Note: Descriptions are shown in the official language in which they were submitted.
CA 02292989 1999-12-21
METHOD AND APPARATUS FOR SUPPORTING
ONE OR MORE SEAMLESS REAR PROJECTOR SCREENS
FIELD OF THE INVENTION
This invention relates to a method and apparatus for supporting video screens
and more particularly to a retention mechanism for an audiovisual screen or a
plurality of
such screens placed in abutment to form a video display wall.
BACKGROUND OF THE INVENTION
Audiovisual (A/V) systems used in amphitheatres, control rooms or large
conference rooms may be separate systems which can be assembled and
disassembled for
movement between one location and another. Typically these types of
audiovisual systems
include a rear projection screen for viewing and an enclosure unit supporting
the screen and
placing the projector in proper alignment for projection of the video images
onto a mirror
which then directs the images onto the screen.
Often, there is a need for a larger screen than can be provided by one
audiovisual unit. Several units are then placed side by side for an enlarged
viewing surface.
However, due to the supporting structure and cabinetry around the screen of
each
audiovisual unit, there is a framing interruption between the screens of each
unit resulting
in a fragmentation of the projected image which disrupts viewing.
There is a need therefore for an audiovisual system in which the supporting
structure of the audiovisual unit allows for multiple screens to be placed
side by side
resulting in a larger screen area with no apparent gaps or interruptions
between screens, or
ideally in the projected image itself, to give the appearance of one larger
continuous screen.
Where an even larger image is required than can be obtained by placing two
or more A/V units side-by-side, a video wall is constructed consisting of
multiple screens
arranged typically in a rectangular pattern of rows and columns of individual
screens. This
requires a framing system that allows the individual screens to be assembled
together with
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accommodate angular orientations between adjacent screens for a concave
curvature of the
video wall relative to the viewing audience if so desired.
One approach to the problem of framing a video wall is disclosed in U.S.
Patent 5,103,339 dated April 7, 1992. The patented system includes front and
rear brackets
positioned at the front and back surfaces of the abutting screens adjacent to
their vertical and
horizontal edges, the brackets being held together by means of threaded
fasteners passing
between the abutting edges of the screens to connect the front and rear
brackets together.
This system requires the use of numerous discrete parts including the brackets
and the
threaded fasteners and requires considerable assembly time. Moreover, the
front brackets
have a substantial width highly visible to viewers that interrupts the
continuity of the
projected image, nor is the system adaptable for use in connection with
discrete audiovisual
units.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and
apparatus for supporting one or more rear projection screens in a manner
intended to obviate
and mitigate from the disadvantages of the prior art.
It is a further object of the present invention to provide a screen retaining
mechanism that eliminates the gap between adjacent screens when placed in
abutting
relationship to one another.
It is a further object of the present invention to provide a framing and
retention mechanism for video projection screens that minimizes the amount of
assembly
required to place the screens in close abutting relationship.
According to the present invention then, there is provided a system for
retaining a video screen in a frame, comprising a video screen having a front,
a back and a
peripheral edge extending thereabout; frame means for supporting said video
screen along
at least a portion of said screen's peripheral edge, said peripheral edge
including a
continuous notch formed therein, said notch extending partially through said
screen from the
back to the front thereof, said notch being shaped to engage said frame means
to locate said
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screen relative to said frame means; and means for biasing said screen against
said frame
means to hold said frame means in said notch.
According to the present invention there is also provided a system for
retaining a video screen in a frame, comprising a video screen having a front
surface and a
rear surface and a peripheral edge extending thereabout, said screen including
a plurality of
holes formed in said rear surface thereof at spaced apart intervals inwardly
adjacent said
peripheral edge, said holes extending only partially through said screen from
said rear
surface towards said front surface; frame means for supporting said screen
along at least a
portion of said peripheral edge; and a plurality of biasing means extending
between said
screen and said frame means for biasing said peripheral edge of said screen
against said
frame means, each biasing means having a first end connectable to said frame
means and a
second end connectable to said screen, wherein said second end of each said
biasing means
is connectingly received into a respective one of said holes in said rear
surface of said
screen.
