JPH0821881A - Detecting method for long buried object - Google Patents

Abstract

PURPOSE:To provide a method for continuously detecting a long buried object along the laying direction such as a power cable. CONSTITUTION:A reacting body C having a resonator C1 and an antenna C2 is buried in advance near a linear conductor B (long buried object), and the excitation signal of the reacting body C is transmitted from a processor A1 via an antenna A2. When the linear conductor B is buried directly below the antenna A2, the magnetic flux M1 generated on the antenna A2 by the excitation signal is linked with the antenna C2, the voltage induced on the antenna C2 is applied to the resonator C1, and the resonator C1 is resonated to emit the resonance signal. The resonance signal is received by the processor A1 via the same mechanism (linkage between magnetic fluxes M3, M4) as that for the excitation signal, and the buried location of the linear conductor B is detected. Since a detecting device A and the reacting body C are connected via the linear conductor B, the continuous detecting action along the linear conductor B can be made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting a buried location of an object buried in the ground, and particularly to a power cable or a water pipe laid in the ground.
The present invention relates to a detection method when a buried object is a very long buried object.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting an underground buried object, a responding body composed of a resonance circuit is buried in the vicinity of the detected object in advance, and the responding body is detected by utilizing its resonance characteristic. A first method of detecting the detected object by
A method called a locating wire method, which is used when the object to be detected is a long object such as a water pipe, and the object to be detected is a metal (electric conductor). High-frequency current is applied from the exposed part to the ground, or if the object to be detected is a non-metal (insulator), a high frequency is applied to the metal wire (locating wire) laid along the object to be detected. There is a second method of detecting an object to be detected by applying a current and thereby detecting a magnetic field generated around the object to be detected or a metal wire on the ground.

[0003]

According to the above-mentioned first conventional method, since it is the buried point of the responder that is detected,
If the object to be detected is a very long and long object such as a power line cable and it is necessary to continuously detect it along the laying direction, a large number of the responders should be embedded along the long object. Since the discontinuity of the detection signal cannot be avoided even when a large number of responders are buried in this way, the laying direction of the detected buried object is especially changed. In this case, the detection work at the turning point becomes very difficult.

Further, according to the second conventional method, it is necessary to connect a high frequency signal oscillating device to the object to be detected, so that the detecting operation is troublesome, and the object to be detected is a metal and a locating wire is used. If not provided, the detection operation itself becomes impossible if there is no exposed part of the object to be detected on the ground, or if it is exposed only at a place where the oscillation device cannot be connected. In some cases, the area requiring detection of the object to be detected may be separated from the connection point of the oscillation device (the ground exposure point of the detection object or the oscillation device connection terminal of the locating wire). Is very difficult to detect.

The present invention has been proposed in order to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a detection method which is easy to detect and is capable of continuously and accurately detecting the laying direction of a long buried object. It is an issue.

[0006]

In the present invention, the long buried object to be detected is a linear conductor itself such as a power cable or a telephone cable.
For example, as in the case of a water pipe using a plastic pipe, it may be a long object made of an insulating material.In the former case, the long buried object itself serves as a transmission path of a detection signal, and in the latter case, A linear conductor is previously attached in the longitudinal direction of the long buried object and buried along with the long buried object, and this serves as a detection signal transmission path.

In order to detect the burying place of the long buried object buried as described above, the present invention resonates by applying a high frequency excitation signal from the outside by electromagnetic induction and has the same frequency as the excitation signal. It is possible to electromagnetically couple the responder, which emits a resonance signal of a frequency, with the linear conductor in the vicinity of the linear conductor (the long buried object itself or the linear conductor attached to it). By burying in advance in the area, by scanning the estimated buried area of the long buried object with a detecting device having a function of transmitting the excitation signal and a function of receiving the resonance signal, the linear conductor is inserted. The excitation signal and the resonance signal are exchanged between the responder and the detection device, and the buried location of the long buried object is detected based on the resonance signal received by the detection device. Is.

[0008]

The operation will be described with reference to FIG.

A linear conductor B is provided in the scanning area by the detection device A.
When the long object to be detected itself or a linear conductor attached to it is embedded, when the antenna A2 of the detection device A approaches the linear conductor B, it is sent from the processor A1. The magnetic flux M1 generated in the antenna A2 by the excitation signal crosses the linear conductor B to induce a voltage in the linear conductor B, and the linear conductor B has the same frequency as the excitation signal. Signal current flows.

