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1. WO2006096962 - OVERHEAD PROJECTION SYSTEM

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[ EN ]

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, hi 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, hi 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 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.

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 generally 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, m 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 vertical 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 frame structure 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 to orient said frame structure.
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 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
Embodiments 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 proj ection 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 crossbar 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 proj ector 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 projector 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 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 50 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 above or 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 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 similar to that disclosed in U.S. Patent Nos. 5,448,263 and 6,141,000 to Martin, assigned to the assignee of the present invention, 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 proj ector 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.