Electricity: measuring and testing – Of geophysical surface or subsurface in situ – For small object detection or location
Reexamination Certificate
2003-05-19
2004-11-02
Le, N. (Department: 2862)
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
For small object detection or location
C324S067000
Reexamination Certificate
active
06812707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a detecting element for detecting a metal pipe before or after it is installed in or on the ground or detecting a body such as a crushing powder, explosive and the like loaded at a predetermined place and to a detecting apparatus using the detecting element.
2. Description of the Related Art
Many kinds of metal pipes having almost the same outside diameter are installed in and on the ground in large Sophisticated plants such as petroleum refining plants, electric power plants, ship yards, chemical plants and the like. When many kinds of metal pipes must be installed at a time so that these large plants are newly constructed in a short period of time, identification codes and characters are conventionally applied to the metal pipes themselves with coloring materials such as paints and the like which are difficult to be decolorized before the metal pipes are connected in order to prevent different kinds of metal pipes from being connected to each other. Then, the installation dates of the metal pipes, the materials of the metal pipes, the sizes of them, the manufacture of them, the names of fluids flowing in the pipes, piping systems of them and other necessary data are written on different drawings and papers or recorded in a computer as electronic data using the identification codes and characters as reference data. When the metal pipes are connected, the identification codes and the like of the metal pipes themselves are visually checked against the drawings, the papers and a computer list for the discrimination thereof. Further, when the metal pipes are inspected, repaired or replaced after they are installed, the identification codes and the like of the metal pipes themselves are visually checked against the drawings and the like for the discrimination thereof so that the metal pipes are checked against their history information in the same manner as that they are installed. Furthermore, the information of the result of inspection and the like of the pipes are recorded on the papers and the like while checked with the identification codes and the like of the metal pipes themselves.
In contrast, these metal pipe identifying and checking jobs are also carried out to various kinds of pipes buried in the ground such as gas pipes, tap water pipes, sewerage pipes, cable pipes, optical fiber pipes, oil transportation pipes, chemicals transportation pipes and the like, similarly. That is, buried metal pipes may be repaired or replaced after they are used for a long period of time. In a construction work carried out at the time, the positions of the buried metal pipes must be accurately located from the ground and earth and sand must be dug. Conventionally, metal pipe detecting markers are known as a device for detecting buried metal pipes. The marker is composed of a columnar ferrite, an antenna coil wound around the ferrite and a capacitor connected to both the ends of the antenna coil. The antenna coil and the capacitor constitutes a resonance circuit. The ferrite, the antenna coil and the capacitor are accommodated in an insulating case. The metal pipe detecting marker is buried at the necessary position of the metal pipe together therewith. Thereafter, the position of the metal pipe is detected by detecting the marker by resonating the resonance circuit from the ground by transmitting a radio wave having a specific frequency using a dedicated detecting apparatus and receiving the resonated radio wave in a construction work.
When a pipe is made of metal, in particular, when the pipe is a magnetic body such as a cast iron pipe, a steel pipe and the like, if the metal pipe detecting marker is directly mounted on the outer surface of the metal body or disposed at a position very near thereto, the resonance frequency of the resonance circuit of the marker is varied by the change of the self-inductance of the resonance circuit as well as the Q value of the coil is greatly lowered. Thus, the marker cannot be accurately detected. To cope with this problem, when the marker is used to detect the metal pipe, it is buried at a position spaced apart from the pipe by a distance larger than the diameter of the pipe.
However, in the conventional method of applying the identification code and the characters to the metal pipe itself and visually discriminating and checking them, a problem arises in that a considerable time and labor are necessary to discriminate and check metal pipes when they are installed under the ground where illumination facilities are not sufficiently provided, when they are installed in the ground or when they are installed on the ground in a complicated fashion, they may be erroneously identified.
To improve the above point, it is tried to mount a non-contact type RFID (radio frequency identification device) on a metal pipe. However, when the metal pipe is the magnetic body such as the cast iron pipe, the steel pipe and the like, if the RFID is directly mounted on the outer surface of the pipe body or disposed at a position very near thereto, the resonance frequency of the radio wave transmitted from an external identification device is varied by the change of the self-inductance of the antenna coil of the RFID as well as the Q value of the antenna coil is greatly lowered. Thus, there arises a problem that the function of the RFID cannot be achieved.
Further, when the markers are buried at positions spaced apart from metal pipes, the positions where the markers are buried and the axial lines of the coils of the markers are varied depending upon workers and a detection error may be increased. Further, when another construction work is carried out after a metal pipe is buried, the marker may be broken or the marker itself may be moved. Accordingly, there is also a disadvantage that the above conventional metal pipe detecting marker cannot detect a metal pipe in such a case.
Further, when a body to be detected is a crushing powder or explosive loaded in a hole drilled in a rock, rock bed, concrete and the like for crushing the rock and the like, it is necessary to accurately detect or search a crushing powder or explosive which remains without being exploded to secure the safety of a job for removing muck such as earth, sands and rocks after the crushing powder or explosive is exploded.
A first object of the present invention is to provide a body detecting element capable of accurately identifying a body without changing the resonance frequency of the radio wave transmitted from an identification device for activating a RFID circuit and without changing the Q value of an antenna coil even if the body detecting element is mounted on a body such as a metal pipe and the like installed in or on the ground integrally therewith and to provide a detecting apparatus using the detecting element.
A second object is to provide a body detecting element which is not almost broken and moved even if a body other than a body to be detected is dug up and to provide a detecting apparatus using the detecting element.
A third object of the present invention is to provide a body detecting element capable of accurately detecting a body such as a crushing powder or explosive which is loaded at a predetermined position and is not yet exploded and to provide a detecting apparatus using the detecting element.
SUMMARY OF THE INVENTION
A first aspect of the invention discloses a body detecting element which is buried in the ground together with a body and includes a magnetic member acting as a magnetic core, an antenna coil wound around the magnetic member and a capacitor or a piezo-resonator connected to both the ends of the antenna coil for forming a resonance circuit together with the antenna coil. In the detecting element, the body is a metal body and the antenna coil is mounted on the body integrally therewith with the outer peripheral surface thereof confronting the outer surface of the body.
When the antenna coil is mounted on the body such that the outer peripheral surface thereof confronts the outer surfac
Endo Takanori
Yahata Seiro
Yonezawa Tadashi
Kinder Darrell
Le N.
Mitsubishi Materials Corporation
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