When a signal current flows through the linear conductor B, the magnetic flux M2 generated in the linear conductor B by the signal current is generated by the responder C.
The voltage of the same frequency as the excitation signal is induced in the antenna C2 by interlinking with the antenna C2 and is applied to the resonator C1.

Since the frequency of the voltage applied to the resonator C1 is the same as the resonance frequency of the resonator C1, the resonator C1 resonates and accumulates vibration energy, and when the excitation signal is cut off. , The resonance signal is emitted from the moment due to the accumulated vibration energy.

The resonance signal emitted from the responder C as described above is (the magnetic flux M3 generated in the antenna C2 crosses the linear conductor B by the action similar to the action of transmitting the excitation signal, , The magnetic flux M4 generated in the linear conductor B crosses the antenna A2.), Is transmitted to the processor A1 of the detection device A in the opposite direction to the excitation signal, and the processor A1 receives the resonance signal. Then, the embedding place of the linear conductor B (the long buried object to be detected) is detected by the analysis processing. That is, in the processor A1, the position directly below the position of the antenna A2 when the resonance signal is received at the strongest level is the embedding place of the long buried object to be detected.

As described above, the linear conductor B and the detector A
The embedded location of the linear conductor B is detected through the electromagnetic coupling between the linear conductor B and the antenna A2 of the responder C, and the electromagnetic coupling between the antenna C2 of the responder C and the linear conductor B. A continuous detection operation that does not include a discontinuity point in the laying direction of the buried object is possible.

[0014]

2 to 9 illustrate an embodiment of the present invention, and FIG. 2 shows a detecting device and an object to be detected (long buried object).
3A and FIG. 3B are diagrams showing a detection structure applied to the detected object when the detected object is an insulating object, and FIG. 4 is a block of the detection device. FIG. 5, FIG. 5 is a circuit diagram of the responder, FIGS. 6 to 8 are time charts, and FIGS. 9A and 9B are diagrams for explaining reception characteristics of the detection signal (resonance signal). In the time chart, the signal waveform of the AC signal is shown as an envelope except for the oscillation signal (the output signal of the oscillator 101) shown in FIG.

As shown in FIG. 2, when the long buried object 2 which is the object to be detected is a power cable 21, for example, the power cable 21 is housed in a protective tube 4 which is usually a plastic tube. It is buried in the underground 51. In many cases, a plurality of power cables 21 are housed in the protective tube 4, but in FIG.
1 is shown by one. Further, the burying place is not limited to the underground 51, and the present invention can be implemented even in a floor, a wall, a pillar or the like of a building, for example.

An appropriate fastener 34 such as a belt is attached to the protective tube 4.
The responder (hereinafter, referred to as a marker) 3 is fixed by the, and the marker 3 is embedded in the ground 51 together with the power cable 21 and the protective tube 4. When the power cable 21 is directly buried without using the protective tube 4, as in the case where the power cable 21 is laid in the joint laying groove of the cable, the marker 3 is directly fixed to the power cable 21.

The above is an example of the case where the long buried object 2 to be detected is a linear conductor itself, as in the case where the long buried object 2 is the power cable 21, for example.
Is an insulating material, such as a water pipe made of a plastic pipe, as shown in FIG. 3 (A),
The linear conductor 6 is fixed along the lengthwise direction of the water pipe 22 by an appropriate method. Further, as shown in FIG. 3B, the water pipe 22 may have a structure in which the linear conductor 6 is embedded in advance.

As described above, the linear conductor 6 is attached to the long buried object 2 which is an insulator, and then the marker 3 is fixed to the long buried object 2.

The detection apparatus 1 is composed of a processor 11 and a locator 12, and the processor 11 transmits an excitation signal to the marker 3, receives a resonance signal from the marker 3, and analyzes the received resonance signal to obtain a long signal. The buried place of the shaku buried object 2 is detected, the detected data is displayed, and the like, and the locator 12 emits the excitation signal and receives the resonance signal.

The locator 12 is an antenna 10 which will be described later.
4 (see FIG. 4) and a case 121, and the case 1
It consists of a handle 122 fixed to 21, and the detection work is done by the handle 12
This is performed by holding 2 and scanning the case 121 in parallel with the ground surface 52.

Further, there are a plurality of types of long buried objects 2 (for example, power cables, telephone lines, water pipes, drain pipes, etc., depending on the purpose of use, or power cables for different areas, for example. Like, depending on the laying direction,
Etc.), marker 3 is required when detection by type is required.
A plurality of types are prepared depending on the difference in resonance frequency, and a marker 3 having a different resonance frequency is attached to the long embedded object 2 for each type.

