JP2014142247A - Measurement device and manufacturing method of cable for differential signal transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement device that can accurately measure the distance between the centers of the conductors of cables for differential signal transmission without limiting the material of an insulation body coating the conductor, in a non-destructive and non-contact manner, and can assure low skew of the cable for differential signal transmission by performing feedback on the basis of the measurement result and controlling the distance between the centers of the conductors, and provide a manufacturing method of the cable for differential signal transmission.SOLUTION: The manufacturing method of the cable for differential signal transmission includes a coating process of coating at least a pair of conductors 4 separated from each other and extending in parallel in a longitudinal direction with an insulation body, and a measurement process of measuring the distance between the centers of at least the pair of conductors 4 through the insulation body at a plurality of places in the longitudinal direction after the coating process.

Description

  The present invention relates to a measuring device for measuring a distance between centers of conductors and a method for manufacturing a differential signal transmission cable using the measuring device.

  Conventionally, since flat cables are inserted into and removed from the connector, the accuracy required for the pitch between conductors and margin width is often severe. Therefore, optically measure the pitch between conductors and margin width of the cable. A measurement method has been proposed (see, for example, Patent Document 1).

  The flat cable targeted by this measuring method is obtained by coating a plurality of conductors with an insulating base material having a light transmittance of 20% to 75%. In the measurement method, light is applied from one side of a flat cable, the luminance distribution of transmitted light is measured on the other side, and the pitch between conductors and the margin width are measured based on the measured luminance distribution.

  On the other hand, in servers, routers, and storage-related devices that handle high-speed digital signals of several Gbps or more, transmission using differential signals is used for signal transmission between devices or between boards in devices, and differential signals are used as the transmission medium. A transmission cable is used (for example, see Patent Document 2).

  In the differential signal transmission, two signals whose phases are inverted by 180 degrees are transmitted by two conductors in pairs, and the difference between the two signals is extracted on the receiving end side.

  The cable for differential signal transmission described in Patent Document 2 collectively covers a pair of or more inner conductors extending in parallel with a foamed insulator having a circular or elliptical cross section, and includes an outer conductor around the foamed insulator. Further, the outer conductor is covered with a foamed insulator with an insulating jacket without any gap. Thereby, the low skew which cannot be attained with the cable (Twinax cable) which made the pair of the foam insulation electric wires which coat | covered the single core with the foam insulation can be implement | achieved.

JP-A-6-68716 JP 2001-35270 A

  However, according to the conventional measuring method, there is a problem that the material of the insulating base material covering the conductor is limited to a light transmissive material. On the other hand, in the method of measuring the distance between the centers of the conductors by directly observing the cross section of the cable (hereinafter referred to as “cross section measurement”), the measurement takes time and labor, and the measurement is performed after production. There is a problem that can not be reflected in. Further, in the differential signal transmission cable, low skew is one of the important characteristics, and improvement of the measurement accuracy of the distance between the centers of the conductors related to the skew and its guarantee are required.

  Therefore, the object of the present invention is to be able to accurately measure the distance between the centers of the conductors of the differential signal transmission cable without being limited to the insulator material covering the conductors. Provided are a measuring apparatus capable of guaranteeing low skew of a differential signal transmission cable by feedback based on the result and controlling the distance between the centers of the conductors, and a method for manufacturing the differential signal transmission cable. There is.

  In order to achieve the above object, one embodiment of the present invention provides the following measuring apparatus and method for manufacturing a differential signal transmission cable.

