Composite cable

Abstract

To provide a small-diameter composite cable having high bending resistance.SOLUTION: The composite cable 1 includes four large-diameter coaxial wires 11, two small-diameter coaxial wires 12, four large-diameter simple wires 13, two small-diameter simple wires 14, a bind layer 3 for bundling these wires, a shield layer 4 made of a metal conductor provided around the bind layer 3, and a sheath 5 for covering the shield layer 4. The outer diameter of the sheath 5 is 2. 0mm or less, and the amount of metallic conductors per unit length used for the shield layer 4 is 0.4 times or more and 0.7 times or less the amount of metallic conductors per unit length used for the plurality of electric wires.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite cable comprising a plurality of wires having metallic conductors and insulation. [Background technology]

[0002] Conventionally, small-diameter medical cables, such as signal cables for endoscopes, have included multiple electric wires, a binding layer that bundles the multiple electric wires together, a shielding layer that is provided around the binding layer, and a sheath that covers the outer periphery of the shielding layer (see, for example, Patent Document 1).

[0003] The endoscope signal cable described in Patent Document 1 has multiple coaxial wires for the drive signal system and output signal system and multiple electric wires for the power supply system all bundled together with a spirally wound insulating bind tape. An overall shield formed by twisting together multiple conductor wires made of a silver-plated copper alloy is provided around the outer periphery of the bind tape, and the overall shield is covered with a sheath. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-176567 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, composite cables used in medical applications, for example, are sometimes required to have a cable diameter of 2 mm or less. The inventors have confirmed that such small-diameter composite cables often fail bending durability tests due to breakage of the shield wires or cracks in the sheath. Therefore, an object of the present invention is to provide a small-diameter composite cable with high bending resistance. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a composite cable comprising: a plurality of electric wires each having a metal conductor and an insulator; a binding layer bundling the plurality of electric wires; a shielding layer made of a metal conductor arranged around the binding layer; and a sheath covering the shielding layer, wherein the outer diameter of the sheath is 2.0 mm or less; and the amount of metal conductor used per unit length in the shielding layer is 0.4 to 0.7 times the amount of metal conductor used per unit length in the plurality of electric wires. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a thin composite cable with high bending resistance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a composite cable according to an embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view showing a large diameter coaxial line. [Figure 3] FIG. 1 is a cross-sectional view showing a small diameter coaxial line. [Figure 4] FIG. 1 is a cross-sectional view showing a simple wire with a large diameter. [Figure 5] FIG. 1 is a cross-sectional view showing a simple line of small diameter. [Figure 6] FIG. 2 is a diagram showing an example of the configuration of a bending tester used in a bending endurance test. [Figure 7] FIG. 2 is a diagram showing an example of the configuration of a twisting tester used in a twisting endurance test. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Embodiment Mode] 1 is a cross-sectional view of a composite cable according to an embodiment of the present invention. This composite cable 1 includes an electric wire group 10 consisting of a plurality of electric wires each having a metal conductor and an insulator, a filler 2 arranged at the center of the electric wire group 10, a binding layer 3 provided around the electric wire group 10, a shielding layer 4 provided around the binding layer 3, and a sheath 5 covering the shielding layer 4. The outer diameter D (cable outer diameter) of the sheath 5 is 2.0 mm or less, and is 1.6 mm in this embodiment.

[0010] In this embodiment, the electric wire group 10 is made up of ten electric wires, including four large diameter coaxial wires 11, two small diameter coaxial wires 12, four large diameter simple wires 13, and two small diameter simple wires 14. The fillers 2 are, for example, fiber bundles made of aramid fibers. The binding layer 3 binds the ten electric wires of the electric wire group 10 together. In this embodiment, the binding layer 3 is formed by spirally winding a strip-shaped binding tape 30 made of a resin such as PI (polyimide) around the electric wire group 10. The thickness T of the binding tape 30 30 is, for example, 0.01 mm. The sheath 5 is formed by extrusion molding a thermoplastic resin such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The thickness T5 (average thickness) of the sheath 5 is preferably 0.07 mm or more and 0.12 mm or less. In this embodiment, as an example, the thickness T5 of the sheath 5 is 0.10 mm.

[0011] The composite cable 1 is an endoscopic cable used in an endoscope equipped with a CCD drive circuit, an A / D converter, an image memory, an image processing circuit, etc. at its tip. The large and small diameter coaxial wires 11 and 12 are used as signal lines for transmitting image signals and control signals. The large and small diameter simple wires 13 and 14 are used as power supply lines for power supply. The two small diameter coaxial wires 12 and the two small diameter simple wires 14 are twisted together around the interposer 2. The four large diameter coaxial wires 11 and the four large diameter simple wires 13 are arranged around the two small diameter coaxial wires 12 and the two small diameter simple wires 14 and twisted in a spiral.

