Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION
Line projecting device
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 United States
Patent No. 3,897,637 granted on August 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.
United States Patent No. 5,539,990 granted on July 30, 1996 to Le
describes a leveling instrument that overcomes the above-mentioned drawbacks
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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. Patent
No. 3,984,154 granted on October 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
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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 a substantially 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
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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
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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 a
substantially 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.
BRIEF DESCRIPTION OF THE DRAWINGS
In the annexed drawings, like reference characters indicate like
elements throughout.
Figure 1 is a perspective view showing an embodiment of a line
projecting device according to the present invention;
Figure 2 is a schematic partially enlarged plan view showing how a
collimated light beam is directed on the cylindrical member and some of the
resulting partial reflections and refractions and the span covered by the
beam;
Figure 3 is a plan view of the embodiment of Fig. 1 in operation and
showing the overlapping span covered by the two projected lines;
Figure 4 is a side elevation view of the embodiment of Fig. 1;
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Figure 5 is a perspective view illustrating the operation of the
embodiment of Fig. 1 and the resulting line projected on the walls of the
surrounding working surface; and
Figure 6 is a perspective view of the embodiment of Fig. 1 shown
mounted on a tripod and adjusted to project a line in a vertically oriented
plane.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1, there is shown a line projecting device 10 that
includes a body member 12; a first and preferably second supports 14, 14a
secured onto the body member 12; a first and second sources of collimated
light
16, 16a, preferably standard lasers, mounted respectively on the first and
second
supports 14, 14a; a first and second cylindrical members 18, 18a each
partially
reflective and partially transparent and each secured on the body member 12;
and a leveling device, preferably a horizontal plane level 20, also secured on
the
body member 12. First and second sources of collimated light 16, 16a and their
corresponding first and second cylindrical members 18, 18a form the first and
second line projectors 21, 21 a respectively.
Referring to Figs. 2 and 3, the first cylindrical member 18 is such
positioned with its axis essentially perpendicular to the body member 12.
Preferably, a first inner surface 22 of the cylindrical member 18 is generally
concentric with a first outer surface 24 of the cylindrical member 18, both
forming
a substantially annular cross-section of the cylindrical member 18. Both first
inner and outer surfaces 22, 24 are optically cylindrical smooth surfaces. The
first source of light 16 is positioned and calibrated to direct a first light
beam 26 in
a radial plane of the cylindrical member 18 and obliquely to the first outer
surface
24 of the cylindrical member 18 to be refracted towards the inner surface 22
in
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such a way that the incident angle against the first inner surface 22 will be
greater
than the critical angle necessary in optical physics to induce at least
partial
(because of existing microscopic imperfections on inner surface 22) or total
internal reflection of the first light beam 26, and in such a way that the
internal
reflected incident angle against the first outer surface 24 will be smaller
than the
critical angle necessary in optical physics to induce partial internal
reflection and
partial refraction of the first light beam 26 through the interface. The first
light
beam 26 upon contact with the first outer surface 24 is refracted to give the
first
refracted ray 28. The latter is then partially internally reflected as
explained
above against the first inner surface 22 and becomes the first reflected ray
30.
The latter is then partially internally reflected against the first outer
surface 24 and
partially outwardly refracted as explained above to give respectively another
internally reflected ray 30 and a outwardly refracted ray 32, and so on going
all
around the cylindrical member 18 at least once (as shown in dotted lines on
Fig. 2). The first refracted ray 28 may also become a partially refracted ray
30'
inwardly from the inner surface 22 to itself re-induce multiple reflected and
refracted rays, all in the same radial plane. The angles of the rays of light
shown
on Figs.2 and 3 are illustrative only, the partially internally reflected and
outwardly refracted angles of the rays of light are in reality in a much
smaller
scale, and induce multiple reflected rays 30 and refracted rays 32. A first
resulting angle A of the span covered by the line L formed by the first
refracted
rays 32 is preferably of at least 220 degree span. It would be understood by
any
person skilled in the art that, practically, the angle A may vary anywhere
between
60 and 300 degrees, preferably of about 220 degrees, depending on the
intensity
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of the beam 26, the transparency of the cylindrical member 18 material and the
blockage induced by the source of collimated light 16.
Here, the term "partially" is used since the first light beam 26 is of a
certain diameter and will therefore hit the non-perfect outer surface 24 and
subsequently the non-perfect inner surface 22 at a multitude of different
angles
over the spread of its diameter (of the beam 26); as opposed to perfectly
theoretical ray hitting perfectly smooth surfaces. Note that the inner surface
22
can be coated with a highly reflective coating that would improve the internal
reflections on that surface.
Also shown is a similar second light beam 26a directed by the
second source of light 16a, a similar second refracted ray 28a, multiple
similar
partially internally reflected rays 30a, multiple similar partially outwardly
refracted
rays 32a, a similar optically smooth second inner surface 22a and a similar
optically smooth second outer surface 24a of the second cylindrical member
18a,
and a similar second resulting angle Aa of the span covered by the line La
formed by the second refracted rays 32a of at least 220 degree span,
preferably.
The first and second line projectors 21, 21 a are preferably oriented
180 degrees from each other (back to back), in a parallel but opposite
direction.
Resulting intersections I between the first resulting angle A and the second
resulting angle Aa give an overlapping of the first and second lines L, La
respectively to give a combined angle formed by the latter two covering the
complete 360 degrees around the line projecting device 10.
As shown on Figs. 3 and 4, the first line L is in a first radial plane P.
Similarly, the second line La is in a second radial plane Pa generally
coplanar to
the first radial plane P due to a proper mounting of both line projectors 21,
21a
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onto the body member 12. Accordingly, the horizontal plane level 20 is mounted
onto the body member 12 so as to align both first and second radial planes P,
Pa
at the preferred angle of 0 degree such that both first and second radial
planes P,
Pa indicate a horizontal plane when the line projecting device 10 is properly
leveled using its horizontal plane level 20.
Fig. 5 shows the line projecting device 10 and a working surface S
on which are projected a first line L from the first line projector 21, and a
second
line La from the second line projector 21 a. The combination of these first
and
second lines L, La from a leveled line projecting device 10 is a horizontal
projected line spanning over 360 degrees, and is used as a permanent
horizontal
reference line on the working surface S as long as the line projecting device
10
remains fixed in that same position.
As shown in Figs.1 and 6, the line projecting device 10 is
preferably provided with different mounting fixtures 34, 35 and 36. These
mounting fixtures 34, 35, 36, each properly aligned with respect to the line
projectors 21, 21a, are preferably used to mount the body member 12 onto a
standard camera tripod T or professional line-surveyor tripod (not shown)
respectively. Such a tripod T can be used to level the line projecting device
10 at
a horizontal level or at another desired angle (substantially vertical angle
shown
in Fig. 6) with the use of a tilting mechanism M of the tripod T once the
horizontal
(and reference) level has been established using the leveling device 20.
It is believed within the reach of one skilled in the art to design a
line projecting device (not shown) provided with a body member adapted to
receive line projectors on more than one plane to simultaneously generate a
plurality of differently oriented projected lines. Similarly, a plurality of
line
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projectors 21, properly mounted on a same surface of a body 12, at equally
angularly spaced apart positions around a complete 360 degree within the
coplanar radial planes P and with all projected lines L overlapping each
adjacent
others, form a joint line spanning 360 degrees from the device 10.
Although the present line projecting device has been described with
a certain degree of particularity, it is to be understood that the disclosure
has
been made by way of example only and that the present invention is not limited
to
the features of the embodiments described and illustrated herein, but includes
all
variations and modifications within the scope and spirit of the invention as
hereinafter claimed.