According to the present invention there is further provided a method of
retaining a light transmitting screen in a frame defining an opening for said
screen,
comprising the steps of shaping the screen to fit in said frame opening, the
screen having a
front surface and a rear surface and a peripheral edge corresponding in shape
to said frame
opening; forming a notch in said peripheral edge extending only partially
through said screen
from said rear surface towards said front surface thereof, said notch being
shaped to engage
said frame to locate said screen in said opening; and applying a biasing force
between said
frame and said screen so that said screen in held in position in said frame
opening.
According to the present invention there is further provided a method of
connecting a tensioner between a light transmitting screen and a frame
supporting said
screen, said tensioner having a first end connectable to the frame and a
second end
connectable to the screen, the method comprising the steps of forming a hole
in said screen
extending only partially therethrough from the back of the screen towards the
front thereof;
inserting said second end of said tensioner into said hole with adhesive for
bonding said
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second end of said tensioner to said screen; and connecting said first end of
said tensioner
to said frame whereby said tensioner pulls said screen against said frame.
According to the present invention there is further provided a system for
retaining a video screen in a frame, comprising a video screen having a front,
a back and a
peripheral edge extending thereabout; frame means for supporting said video
screen along
at least a portion of said screen's peripheral edge, said peripheral edge
including a
continuous notch formed therein, said notch extending partially through said
screen from the
back to the front thereof, said notch being shaped to engage said frame means
to locate said
screen relative to said frame means; a plurality of spaced apart holes formed
in said back of
said video screen, said holes extending only partially through said screen
from the back to
the front thereof and being spaced inwardly of said notch; and means for
resiliently biasing
said screen against said frame means to hold said frame means in said notch,
each biasing
means having a first end connectable to said frame means and a second end
connectable to
said screen, wherein said second end of each said biasing means is
connectingly received
into a respective one of said holes in said back of said screen.
According to the present invention there is further provided a system for
retaining a video screen in a frame, comprising a video screen having a front
surface and a
rear surface and a peripheral edge extending thereabout, said screen including
a plurality of
holes formed in said rear surface thereof at spaced apart intervals inwardly
adjacent of said
peripheral edge, said holes extending only partially through said screen from
said rear
surface towards said front surface; frame means for supporting said screen
along at least a
portion of said peripheral edge; and a plurality of biasing means extending
between said
screen and said frame means for resiliently biasing said peripheral edge of
said screen
against said frame means, each biasing means having a first end connectable to
said frame
means and a second end connectable to said screen, wherein said second end of
each said
biasing means is connectingly received into a respective one of said holes in
said rear surface
of said screen.
According to the present invention there is further provided a method of
retaining a light transmitting screen in a frame defining an opening for said
screen,
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comprising the steps of shaping the screen to fit in said frame opening, the
screen having a
front surface and a rear surface and a peripheral edge corresponding in shape
to said frame
opening; forming a notch in said peripheral edge extending only partially
through said screen
from said rear surface towards said front surface thereof, said notch being
shaped to engage
said frame to locate said screen in said opening; forming a plurality of
spaced apart holes in
said rear surface of said screen to extend peripherally around said screen
inwardly adjacent
to said notch; and applying a resilient biasing force between said frame and
said screen so
that said screen is held in position in said frame opening by biasing said
notch against said
frame, said biasing force being applied by means of a plurality of tensioning
members, each
of which is connected at one end thereof to said frame and at an opposite end
thereof into
a respective one of said holes in said rear surface of said screen.
According to the present invention there is further provided a frame member
for supporting an edge of a light transmitting screen, said frame member
comprising an inner
portion and an outer portion, said outer portion including a substantially
planar flange having
side surfaces and an outer edge surface adapted to intersect with an engage a
contiguous
edge of said screen, wherein the sides of said frame member taper from said
inner portion
to said flange.