[0012] The shield layer 4 is a spirally wound shield layer in which a plurality of shield wires 40 made of a metal conductor are spirally wound, and collectively shields each electric wire of the electric wire group 10. In the present embodiment, as an example, the shield layer 4 is made of 84 shield wires 40. The shield wires 40 are wire rods made of a copper alloy and have a circular cross section. The diameter (wire diameter) D of the shield wires 40 is 40 The diameter D of the shield wire 40 is preferably 0.03 mm or more, which corresponds to 48 AWG (American Wire Gauge), and 0.05 mm or less, which corresponds to 45 AWG. 40 If the diameter D of the shield wire 40 is less than 0.03 mm, the shield wire 40 is likely to break. 40 If the diameter D of the shield wire 40 exceeds 0.05 mm, the diameter of the composite cable 1 will be too large. 40 is 0.05mm.

[0013] In order to prevent the sheath 5 from cracking when the composite cable 1 is bent, the thickness T5 of the sheath 5 is set to be smaller than the diameter D of the shield wire 40. 40 It is desirable that the thickness T5 of the sheath 5 is 1.4 times or more and 3.0 times or less than the diameter D of the shield wire 40. 40 If the thickness T5 of the sheath 5 is less than 1.4 times the diameter D of the shield wire 40, the strength of the sheath 5 will be low, and 40 If the thickness T5 of the sheath 5 exceeds 3.0 times the diameter D of the shield wire 40, the shield wire 40 will be more likely to break due to the rigidity of the sheath 5, and the diameter D of the composite cable 1 will be too large. 40 When the thickness T5 of the sheath 5 is 0.05 mm, the diameter D of the shield wire 40 is 40 It is twice as much.

[0014] 2 is a cross-sectional view showing a large-diameter coaxial wire 11. The large-diameter coaxial wire 11 has a central conductor 111, an outer conductor 112, a resin insulator 113 arranged between the central conductor 111 and the outer conductor 112, and a resin jacket 114 arranged around the outer conductor 112. The central conductor 111 is a stranded wire formed by twisting together a plurality of strands 111a. The outer conductor 112 is formed by winding a plurality of strands 112a spirally around the outer periphery of the insulator 113.

[0015] In this embodiment, as an example, the central conductor 111 of the large-diameter coaxial cable 11 is made up of seven strands 111a, and the outer conductor 112 is made up of 26 strands 112a. These strands 111a, 112a are metal conductors made of copper alloy and have a circular cross section. The central conductor 111 is equivalent to 40 AWG, and the diameter D of the strands 111a is 112a. 11 The diameter D of the wire 112a of the outer conductor 112 is 0.03 mm. 12 The insulator 113 and the jacket 114 are made of, for example, PFA, and the thickness T 11 is 0.07 mm, the thickness of the jacket 114 T 12 The outer diameter D1 of the jacket 114 is 0.35 mm.

[0016] 3 is a cross-sectional view showing the small diameter coaxial wire 12. The small diameter coaxial wire 12 has the same configuration as the large diameter coaxial wire 11. That is, the small diameter coaxial wire 12 has a center conductor 121, an outer conductor 122, a resin insulator 123 arranged between the center conductor 121 and the outer conductor 122, and a resin jacket 124 arranged around the outer conductor 122. The center conductor 121 is a stranded wire formed by twisting together a plurality of element wires 121a, and the outer conductor 122 is formed by winding a plurality of element wires 122a spirally around the outer periphery of the insulator 123.

[0017] In this embodiment, as an example, the central conductor 121 of the small diameter coaxial cable 12 is made up of seven strands 121a, and the outer conductor 122 is made up of 28 strands 122a. These strands 121a, 122a are metal conductors made of copper alloy and have a circular cross section. The central conductor 121 is equivalent to 44 AWG, and the diameter D of the strands 121a is 122a. 21 The diameter D of the wire 122a of the outer conductor 122 is 0.02 mm. 22 The insulator 123 and the jacket 124 are made of, for example, PFA, and the thickness T 21 is 0.05mm, the thickness of the jacket 124 T 22 The outer diameter D2 of the jacket 124 is 0.25 mm.

