an electric wire cable group of the internal layer L1 and an electric wire cable group of the external layer L2 are arranged, but the number of layers may be three or more and also, arrangement of an electric wire cable in each layer is not limited to this arrangement, as long as the electric wire cables are arranged concentrically and point symmetrically with respect to the center P0. In addition, various combinations of diameters of the internal layer L1 and the external layer L2 can be considered. The diameter of each layer can be determined freely.
According to the embodiment, the electric wire units 11, 12, 13 are arranged such that each of the layers is stranded in the same direction at an equal pitch. The pitch refers to a strand pitch (a pitch in a longitudinal direction of the electric wire unit) for stranding and collecting the layer, and is also called a collective pitch. When the collective pitch differs or when a strand direction is opposite even for the same collective pitch, a positional relationship between the electric wire unit group of the internal layer L1 and the electric wire unit group of the external layer L2 deviates depending on a cut place. Hence, in the multi-core cable 10 of the embodiment, each of the layers is stranded in the same direction at the equal pitch. Consequently, the positional relationship between the respective electric wire units becomes equal in other cross sections as well as a cross section shown in
By stranding each of the layers in the same direction at the equal pitch, even when the multi-core cable 10 is cut in any position, the electric wires can be arranged so as not to be mutually crossed in a wire alignment step of soldering to a substrate. As a result, wire alignment workability improves. Further, even when a strain relief part between the multi-core cable and the substrate is bent, the electric wire is not strained in the strain relief part. Therefore, mechanical reliability can be improved.
In the multi-core cable 10, preferably, the plural electric wire units 11, 12, 13 are collectively covered with a shielding layer 22, and the shielding layer 22 is further covered with the sheath 30, as shown in
In the center P0 of the multi-core cable 10, that is, inside the electric wire units 11, 12, 13, a bundle of high-tensile fibers (tension members) may be arranged. Also, around the electric wire units 11, 12, 13, fibers may be interposed so as to fill gaps between the electric wire units 11, 12, 13.
As shown in
When both of a wrapping 21 and a shielding layer 22 are provided, the shielding layer 22 is the “inside layer of the sheath 30”. When only the wrapping 21 is provided and the shielding layer 22 is omitted, the wrapping 21 is the “inside layer of the sheath 30”. And, when both of the shielding layer 22 and the wrapping 21 are not provided, an external layer L2 is the “inside layer of the sheath 30. Since the other configuration in the multi-core cable 10a is similar to that of the multi-core cable 10 of
When each of the layers is stranded in the same direction at the equal pitch, unevenness in appearance may occur. However, by forming the gap 23 between the sheath 30 and the inside layer of the sheath 30 in this manner, even if unevenness in appearance occurs, the gap 23 can make it difficult to see its unevenness from the outside of the sheath 30. Specifically, by setting the gap 23 at 0.2 mm or more, the gap 23 can make it difficult to see the unevenness in appearance of the multi-core cable 10a. Also, flexibility of the cable improves by forming the gap 23.
Number | Date | Country | Kind |
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2012-199218 | Sep 2012 | JP | national |