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BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention will now be described in
greater detail and will be better understood when read in conjunction with the
accompanying
drawings, in which:
Figure 1 is a perspective partially cut away view of the screen retention
system of the present invention;
Figure 2 is a reverse angle perspective view of the system of Figure 1;
Figure 3 is a cross-sectional view of one sector of the present retention
system;
Figure 4 is an enlarged view of a portion of the view of Figure 3;
Figure 5 is an enlarged view of a portion of the view of Figure 3 showing a
modified embodiment;
Figure 6 is a perspective view of a screen with monofilament cord connected
thereto;
Figure 7 is a perspective view of dual element screen with monofilament cord
connected thereto;
Figure 8 is a side elevational view of the dual element screen of Figure 7;
Figure 9 is a rear elevational view of a screen with holes for the
monofilaments;
Figure 10 is a cross-sectional view of a modified frame member for the
present system; and
Figure 11 is a cross-sectional view of the frame member of Figure 10 with
an extrusion trim connected thereto.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to Figure 1 of the drawings, one embodiment of the present
invention comprises a screen retention system ideally suited for a large
screen display
system consisting of a plurality of rear projection screens arranged in a
pattern of rows and
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columns. For purposes of illustration only, in one example contemplated by the
applicant,
eight screens are configured two high by four wide with each screen being 84
inches across
its diagonal. The screens themselves will typically be cleanable, graphite
gray density
acrylic for a high contrast ratio. The screens may be fresnel-lenticular
construction,
diffusion or other types for high resolution, color corrected images.
As mentioned above, the problem with multiple screen video walls to date
has been frame interruptions between the individual screens. To virtually
minimize such
interruptions, the applicant has developed a system in which adjacent screens
abut one
another directly with no intervening frame means and wherein the screens are
held in place
against a structural framework by means of tension applied through springs and
cords.
Referring now to Figures 1 to 3, individual screens 10 are shown supported
against a structural framework 15. The framework can be metal, wood, plastic
or any other
material having the strength to provide sufficient rigidity and to support the
weight of
however many screens are to make up the video display wall. In one embodiment
constructed by the applicant, the framework is made of extruded aluminum frame
members
20. The extrusions can be manufactured inexpensively as a continuous
extrusion, preferably
from aluminum, and cut to the required lengths for constructing the frame
matrix.
The frame members themselves consist of a rectangular inner section 21 and
an outer section 22 that tapers forwardly to merge into a forwardly extending
flange 23 with
a shoulder 25 that extends along the length thereof.
The peripheral edge of each screen along its rear surface is notched to form
a locator notch 30 best seen in the enlargement of Figure 4. With two screens
abutting one
another, the locator notches combine to form a larger rectangular notch 31 for
engaging the
outer end of flange 23. Flanges 23 therefore extend completely around the
peripheral edge
of each screen so that the weight of each screen is supported by framework 15
and the
screens themselves form no part of the supporting structure, nor do they
connect to or
support one another. Nevertheless, the screens touch or come close to touching
all along
their connecting sides to form gapless, hairline joints without any framing
interruptions.
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To hold the screens against framing members 20 and particularly against
shoulders 25 on flanges 23, the screens are pulled or biased into place. With
reference to
Figures 3 and 4, frame members 20 are fitted with a plurality of spaced apart
pins 37 which
anchor one end 41 of a tension spring 40. The spring's other end 42 is hooked
to form a crux
which captures, for example, a knot at one end of a loop of cord 50. The other
end of the
looped cord is attached to the lens. One means of accomplishing this is to
solvent weld the
cord into a pilot hole 55 drilled partially through the lens from its rear
surface. The cord 50
is preferably nylon monofilament which, because of its translucent nature,
will transmit at
least some light to minimize any shadowing. The solvent used to weld the
monofilament
to the lens should also be carefully chosen for its strength and its light
transmitting
properties. A suitable solvent used by the applicant is CA 50 from the 3M
Company. The
solvent can be added to the pilot holes using a syringe prior to insertion of
the monofilament.
Enough adhesive is added so that upon insertion of the monofilament, the
surface of the
adhesive rises preferably no higher than to the level of the screen's rear
surface. The pilot
holes themselves can be drilled to a depth of approximately two-thirds of the
thickness of
the screens using a No. 60 drill bit.
This method of connecting the monofilament to the screen is particularly
preferred in a single element screen system.
In some applications, a dual element screen, for example separate lenticular
and Fresnel lenses layered together, is used. Figure 7 and 8 illustrate a
method of connecting
the monofilament to a dual element screen, and it will be appreciated that
this same method
can be used for single element screens, or screens having more than two
elements.
As shown in Figure 7, a pair of side by side holes 55 and 56 are formed in
alignment through juxtaposed screens 9 and 10. The monofilament is run in
through holes
55, out of holes 56, it's then looped back in through holes 55 and back out
through holes 56
and tightened as shown in Figure 8 to hold the two screens together. This
method has the
added advantage that the monofilament can be loosened and the screens
separated to allow
for the use of some padding between the lenses during shipping and handling.