The configuration of the detection device 1 will be described with reference to FIG.

Reference numeral 101 denotes an oscillating portion, which oscillates a high frequency signal having a frequency substantially the same as the resonance frequency of the marker 3. In addition,
Here, “substantially the same” means the frequency of the high frequency signal and the marker 3
The difference with the resonance frequency of is within the allowable error range. Further, the oscillation frequency of the oscillator 101 is changed by switching in some embodiments.

Reference numeral 102 denotes a transmitter, which sends out an excitation signal for exciting the marker 3 by power-amplifying the high frequency signal from the oscillator 101.

Reference numeral 103 denotes a receiving unit which receives the resonance signal returned from the marker 3. The receiving unit 103 is
In some embodiments, a plurality of signals having different frequencies are discriminated and received for each frequency.

Reference numeral 104 denotes an antenna for electromagnetic induction signals for both transmission and reception, which sends the excitation signal from the transmission unit 102 toward the long embedded object 2 which is the object to be detected, and the resonance signal from the marker 3 to the above long object. Received via the buried object 2. The antenna 104 is composed of a loop coil, and the posture formed by the loop coil is parallel to the ground surface 52.
Alternatively, the locator 12 should be positioned so that it is perpendicular to the ground surface 52.
It is housed in a case 121 (see FIG. 2).

Reference numeral 105 denotes a transmission / reception switching unit, which alternately connects the antenna 104 to the transmission unit 102 and the reception unit 103.

Reference numeral 106 denotes a signal detector which detects the level of the signal received from the receiver 103 when the level of the signal is higher than a set level and outputs a detection signal. It should be noted that the detection signal is output as a signal having a level proportional to the reception level with respect to the reception signal having the set level or higher in some embodiments.

Reference numeral 107 denotes a display controller, which is a signal detector 106.
It is activated by the detection signal output from the device and outputs the display signal. The display signal includes a visible display signal and an audible display signal, the visible display signal is usually a DC signal, and the audible display signal is usually a low frequency signal in the audible range. The above signal may be a continuous signal or an intermittent signal, and when it is an intermittent signal, particularly when the detection signal from the signal detection unit 106 is a signal having a level proportional to the reception level of the reception signal, The intermittent cycle is controlled so as to change.

Reference numeral 108 denotes a display section, which is composed of a visible display means such as a light emitting diode and an audible display means such as a speaker. The display means may be either a visible display means or an audible display means. In this case, either the visible display signal or the audible display signal from the display control unit 107 is displayed. A display signal may be output.

Reference numeral 109 is a transmission / reception switching control unit, which is a transmission / reception switching unit 1
A transmission / reception switching signal is sent to 05.

Reference numeral 110 denotes a frequency switching unit, which is required when a plurality of types of markers 3 having different resonance frequencies are provided. The frequency switching unit 110 is attached to the long embedded object 2 to detect the oscillation frequency of the oscillation unit 101. The switching frequency is set to the response frequency (resonance frequency) of the marker 3.

The switching control in the frequency switching unit 110 may be performed manually according to the embodiment.
There are cases where it is performed automatically, and cases where it is selectively performed both manually and automatically.

Next, the structure of the marker 3 will be described with reference to FIG.

Reference numeral 31 is a crystal oscillator used as a resonance oscillator, and the frequency of the excitation signal sent from the detection device 1 is used as its resonance frequency, and when the excitation signal is applied, it is excited and vibrates to generate vibration energy. Accumulated. After that, when the application of the excitation signal is cut off, the excitation is stopped, but the vibration due to the resonance frequency due to the stored vibration energy continues for a while while being attenuated as the vibration energy is consumed, and the resonance signal is emitted during that time. In addition, as the resonance vibrating body, a piezoelectric vibrating element (ceramic resonator, etc. in addition to the crystal resonator) can be generally used. Among them, the vibration energy storage efficiency, the resonance frequency peak characteristic, etc. The crystal oscillator is optimal depending on the conditions.

Reference numeral 32 denotes an electromagnetic induction signal antenna for both transmission and reception, which is a linear conductive wire connected to both electrodes of the crystal unit 31, and receives an excitation signal from the detection device 1 to receive the crystal unit. 31 and emits a resonance signal of the crystal oscillator 31. In addition, the antenna 32
Can be configured with a loop antenna, and the loop antenna in this case has several turns (2 to 3 turns, at most 10 turns).
It consists of a loop coil of less than the turn).