[0018] 4 is a cross-sectional view showing a large-diameter simple wire 13. The large-diameter simple wire 13 has a core wire 131 provided in the center and a resin insulator 132 covering the core wire 131. In this embodiment, as an example, the core wire 131 of the large-diameter simple wire 13 is a stranded wire formed by twisting together 19 strands 131a. The strands 131a are metal conductors made of a copper alloy and have a circular cross section, and their diameter D 31 The insulator 132 is made of, for example, PFA, and has a thickness T 31 The outer diameter D3 of the insulator 132 is 0.35 mm.

[0019] 5 is a cross-sectional view showing a small diameter simple wire 14. The small diameter simple wire 14 has a core wire 141 provided in the center and a resin insulator 142 covering the core wire 141. In this embodiment, as an example, the core wire 141 of the small diameter simple wire 14 is a stranded wire formed by twisting together 19 strands 141a. The strands 141a are metal conductors made of a copper alloy and have a circular cross section, and their diameter D 41 The insulator 142 is made of, for example, PFA, and has a thickness T 41 The outer diameter D4 of the insulator 142 is 0.23 mm.

[0020] In this embodiment, to improve the bending resistance of the composite cable 1, thinner shield wires 40 are used than those used in conventional thin composite cables. The diameter of the shield wires in a conventional composite cable with an outer diameter of 2 mm or less is, for example, 0.08 mm to 0.10 mm. Furthermore, in this embodiment, the amount of metal conductor per unit length used in the shield layer 4 is set to be 0.4 to 0.7 times the amount of metal conductor per unit length used in each electric wire in the electric wire group 10. If this ratio is less than 0.4, breakage is likely to occur in the shield layer 4. If this ratio exceeds 0.7, the composite cable 1 becomes too thick, making it difficult to keep the cable outer diameter, for example, to 2.0 mm or less. Furthermore, in this embodiment, to prevent breakage of the shield wires 40, wire material having a tensile strength of 320 MPa or more and a breaking elongation of 10% or more is used as the shield wires 40.

[0021] In a cross section perpendicular to the longitudinal direction of the composite cable 1, the cross-sectional area S of the metal conductor (copper alloy in this embodiment) of the large-diameter coaxial wire 11 is 11 is the diameter of the wire 111a of the central conductor 111. 11 , the number is N 11 and the diameter of the wire 112a of the outer conductor 112 is D 12 , the number is N 12 Then, S 11 =(D 11 / 2)^2×π×N 11 +(D 12 / 2)^2×π×N 12 Similarly, the cross-sectional area S of the metal conductor of the small diameter coaxial cable 12 is 12 is the diameter of the wire 121a of the central conductor 121. 21 , the number is N 21 and the diameter of the wire 122a of the outer conductor 122 is D 22 , the number is N 22 Then, S 12 =(D 21 / 2)^2×π×N 21 +(D 22 / 2)^2×π×N 22 The cross-sectional area S of the metal conductor of the large diameter simple wire 13 is calculated by the formula 13is the diameter of the wire 131a, D 31 , the number is N 31 Then, S 13 =(D 31 / 2)^2×π×N 31 The cross-sectional area S of the metal conductor of a small diameter simple wire 14 is calculated by the formula 14 is the diameter of the wire 141a, D 41 , the number is N 41 Then, S 14 =(D 41 / 2)^2×π×N 41 It can be calculated using the following formula.

[0022] Applying the above values ​​for the diameter and number of wires to these calculation formulas, S 11 ~S 14 When we calculate S 11 =0.0233mm 2 , S 12 =0.0110mm 2 , S 13 =0.0373mm 2 , S 14 =0.0134mm 2 In this embodiment, the composite cable 1 has four large-diameter coaxial wires 11, two small-diameter coaxial wires 12, four large-diameter simple wires 13, and two small-diameter simple wires 14, so the cross-sectional area S1 of the entire metal conductor of the electric wire group 10 is S1=S 11 ×4+S 12 ×2+S 13 ×4+S 14 ×2 calculation gives 0.2914mm 2 It is required that:

[0023] On the other hand, the cross-sectional area S2 of the metal conductor of the plurality of shielding wires 40 of the shielding layer 4 is set to D 40 , the number is N 40 Then, S2=(D 40 / 2)^2×π×N 40 Applying the above diameter and number of pieces to this formula to find S2 gives S2 = 0.1649 mm 2This value is approximately 0.566 times the value of S1. That is, in this embodiment, the amount of metal conductor per unit length used in the shielding layer 4 is approximately 0.566 times the amount of metal conductor per unit length used in each electric wire of the electric wire group 10.

