Optics: image projectors – Methods
Patent
1980-07-03
1983-01-04
Stephan, Steven L.
Optics: image projectors
Methods
33 1H, 33DIG21, 173 2, 299 1, 353122, G01C 706, E21D 914, F42D 304
Patent
active
043670210
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
A tunneling method for marking out drill hole patterns on the face of the rock by projecting the image of a slide provided with markings representing the positions of holes to be drilled on a reduced scale belongs to prior art is described in U.S. Pat. No. 3,431,049. This known method necessitates a separate direction determining means, a direction laser, for instance, as a reference in respect of the tunnel direction, as well as comparatively complicated measures for correcting the position of pattern points of a slide to correspond to correct positions of drill spots on the rock surface when projecting the slide image onto the rock face. This is due to the fact that the face of the rock, after a blast for instance, has varying shapes, which seldom or never constitute a substantially flat surface extending perpendicularly to the optical axis of the projector which projects the slide onto the rock surface. FIG. 1 of the accompanying drawing shows this.
OBJECT AND SUMMARY OF THE INVENTION
One object of the invention is to avoid the abovementioned drawbacks, in particular the need for correcting the slides used for projecting markings for drill holes with respect to a variable shape of the rock surface.
This object is attained in accordance with the invention by utilizing the fact that a projection of a narrow unidirectional light bunch such as and in particular, a laser based projection, allows for such a range of projection as compared with what could normally be effected by means of a projector in which the representation of a pattern is illuminated in its entirety by means of a condensing lens system, that the light beams representing different locations on the drilling spot pattern on the rock surface run substantially parellel to the direction of the tunnel. As a result no measures are required to compensate for irregularities in the rock surface, onto which the drill hole markings are projected.
In practice, the invention brings about a valuable improvement, in that additional work to adjust the shape of the rock surface after blasting in order to obtain a correct marking of the drill holes will not be necessary, thus allowing the desired drill hole pattern on the slide to be projected without any correction.
In a preferred embodiment of the invention, its device comprises one single light source, generating a beam of substantially parallel light rays, suspended from the roof of the tunnel, to be used during a plurality of markings for subsequent drillings and blastings, for example by means of a "remote control box", which, in case the device is equipped with a data program defining different surface drill spot patterns, obviously may be arranged for selecting a desired program and marking of a selected drill spot of the pattern. An important advantage of using light beams consisting of unidirectional rays, laser beams in particular, when projecting images corresponding to drill locations is the possibility thereby to obtain on the rock wall distinct and easily observable spots under varying ambient light conditions and projection distances. Further, the invention makes it possible to use one single laser source for the vitally important laying-out of tunnel direction as well as for the laying-out of drill spot positions in a manner superior to prior art. A still further advantage is that the device can be used within coal mines, in which conventional light projection of drill hole is not allowed because of safety rules aimed at avoiding explosions.
BRIEF DESCRIPTION OF THE DRAWING
The invention will become more apparent from the following description of a preferred embodiment thereof, illustrating a best mode of the invention, in connection with the accompanying drawing, whereas
FIG. 1 illustrates a prior art method for defining a tunnel direction by aid of a reference laser light beam in connection with marking of drill hole positions by means of film slide projection utilizing either a fixed predetermined distance between a lens system projector and the image pla
REFERENCES:
patent: 3431049 (1969-03-01), Nordgren
patent: 3896885 (1975-07-01), Dahlstrom et al.
patent: 4023861 (1977-05-01), Schnell
patent: 4267892 (1981-05-01), Mayer
Akerlind Bo
Biedermann Klaus
Nordgren Bo G.
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