[1] A distance between centers of at least a pair of conductors of a differential signal transmission cable having at least a pair of conductors extending away from each other in parallel in a longitudinal direction and an insulator covering the at least the pair of conductors. Measuring part to measure through
Measuring device.
[2] The measurement unit includes:
A detection unit for detecting magnetic field strength generated from the conductor when current is passed through the at least one pair of conductors at at least two predetermined positions;
A calculation unit that calculates a distance between centers of the at least a pair of conductors based on coordinate information of the detection unit and at least two magnetic field strengths detected by the detection unit;
The measuring apparatus according to [1], further comprising:
[3] The measurement apparatus according to [1] or [2], wherein the measurement unit measures a distance between centers of the at least a pair of conductors at a plurality of locations along the longitudinal direction.
[4] The measuring device according to [2], wherein the detection unit includes a magnetic sensor disposed at each of the at least two predetermined positions.
[5] The measurement unit moves the magnetic sensor in the longitudinal direction relative to the differential signal transmission cable, and measures the distance between the centers of the conductors at a plurality of locations along the longitudinal direction. The measuring apparatus according to [4] above.
[6] The measuring unit determines the distance between the centers of the conductors at the plurality of locations along the longitudinal direction while the differential signal transmission cable is moving on the production line with the position of the magnetic sensor fixed. The measurement apparatus according to [5], wherein the measurement is performed.

[7] A covering step of covering at least a pair of conductors that are separated from each other and extend in parallel in the longitudinal direction with an insulator so that the distance between the centers of the conductors is a predetermined value;
A measuring step of measuring a distance between centers of the at least a pair of conductors at a plurality of locations in the longitudinal direction via the insulator after the covering step;
When the measured center-to-center distance of the conductor deviates from the predetermined value, an adjustment step of feeding back to the production line so that the center-to-center distance of the conductor becomes a predetermined value and controlling the center-to-center distance of the conductor; ,
A method for manufacturing a cable for differential signal transmission including:
[8] The measurement step includes
A detection step of detecting magnetic field strength generated from the conductor when a current is passed through the at least one pair of conductors in at least two predetermined positions;
A calculation step of calculating a distance between centers of the at least one pair of conductors based on coordinate information of the at least two predetermined positions and the at least two magnetic field strengths detected in the detection step;
The manufacturing method of the cable for differential signal transmission of said [7] containing.
[9] The differential signal transmission cable manufacturing method according to [8], wherein the detection step is performed using the magnetic sensors respectively disposed at the at least two predetermined positions.
[10] In the measurement step, the at least two magnetic sensors are moved in the longitudinal direction relative to the differential signal transmission cable, and the distance between the centers is determined at the plurality of locations along the longitudinal direction. The method for manufacturing a differential signal transmission cable according to [9], wherein the differential signal transmission cable is measured.
[11] In the measurement step, the position of the at least two magnetic sensors is fixed, and the at least one pair of conductors is moved at a plurality of locations along the longitudinal direction while the at least one pair of conductors moves on the production line. The method for manufacturing a cable for differential signal transmission according to [10], wherein the distance between the centers is measured.
[12] The differential signal transmission cable according to any one of [7] to [11], wherein in the covering step, the insulator collectively covers the at least one pair of conductors by extrusion molding. Production method.
[13] An adjustment step of adjusting the center-to-center distance between the at least one pair of conductors based on the measurement result of the center-to-center distance between the pair of conductors according to the measurement step.
Furthermore, the manufacturing method of the cable for differential signal transmission in any one of said [7] thru | or [12].

  According to the present invention, the distance between the centers of the conductors of the differential signal transmission cable can be accurately measured in a non-destructive and non-contact manner without being limited to the insulator material covering the conductors. It is possible to guarantee a low skew of the differential signal transmission cable by feedback based on the control and controlling the distance between the centers of the conductors.

FIG. 1 is a diagram showing a schematic configuration example of a manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a differential signal transmission cable manufactured by the manufacturing apparatus shown in FIG. FIG. 3 is a diagram illustrating an example of the configuration of the detection unit. FIG. 4 is a diagram for explaining an example of the method for measuring the distance between the core wires according to the present embodiment. FIG. 5 is a cross-sectional view of a differential signal transmission cable according to the first modification. FIG. 6 is a cross-sectional view of a differential signal transmission cable according to the second modification. FIG. 7 is a diagram for explaining a method for measuring the distance between the core wires according to the first and second embodiments. FIG. 8 is a graph showing the distribution of the magnetic field strength according to the second embodiment. FIG. 9 is a diagram illustrating a schematic configuration example of the manufacturing apparatus according to the first embodiment and the comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

[Summary of embodiment]
The measuring apparatus according to the present embodiment includes the at least one pair of conductors of the differential signal transmission cable including at least a pair of conductors that are separated from each other and extend in parallel in the longitudinal direction and an insulator that covers the at least one pair of conductors. A measurement unit that measures the distance between the centers through the insulator.

