Note: Descriptions are shown in the official language in which they were submitted.
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OVERHEAD PROJECTION SYSTEM
Field Of The Invention
The present invention relates generally to projection systems and in
particular to an overhead projection system and to a projector assembly
therefor.
Background Of The Invention
Overhead projection systems are well known in the art and typically
include a ceiling mounted projector that is spaced from and aimed downwardly
at a
generally planar display surface onto which projected images are to be
displayed. The
projector is secured to a mounting assembly including a mounting plate to
which the
projector is fastened and an upright in the form of a bar or pipe extending
from the
mounting plate that is anchored to the ceiling. Unfortunately, ceiling mounted
projectors of this type suffer from a number of disadvantages.
For example, many types of ceilings such as drop tile ceilings or other
types of suspended ceilings, do not include the necessary structure to support
such
overhead projectors. As a result, structural reinforcements for ceilings of
this nature
are necessary before overhead projectors can be ceiling mounted.
Alternatively, the
uprights must extend beyond the drop tiles and be anchored to the overhead
structural
ceilings. In these later situations, HVAC and/or lighting may be positioned
between
the drop tiles and the overhead structural ceilings at positions where it is
necessary to
mount the projectors. If so, the HVAC and/or lighting must be moved before the
projectors can be mounted. Furthermore, ceiling mounted projectors typically
require
specialized power and signal wiring that must be installed in the ceilings. In
addition,
registering ceiling mounted projectors with display screens requires
specialized skill
and calculations on the part of installers and typically leads to the use of
expensive
projectors with zoom and lens shift capabilities. These above-described
problems
result in expensive and onerous installations.
Mounting a projector to a wall surface has also been considered. For
example, U.S. Patent No. 5,490,655 to Bates discloses a video/data projector
and
monitor ceiling/wall mount. The wall mount includes a wall support assembly
fixedly
secured to a wall surface. A pair of struts extends horizontally from the wall
support
assembly. A projector/monitor adapter is supported by the ends of the struts.
The
wall support assembly includes a strut adapter that rests between a pair of
adapter
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plates extending from a wall plate. A fastener secures the strut adapter to
the adapter
plates in a manner to permit rotation of the adapter plate and hence, the
struts about a
vertical axis.
U.S. Patent No. 6,540,366 to Keenan et al. discloses an overhead
projection system comprising an overhead projector support assembly extending
outwardly from a generally vertical support surface. A display screen having a
display surface is mounted on the support surface beneath the projector
support
assembly. A projector is mounted on the projector support assembly and is
aimed to
project images onto the display surface of the display screen. The projector
support
assembly includes a damper and spring arrangement to control downward pivotal
movement of the projector support assembly when a load is placed on the
projector
support assembly and to return the projector support assembly to a generally
horizontal orientation when the load is removed. Although this overhead
projection
system works extremely well, some set up time is required to install,
calibrate and
align the projector and display surface. Also, the provision of the damper and
spring
arrangement, although useful, adds to overhead projection system cost. In many
environments cost is of primary concern. As a result, there exists a need for
an
overhead projection system that is inexpensive and easy to install and
register and that
avoids the problems associated with ceiling mounted projectors.
It is therefore an object of the present invention to provide a novel
overhead projection system and a projector assembly therefor.
Summary Of The Invention
Accordingly, in one aspect there is provided an overhead projection
system comprising:
a generally horizontal projector assembly;
a display screen having a display surface disposed beneath said
projector assembly, said projector assembly comprising a projector aimed to
project
images onto the display surface of said display screen; and
at least one tether acting between said projector assembly and a
structural element above said projector assembly.
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In one embodiment, the projector assembly is pivotable relative to a
generally vertical support surface on which the display screen is mounted. In
particular, the projector assembly is pivotally mounted on a bracket secured
to the
support surface. The display screen is also mounted on the bracket below the
projector assembly. The projector assembly comprises a pair of elongate
members
arranged to form an A-frame structure with the projector being mounted
adjacent the
distal ends of the elongate members. At least one of the elongate members is
tubular
and accommodates cabling running to the projector.
The length of the tether may be adjustable to enable the orientation of
the projector assembly to be altered. In this case, the overhead projection
system may
further comprise a level indicator on the projector assembly.
Depending on the environment, the tether may extend between the
projector assembly and an overhead structural ceiling or between the projector
assembly and the support surface. Of course if desired, more than one tether
can be
used to couple the projector assembly to one or more overhead structural
elements.
According to another aspect there is provided a projection system
comprising:
a generally horizontal frame adapted to extend outwardly from a
generally vertical support surface and to support a projector at a location
spaced from
said support surface;
a bracket to which said frame is pivotally coupled, said bracket being
adapted to be secured to said support surface; and
at least one tether connected at one end to said frame and having an
opposite end adapted to be secured to an overhead structural element.
The overhead projection system provides advantages in that since both
the projector assembly and the display screen are coupled to the same mounting
bracket, once mounted the projector assembly and display screen are always
properly
positioned with respect to one another. This avoids the requirement to center
and
otherwise position the projector with respect to the display screen. As a
tether is used
to couple the projector assembly to an overhead structural element, great
flexibility in
installation is provided as the tether may be coupled to any conveniently
placed
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structural element. Also as the A-frame comprises tubular members, the tubular
members provide a conduit for power and data cabling running to the projector.
