JP2002056726A - Disconnection prediction cable and cable exchange time detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disconnection prediction cable and a cable exchange time detection system wherein a necessity of cable exchange can be known before the cable is disconnected when the cable reaches the end of its fatigue lifetime and wherein the cable can be safely used because a supervisor is made sure to recognize the cable exchange time by monitoring a state of a detection cable arranged separately in the cable. SOLUTION: The cable 10 and the detection cable 2 whose fatigue lifetime is shorter than that of the cable 10 are integrally arranged and installed, and because the detection cable 2 reaches the end of the fatigue lifetime and disconnects before the cable 10 does, the supervisor can distinctly grasp disconnection of the detection cable from outside if changes in a state of signal transmission in the detection cable 2 are made to be detected and informed of, and by the disconnection of this detection cable 2, the timing when the cable 10 is an immediate state before its fatigue lifetime is made confirmed by the supervisor as an appropriate exchange time, and safety is secured by prevention or the like of a sudden stop of equipment due to disconnection of the cable 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable used for signal transmission and power supply in a use state where bending and stretching are repeated, and more particularly, to management from a disconnection of a detection cable built in or separately provided in the cable. The present invention relates to a disconnection prediction cable and a cable replacement time detection system that allow a user to recognize that a cable disconnection is near and recognize the necessity of cable replacement.

[0002]

2. Description of the Related Art In general, in a mechatronic device such as an industrial robot, each actuator and a control unit or a power supply unit are connected to a plurality of actuators distributed to move each operation part. Cable is used to connect the.

In such a cable for a mechatronic device, the relative distance between the two ends of the cable connected to each of the mechanical components is often caused by the relative movement of each mechanical component of each component of the device accompanying the operation of the device. Since the cable is repeatedly bent and stretched from a bent state, it is an essential condition that the cable has a predetermined durability against the repeated bending and elongation. The conductor and coating material to be made have sufficient flexibility,
The structure had a sufficient fatigue life against bending and elongation.

FIG. 3 shows an example of a conventional cable having excellent durability against such repeated bending and elongation. This figure 3
FIG. 2 is a schematic configuration diagram of a conventional cable. In each of the drawings, the conventional cable 10 includes a core wire 11 disposed at the center to maintain the strength of the entire cable, and a plurality of signal lines for transmitting control signals and the like between predetermined electronic circuits in two connected mechanical components. 12, a protective layer 13 for covering and protecting the core wire 11 and the signal line 12 collectively, a metal braid 14 disposed on the outer periphery of the protective layer 13 as a shield layer, and a sheath 15 covering the whole as an outermost layer further outside. It is a configuration provided with:

The signal line 12 is formed by covering a stranded wire formed by twisting a large number of thin metal wires with an insulating jacket, and a plurality of signal wires 12 are provided in the cable 10 in accordance with signals to be exchanged. The cable 10 has a multi-core structure.

[0006]

Since the conventional cable is configured as described above, when the cable 10 is repeatedly bent and stretched beyond a predetermined number of times, a signal in the cable 10 is It is clear that the wire 12 is broken due to fatigue and cannot perform its original function, and it is common to replace the cable 10 with a new one before reaching the fatigue life.

The fatigue life of the signal line 12 of the cable 10 is as follows:
Depending on the material and structure of the conductor in the signal line 12,
Since the longer the fatigue life, the higher the cost due to the special material and structure, the cable 10 is usually used to optimize the balance between cost and fatigue life for the operating conditions. A method of replacing the battery with a predetermined replacement cycle before the end of the service life is adopted.

[0008] However, the replacement cycle of the cable 10 is as follows.
Since the fatigue life is predicted and obtained from the frequency of bending and elongation in the equipment using the cable 10, or is empirically obtained from the past disconnection time, etc., it is difficult to specify it accurately. Sometimes the timing of the exchange was too early or too late. Assuming that the cable 1
If the life expectancy of 0 is incorrect and the cable 10 is continued to be used beyond the original replacement time, there is a problem that the cable 10 may be disconnected during the work and the device may suddenly stop or operate abnormally. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. By monitoring the condition of a detection cable separately provided on a cable, the cable can be replaced before the cable reaches its fatigue life and is disconnected. An object of the present invention is to provide a disconnection prediction cable that can be used to know the necessity and that can be used safely by ensuring that an administrator recognizes a cable replacement time and a cable replacement time detection system that uses the disconnection prediction cable.