The marker 3 is constructed by housing the above-mentioned two elements 31 and 32 in a plastic case (not shown), and in the case, as described above, the long embedded object 2 is used.
An appropriate fastener 34 (see FIG. 2) is provided for securing to. The operating energy of the marker 3 is an excitation signal from the detection device 1, and the marker 3 itself does not require a power source such as a battery.

The fixed position of the marker 3 to the long buried object 2 is such that the marker 3 and the long buried object 2 (or, when the long buried object 2 is an insulator, a linear conductive material attached to this). The body 6) is set within a distance in which the detection signals (excitation signal and resonance signal) flowing therethrough are effectively electromagnetically coupled to each other.

When the antenna 32 is a linear antenna, the fixing direction of the marker 3 is such that the directional direction of the antenna 32 coincides with and is parallel to the long direction of the long embedded object 2. When the antenna 32 is a loop antenna, the direction is set so that the long embedded object 2 is not in the plane perpendicular to the loop plane on the line that symmetrically bisects the loop plane. Typically, the loop surface is set in a direction perpendicular to the ground surface 52. Incidentally, as a reminder, if there is a long embedded object 2 in the plane perpendicular to the symmetrical bisecting line of the loop plane, the left half of the symmetrical bisecting line of the loop antenna will have a long embedded object at any point. Since they are equidistant from 2, the induced voltages generated in the left and right halves are equal, and their polarities cancel each other, so that the detection signal cannot be transmitted through the long buried object 2. It will be impossible.

Next, the operation of the embodiment will be described with reference to the time chart shown in FIG.

The operation shown in FIG. 6 is an operation of an embodiment in which only the burying place of the long buried object 2 is detected (the type of the long buried object 2 is not identified). In this embodiment, the marker is used. There are only three types, and the detection device 1 does not require the frequency switching unit 110.

The oscillating section 101 constantly oscillates a high frequency signal having a constant frequency as shown in FIG. The frequency of this high-frequency signal matches the resonance frequency of the crystal oscillator 31 of the marker 3 within an allowable error range, and is 1 in the embodiment.
The frequency is set to 0 MHZ or higher.

The transmitting unit 102 power-amplifies the high-frequency signal output from the oscillating unit 101 to generate an excitation signal of a level sufficient to excite the marker 3, and sends it to the transmission / reception switching unit 105.

The transmission / reception switching control unit 109 is a transmission / reception switching unit 105.
6B, the transmission / reception switching signal shown in FIG. 6B is output at the cycle t, and the transmission / reception switching unit 105 receives the transmission / reception switching signal.
6 alternately switches and connects the antenna 104 to the transmitting unit 102 and the receiving unit 103 at each cycle t as shown in FIG.

The excitation signal output from the transmission unit 102 is transmitted from the antenna 104 as shown in FIG. 6D every time the transmission / reception switching unit 105 connects the antenna 104 to the transmission unit 102. Delivered towards surface 52. That is, the excitation signal becomes a transmission signal which continues intermittently every t hours at intervals of a cycle of 2t and is transmitted toward the long buried object 2.

When the locator 12 (see FIG. 2) approaches the burying place of the long buried object 2 by scanning the ground surface 52 by the detection device 1, when the long buried object 2 is a linear conductor, the above-mentioned action is performed. As described in the section, the excitation signal is changed to the marker 3 by the electromagnetic coupling between the antenna 104 of the detection device 1 and the long embedded object 2 and the electromagnetic coupling between the long embedded object 2 and the antenna 32 of the marker 3. Applied to. When the linear conductor 6 is attached to the long buried object 2 (when the long buried object 2 is made of an insulating material, see FIG. 3), as described above, Electromagnetic coupling occurs between the two antennas 104 and 32 and the linear conductor 6. In the following description, the long embedded object 2 itself is a linear conductor unless otherwise specified.

When the excitation signal is applied to the marker 3 as described above, the marker 3 responds as shown in (e) of FIG. That is, when the excitation signal is applied to the crystal oscillator 31, the crystal oscillator 31 resonates and vibrates at its own resonance frequency according to the applied level while the excitation signal is applied.