Brief Description Of The Drawings
An embodiment will now be described more fully with reference to the
accompanying drawings in which:
Figure 1 is a perspective view of an overhead projection system;
Figure 2 is a side elevation view of the overhead projection system of
Figure 1;
Figure 3 is a partial side elevation view of the overhead projection
system of Figure 1;
Figure 4 is a perspective view of a wall bracket forming part of the
overhead projection system of Figure 1;
Figure 5 is a cut-away perspective view of the wall bracket and a
tubular elongate member forming part of a projector assembly;
Figure 6 is a cut-away perspective view of a level indicator and cross-
bar forming part of the projector assembly;
Figure 7 is a cut-away perspective view of a tether and a cross-bar
forming part of the projector assembly; and
Figure 8 is a cut-away perspective view of a turnbuckle on the tether.
Detailed Description Of The Embodiments
Turning now to Figures 1 to 8, an overhead projection system is shown
and is generally identified by reference numeral 20. As can be seen, overhead
projection system 20 includes a generally horizontal projector assembly 22
that
extends outwardly from a generally vertical support structure such as a wall
24. A
touch-sensitive display screen 26, such as that sold under the name SmartBoard
by
SMART Technologies Inc. of Calgary, Alberta, Canada, is also mounted on the
wall
24 beneath the proj ector assembly 22.
The projector assembly 22 comprises an A-frame 30 including a pair
of tubular elongate members 32 and 34. One end of each tubular member 32, 34
is
pivotally coupled to a connector 35 on a wall bracket 36 that is secured to
the wall 24
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by fasteners (not shown). The other ends of the tubular members 32, 34 are
joined
together by a cross-bar 39. Intermediate cross-bars 40 and 41 bridge the
tubular
members 32 and 34 at spaced locations to give the A-frame 30 structural
rigidity. A
pair of spaced rails 42 bridge the cross-bar 39 and intermediate cross-bar 40.
A
projector 44 is secured to the rails 42 by releasable fasteners (not shown)
and is aimed
to project images directly onto the display surface 26a of the touch sensitive
display
screen 26. A level indicator 46 is mounted on intermediate cross-bar 41 to
indicate
visually the orientation of the A-frame 30 relative to the horizontal.
A wire rope tether 50 is attached at one end to a connector 52 provided
on the intermediate cross-bar 40. The other end of the tether 50 is anchored
to an
overhead structural element thereby to support the distal end of the projector
assembly
22. In this example, the tether 50 is anchored to the wall 24 via a drywall
brace 54.
Alternatively as shown in Figure 2 by dotted lines, the tether SO may pass
through the
drop tiles of a suspended ceiling 60 and be anchored to an overhead structural
ceiling
62 at a location intermediate the length of the A-frame 30 or may be anchored
to the
overhead structural ceiling 62 beyond the distal end of the A-frame 30.
A turnbuckle 70 is provided on the tether 50 to allow the length of the
tether as it extends between the A-frame 30 and the drywall brace 54 to be
adjusted.
In this manner, the distal end of the projector assembly 22 can be raised or
lowered as
required to bring the projector assembly into its desired horizontal
orientation. The
level indicator 46 on the intermediate cross-bar 41 provides visual feedback
to
facilitate the above.
The display screen 26 is also mounted to the wall bracket 36 and as a
result, the position of the A-frame 30 and projector 44 with respect to the
display
screen 26 is correctly maintained once the wall bracket 36 is secured to the
wall 24.
This helps to ensure proper registration of the projector 44 and the display
surface 26a
of the display screen 26. In particular, the wall bracket 36 includes an
upwardly
angled support 72 that receives a downwardly angled flange 74 provided on the
back
of the display screen 26.
A personal computer (not shown) executing one or more application
programs is also provided. The personal computer is electrically coupled to
the
display screen 26 and to the projector 44. Power and data cabling running to
the
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projector 44 is accommodated by one or both of the tubular members 32, 34. The
personal computer, touch-sensitive display screen 26 and projector 44 form a
closed
loop to define an interactive display system of the type disclosed in U.S.
Patent Nos.
5,448,263 and 6,141,000 to Martin, assigned to the assignee of the present
invention,
S the contents of which are incorporated herein by reference. Thus, the touch
sensitive
display screen 26 outputs control signals in response to contacts made on the
display
surface 26a of the touch sensitive display screen 26. The control signals are
conveyed
to the personal computer, which uses the control signals to update the
application
program being executed and to update the images provided to the projector 44
for
projection and display on the display surface 26a.
As will be appreciated, the overhead projection system described
above can be easily set up by a very junior installer in a short period of
time while
ensuring registration of the projector and the display surface of the display
screen.
The use of the tether provides the installer with significant flexibility as
regards
selection of the structural element to which the tether is to be anchored
without the
installer having to worry about where the display screen 26, A-frame 30 and/or
projector 44 are located. The tether can be attached to a wall or ceiling at
virtually
any angle subject to the strength of the tether, rigidity of the A-frame and
weight of
the projector.
Although the display screen is described as being a SmartBoard touch
sensitive display screen, those of skill in the art will appreciate that other
types of
touch panels may be used. Also, if a closed loop interactive display system is
not
required, any planar surface including the supporting wall to display images
projected
by the projector may be used.
Although a wire rope tether is disclosed, tethers formed of other
suitable material may be used. Also, more than one tether may be used to
couple the
overhead projector assembly to overhead structural elements.
Although a preferred embodiment has been described, those of skill in
the art will appreciate that variations and modifications may be made without
departing from the spirit and scope thereof as defined by the appended claims.