[0010]

A disconnection predicting cable according to the present invention has both ends connected to two mechanical parts for changing the positional relationship of each other as required, and the relative positional change between the two mechanical parts. A cable having a predetermined fatigue life with respect to bending and elongation repeated according to, having a predetermined signal transmission path, and having a structure in which the fatigue life is shorter than at least the cable, A detection cable disposed in the cable longitudinal direction. As described above, in the present invention, the detection cable having a shorter fatigue life than the cable is integrally disposed in the cable that is repeatedly bent and stretched, and the detection cable has a fatigue life before the cable reaches the fatigue life and is disconnected. When the detection cable is disconnected and a predetermined detection means is connected to the detection cable to detect and report a change in the signal transmission state of the detection cable, the disconnection of the detection cable can be clearly grasped from outside by an administrator. By using the disconnection of the detection cable, the administrator can confirm the timing when the cable is in the state immediately before fatigue life as an appropriate cable replacement time, and prevent sudden stop of equipment due to cable disconnection for safety. Can be secured.

Further, the disconnection predicting cable according to the present invention comprises:
A cable having both ends connected to two mechanical parts that change the positional relationship of each other as necessary, and having a predetermined fatigue life against repeated bending and elongation according to the change in the relative position of the two mechanical parts. And a detection cable having a predetermined signal transmission path and having a fatigue life shorter than at least the cable, and provided integrally with the cable along the outer surface of the cable. Things. As described above, in the present invention, the detection cable having a shorter fatigue life than the cable is integrally disposed outside the cable where bending and stretching are repeated, and the detection cable has a fatigue life before the cable reaches the fatigue life and is disconnected. When the detection cable is disconnected and a predetermined detection means is connected to the detection cable to detect and notify the signal transmission state change in the detection cable, the disconnection of the detection cable can be clearly grasped from the outside. By using the disconnection of the detection cable, the administrator can confirm the timing when the cable is in the state just before fatigue life as an appropriate cable replacement time, and it is possible to ensure safety such as preventing sudden stop of equipment due to cable disconnection In addition, it has a simple structure in which the detection cable is integrated along with the general cable. There is no need to manufacture as built the special structure, and thus be significantly suppressed the cost of the cable.

Further, the disconnection predicting cable according to the present invention comprises:
The cable is an optical fiber cable.
As described above, in the present invention, since the fatigue life of the optical fiber cable against bending and elongation is detected by the detection cable, deterioration of the optical fiber cable having a limit in the curvature of bending can be detected in advance. Further, the cable replacement time detection system according to the present invention is connected to the detection cable in the disconnection prediction cable as needed, and transmits a predetermined signal to the detection cable, and simultaneously monitors a signal transmission state, and performs detection. Detecting means for detecting a change in the signal transmission state of the cable for use and notifying a predetermined manager of the change, the detection means changing the state of the cable for detection from a state where signal transmission is possible to a state where signal transmission is impossible. Is detected, the administrator is notified that the cable has reached the replacement time. As described above, according to the present invention, the detecting means is connected to the detecting cable which is disposed integrally with the cable and reaches the fatigue life before the cable is disconnected, and is disconnected. The detecting means changes the signal transmission state in the detecting cable. By detecting the disconnection of the cable for detection to the external administrator, the administrator can clearly understand the disconnection of the cable for detection and the state immediately before the fatigue life of the cable. The administrator can recognize a certain timing as an appropriate cable replacement time, and safety can be ensured, such as preventing sudden stop of equipment due to cable disconnection.