By the operation of the transmission / reception switching unit 105, the antenna 1
When 04 is switched to the receiving unit 103 side, the sending of the excitation signal from the antenna 104 is stopped, and the application of the excitation signal to the crystal oscillator 31 is also cut off, but the crystal oscillator 31 does not operate during the excitation period. Immediately after the application of the excitation signal is stopped by the accumulated vibration energy, the resonance vibration is maintained at the same resonance frequency while being attenuated as the vibration energy is consumed, and the resonance vibration is maintained for a while.

Due to the above-described damped resonance vibration of the crystal oscillator 31, a resonance signal of damped vibration as shown in FIG. 6 (f) is emitted from the antenna 32 of the marker 3 in the same manner as the excitation signal transmission function. , The resonance signal is a long embedded object 2
It is incident on the antenna 104 of the detection device 1 via.

When the resonance signal is incident on the antenna 104, the antenna 104 is connected to the receiving unit 103 by the transmission / reception switching unit 105, so that the receiving unit 10 is connected.
A resonance signal as shown in (f) of FIG. 6 is input to 3,
The receiving unit 103 receives the resonance signal.

Upon receiving the resonance signal, the receiving section 103 detects and rectifies the resonance signal and outputs a reception signal having a level proportional to the reception level of the resonance signal as shown in (g) of FIG.

The received signal output from the receiver 103 is compared with the reference level L by the signal detector 106, and when the level of the received signal is higher than the reference level L, the signal detector 1
Reference numeral 06 denotes the detection signal shown in FIG.
Output to. The reason why the signal detection unit 106 sets the reference level L for the signal detection of the reception signal of the reception unit 103 in this way is to eliminate erroneous detection due to noise appearing in the output of the reception unit 103.

Further, while the scanning position by the locator 12 (see FIG. 2) is within the detection range of the long embedded object 2, the above operation is repeated every time the excitation signal is transmitted from the antenna 104, so that the above signal detection is performed. The transmission cycle of the detection signal output from the unit 106 is 2t.

The display control unit 107 outputs a display signal to the display unit 108 according to the above detection signal. This display signal is continuously output from the display control unit 107 as shown in (i) of FIG. 6 while the output of the detection signal is repeated from the signal detection unit 106 at the cycle 2t, and the display unit 108 is As a result, the presence of the long buried object 2 is visually or / and audibly displayed.

The display signal output from the display control unit 107 is a DC signal (visible display signal) for causing a light emitting element such as a light emitting diode to emit light, and a sounding element such as a speaker for ringing. There are low-frequency alternating current signals (audible display signals), and these display signals can be made into intermittent signals by the intermittent control in the display control unit 107.

Here, the relationship between the attitude of the antenna 104 of the detection apparatus 1 facing the long embedded object 2 and the detection level of the signal in the signal detection unit 106 (the level of the reception signal output by the reception unit 103) will be described.

FIGS. 9A and 9B show the antenna 104.
The detection level characteristics are shown for two scanning orientations of (locator antenna).

The antenna 104 is composed of a loop antenna as described above, and as shown in FIG. 9 (A), the antenna 1 has its loop surface parallel to the ground surface 52.
When 04 is moved, when the long embedded object 2 is located directly below the center of the antenna 104 (a line that symmetrically divides the loop surface), the detection level sharply decreases, and both ends of the point are detected. When the maximum detection level has a bimodal characteristic, and when the antenna 104 is moved so that the loop surface is perpendicular to the ground surface 52 as shown in FIG. 9B,
When the long embedded object 2 is located immediately below the center of the antenna 104 (the center line of the winding width when the loop surface is in the vertical direction), there is a single peak characteristic of the maximum detection level.

In the case shown in FIG. 9A, that is, when the loop surface of the antenna 104 is scanned in parallel with the ground surface 52, the level decreases while the detection level once reaches the peak and then again reaches the peak. By detecting the points, the buried location of the long buried object 2 can be detected accurately. However, since the detection level is the level of the difference between the induced voltages induced on both sides of the symmetrical bisecting line of the loop plane,
The detection level is lower than that in the case shown in (B), and it is difficult to detect when the long embedded object 2 to be detected is deeply buried.

In the case shown in FIG. 9B, that is,
When scanning is performed with the loop surface of the antenna 104 perpendicular to the ground surface 52, the level of the peak point of the detection level is shown in FIG.
Since it is higher than in the case of (A), detection can be performed with high sensitivity. However, the detection point is the peak point of the detection level,
Moreover, since the level change width is small in the vicinity of the peak point, there is some difficulty in the detection accuracy.

