Television – Responsive to nonvisible energy – Infrared
Reexamination Certificate
1997-09-09
2001-08-07
Kelley, Chris (Department: 2613)
Television
Responsive to nonvisible energy
Infrared
C374S057000, C374S124000, C250S341300
Reexamination Certificate
active
06271878
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a peeling detector for a tunnel wall, which detects peeling of a wall of a tunnel while moving in the tunnel.
In inspecting a tunnel wall peeling, it has been customary practice to beat the wall surface manually with a hammer or the like, hear the sounds, and locate the site of peeling based on differences in sound.
Among methods for detecting the peeling of a concrete structure by use of infrared radiation is a method for detecting the difference in temperature between a peeled part and a normal part that occurs because of a change in the ambient temperature. This method has been used mainly in the inspection of a bridge footing or a building wall surface.
With the above-described hammering test of the tunnel wall, this wall is so wide that the sounding of the entire wall takes an enormous time.
The testing method using infrared rays poses the following problem: The interior of a tunnel is a closed space, and unlike a bridge footing or a building wall, is free from changes in the ambient temperature or exposure to sunlight throughout the day. In a natural condition, there is no difference in the wall temperature between the peeled part and normal part. Thus, the infrared (IR) method was not applicable to the inspection of the tunnel wall.
SUMMARY OF THE INVENTION
The object of the present invention is therefore, to provide a peeling detector for a tunnel wall, the detector being capable of rapidly inspecting the tunnel wall with the effective use of infrared radiation.
To attain the above object, the peeling detector for a tunnel wall related to the present invention comprises: heating means for uniformly heating a tunnel wall from the surface side by use of a light emitting heater such as an infrared lamp; and infrared radiation detecting means for detecting infrared radiation radiated from the tunnel wall by an infrared camera and producing a predetermined output relevant to the presence or absence of peeling of the tunnel wall, the heating means and the infrared camera being provided on a vehicle to heat and inspect the tunnel wall while moving.
When the light emitting heater heats the face of the tunnel wall while moving, the temperature of the face of the tunnel wall surface rises, causing a flow of heat from the face toward the back of the wall surface. If a cavity due to peeling is present in the interior of the wall surface, this flow of heat is interrupted by the cavity. As a result, the flow of heat at a site where peeling exists is slower compared with the flow of heat at a site where peeling does not exist. Thus, the surface temperature after heating lowers more slowly at the former site than at the latter site. Consequently, the wall temperature is higher at the site with peeling than at the site without peeling.
The heating-associated difference in wall temperature is detected by the infrared camera as temperature distribution images. These temperature distribution images are image processed by a computer, and outputted in the form of, say, a map showing the presence and/or absence of peeling in the tunnel wall. Without image processing, an inspector may directly observe the temperature distribution images on a display such as TV monitor, and judge whether peeling exists or not in the wall surface.
REFERENCES:
patent: 4654702 (1987-03-01), Tolino
patent: 4722001 (1988-01-01), Rohrich
patent: 4913558 (1990-04-01), Wettervik
patent: 4988210 (1991-01-01), Koshihara
patent: 5709469 (1998-01-01), White
patent: 5770800 (1998-06-01), Jenkins
patent: 5108796 (1993-04-01), None
An Shawn S.
Kelley Chris
Mitsubishi Heavy Industries Ltd.
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