Further, the disconnection predicting cable according to the present invention comprises:
A cable having both ends connected to two mechanical parts that change the positional relationship of each other as necessary, and having a predetermined fatigue life against repeated bending and elongation according to the change in the relative position of the two mechanical parts. And a detection conductor in which a predetermined conductive material whose electric resistance increases with an increase in the number of repetitions when a repetitive stress is applied is made continuous within the cable in the longitudinal direction of the cable with an equal cross-sectional area. Things. As described above, in the present invention, a predetermined conductive substance whose electrical resistance increases as the number of repetitions of the bending back increases increases is disposed in the cable to serve as a detection conductor, and the detection conductor is bent. When the resistance changes with repeated repetition and approaches the specified resistance value corresponding to the fatigue life of the cable, the change in the electrical resistance of the detection conductor is detected and reported by the specified detection means. It is possible for the administrator to clearly understand from the outside from the outside that the cable is in the state immediately before fatigue life as an appropriate cable replacement time, so that the administrator can confirm the timing as appropriate, and prevent sudden stop of equipment due to cable disconnection, etc. Nature can be secured.

Further, the disconnection predicting cable according to the present invention comprises:
Both ends are respectively connected to two mechanical parts that change the mutual positional relationship as needed, and light having a predetermined fatigue life against repeated bending and elongation according to the change in the relative position of the two mechanical parts. A fiber cable and a predetermined translucent substance, in which the propagation loss of an optical signal increases with an increase in the number of repetitions when a repetitive stress is applied, is continuous inside the optical fiber cable at an equal cross-sectional area in the longitudinal direction of the optical fiber cable. And a light transmitting body for detection. As described above, in the present invention, a predetermined light-transmitting substance in which a change in which the propagation loss of an optical signal increases as the number of repetitions of the bending back increases is disposed in the optical fiber cable to form a light-transmitting member for detection, The propagation loss of the light transmitting body for detection is changed by repeated bending and approaches a predetermined resistance value corresponding to the fatigue life of the optical fiber cable. If the optical fiber cable is in the state immediately before fatigue life, the administrator can clearly understand from the outside that the optical fiber cable is in the state immediately before fatigue life. As a result, it is possible to ensure safety by preventing an abrupt stop of the device due to disconnection of the optical fiber cable.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment of the Present Invention) Hereinafter, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a disconnection prediction cable according to the present embodiment and a block diagram of a used state. The disconnection prediction cable 1 according to the present embodiment shown in each of the drawings has a core wire 11 and a signal line 12 as the conventional cable 10.
And a detection cable 2 integrally provided in the protective layer 13 along the outside of the signal line 12 in addition to the configuration including the protective layer 13, the metal braid 14, and the sheath 15. It is.

The detection cable 2 has a conductor 2a serving as a transmission path of an electric signal, and an insulating jacket 2b which covers the periphery thereof and insulates the outside from the outside. The conductor 2a
In this case, a single wire or a stranded wire having a small number of wires is used so that the fatigue life against bending and elongation is slightly shorter than that of the signal wire 12. This detection cable 2 is a cable 10
And is connected to the detecting means 3 comprising a predetermined electronic circuit to transmit a signal from the detecting means 3 and at the same time, the signal transmitting state is monitored by the detecting means 3 and a change occurs in the signal transmitting state due to disconnection. And it is a mechanism to detect this.

Next, the use state of the disconnection prediction cable of the present embodiment will be described. With the operation of the equipment provided with the disconnection prediction cable 1, bending and elongation of the entire disconnection prediction cable 1 are repeated, and stress due to bending and elongation is applied to the signal line 12 and the detection cable 2. Cable 10
When the number of repetitions of bending and elongation reaches just before the fatigue life of the cable 10, the detection cable 2 in the cable 10 reaches the fatigue life before the signal line 12 and breaks, and can function as a transmission line. There is no state. The detecting means 3 connected to the detection cable 2 detects the transition of the detection cable 2 from the signal transmission enabled state to the signal transmission disabled state, and informs the administrator that the detection cable 2 has been disconnected. That is, it notifies that the cable 10 has reached the replacement time. The disconnection of the detection cable 2 that reaches the fatigue life slightly earlier than the cable 10 can clearly indicate that the cable 10 will soon reach the fatigue life, and the manager can be surely notified of the time to replace the cable with a new cable.