Which of the above methods is used to scan the ground may be determined depending on the burial condition of the object to be detected (long buried object 2) and the required detection position accuracy, and both methods should be used in combination. It is also easy (the case 121 of the locator 12 may be pivotally supported on the handle 122 so that the angle of the case 121 with respect to the ground surface 52 can be changed).

Next, an embodiment will be described in which there are a plurality of types of long buried objects 2 to be detected, and the type of the long buried object 2 is detected as well as the location of the buried object 2 is detected.

In this embodiment, the marker 3 having the crystal oscillator 31 having a different resonance frequency for each type of the long buried object 2.
Is buried. Since the resonance characteristic of the crystal unit 31 has a sharp peak characteristic, the frequency band width occupied by the resonance frequency of one type of crystal unit 31 may be narrow, and therefore many types within a limited frequency band. Marker 3 can be made.

Further, in this embodiment, the detection apparatus 1 is provided with the frequency switching unit 110, and the oscillation frequency of the oscillation unit 101 is within the range of the resonance frequency of the plurality of types of markers 3 (resonance frequency of the crystal oscillator 31). The receiving unit 103 is configured to receive the plurality of types of markers 3 discriminatively for each resonance frequency,
The signal detection unit 106 outputs a separate detection signal (for example, a signal output to a separate terminal) for each frequency discrimination reception output of the reception unit 103, and further, the display control unit 1
07 outputs a separate display signal for each separate detection signal output by the signal detecting unit 106, that is, depending on the type of the marker 3.

The frequency switching control by the switching control unit 110 includes a manual switching control for fixedly setting a frequency to one specific frequency, and an automatic switching control for cyclically switching the frequency at fixed intervals. .

First, the operation by the manual switching control will be described. The manual switching control is used when the long embedded object 2 for the purpose of detection is one specific type when performing the detection.

Manual operation at the frequency switching unit 110 (for example,
By inputting the type data of the marker 3 associated with the long embedded object 2 to be detected by push button operation),
The oscillation frequency of the oscillator 101 is set to the same frequency as the resonance frequency of the marker 3, and the display signal output from the display controller 107 is a display signal corresponding to the type of the marker 3. Here, the display signal corresponding to the type of the marker 3 is a visible display, for example, when a light emitting diode is provided for each type of the marker 3, a light emitting element to be driven to emit light is selected and output to this. In the case of an audible display, for example, when an intermittent period of speaker ringing is set for each type of marker 3, an intermittent period to be sounded is selected and output by this intermittent period. This is a display signal.

When the visual display and the audible display are used together, the display for each type of the marker 3 may be used for either one, and the visual display is usually the display for each type. It is easier to identify.

If the visual display means is composed of an LCD (liquid crystal display) capable of displaying characters,
The display signal for each type of the marker 3 can be a display signal that specifically displays the type number of the marker 3, for example.

The operation by the manual switching control will be described with reference to FIG. 6 according to the set frequency after the frequency is set (the type of the marker 3 is set) by the manual operation in the frequency switching unit 110 as described above. When the locator 12 scans the intended buried location of the long buried object 2, the display control section 107 outputs a display signal corresponding to the type of the long buried object 2 and the display section 108 operates. The existence and type of the long buried object 2 are displayed on the screen. In the manual switching control, the long embedded object 2 to be detected is fixedly determined by the manual operation (the marker 3 to be detected is only one specific type), and thus the display of the above type may be omitted.

Next, the operation by the automatic switching control will be described.

In the automatic switching control, there are a plurality of types of long embedded objects 2 to be detected, and a plurality of types of long embedded objects 2 can be simultaneously detected by one operation of ground scanning by the locator 12. It is used when detecting. It should be noted that the automatic switching control is performed by a first method of sequentially cyclically switching frequencies for all types of markers 3 (all types of long buried objects 2) set in advance and all of the markers 3 concerned. Specify the desired marker 3 from multiple types in advance,
There is a second method of cyclically switching frequencies for the designated type of marker 3, and in the case of adopting the second method, the detected marker is, for example, operated by a button in the frequency switching unit 110. 3 types (plural)
Is set (when the detected marker 3 is of one type, the manual switching control is performed).

FIG. 7 shows four types of markers 3 whose response frequencies (resonance frequencies of the crystal unit 31) are f1 to f4, respectively.
6 is a time chart showing a frequency switching operation when four types of long embedded objects 2 are detected by type.

From the frequency switching unit 110, the frequency switching signal as shown in FIG.
Each time the oscillator 101 receives the frequency switching signal, the oscillator 101 in FIG.
The oscillation frequency is cyclically switched as shown in (L) of.

