BACKGROUND OF THE INVENTION Air conditioning systems operate in most major buildings throughout the world. As well as changing the temperature of the air that circulates throughout the building, air conditioning systems also function to remove airborne impurities such as dust, pollen, smoke and other microscopic particles. This is achieved through the use of air conditioning filters.

Air conditioning filters are positioned with air condition vents so any air that passes through the vents must also pass through the air conditioning filter. Commonly, in a ten-storey building there are at least 4 filter banks that comprises up to 100 air conditioning filters in each filter bank. Air condition filters are normally changed quarterly, half-yearly or annually depending on the requirements of the building.

Each air conditioning filter is held in position using a support that holds a mouth of the filter in an open position to allow air to pass through the air conditioning filter. A frame, attached to the support, extends inside the filter to hold the filter in an upright position to enable the largest surface area for airborne impurities to be caught by the air conditioning filter.

To install each air conditioning filter, the frame needs to be removed from the support with the air conditioning filter. The air conditioning filter is then replaced and a new filter is carefully placed over the frame taking care not to tear the air conditioning filter. The frame is then replaced over the support making sure that the mouth of the air conditioning filter extends the periphery of the support. This is a very time consuming process.

Air conditioning filters are often produced using sheets of heat bonded polyester fibres. This sheeting is cut to a desired shape and sewn together to produce air conditioning filters. The problem with producing air conditioning filters in this manner is that it is both labour intensive and time consuming.

Further, air conditioning filters that are produced using heat bonded polyester fibre matting are typically white. Therefore, different grades of filters that are produced for different applications cannot easily be differentiated from each other. To overcome this problem the polyester fibres have been dyed different colours to distinguish different grades.

However, this impedes visual inspection of the air conditioning filter for impurity build-up. Also, if the polyester fibres are recycled, the dye must be removed and discarded which is not environmentally friendly.

OBJECT OF THE INVENTION The object of the invention is to overcome or alleviate one or more of the above disadvantages to provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION In one form, although not necessarily the only or broadest form, the invention resides in a filter for use in an air conditioning system comprising: a plurality of sheets of filter media; and at least one structural element, said sheets of filter media and said structural element being secured together at a join; wherein said structural element provides structural rigidity to said sheets of filter media at said join.

The sheets of filter media may be constructed of any suitable material. Normally the filter media is constructed from a series of intertwined and/or interlinked fibres. The fibres may be cellulous fibre or plastics fibre or the like. Normally, the fibres are polyester fibres or paper fibres.

Preferably there are two or three sheets of filter media that are used to produce the air conditioning filter.

The structural element may be made of any suitable material such as metal or plastics. The structural element may be a plastics strip or a metal wire or combination thereof.

The structural element may be secured to the sheets of filter media through the use of an adhesive.

Alternatively, the structural element may be solely adhesive.

Still alternatively, the structural element may be fused to the sheets of filter media. The structural element and/or filter media may be heated to join the sheets of filter media together. The structural element and/or filter material may be heated using die electric welding. High- Frequency or Radio Frequency welding may be used.

The structural element may be provided between the sheets of filter media or only one side of the sheets of filter media.

The structural element may be coloured. Preferably, the structural element is coloured to represent the grade of filter media used.

In another form, although not necessarily the only or broadest form, the invention resides in a method of manufacturing a filter including the steps of: placing a plurality of sheets of filter media adjacent each other; and securing said sheets of filter material to a structural elements to form a join having structural rigidity.

In another form, the invention resides in an air conditioning filter system comprising: at least one air conditioning filter having a mouth and a body; a support onto which a mouth of an air conditioning filter is secured; and securing means to hold said air conditioning filter to said support; wherein the securing means does not substantially extend past the support into the body of the air conditioning filter.

The air conditioning filter may be the same as the air

conditioning filter as described above.

The support may be a rectangular surround that is currently used in air conditioning units.

The securing means may include a frame that can be located within the mouth of the air conditioning bag and also attached to the support.

The frame may be attached to the support using a plurality of clips. The clips may releasably engage the frame and air conditioning filter.