As described above, in the disconnection prediction cable according to the present embodiment, the cable 1 that is repeatedly bent and stretched is used.
Detection cable 2 having a shorter fatigue life than signal line 12 within 0
Since the detection cable 2 reaches the fatigue life and breaks before the signal line 12 reaches the fatigue life and breaks, the detection means 3 is connected to the detection cable 2 to perform the detection. The disconnection of the cable 2 is detected and notified, and the disconnection of the detection cable 2 is grasped by the administrator and can be recognized as the replacement time of the cable 10. Thus, safety can be ensured, for example, by exchanging the cable 10 and preventing sudden stoppage of the device due to disconnection of the cable 10.

(Second Embodiment of the Present Invention) The second embodiment of the present invention
An embodiment will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the disconnection prediction cable according to the present embodiment.
Disconnection predicting cable 1 according to the present embodiment shown in each of the drawings.
Are the core wire 11 and the signal line 12 as in the first embodiment.
, A protective layer 13, a metal braid 14, a sheath 15, and a detection cable 2, except that the detection cable 2 is not in the cable 10 but in the sheath 15.
Are arranged integrally along the outer side of the.

As in the first embodiment, the detection cable 2 has a conductor 2a and an insulating jacket 2b. The detection cable 2 is further extended from the cable 10 and connected to the detection means 3 to detect the signal. The signal transmission state is monitored by the detection means 3 at the same time when the signal from the means 3 is transmitted, and when a change occurs in the signal transmission state due to disconnection, this is detected.

Next, the use state of the disconnection prediction cable of the present embodiment will be described. As in the first embodiment, with the operation of the device provided with the disconnection prediction cable 1,
The bending and elongation of the entire disconnection prediction cable 1 are repeated,
The signal line 12 and the detection cable 2 are stressed by bending and elongation. When the number of repetitions of bending and elongation to the cable 10 reaches just before the fatigue life of the cable 10, the detection cable 2 along the cable 10 reaches the fatigue life before the signal line 12 and breaks, and signal transmission becomes impossible. State. The detection means 3 connected to the detection cable 2 detects the transition of the detection cable 2 from the signal transmission enabled state to the signal transmission disabled state, and notifies the administrator that the cable 10 has reached the replacement time. Notify. The disconnection of the detection cable 2 that reaches the fatigue life slightly earlier than the cable 10 can clearly indicate that the cable 10 will soon reach the fatigue life, and the manager can be surely notified of the time to replace the cable with a new cable.

As described above, in the disconnection prediction cable according to the present embodiment, the cable 1 that is repeatedly bent and stretched is used.
0, the detection cable 2 having a shorter fatigue life than the signal line 12 is integrally provided, and the detection cable 2 reaches the fatigue life and is disconnected before the signal line 12 reaches the fatigue life and is disconnected. From this, the detecting means 3 is connected to the detecting cable 2 to detect and inform the disconnection of the detecting cable 2, and the administrator grasps the disconnection of the detecting cable 2 and
Of the cable 10
The operator can replace the cable 10 at the optimal timing just before the fatigue life, so that safety can be ensured, for example, by preventing a sudden stop of the device due to the disconnection of the cable 10 beforehand. In addition, it has a simple structure in which the detection cable 2 is integrated with the cable 10 similar to the conventional one,
There is no need to manufacture the cable 10 as a special structure including the detection cable 2, and the cost of the entire cable can be suppressed.

In the cable for predicting disconnection according to each of the first and second embodiments, a plurality of signal lines 12 serving as signal transmission paths are provided in the cable 10 and are integrally formed with these signal lines. Although the configuration is such that the cable 2 is provided, the present invention is not limited to this, and a power line for supplying power is provided instead of the signal line 12, and the detection cable 2 is provided along the power line.
May be provided. In addition, signal line 1
Although it is configured to use a general metal conductor as 2,
However, the present invention is not limited to this, and a signal line using another material such as an optical fiber may be used.
The administrator can be surely notified of the replacement time of 0. Further, the detection cable 2 is not limited to a metal conductor, but may be configured to use another material such as an optical fiber. The detection means 3 for detecting disconnection is configured as an optical signal detection circuit corresponding to this. Similarly, disconnection can be detected.

