FIELD OF THE INVENTION The present invention relates to joint assemblies. In particular, the present invention relates to joints which give multiple degrees of freedom.

BACKGROUND OF THE INVENTION Assemblies for mounting objects such as video or data projectors (e. g. single gun LCD or three gun CRT) and televisions should preferably contain a joint which provide multiple degrees of rotational freedom for proper alignment to be maintained. Prior art assemblies of this type usually give only one or two degrees of rotation freedom, which are adequate for mounting equipment such as loud speakers and television. But for other types of equipment, such as projectors, which require finer spatial alignment, mounting assemblies which give only two degrees of freedom become very tricky to use. Furthermore, prior art assemblies are often complicated, with numerous components involved, making the assembling process tedious and difficult, particularly for a lay-person who wants to Do- it-yourself.

OBJECT OF THE INVENTION It is therefore an object of the present invention to provide a joint assembly which overcome the shortcomings as stated above.

It is another object to provide one embodiment of a joint assembly with two degrees of rotational freedom.

It is another object to provide another embodiment of a joint assembly with three degrees of rotational freedom.

SUMMARY OF THE INVENTION According to the objects of the present invention, there is provided a simple yet versatile joint assembly that offers multiple degrees of rotation freedom to objects attached to opposing sides of the joint. This joint is provided with a cross-shaped attachment member with the first and second arm both having cylindrical ends. A first and a second bracket each with two holes, are rotatably attached to the ends of the first and second arms respectively by fastening members. When the fastening members are not tightly fastened, rotation movements via the longitudinal axes of the respective arms are allowed for the respective brackets. As the two arms are substantially perpendicularly disposed, there are provided two degrees of rotation freedom for an object attached to the first bracket in relation to a second object attached to the second bracket. For a third degree of

freedom, one embodiment provides an additional rotating means which can be attached to one of the brackets.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded view of the preferred embodiment of the present invention.

Figure 2 is a perspective view of the preferred embodiment of the present invention.

Figure 3 is a perspective view of the cross member of the preferred embodiment.

Figure 4A to C are additional embodiments according to the present invention.

DESCRIPTION OF THE INVENTION Figure 1 shows the specific preferred embodiment of the present invention wherein a first bracket 20 and a second bracket 22 are attached to a cross member 24. In this embodiment, the two brackets are identical and are generally saddle-shaped, with a flat base 26 and two lugs 28 extending perpendicularly outwards from the two opposing edges of the flat base. A circular hole 30 is provided on the end of each lug and is adapted for engaging the ends of the arms of the cross member. In this embodiment, the arms are hollow and contain internal threads, such that screws 32 may be used to secure the bracket onto the ends of the arms. For rotation movement of a bracket along the longitudinal axis of the corresponding

arm, the screw may be loosened. For fixed positioning, the screws may be re-tightened after the proper position has been obtained.

For a third degree of rotation, a number of different rotating joints may be attached to one of the brackets. In the example shown in Figure 1, an L-bar 34 with an arcuate end 36 is used to engage the neck 38 of a column 40.

Column 40 has one end attached to the first bracket, with the remaining portion of the column adapted for insertion into a cylindrical member or tube 42. The column is secured within the cylindrical tube by the L-bar, which is attached by a screw 44 to the external surface of the cylindrical tube. The arcuate end 36 of the L-bar may be fitted as a brace around neck 38 through slot 46 of the cylindrical tube. This allows the column to rotate along the longitudinal axis of the cylindrical tube, providing a third degree of rotational freedom.

For mounting equipment which require alignment adjustment along all three axis of rotation, the embodiment as shown in Figure 1 and 2 is ideal.

Attachment means such as holes 48 may be provided on the cylindrical element for attachment onto a ceiling or wall. Fastening means such as holes 50 and screws may also be provided on the second bracket for mounting the equipment. A base plate 52 may also be provided for fastening larger equipment.

Figure 2 shows the specific preferred embodiment and the three axes of rotation. It is clear that using the present embodiment, a piece of equipment may be adjusted by rotation in all directions.

Figure 3 shows a cross member which may be used to practice the present invention. The arms are cylindrical to allow rotational movement of the brackets. The end of each arm has a flange for the engagement of the bracket. If screws are used for tightening the bracket onto the end of the arm, then the cross member should have hollow arms with internal thread.

Alternatively, the threads may be provided externally onto a longer flange, in which case the arms may be solid rods and nuts can be used to secure the brackets.

While the present invention has been described particularly with references to Figs 1 to 3 with emphasis on a joint assembly for hanging equipment from a wall or ceiling, it should be understood that the figures are for illustration only and should not be taken as limitation on the invention. It is furthermore clear that the method and apparatus of the present invention has utility in many applications where rotatable joints are required. It is contemplated that many changes and modifications may be made by one of ordinary skill in the art without departing from the spirit and the scope of the invention described. For example, Figure 4 A to D show additional embodiments according to the present invention. Figure 4A shows a joint assembly which is provided with an additional cable 54 for safety purposes. Figure 4B to C show cross joints which have been modified to appear as a rectangular block 56, a spherical block 58 or a cube 60. It is clear that although these blocks have different shaped, their principe of operation is the same. i. e. to provide functional arms with holes arranged into a cross-shape, such that two brackets may be attached and rotated with two degrees of freedom.