The securing means may also include a joinerwhere more than one air conditioning filter is attached to the support. The joiner may join the air conditioning filters together and assist in securing them to the frame.

The joiner may include two retention members and a plurality of clasps. The retention member may engage the two adjacent air conditioning filters. The clasps may be used to hold the retention members adjacent each other thereby causing the retention members to hold the air conditioning filters. Each retention member may include locating portions that attach the retention member to the frame.

In another form, the invention resides in a method of installing an air conditioning filter with an air conditioning filter system including the steps of: locating a mouth of an air conditioning filter to a support; securing a securing means to said air conditioning filter to secure said mouth of the air conditioning filter to said support.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention, by way of example only, will be described with reference to the accompanying drawings in which: FIG. 1 is a perspective view of an air conditioning filter, adjacent a support, in an expanded position; FIG. 2 is a perspective view of the air conditioning filter of FIG.

1 in a collapsed position; FIG. 3 is a side view of an air conditioning filter of FIG. 2; FIG. 4 is a top view of an apparatus for the production of air conditioning filters as shown in FIG. 1;

FIG. 5 is a perspective view of a platen of the apparatus of FIG. 4; FIG. 6 is a perspective view of an alternative platen of the apparatus of platen of FIG. 4; FIG. 7 is a partial perspective view of the platen of FIG. 6; FIG. 8 is a perspective view of an alternative air conditioning filter ; FIG. 9 is a partial perspective view of a join of an air conditioning filter ; FIG. 10 is an alternative partial perspective view of a join of an air conditioning filter ; FIG. 11 is a perspective view of an air conditioning filter system according to an embodiment of the invention ; FIG. 12 is a perspective view of a support of the air conditioning filter system of FIG. 11; FIG. 13 is a further perspective view of a support of the air conditioning filter system of FIG. 11; FIG. 14 is a perspective view of a clip used with the support of FIG. 13; FIG. 15 is a partial side section view of the support of FIG. 12; FIG. 16 is a perspective view of a connecter of the air conditioning system of FIG. 11; FIG. 17 is a partial perspective view of the connector of FIG. 16 in situ; FIG. 18 is a further partial perspective view of the connector of FIG. 16 ; FIG. 19 is a further perspective view of the connector of FIG. 16; and FIG. 20 is a perspective view of an air conditioning filter according to a further embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFFERRED EMBODIMENT FIG. 1 shows an air conditioning filter 10 adjacent a support 11

that is located within a vent (not shown) of an air conditioning system (not shown).

The air conditioning filter 10 comprises a body 12 that filters impurities from the air and a mouth 13 that is used to attach the air conditioning filter 10 to the support 11.

The air conditioning filter 10 is manufactured using three sheets of head bonded polyester fibre. The three sheets of polyester fibre are fused together using six high-density polyethylene strips to form six joins 14. The joins 14 are located at the periphery of the air conditioning filter 10. This forms the body 12 of the air conditioning filter. The mouth 13 is formed from unfused edges of the sheets of filter media.

The six high-density polyethylene strips form two substantially C-shaped structures that provide structural rigidity to the filter media. The C- shaped structures hold the filter media in a desired configuration so that when they are attached to the support 11 they cause the body 12 to be held in an open and upright position without any additional support. This allows the maximum area of filter media to capture air borne impurities as they flow through the air conditioning system.

FIG. 4 shows an apparatus 30 used to manufacture the air conditioning filters shown in FIG. 1. The apparatus 30 includes three rolls 31,32 and 33 of sheet filter media that are fed into a press 34 to produce air conditioning filters 10.

The rolls of sheet filter media are orientated so that the second roll 32 and third roll 33 of sheet filter are rolled onto the first sheet of filter media. The first roll 31 of sheet filter media is over double the width of the second roll 32 and third roll 33 of sheet filter media.

The press 34 includes a rotatable platform onto which four bottom dies 35 are mounted. A single top die (not shown) is mounted to a reciprocateable ram (not shown).