In the cable for predicting disconnection according to each of the first and second embodiments, one detection cable 2 is provided inside or outside the cable 10. It is also possible to arrange a plurality of detection cables each having a different fatigue life integrally with the cable 10, and the plurality of detection cables are disconnected one by one at a time interval, thereby reducing the fatigue of the signal line 12. This allows the administrator to recognize the state approaching the service life in more detail, prompts the administrator to replace the cable, and ensures that the cable is replaced.

In the disconnection prediction cable according to each of the first and second embodiments, when the signal cable 12 and the detection cable 2 having a different fatigue life are disconnected first, it is time to replace the cable 10. However, the present invention is not limited to this, and a predetermined conductive substance whose electric resistance increases as the number of repetitions of the bending back increases increases as a detection conductor in the form of a coating layer or a linear body in the cable 10. It is also possible to adopt a configuration in which the conductor is continuously arranged in the longitudinal direction of the cable, and a state in which the resistance of the conductor for detection changes due to repeated bending and approaches a predetermined resistance value corresponding to the fatigue life of the cable 10 is determined. The detection and notification by the detection means can clearly indicate that the cable 10 will soon reach the fatigue life, as described above, and provide the cable 1 to the administrator.
The replacement time of 0 can be surely recognized.

Further, a predetermined light-transmitting substance, in which the propagation loss of an optical signal increases as the number of repetitions of bending back increases, is not limited to the conductor for detection, and is used as a light-transmitting substance for detection as a coating layer or A configuration such as a linear body may be provided so as to be continuously arranged in the longitudinal direction of the cable, and the light transmitting body for detection may have a predetermined loss corresponding to the fatigue life of the cable 10 due to a change in propagation loss due to repeated bending back. As described above, it is possible to clearly indicate that the cable 10 will soon reach its fatigue life by detecting and notifying the state approaching the propagation loss value by the predetermined detection means, and to surely inform the administrator of the time to replace the cable 10. Be recognized.

[0027]

As described above, according to the present invention, a detecting cable having a shorter fatigue life than a cable is integrally disposed in a cable that is repeatedly bent and stretched, and before the cable reaches its fatigue life and is disconnected. When the detection cable reaches the end of its fatigue life and breaks, a predetermined detection means is connected to the detection cable to detect and notify the signal transmission state change in the detection cable. By using this disconnection of the detection cable, the administrator can confirm the timing when the cable is in the state immediately before the fatigue life as an appropriate cable replacement time, and the sudden disconnection of the equipment due to the disconnection of the cable This has the effect of ensuring safety, for example by preventing stoppage.

According to the present invention, a detection cable having a shorter fatigue life than the cable is integrally disposed outside the cable where bending and stretching are repeated, and the detection cable is provided before the cable reaches the fatigue life and is disconnected. When the detection cable reaches the end of its fatigue life and breaks, the specified detection means is connected to the detection cable to detect and report a change in the signal transmission state of the detection cable. Using this disconnection of the detection cable, the administrator can confirm the timing when the cable is in the state just before fatigue life as an appropriate cable replacement time, preventing sudden stop of equipment due to cable disconnection, etc.
In addition to ensuring safety, it has a simple structure in which a detection cable is integrated along with a general cable, eliminating the need to manufacture the cable as a special structure with a built-in detection cable, reducing the cost of cables. This has the effect of being greatly suppressed.

Further, in the present invention, since the fatigue life of the optical fiber cable against bending and elongation is detected by the detecting cable, deterioration of the optical fiber cable having a limit in bending curvature can be detected in advance. It has the effect of. Further, according to the present invention, the detecting means is connected to a detecting cable which is disposed integrally with the cable and which reaches its fatigue life and breaks before the cable is broken, and the detecting means changes the signal transmission state in the detecting cable. By detecting the disconnection of the cable for detection to the external administrator, the administrator can clearly understand the disconnection of the cable for detection and the state immediately before the fatigue life of the cable. This allows the administrator to recognize a certain timing as an appropriate cable replacement time, and has an effect that safety can be ensured by preventing a sudden stop of a device due to disconnection of a cable.