  In the method for manufacturing a differential signal transmission cable according to the present embodiment, at least a pair of conductors that are separated from each other and extend in parallel in the longitudinal direction are covered with an insulator so that the distance between the centers of the conductors becomes a predetermined value. Measuring the center-to-center distance of the at least one pair of conductors at a plurality of locations in the longitudinal direction via the insulator after the covering step, and the measured center-to-center distance of the conductor is the predetermined value And the adjustment step of feeding back to the production line so that the distance between the centers of the conductors becomes the predetermined value and controlling the distance between the centers of the conductors.

  According to the above configuration, in the measuring apparatus, the center-to-center distance between the pair of conductors can be accurately measured, and the center-to-center distance between the conductors is controlled by feedback from the measured center-to-center distance in the manufacturing process. By keeping the distance between the centers within a certain range, a low skew can be guaranteed.

[Embodiment]
FIG. 1 is a diagram showing a schematic configuration example of a manufacturing apparatus according to an embodiment of the present invention. The manufacturing apparatus 1 measures the distance between the centers of a pair of conductors 4 constituting the differential signal transmission cable 10 in the production line 2 of the differential signal transmission cable 10 (hereinafter referred to as “inter-core distance”). The device 12 is inlined.

  More specifically, the manufacturing apparatus 1 includes a feeder 3 that sends out a conductor 4, a heater 5 that heats the conductor 4, and a cross through which the conductor 4 passes, to the production line 2 of the differential signal transmission cable 10. The head 6 and the pair of conductors 4 are covered with the foam insulator 8 and the extruder 7 for covering the foam insulator 8 with the skin layer 9 and the pair of conductors 4 are covered with the foam insulator 8 and the skin layer 9. A water tank 11 for cooling the obtained differential signal transmission cable 10, a measuring device 12 for measuring the distance between the core wires, a dancer 13 for applying tension to the differential signal transmission cable 10, and a differential signal transmission cable And a winder 14 for winding 10. Here, the measuring device 12 is an example of a measuring unit.

  The cross head 6 is configured so that the shape and size of the extrusion die can be changed. When manufacturing a differential signal transmission cable with an elliptical cross section, use an elliptical extrusion port, and when manufacturing a differential signal transmission cable with a circular cross section, the extrusion port is circular. Use one.

  The measuring device 12 includes a detection unit 15 that detects a magnetic field intensity generated from the conductor 4 when a current is passed through the conductor 4, and a control device 16 that controls each unit of the manufacturing apparatus 1. Details of the detection unit 15 will be described later.

  The control device 16 calculates the inter-core distance based on the magnetic field intensity detected by the detection unit 15, and also includes a control unit 160 having a CPU and the like for controlling each part of the manufacturing apparatus 1, a CPU program, and various data Is stored, and a display unit 162 that displays the measurement result of the distance between the cores is provided. The control device 16 can be realized by a computer. Here, the control unit 160 is an example of a calculation unit.

The control unit 160 calculates the inter-core distance based on the coordinate information of the positions of _two magnetic sensors 154 ₁ , 154 ₂ shown in FIG. 4 to be described later, and the magnetic field strength detected by the _two magnetic sensors 154 ₁ , 154 _2. . Further, the control unit 160 compares the calculated inter-core distance with a predetermined value, and when the calculated inter-core distance deviates from the predetermined value, the re-measured and calculated inter-core distance satisfies the predetermined value. Feedback control is performed on the production line 2, that is, the speed of the production line 2, the extrusion conditions, the water level of the water tank 11, the tension to the differential signal transmission cable 10, etc. are adjusted to control the distance between the core wires.

  FIG. 2 is a cross-sectional view showing an example of the differential signal transmission cable 10 manufactured by the manufacturing apparatus 1 shown in FIG. As shown in FIG. 2, the differential signal transmission cable 10 includes a pair of conductors 4 that are separated from each other and extend in parallel in the longitudinal direction, a foam insulator 8 having an elliptical cross section that covers the pair of conductors 4, and foam And a skin layer 9 covering the periphery of the insulator 8. A shield layer or the like may be formed around a configuration (core) in which the pair of conductors 4 are covered with the foamed insulator 8 and the skin layer 9.

  As the conductor 4, for example, a single wire made of a good electrical conductor such as copper, copper alloy, aluminum, aluminum alloy, or steel, or a single wire obtained by plating the good electrical conductor can be used. The conductor 4 may be a stranded wire formed by twisting a plurality of conducting wires made of the same material as that of a single wire when flexibility is important. Further, the differential signal transmission cable 10 is not limited to the two-core cable shown in FIG. 2, and may be an even-numbered multi-core having four or more cores.

  The foamed insulator 8 is not particularly limited as long as it is pressure-proof and has a low dielectric constant. However, for the convenience of batch-coating a pair of conductors 4 by batch extrusion, extrudability and curability. It is preferable to use known thermoplastic polymers such as fluoroethylene propylene copolymer (FEP), perfluoroalkoxy copolymer (PFA), ethylene tetrafluoroethylene copolymer (ETFE), and polyolefin copolymer. The foamed insulator 8 may be an insulator that is not foamed.

  The skin layer 9 is made of, for example, an insulator that is not foamed, or an insulator that has a lower foaming degree than the foamed insulator 8. Examples of the insulator for the skin layer 9 include ethylene tetrafluoride / perfluoropropyl vinyl ether copolymer (PFA), ethylene tetrafluoride / hexafluoropropylene copolymer (FEP), and ethylene / tetrafluoroethylene copolymer. A polymer (ETFE) can be used. The skin layer 9 may be one in which a tape such as a PET (polyethylene terephthalate) tape is wound.

  FIG. 3 is a diagram illustrating an example of the configuration of the detection unit 15. The detection unit 15 includes an AC power supply 150 that applies an AC voltage to the conductor 4, a resistor 151 connected between the AC power supply 150 and the conductor 4, an ammeter 152 that displays the current flowing through the conductor 4, and the magnetic field strength. And a line sensor 153 for detecting. The voltage applied to the conductor 4 is suitably applied by an induced electromotive force generated by the coil. In this case, the electromotive force between the conductors 4 is mainly in phase. When voltages can be separately applied to the conductors 4 by other methods, more accurate measurement can be expected by using the differential method.

FIG. 4 is a diagram for explaining an example of a method for measuring the distance between the core wires. The differential signal transmission cable 10 is arranged on the table 17 so that the center of each conductor 4 is positioned on the X axis in FIG. 4 when the inter-core distance p is measured. In this case, the number of magnetic sensors may be the same as or more than the number of conductors 4. The line sensor 153 of this embodiment uses two magnetic sensors 154 ₁ , 154 ₂ (referred to collectively as magnetic sensors 154) arranged in a line along the X axis. The differential signal transmission cable 10 may be sandwiched between the pair of tables 17 from above and below. The magnetic sensor 154 outputs a current corresponding to the magnetic field strength. As the magnetic sensor 154, a coil, a Hall element, or the like can be used. In this embodiment, a spiral pattern printed coil made of a conductive material is used on a substrate.

The current value is read by the ammeter 152 for each of the magnetic sensors 154 ₁ and 154 ₂ , and is calculated by the control device 16 to be graphed. At this time, a program for calculating the distance between the core wires by the following formula [1] by comparing with a current waveform obtained by measuring a reference cable having a distance between the core wires of 1 mm in advance was created. This program is stored in the storage unit 161.

ここで、Ｉは電流（ｍＡ）、（ｘ，ｙ）は磁気センサ１５４の位置（センサ位置）の座標（ｍｍ）、ｘ_１、ｘ_２はそれぞれの導体４の中心位置（ｍｍ）、Ｈが磁場強度（ｎＨ）である。

Here, I is the current (mA), (x, y) is the coordinate (mm) of the position (sensor position) of the magnetic sensor 154, x _{1 and} x ₂ are the center position (mm) of each conductor 4, and H is Magnetic field strength (nH).

In the measurement system in FIG. 4, the known amounts are current I (mA), sensor position (x, y) (mm), and magnetic field strength H (nH). For this reason, by using the two magnetic sensors 154 ₁ , 154 ₂ arranged at predetermined positions, data such as the following equations [2] and [3] can be obtained. The two magnetic sensors 154 ₁ , 154 ₂ are preferably arranged at different positions on a plane orthogonal to the central axis of the differential signal transmission cable 10. Thereby, the distance between the core wires on the surface can be measured. The line sensor 153 is preferably supported as close as possible to the differential signal transmission cable 10 by a support member (not shown) for highly accurate measurement.

ここで、上記式[2]、[3]において、(1)，(2)の添え字は、磁気センサ１５４毎のデータを表している。式[2]、[3]をｘ_１とｘ_２について解いて｜ｘ_１−ｘ_２｜を算出することにより芯線間距離ｐを求めることができる。

Here, in the above formulas [2] and [3], the subscripts (1) and (2) represent data for each magnetic sensor 154. The inter-core distance p can be obtained by solving the equations [2] and [3] for x ₁ and x ₂ and calculating | x ₁ −x ₂ |.

The number of magnetic sensors may be n, which is larger than the number of conductors 4. In this case, the x-coordinates x ₁ and x ₂ of each conductor 4 can be calculated by calculating the average value by the method of least squares.

  Further, the distance between the core wires may be measured by arranging four or more magnetic sensors without disposing each conductor 4 on the X axis.

  In addition, when using a standard cable with a known distance between the core wires, the magnetic field strength is measured by the above-described method, and when the cable is newly manufactured, the magnetic field strength is in-line (or offline) in the cable manufacturing process. The distance between the core wires can be adjusted to the same value as that of the reference cable by reducing the difference from the magnetic field strength of the reference cable, and the distance between the core wires can be adjusted and manufactured with high accuracy. is there.

(Production method)
Next, an example of a manufacturing method of the differential signal transmission cable 10 by the manufacturing apparatus 1 described above will be described.

(1) Covering Step When the conductor 4 is sent out from the sending machine 3, the conductor 4 is heated by the heater 5 and then passes through the crosshead 6. When the conductor 4 passes through the crosshead 6, the pair of conductors 4 are covered with the foamed insulator 8 by the extruder 7, and the foamed insulator 8 is further covered with the skin layer 9 to obtain the differential signal transmission cable 10. It is done. Subsequently, the differential signal transmission cable 10 is cooled in the water tank 11.

(2) Measurement process In this measurement process, the distance between the core wires is measured at a plurality of locations along the longitudinal direction over the entire length of the differential signal transmission cable 10 while the differential signal transmission cable 10 is moving on the production line 2. Is done. That is, when the differential signal transmission cable 10 cooled in the water tank 11 passes through the detection unit 15, an AC voltage is applied to the pair of conductors 4 from the AC power supply 150, and a magnetic field is generated from the conductors 4 by the current flowing through the conductors 4. Will occur. Magnetic sensors 154 ₁ and 154 ₂ of the line sensor 153 of the detection unit 15 output a current corresponding to the magnetic field intensity generated from the conductor 4 to the control unit 160 as a detection signal. The controller 160 calculates the inter-core distance based on detection signals from the magnetic sensors 154 ₁ , 154 ₂ . Note that the measurement of the distance between the core wires may be performed intermittently or continuously.

  The differential signal transmission cable 10 that has passed through the detection unit 15 of the measuring device 12 passes through the dancer 13 and is wound around the winder 14.

(3) Adjustment process The control part 160 performs feedback control with respect to the production line 2 so that a predetermined value may be satisfy | filled, when the distance between core wires obtained by calculation does not satisfy a predetermined value.

(Effect of embodiment)
According to the present embodiment, the following effects can be obtained.
(A) Since the current between the conductors 4 is measured to measure the magnetic field intensity generated from the conductors 4 to determine the distance between the core wires, the distance between the core wires can be measured with high accuracy, and the insulator material that covers the conductor 4 can be used. Without being limited, the inter-core distance can be measured in a non-destructive and non-contact manner.
(B) By measuring the distance between the core wires over the entire length of the differential signal transmission cable and keeping the distance between the core wires in a certain range, it is possible to guarantee a low skew.
(C) In-line measurement is possible by fixing the magnetic sensor 154 and moving the differential signal transmission cable 10 and measuring the distance between the core wires. Compared with the case where the magnetic sensor 154 is moved, the measuring apparatus 12 Is not complicated.
(D) Since the distance between the core wires can be adjusted to satisfy the predetermined value by feedback control, the highly reliable differential signal transmission cable 10 can be manufactured.

(Modification 1)
FIG. 5 is a cross-sectional view of a differential signal transmission cable according to the first modification. The differential signal transmission cable 10 according to the first modification is a multi-core type with a cross section in which two pairs of conductors 4 are arranged in a horizontal example, and the other configuration is the same as that of the embodiment. In the case of a multi-core type (the number of core wires is N), the number of magnetic sensors is required to be at least the number of core wires (N). In order to calculate the position of each conductor 4, equation [1] must be changed, but by applying a voltage to every two cores, the conductor position can be calculated using the same scheme as described above. is there. The number of core wires may be six or more arranged in a horizontal row.

(Modification 2)
FIG. 6 is a cross-sectional view of a differential signal transmission cable according to the second modification. The differential signal transmission cable 10 according to the modification 2 is a multi-core type with a circular cross section in which four conductors 4 are arranged on concentric circles, and the other configuration is the same as in the embodiment. In the second modification, similarly to the first modification, the conductor position can be calculated by the same scheme as described above by applying a voltage for every two cores. The number of core wires may be six or more arranged on concentric circles.

  Next, examples of the present invention will be described. As the samples A and B of Example 1 and Comparative Example, the differential signal transmission cable 10 shown in FIG. 2 was manufactured using the manufacturing apparatus 100 shown in FIG. FIG. 9 shows a general-purpose manufacturing apparatus 100 that does not have the measuring apparatus 12 with respect to the manufacturing apparatus 1 shown in FIG.

  The pair of conductors 4 is a two-core 24 AWG silver-plated copper wire. As the polymer constituting the foamed insulator 8, polyethylene and ADCA (azodicarbonamide) were used as the foaming agent, and the addition amount was 1% with respect to the resin. The foaming degree is 45 ± 1% in all cases.

  An elliptical extrusion die was used as the cross head 6 and a 45 mm extruder 7 manufactured by SAMP, Italy was used as the extruder 7. Two-core 24AWG silver-plated copper wire was extruded at once by adjusting the rotational speed and wire speed of the screw. Cables of a reference sample, a specimen A of 0.9 mm, and a specimen B of 1.10 mm, each having an inter-core distance p of 1.00 mm, were manufactured.

(Comparative example)
First, the distance between the core wires of the reference sample and the samples A and B was measured by measuring the cross section. The cross-section measurement is a cross-section cut at an arbitrary point in the cable longitudinal direction and the distance between the core wires is measured, and is shown as an average value of values measured in the same manner at 10 locations in the cable longitudinal direction.

Example 1
As Example 1, the magnetic field strength of the cable manufactured as described above was measured by the above-described method using the measurement apparatus of the present embodiment off-line. For off-line magnetic field measurement, an AC voltage is applied in parallel (in phase) to the two core wires as shown in Fig. 3 on a cable sample cut to a length of 1 m, and the effective value of the current generated by electromagnetic induction is recorded for each magnetic sensor. The distance between the core wires was calculated based on the deviation from the magnetic field distribution of the reference sample having a distance between the core wires of 1.00 mm.

(Example 2)
In Example 2, the magnetic field of the cable similar to that in Example 1 was measured in-line. As shown in FIG. 1, the measurement apparatus was incorporated in the production line, and the magnetic field strength was continuously measured in-line during the production process. The values in Table 1 are average values of the measured values. FIG. 7 is a diagram for explaining a method for measuring the distance between the conductors of the conductors according to the first and second embodiments. FIG. 8 is a graph showing the distribution of the magnetic field strength according to the second embodiment. As the line sensor 153, as shown in FIG. 7, a sensor in which four magnetic sensors 154 _{1 to} 154 ₄ are arranged along the X-axis direction is used. The line sensor 153 was moved close to the core by about 1 mm by a support member (not shown). As the distribution of the magnetic field strength, the current values (sensor outputs of the sample measurement values) of the magnetic sensors 154 _{1 to} 154 ₄ when measuring the sample A (p = 1.1 mm) and the sample B (p = 0.9 mm) are used as the reference sample. FIG. 8 shows a value divided by the current values of the magnetic sensors 154 _{1 to} 154 ₄ at the time of measurement (sensor output at the time of measuring the reference sample). It can be seen from FIG. 8 that the magnetic sensors 154 ₁ and 154 ₃ located on both sides of the magnetic sensors 154 ₁ and 154 ₄ , that is, the magnetic sensors 154 ₂ and 154 ₃ close to the conductor 4 have higher sensitivity. Therefore, when two magnetic sensors 154 are used, magnetic sensors 154 ₂ and 154 ₃ close to the conductor 4 are used.

  Table 1 shows the measurement results of the distance between the core wires by each measurement method. The line sensor 153 shown in FIG. 7 was used. In-line measurement was performed by running a section of 2000 m at 40 m / min and 80 m / min, respectively, and the one with the larger outer diameter fluctuation was described. However, the in-line magnetic field measurement of the reference sample is not a measurement in the manufacturing process, but is performed by passing the reference sample through the measurement apparatus according to the present embodiment at the same linear velocity as the linear velocity when the samples A and B are manufactured. It is a thing.

  From Table 1, the distance between the core wires calculated by measuring the magnetic field with the measuring device of the present embodiment is small in error in both offline magnetic field measurement and in-line magnetic field measurement, as in the case of cross-sectional measurement, and with good accuracy. You can see that they match. In addition, it was confirmed that the same result as the above-described experiment was obtained by arranging the measuring device 12 in the production line 2 and suppressing the vibration of the cable with the roller in the in-line full length inspection. The measurement data can be recorded in the control device 16 in time series and used for quality assurance of the manufactured differential signal transmission cable. Further, by applying the present invention, it is possible to measure the distance between core wires with high accuracy without taking time and labor as in the conventional cross-sectional measurement.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications and implementations are possible without departing from the scope of the present invention. For example, in the above-described embodiment, the cable to be measured is formed by covering a pair of conductors together with a foamed insulator, but may be formed by using a pair of electric wires having a single core covered with an insulator as a cable. A cable in which a plurality of electric wires obtained by collectively covering a pair of conductors with an insulator is further covered with an insulator may be used.

  Alternatively, the distance between the core wires may be measured by irradiating the measurement target cable with X-rays.

  In the above embodiment, while the magnetic sensor is fixed, the distance between the core wires is measured at a plurality of locations along the longitudinal direction of the cable while the cable for differential signal transmission is moving. With the cable fixed, the distance between the core wires may be measured by moving the magnetic sensor in the longitudinal direction of the cable.

  Moreover, it is possible to omit some of the constituent elements of the above-described embodiment within a range not changing the gist of the present invention. For example, in the above embodiment, two magnetic sensors are used, but only one magnetic sensor may be used. That is, after measuring the magnetic field strength with one magnetic sensor, one magnetic sensor may be moved to the position of the other magnetic sensor, and the magnetic field strength may be measured there.