The bottom die 35, shown in FIG. 5 and FIG. 7, includes a seat 36 on which the strips of high-density polyethylene strips are placed and a blade 37 to cut the sheets of filter media. A channel 38 is provided within the

seat 36 for location of the strips. The top die (not shown) is a similar configuration to the bottom die 35 except the blade mirrors the entire periphery of the completed air conditioning filter. The top and bottom dies also provide high frequency die electric welding through the seat 36.

The apparatus 30 is operated by loading the bottom die 35 with high-density polyethylene strips in the channels 38. The platform is rotated until the bottom die 35 is located underneath the sheets of filter media. The top die is then bought down until the filter media and strips are held between the seats 36 of top die and bottom die 35.

The high frequency die electric welding is then activated. This causes the polyethylene strips and filter media to melt together. The seat 36 is then cooled to solidify the polyethylene strips and filter media. Joins 14 are thus formed that have structural rigidity. FIG. 9 shows the finished join 14 that is formed.

The high-density polyethylene strip is coloured to reflect the grade of the filter medium that is used. This provides a clear indication to a user of the capabilities of the air conditioning filter. However, it does not interfere with the recycling process as the remainder of the filter remains white.

FIG. 6 shows a variation on the bottom die 35A that may be used. This produces a rectangular shaped join 14 as shown in FIG. 10.

However, the same manufacturing process is used. Similarly, a different profiled seat can be used to obtain the air conditioning filter 10 of FIG. 8.

When the joins 14 have been formed, the top die is pressed down further to cause the filter material to be cut adjacent the join by the blade 37. The air conditioning filter 10 is then removed from the die. At this stage, the air conditioning filter is as shown in FIG. 2 and FIG. 3. The air conditioning filter 10 can therefore be transported easily as it is substantially flat.

It should be appreciated that the various other method and materials may be used to form a join within the filter media that provides structural rigidity. For example, wire may be placed between the sheets of

filter media and an adhesive may be applied to obtain the join. Alternatively, the sheets of filter material may be heated to encapsulate the wire. Still alternately, the wire may be plastic coated and heated so that the plastic coating and sheets of filter material become fused. In another alternative, only adhesive is applied to the sheets of filter media. However, the cured adhesive is rigid to give the join structural rigidity.

FIG. 11 shows a pair of air conditioning filters 10 attached to the support using securing means 40. The securing means 40 includes a pair of clips 41, a rectangular frame member 42 and a joiner 43.

Each clip 41, shown in detail in FIG. 14 includes, an attachment portion 44 and a depressible portion 45. The attachment portion 44 locates the clip 41 onto the support 11 as shown in FIG. 13. The depressible portion 45 causes a channel 46 of the clip 41 to capture or release the frame member 42 from the clip 41. FIG. 12 shows the frame member 42 being captured by a pair of clips 41.

Referring to FIG. 15, the air conditioning filter 10 is secured to the support 11 by placing the frame member within the mouth 13 of the air conditioning filter 10. The frame member 42 and air conditioning filter 10 are then placed within the channel 46 of the clip 41 by depressing the depressible portion 45. The depressible portion 45 is depressed to allowthe air conditioning filter 10 to be removed with the frame member 42.

FIGS. 16-19 show details of the joiner 43. The joiner includes a pair of retention members 47 and a pair of clasps 48.

Each retention member 47 is made from an elongate metal strip. Locating portions 49 are positioned at each end of each retention member 47. The locating portions 49 mate with the frame member 42 to hold the joiner 43 to the support Recesses 50 are located along the length of the retention members to accommodate the clasps 48.

To secure adjacent air conditioning filters 10 together, the retention members 47 are positioned along mouths 13 of respective air conditioning filters 10. The clasps 48 are then placed over the retention members 47 within the recesses 50 to hold the air conditioning filters 10

adjacent each other. The locating portions 49 are then positioned on the frame member 42 to hold the joiner to the support.

FIG. 20 shows a variation of the air conditioning filter 10. In this embodiment the air conditioning filters 10 have been made so that the mouths of the air conditioning filters 10 are smaller than those shown in FIG 1. This allows for a larger filter area for air passing through the air conditioning system.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention.