Geometrical instruments – Straight-line light ray type – Level
Reexamination Certificate
2000-04-27
2003-04-01
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Straight-line light ray type
Level
C033S227000, C033SDIG002
Reexamination Certificate
active
06539638
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a line projecting device and more specifically to an optical system used in leveling and projecting a line on a working surface that spans over 360 degrees around the device.
BACKGROUND OF THE INVENTION
Levels are essential tools in many fields of activity whenever perfectly horizontal or vertical lines are required. The most commonly used level consists of a leveling device mounted on a straight support. A drawback of such a level is that it makes it difficult to simultaneously adjust the orientation of the support and draw a line, especially when that line intersects different surfaces. The length of the line that can be drawn is also limited to the length of the support.
A solution to this problem has been proposed in U.S. Pat. No. 3,897,637 granted on Aug. 5, 1975 to Genho, where an apparatus that can direct two perpendicular laser beams is described. The apparatus can be positioned, for example, in a corner of a room, to produce two perpendicular lines that can be used as references. A drawback of Genho's level is that, since the leveling lines are not projected but directly emitted from the apparatus, it is not possible to project the leveling lines directly on the surfaces where the work is to be done. Another drawback is that it can be difficult to produce a line near a remote plane such as a high ceiling.
U.S. Pat. No. 5,539,990 granted on Jul. 30, 1996 to Le describes a leveling instrument that overcomes the above-mentioned drawbacks by projecting lines instead of using directly the light beam produced. However, the mechanism used to project the line is complicated and fragile, therefore expensive. Moreover, since the projector is universally pendulously mounted, the leveling is done automatically, rendering it difficult to project lines having other angles than the one initially designed for.
Another example of optical leveling system is found in U.S. Pat. No. 3,984,154 granted on Oct. 5, 1976 to Chin et al. and entitled “Optical Fan Levelling System”. In this patent the two cylindrical concentric reflective surfaces are bridged by an edge face that is expensive to manufacture, hence not permitting a line spanning over 360 degrees from the line projecting device. In the case where such a need would be required, one would have to move the “Optical Fan Levelling System”, losing precious time, and possibly disturbing the leveling mechanism and setting. That 360 degree span is also limited by the fact that the light beam generator is in the same plane as the projected line thus providing partial obstruction that could possibly be avoided with an expensive arrangement of special and accurate mirrors.
OBJECTS OF THE INVENTION
It is therefore a general object of the present invention to provide a line projecting device of the character described which obviates the above noted disadvantages.
Another object of the present invention is to provide a line projecting device that allows a leveling light to be projected and spanning horizontally over a 360 degree sector around the line projecting device.
Another object of the present invention is to provide a line projecting device that can be easily mounted on a variety of leveling aid support which can be adjusted to give a projected and spanning light over a 360 degree sector around the line projecting device but at differently selected slanted planes.
A further object of the present invention is to provide a line projecting device that will not require frequent adjustments once properly set.
SUMMARY OF THE INVENTION
The present invention consists of a line projecting device for projecting a line on a working surface comprising:
a partially reflective and partially transparent cylindrical member with an optically smooth outer surface;
a source of collimated light to direct a light beam intersecting said cylindrical member in a radial plane and obliquely to said outer surface, said cylindrical member inducing multiple internal reflections and refractions of said beam on said outer surface for projection of said line onto said working surface, said line spanning over at least 60 degrees from said device;
a body member adapted to fixedly receive said cylindrical member and said light source in proper relative position.
Preferably, the cylindrical member further includes an optically smooth inner cylindrical surface generally concentric with said outer surface to form an essentially annular cross-section of said cylindrical member, both said inner and outer surfaces inducing multiple internal reflections and refractions of said beam.
Preferably, the line spans over at least 220 degrees from said device.
Preferably, the body member is adapted to fixedly receive, in proper relative position a plurality of additional partially reflective and partially transparent cylindrical member with each a respective additional optically smooth outer surface, and a respective additional source of collimated light to direct a respective additional light beam intersecting said respective additional cylindrical member in a respective additional radial plane and obliquely to said respective additional outer surface, said respective additional cylindrical member inducing multiple internal reflections and refractions of said beam on said respective additional outer surface for projection of a respective additional line onto said working surface, said respective additional radial plane being coplanar to said first radial plane, all of said cylindrical members and light sources being generally oriented in generally equally angularly spaced apart positions around a complete 360 degree angle within said radial planes to have all of said lines slightly overlapping each adjacent others and jointly spanning over 360 degrees from said device.
Alternatively, the body member is adapted to fixedly receive, in proper relative position a second partially reflective and partially transparent cylindrical member with a second optically smooth outer surface, and a second source of collimated light to direct a second light beam intersecting said second cylindrical member in a second radial plane and obliquely to said second outer surface, said second cylindrical member inducing multiple internal reflections and refractions of said beam on said second outer surface for projection of a second line onto said working surface, said second radial plane being coplanar to said first radial plane, said second cylindrical member and second light source being generally oriented 180 degrees from said first cylindrical member and first light source within said radial planes to have said first and second lines, each spanning over at least 220 degrees, slightly overlapping each other and jointly spanning over 360 degrees from said device.
Preferably, the first and second cylindrical members further includes, respectively, a first and second optically smooth inner cylindrical surface generally concentric with said respective outer surface to form an essentially annular cross-section of said respective cylindrical member with both said inner and outer surfaces inducing multiple internal reflections and refractions of said respective beam.
Preferably, the body member further includes a leveling device properly aligned with a preferred angle relative to said first and second radial planes.
Preferably, the preferred angle is zero so as to orient said first and second lines into a horizontal plane when said body member is maintained in a position with said leveling device indicating a horizontal leveling.
REFERENCES:
patent: 3820903 (1974-06-01), Kindl et al.
patent: 3858984 (1975-01-01), Denton et al.
patent: 3887282 (1975-06-01), Hansen
patent: 3984154 (1976-10-01), Chin et al.
patent: 4123148 (1978-10-01), Laird
patent: 4699186 (1987-10-01), Palin et al.
patent: 5594993 (1997-01-01), Tager et al.
patent: 5836081 (1998-11-01), Orosz, Jr.
patent: 5872657 (1999-02-01), Rando
patent: 5983510 (1999-11-01), Wu et al.
patent: 6065217 (2000-05-01), Dong
patent: 6256895 (2001-07-01), Akers
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