The frequency switching unit 110 receives the transmission / reception switching timing information from the transmission / reception switching unit 105, and outputs the frequency switching signal at the same timing in each reception period while the transmission / reception switching unit 105 is switched to the reception side. To be done. Therefore,
The oscillation frequency of the oscillator 101 changes as f1, f2, f3, f4, f1 ... With each arrival of the transmission period, and as shown in FIG. The frequency is cyclically changed like f1, f2, f3, f4, f1 ...
It will be sent from 04.

When the excitation signal whose frequency cyclically changes is transmitted as described above, the crystal oscillator 31 of the marker 3 resonates when the excitation signal of the frequency matching the resonance frequency of the marker 3 is received. Since the resonance signal having the same frequency as the excitation signal is returned via the long embedded object 2 which is the object to be detected, the reception unit 103 discriminates and receives the resonance signal according to the frequency, and the display unit 108 displays The same display as in the manual switching control is displayed.

Next, a description will be given of an embodiment capable of displaying the degree to which the locator 12 (antenna 104) has approached the intended long buried object 2 during the detection work.

In this embodiment, the signal detection unit 106 is configured to output a detection signal (reception level detection signal) having a level proportional to the level of the reception signal from the reception unit 103, and the display control unit 107. The display unit 108 is configured to output a display signal that changes according to the level of the reception level detection signal.
The display is made according to the distance between the long buried object 2 and the long buried object 2.

FIG. 8 shows a time chart of a portion related to the above embodiment.

The antenna 104 is scanned by the locator 12
8 approaches the long buried object 2, the level of the excitation signal received by the marker 3 via the long buried object 2 becomes higher, and the crystal oscillator 31 of the marker 3 becomes As shown in (e), it vibrates intermittently while increasing its amplitude. Therefore, the peak value of the resonance signal input to the receiving unit 103 also increases as shown in FIG. As the antenna 104 moves away from the long embedded object 2, the peak value of the resonance signal becomes smaller.

Upon receiving such a resonance signal, the receiving section 10
As shown in FIG. 8G, 3 outputs a reception signal having a level proportional to the resonance signal, and the signal detection unit 106 compares the peak value level of the reception signal with the reference level L to obtain the reference value. With respect to the received signal exceeding the level L, as shown in (e) of FIG. 8, a received level detection signal of a level corresponding to the peak value level is output to the display control unit 107. As shown in (e) of FIG. 8, this reception level detection signal is output in such a form that when a new reception signal is input, it changes to a level corresponding to this new reception signal.

When the reception level detection signal is input, the display control section 107 changes the signal form to S1, S2, S3 ... As the level changes, as shown in FIG.
A display signal that changes with the locator 12 (antenna 104) is output to the display unit 108, and the display unit 108 displays while changing the display form according to the change in the signal form of the display signal. The degree of approach to the long buried object 2 is displayed.

The display of the degree of approach on the display unit 108 is performed by the following method, for example. That is,
In the visual display, for example, a plurality of light emitting diodes are provided as detection display means, and the number of light emitting diodes driven to emit light increases as the level of the reception level detection signal increases to display the degree of approach. In the audible display, for example, the ringing signal of the speaker is used as an intermittent signal, and the intermittent period of the intermittent signal is shortened as the level of the reception level detection signal becomes higher (the antenna 104 is embedded longer). When the object 2 is closest to the object 2, it may be a continuous signal.) To display the degree of approach.

The display of the degree of approach between the locator 12 and the long buried object 2 described above is based on the difference in the buried depth of the long buried object 2, the scanning height of the locator 12 from the ground surface 52, and the like. Since the display form also changes depending on the
Although the display form on 8 and the distance of the locator 12 to the long buried object 2 do not absolutely correspond to each other, in a series of scanning operations of the locator 12, the scanning point where the light emitting diode emits the most light or the ringing signal. Since the scanning point where the intermittent cycle becomes the shortest can be judged from the display form before and after the scanning point, this embodiment is sufficiently effective in specifying the intended buried location of the long buried object 2.

As described above, displaying the degree of approach between the locator 12 and the long buried object 2 is possible in any of the embodiments described with reference to FIGS. 6 and 7.