When
connected to springs 40, the monofilament is self-tightening.
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As will be appreciated, if shadowing of the screens is less of a concern, more
direct methods can be used to pull the screens against the framing members.
For example,
small hooks can be attached to the pilot holes by threads or glue, and longer
springs can be
used that extend the distance between pins 37 and these hooks. Cord or wire
can be used
in place of a spring/cord combination, or a spring alone. Strong elastics,
like bungee cords,
can also be substituted. If the screen is held in place by a system that does
not include a
resilient tensioning member such as a spring, care should be taken to balance
or equalize as
best possible the amount of biasing force exerted by each cord or wire or
whatever means
is used.
With reference once again to Figures 3 and 4, the tapering of the outer
portions 22 of members 20 and the width of shoulders 25 is selected so that
light from
adjacent projectors, indicated diagrammatically by broken lines 71 and 72, can
converge just
behind or at the front surfaces of the screens so that there is little or no
shadowing of the
projected images by the structural components.
The incorporation of a shoulder 25 on flange 23 is optional. The enlargement
of Figure 5, in which like numerals are used to identify like elements, shows
the connection
of the screens to flange 23 without the use of a shoulder.
Figure 9 illustrates the placement of the pilot holes 55, or pairs of holes
55,
56, for connection of the monofilaments. Holes are closely spaced into the
corners of the
screen and the remaining holes are formed, for example, at 12 inch intervals
along the
screen's edges. Good results have been obtained using 0.020" diameter
monofilament cord
and miniature tempered high carbon steel springs.
Figure 10 illustrates a modified extruded aluminum frame member 120. In
this figure, like reference numerals are used to denote like elements. This
modified member
consists of the same basic configuration as member 20 and includes a
rectangular inner
section 21, forwardly tapering outer section 22 and a forwardly extending
flange 23. Inner
section 21 includes along its rear surface 124 a pair of longitudinally
extending slots 125 that
are used to engage ends 41 of springs 40 in place of pins 37. The inner
section additionally
includes a number of longitudinally extending T-slots 128, recesses 129 and
apertures 130
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and 131 useful for example for hardware used to connect the frame members into
a screen
supporting framework, to reinforce the framework's rigidity and to connect the
framework
to surrounding cabinetry.
For example, aperture 130 is adapted for the insertion of a squared tubing 155
(broken lines) that aligns and connects the frame members together and that
also prevents
rotational movement of one member relative to the next. A small longitudinally
extending
groove 133 in outer surface 135 of the frame member can serve as a pilot for
holes drilled
for fasteners (not shown) that secure the squared tubing to the frame member.
Another means of providing a torsionally resistant connection between
adjacent members is by means of a sheet metal spline 160 shown by dotted lines
in Figure
11 received into notches 137 and 138 inside forward section 22 of the frame
member.
Groove 139, like groove 133, serves as a convenient tap to spot holes drilled
for fasteners
to secure the spline to the frame member.
As will be seen, flange 23 can be elongated compared to the corresponding
flange shown in Figure 4. Nor does the flange include a shoulder 25. This
longer flange
therefore spaces the screen's 10 further forward relative to frame sections 21
and 22 and the
notches 30 in the screen edges bear directly against the flange's tip 134. The
flange is also
ribbed as shown at 136. These ribs function to reflect back any light that
strikes them
instead of reflecting forwardly which might interfere with the projected
image.
With reference to Figure 11, frame member 120 is shown in combination
with a trim extrusion 150 useful to close the gap between the assembled
screens and the
customer's wall. Trim strip 150 includes a flange 152 that hooks into one of
notches 140
in forward section 22 of the frame member, and a small rib 144 that slots into
one of
recesses 129 as shown for registration and alignment purposes. Holes can be
drilled at
points 153 and 154 for as many spaced apart fasteners as are required to
securely connect
the trim strip to the frame member along their respective lengths.
The above-described embodiments of the present invention are meant to be
illustrative of preferred embodiments and are not intended to limit the scope
of the present
invention. Various modifications, which would be readily apparent to one
skilled in the art,
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are intended to be within the scope of the present invention. The only
limitations to the
scope of the present invention are set forth in the following claims appended
hereto. As well
the present system can be used for mounting and retaining members other than
video
screens. Examples include other light transmitting panels, opaque plates,
decorative plates
or panels or members of virtually any kind.
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