[0024] (Evaluation of composite cable durability) The composite cable 1 configured as described above can withstand 50,000 or more bends at a bending diameter of 15 mm, a bending angle of ±90° or more, and a load of 100 g. The composite cable 1 can also withstand 100,000 or more twists at a twist pitch of 200 mm, a bending angle of ±180° or more, and a load of 150 g. These test results were obtained by conducting a bending endurance test and a twisting endurance test using the bending tester and twisting tester described below.

[0025] FIG. 6 is a diagram showing an example of the configuration of a bending tester 6 used in a bending endurance test. The bending tester 6 has a pair of bending diameter setting jigs 61, 61, a test piece fixing portion 62, and a weight 63. The bending diameter setting jigs 61, 61 are cylindrical, and their diameter D6 is the bending diameter. One end of a test piece 100, which is obtained by cutting the composite cable 1 to a predetermined length, is fixed to the test piece fixing portion 62. A weight 63 corresponding to the applied load is fixed to the other end of the test piece 100. The bending endurance test is performed by clamping a portion of the longitudinal direction of the test piece 100 between the pair of bending diameter setting jigs 61, 61, and moving the test piece fixing portion 62 back and forth in an arc within a range of an angle ±θ1 corresponding to the bending angle.

[0026] FIG. 7 is a diagram showing an example of the configuration of a twisting tester 7 used in a twisting endurance test. The twisting tester 7 has a cylindrical support jig 71, a disk-shaped twisting jig 72, and a weight 73. One end of a test piece 100 is fixed to the twisting jig 72. A weight 73 having a weight corresponding to the applied load is fixed to the other end of the test piece 100. A distance D7 between the twisting jig 72 and the support jig 71 is set to a dimension corresponding to the twisting pitch. The twisting jig 72 rotates back and forth within a range of an angle ±θ2 corresponding to the bending angle.

[0027] In the bending endurance test and twisting endurance test of the composite cable 1, the cable was checked every 10,000 times for any external abnormalities such as cracks in the sheath 5, and for any breaks in the shield wire 40 or the wires in the wire group 10, and the test was continued if no abnormalities were found. In the bending endurance test, no abnormalities were found even after 50,000 times, and in the twisting endurance test, no abnormalities were found even after 100,000 times.

[0028] (Effects of the embodiment) According to the embodiment described above, the amount of metal conductor per unit length used in the shield layer 4 is 0.4 to 0.7 times the amount of metal conductor per unit length used in the plurality of electric wires of the electric wire group 10, so that the composite cable 1 can have a diameter of 2.0 mm or less and still have high bending resistance. Furthermore, according to this embodiment, the thickness T5 of the sheath 5 is 0.4 to 0.7 times the diameter D of the shield wire 40. 40 and the diameter D of the shield wire 40 is 1.4 times or more and 3.0 times or less. 40 By making the thickness of the shield wire 40 between 0.03 mm and 0.05 mm, the diameter of the composite cable 1 can be reduced while ensuring the strength of the sheath 5, and breakage of the shield wires 40 can also be suppressed.

[0029] (Variation) In the above embodiment, the case where the shield wires 40 have a tensile strength of 320 MPa or more and a breaking elongation of 10% or more has been described, but shield wires 40 having a tensile strength of 380 MPa or more and a breaking elongation of 5% or more may also be used. A composite cable 1 using such shield wires 40 having a tensile strength of 380 MPa or more and a breaking elongation of 5% or more can also achieve high bending resistance.

[0030] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0031] [1] A composite cable (1) comprising: a plurality of electric wires (11 to 14) having a metal conductor and an insulator; a binding layer (3) bundling the plurality of electric wires (11 to 14); a shielding layer (4) made of a metal conductor provided around the binding layer (3); and a sheath (5) covering the periphery of the shielding layer (4), wherein the outer diameter (D) of the sheath (5) is 2.0 mm or less, and the amount of metal conductor used per unit length in the shielding layer (4) is 0.4 to 0.7 times the amount of metal conductor used per unit length in the plurality of electric wires (11 to 14).

[0032] [2] The composite cable (1) according to the above [1], wherein the shielding layer (4) is a spirally wound shielding layer in which a plurality of shielding wires (40) made of a metal conductor are spirally wound.

[0033] [3] The average thickness (T5) of the sheath (5) is equal to or less than the diameter (D 40 ) is 1.4 times or more and 3.0 times or less.

[0034] [4] The diameter (D 40 The composite cable (1) according to the above [2] or [3], wherein the thickness of the composite cable (1) is 0.03 mm or more and 0.05 mm or less.