[0086]

As described above, according to the present invention, a long buried object as a detection object or a linear conductor attached thereto and an antenna of a detection device and an antenna of a responder (marker) are provided. It is intended to detect the buried location of a long buried object by exchanging a detection signal between the above-mentioned detecting device and the responder through electromagnetic coupling between Since continuous detection without discontinuity is possible along the embedding direction, even when a power cable or the like is laid in a complicated direction, it is possible to detect the laying direction of the power cable. Exactly possible.

Further, the number of responding bodies to be buried in advance together with the long buried object to be detected may be very small as compared with the conventional method (method for detecting the responding body itself) by the same method. The cost required in advance is very low.

Further, by preparing responding bodies having different characteristics (resonance frequencies), it is possible to easily detect the long buried object to be detected for each type, and further to detect the long buried object and the responding body. Since the detection device and the detection device are connected to each other in a non-contact manner, the device connection work for the detection work is hardly required and the detection work is easy.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of the present invention.

FIG. 2 is a system configuration diagram of an embodiment of the present invention.

3A and 3B are diagrams showing an example of a detected object according to an embodiment of the present invention.

FIG. 4 is a block diagram of a detection device according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a marker according to an embodiment of the present invention.

FIG. 6 is a time chart showing the basic operation of the embodiment of the present invention.

FIG. 7 is a time chart showing the oscillation frequency switching operation of the embodiment of the present invention.

FIG. 8 is a time chart showing the level detection operation of the received signal according to the embodiment of the present invention.

9A and 9B are diagrams showing detection signal detection level characteristics of the embodiment of the present invention.

[Explanation of symbols]

A, 1 ... Detecting device 2 ... Long buried object B, 6 ... Linear conductor C, 3 ... Reactor (marker) A1, 11 ... Processor 12 ... Locator 101 ... Oscillator 102 ... Transmitter 103 ... Receiver 104, A2 ... Antenna 105 ... Transmission / reception switching unit 106 ... Signal detection unit 107 ... Display control unit 108 ... Display unit 109 ... Transmission / reception switching unit 110 ... Frequency switching unit 31, C1 ... Resonator (crystal oscillator) 32, C2 ... Antenna M1 to M4 ... Magnetic flux

Claims (7)

[Claims] 1. A method for detecting a buried location of a long buried object, wherein the long buried object itself is a linear conductor, or a wire in a longitudinal direction of the long buried object. A conductor is additionally provided, and a response body that resonates by applying a high-frequency excitation signal from the outside by electromagnetic induction from the outside and emits a resonance signal having the same frequency as the frequency of the excitation signal is It is embedded in advance in a region where it can be electromagnetically coupled to the linear conductor in the vicinity, and a detection device having a function of transmitting the excitation signal and a function of receiving the resonance signal is used to estimate the embedded region of the long embedded object. By scanning, to exchange the excitation signal and the resonance signal between the responder and the detection device via the linear conductor, based on the resonance signal received by the detection device. I tried to detect the burial place of the above long buried objects How to detect long buried objects. 2. A method for detecting a buried location of a plurality of types of long buried objects to be distinguished from each other, wherein a responder having a resonance frequency is buried for each kind of the long buried objects.
By changing the frequency of the excitation signal transmitted from the detection device according to the type of long buried object to be detected,
The method for detecting a long buried object according to claim 1, wherein the long buried object is detected by its type. 3. An excitation signal of a specific frequency is transmitted from a detection device by manually switching and setting the frequency of the excitation signal, and the buried location of a specific type of long buried object is detected. The method for detecting a long buried object according to item 2. 4. A plurality of excitation signals of different frequencies are sequentially and cyclically transmitted from a detection device by automatically and continuously controlling the switching of the frequencies of the excitation signals, and a plurality of types of long buried objects are classified by type. The method for detecting a long buried object according to claim 2, wherein the buried place is detected. 5. The detection level of the resonance signal from the responder received by the detection device is detected, and the degree of approach of the detection device to the long buried object is detected based on the detected level. The method for detecting a long buried object according to any one of 1. 6. The posture in which the responder has a linear antenna for transmitting and receiving an excitation signal and a resonance signal, and the directivity direction of the linear antenna is in parallel with and parallel to the longitudinal direction of the long embedded object. The method for detecting a long embedded object according to any one of claims 1 to 5, wherein the responding body is embedded in. 7. The responder has a loop antenna for transmitting and receiving an excitation signal and a resonance signal, and the long embedded object is present in a plane other than the plane perpendicular to the symmetrical bisector of the loop plane of the loop antenna. The method for detecting a long embedded object according to any one of claims 1 to 5, wherein the responder is embedded.