Further, according to the present invention, a predetermined conductive substance whose electrical resistance increases as the number of times of bending back increases increases is disposed in the cable to be used as a detection conductor. When the body changes resistance due to repeated bending back and approaches a predetermined resistance value corresponding to the fatigue life of the cable, the electrical resistance change of the detection conductor is detected and notified by the predetermined detection means. The administrator can clearly understand from the outside that the cable is in the state immediately before the end of its life, and the administrator can check the timing when the cable is in the state immediately before the end of its life as an appropriate cable replacement time, and suddenly stop the equipment due to disconnection of the cable. It has the effect that safety can be ensured by preventing it.

Further, according to the present invention, a predetermined light-transmitting substance which causes a change in which the propagation loss of an optical signal increases as the number of repetitions of the bending back increases is disposed in the optical fiber cable, and the light-transmitting material for detection is provided. The transmission loss of the optical signal of the detection light transmitting body is changed by approaching a predetermined resistance value corresponding to the fatigue life of the optical fiber cable by changing the propagation loss of the detection light transmitting body due to repeated bending back. If the change is detected and notified by the predetermined detection means, the administrator can clearly understand from the outside that the optical fiber cable is in the state immediately before the fatigue life, and the timing when the optical fiber cable is in the state immediately before the fatigue life can be appropriately determined. This has an effect that the administrator can be confirmed as a cable replacement time, and safety can be ensured by preventing sudden stop of the device due to disconnection of the optical fiber cable.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a disconnection prediction cable according to a first embodiment of the present invention and a block diagram of a used state.

FIG. 2 is a schematic configuration diagram of a disconnection prediction cable according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a conventional cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disconnection prediction cable 2 Detection cable 2a Conductor 2b Insulation jacket 3 Detecting means 10 Cable 11 Core wire 12 Signal wire 13 Protective layer 14 Metal braid 15 Sheath

Continued on the front page F term (reference) 2G014 AA02 AA13 AA32 AB32 AB36 AB40 AC19 2H001 FF01 PP00 5G309 KA01 KA02 5G315 BA09

Claims (6)

[Claims] 1. Both ends are respectively connected to two mechanical components that change the positional relationship of each other as necessary, and a predetermined value is provided for bending and stretching that is repeated according to a change in the relative position of the two mechanical components. A cable having a fatigue life, a detection cable having a predetermined signal transmission path, and having a configuration in which the fatigue life is shorter than at least the cable, and being disposed inside the cable in a longitudinal direction of the cable; A disconnection predicting cable comprising: 2. Both ends are respectively connected to two mechanical parts for changing the mutual positional relationship as needed, and a predetermined bending and elongation is repeated in accordance with a change in the relative position of the two mechanical parts. A cable having a fatigue life, a detection having a predetermined signal transmission path, and having a configuration in which the fatigue life is at least shorter than that of the cable, and disposed integrally with the cable along the outer surface of the cable; And a disconnection predicting cable. 3. The disconnection prediction cable according to claim 1, wherein the cable is an optical fiber cable. 4. The detection predictive cable according to claim 1, wherein said disconnection predicting cable is connected to said detection cable to transmit a predetermined signal to said detection cable and simultaneously monitor a signal transmission state. A predetermined detection means for detecting a change in the signal transmission state of the cable and notifying a predetermined manager of the change, the detection means changing the state of the detection cable from a state in which signal transmission is possible to a state in which signal transmission is not possible When detected,
A cable replacement time detection system that notifies the manager that the cable has reached the replacement time. 5. Both ends are respectively connected to two mechanical components for changing the mutual positional relationship as needed, and a predetermined bending and elongating operation is repeated according to the relative positional change of the two mechanical components. A cable having a fatigue life, and a detecting member which is made of a predetermined conductive material whose electric resistance increases with an increase in the number of repetitions when a repetitive stress is applied. A cable for predicting disconnection, comprising a conductor. 6. Both ends are respectively connected to two mechanical parts for changing the mutual positional relationship as needed, and a predetermined bending and elongation is repeated according to a change in the relative position of the two mechanical parts. An optical fiber cable having a fatigue life, and a predetermined translucent substance, in which the propagation loss of an optical signal increases with an increase in the number of repetitions when a repetitive stress is applied, is placed inside the optical fiber cable in the longitudinal direction of the optical fiber cable. A cable for predicting disconnection, comprising: a light-transmitting body for detection formed continuously with an equal cross-sectional area.