[0035] [5] The composite cable (1) according to any one of the above [2] to [4], wherein the shield wires (40) have a tensile strength of 320 MPa or more and a breaking elongation of 10% or more.

[0036] [6] The composite cable (1) according to any one of the above [2] to [4], wherein the shield wires (40) have a tensile strength of 380 MPa or more and a breaking elongation of 5% or more.

[0037] [7] The composite cable (1) according to any one of [1] to [6] above, wherein some of the electric wires (13, 14) among the plurality of electric wires (11 to 14) are simple wires each having a core wire (131, 141) made of a metal conductor covered with an insulator (132, 142), and the remaining electric wires are coaxial wires (11, 12) each having a center conductor (111, 121) and an outer conductor (112, 122) made of a metal conductor, and an insulator (113, 114) arranged between the center conductor (111, 121) and the outer conductor (112, 122).

[0038] [8] A composite cable (1) according to any one of [1] to [7] above, having a bending diameter of 15 mm, a bending angle of ±90° or more, and a bending resistance of 50,000 times or more under a load of 100 g.

[0039] [9] A composite cable (1) according to any one of [1] to [8] above, having a twist pitch of 200 mm, a bending angle of ±180° or more, and a twist resistance of 100,000 times or more under a load of 150 g.

[0040] Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the embodiments described above. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention.

[0041] Furthermore, the present invention can be appropriately modified and implemented without departing from the spirit and scope of the invention. For example, in the above embodiment, the composite cable 1 has been described as having four large-diameter coaxial wires 11, two small-diameter coaxial wires 12, four large-diameter simple wires 13, and two small-diameter simple wires 14. However, the number and types of wires are not limited to this, and a composite cable can be constructed by combining multiple wires depending on the application. Furthermore, the application of the composite cable is not limited to medical cables such as endoscope cables, and the composite cable of the present invention can be used for various applications that require a small diameter and high bending resistance. [Explanation of symbols]

[0042] 1...Composite cable 11...Large diameter coaxial cable (electric wire) 12...Small diameter coaxial wire (electric wire) 111, 121...Center conductor 111a, 121a...Elemental wire (metal conductor) 112, 122...Outer conductor 112a, 122a...Elemental wire (metal conductor) 113, 123...Insulator 13...Large diameter simple wire (electric wire) 14...Small diameter simple wire (electric wire) 131, 141... Core wire 131a, 141a... Element wire (metal conductor) 132,142...insulator 3...binding layer 4...Shield layer 40...Shield wire (metal conductor) 5...Sheath

Claims

1. The cable includes a plurality of electric wires each having a metal conductor and an insulator, a binding layer that binds the plurality of electric wires together, a shielding layer made of a metal conductor and provided around the binding layer, and a sheath that covers the periphery of the shielding layer, The outer diameter of the sheath is 2.0 mm or less, Some of the plurality of electric wires are simple wires each having a core wire made of a metal conductor covered with an insulator, The remaining electric wire is a coaxial wire having a central conductor and an outer conductor made of a metal conductor, and an insulator disposed between the central conductor and the outer conductor, the shield layer is a spirally wound shield layer in which a plurality of shield wires made of a metal conductor are spirally wound, the amount of metal conductor used in the shielding layer per unit length is 0.4 to 0.7 times the amount of metal conductor used in the plurality of electric wires per unit length; Composite cable.

2. The coaxial lines include a large diameter coaxial line and a small diameter coaxial line. The composite cable of claim 1 .

3. The thickness of the sheath is 1.4 times or more and 3.0 times or less the diameter of the shield wire. The composite cable according to claim 1 or 2.

4. The diameter of the shield wire is 0.03 mm or more and 0.05 mm or less.

4. The composite cable according to claim 1.

5. The shield wire has a tensile strength of 320 MPa or more and a breaking elongation of 10% or more. The composite cable according to any one of claims 1 to 4.

6. The shield wire has a tensile strength of 380 MPa or more and a breaking elongation of 5% or more. The composite cable according to any one of claims 1 to 4.

7. The simple wires include a large diameter simple wire and a small diameter simple wire. The composite cable according to any one of claims 1 to 6.

8. A bending diameter of 15 mm, a bending angle of ±90° or more, and a bending resistance of 50,000 times or more under a load of 100 g. The composite cable according to any one of claims 1 to 7.

9. A twist pitch of 200 mm, a bending angle of ±180° or more, and a twist resistance of 100,000 or more times under a load of 150 g.

9. A composite cable according to any one of claims 1 to 8.

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