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus, 2 ... Production line, 3 ... Delivery machine, 4 ... Conductor, 5 ... Heater, 6 ... Cross head, 7 ... Extruder, 8 ... Foam insulator, 9 ... Skin layer, 10 ... Differential signal Transmission cable, 11 ... water tank, 12 ... measuring device, 13 ... dancer, 14 ... winder, 15 ... detector, 16 ... control device, 17 ... table, 100 ... manufacturing device, 150 ... AC power supply, 151 ... resistance , 152 ... Ammeter, 153 ... Line sensor, 154 _{1 to} 154 ₄ ... Magnetic sensor, 160 ... Control unit, 161 ... Storage unit, 162 ... Display unit

Claims (13)

The distance between the centers of the at least one pair of conductors of the differential signal transmission cable having at least a pair of conductors extending away from each other and extending in parallel in the longitudinal direction and an insulator covering the at least one pair of conductors through the insulator. Measuring unit to measure,
Measuring device. The measuring unit is
A detection unit for detecting magnetic field strength generated from the conductor when current is passed through the at least one pair of conductors at at least two predetermined positions;
A calculation unit that calculates a distance between centers of the at least a pair of conductors based on coordinate information of the detection unit and at least two magnetic field strengths detected by the detection unit;
The measuring apparatus according to claim 1, further comprising:   The measuring device according to claim 1, wherein the measuring unit measures a distance between centers of the at least one pair of conductors at a plurality of locations along the longitudinal direction.   The measurement device according to claim 2, wherein the detection unit includes a magnetic sensor disposed at each of the at least two predetermined positions.   The measurement unit moves the magnetic sensor in the longitudinal direction relative to the differential signal transmission cable to measure the distance between the centers of the conductors at a plurality of locations along the longitudinal direction. The measuring device described.   The measuring unit measures the distance between the centers of the conductors at the plurality of locations along the longitudinal direction while the differential signal transmission cable is moving on a production line with the position of the magnetic sensor fixed. Item 6. The measuring device according to Item 5. A covering step of covering at least a pair of conductors extending away from each other in parallel in the longitudinal direction with an insulator so that the distance between the centers of the conductors is a predetermined value;
A measuring step of measuring a distance between centers of the at least a pair of conductors at a plurality of locations in the longitudinal direction via the insulator after the covering step;
When the measured distance between the centers of the conductors deviates from the predetermined value, an adjustment step of feeding back to the production line so that the distance between the centers of the conductors becomes the predetermined value and controlling the distance between the centers of the conductors. When,
A method for manufacturing a cable for differential signal transmission including: The measurement step includes
A detection step of detecting magnetic field strength generated from the conductor when a current is passed through the at least one pair of conductors in at least two predetermined positions;
A calculation step of calculating a distance between centers of the at least one pair of conductors based on coordinate information of the at least two predetermined positions and the at least two magnetic field strengths detected in the detection step;
The manufacturing method of the cable for differential signal transmission of Claim 7 containing.   The differential signal transmission cable manufacturing method according to claim 8, wherein the detection step is performed using magnetic sensors respectively disposed at the at least two predetermined positions.   The measuring step includes moving the at least two magnetic sensors in the longitudinal direction relative to the differential signal transmission cable to measure the center-to-center distance at the plurality of locations along the longitudinal direction. Item 10. A method for manufacturing a cable for differential signal transmission according to Item 9.   The measuring step includes a distance between the centers of the at least one pair of conductors at the plurality of locations along the longitudinal direction while the at least two pairs of conductors are moving on the production line in a state where the positions of the at least two magnetic sensors are fixed. The method for manufacturing a differential signal transmission cable according to claim 10, wherein:   The method for manufacturing a cable for differential signal transmission according to any one of claims 7 to 11, wherein in the covering step, the insulator collectively covers the at least one pair of conductors by extrusion molding. An adjustment step of adjusting the center-to-center distance of the at least one pair of conductors based on the measurement result of the center-to-center distance between the pair of conductors by the measurement step;
Furthermore, the manufacturing method of the cable for differential signal transmission of any one of Claims 7 thru | or 12 included.

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