Field of the Invention

[0001] The present invention relates to a collapsible ladder.

Background of the Invention

[0002] Ladders are ubiquitous and have been known for millennia. The devices are used to access areas at height. In modern times their typical uses include decorating, loft access, construction and repair.

[0003] For the casual DIY user who may only use a ladder sporadically two factors will be important in ladder choice, safety, and storage.

[0004] Ladder storage issues increase with the size of the ladder, traditional would be non-trivial. The user would require at least a folding ladder and these are bulky to store. Furthermore traditional two legged ladders can be dangerous, and care must be taken to keep the ladder steady, often with a second person required to hold the ladder still at the bottom. [0005] Current ladder designs even if three or four legged do not negate this requirement as they are still unsteady, especially due to the popularity of light weight construction materials such as aluminium.

[0006] When a person is at height on an aluminium ladder the centre of gravity may be high due to the light weight nature of the ladder. This increases the chance of falls and accidents.

[0007] Furthermore the use of equipment up ladders is difficult, especially if the equipment needs to be temporarily stowed at the top of the ladder. On traditional two leg ladders there is no surplus area to place a paint pot or drill, this again increases the risk of working at height. Summary of the Invention

[0008] The present disclosure relates to a collapsible ladder that advantageously may collapse to a small cross section while providing a stable ladder. Advantageously embodiments may comprise more than two legs where by the ladder adopts a more stable conformation.

[0009] According to a first aspect there of the present invention, there is provided a collapsible ladder comprising; at least two legs each having two ends; at least one step; and a crown wherein; one end of each leg is attached to the crown and; at least one leg is adjustably attached to crown such that it may rotate relative to the crown, and; the at least one step is adjustably attached to at least one leg such that it may rotate from a position substantially in line with the leg to a position substantially perpendicular to the leg characterised in that; the at least one step may removeably attach to the at least one other form a ladder.

[0010] Suitably the ladder comprises three or more legs wherein each leg prises either steps or step attachment and detachment means wherein the legs are arranged with the steps or step attachment and detachment means complementary to each other.

[0011] Preferably the legs comprise a bend arranged toward the crown such that after the bend the legs, when the ladder is erect, are substantially parallel.

[0012] Alternatively the crown comprises a stop wherein the legs may not rotate past the stop. [0013] Preferably the ladder comprises a plurality of steps, wherein said steps are stowable within a leg.

[0014] Suitably the plurality of steps, when stowed, are nested within each other.

[0015] Potentially the legs further comprise temporary leg attachment means, such that when the ladder is collapsed the legs attach to each other.

[0016] Suitably the at least one step is inclined away from the deployed ladder such that a user leans toward the ladder when the user is upon the at least one step.

[0017] Preferably the ladder comprises feet attached to the legs. [0018] As such the feet may further comprise leg length adjustment means.

[0019] Suitably the at least one step that may removeably attach to the at least one other leg comprises a safety lock to prevent accidental step detachment. [0020] Alternatively, the at least one other leg, for receiving at least one step that may removeably attach to the at least one other leg, further comprises a safety lock to prevent accidental step detachment. [0021] A collapsible ladder as depicted in the figures.

[0022] Other aspects are as set out in the claims herein.

Brief Description of the Drawings

[0023] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 illustrates a front plane of the folded ladder.

Figure 2 illustrates a front plane of the un-folded ladder.

Figure 3 is a close up of a front plane of the apex of the folded ladder.

Figure 4 is a close up of a front plane of the apex of the unfolded ladder.

Figure 5 is an illustration of the connection of a ladder leg to the ladder crown.

Figure 6 illustrates a cross section through the folded ladder.

Figure 7 illustrates a 4 legged embodiment of the unfolded ladder.

Figure 8 is a plan view of a 4 legged embodiment of the folded ladder. Figure 9 is a plan view of a 4 legged embodiment of the unfolded ladder.

Figure 10 is a cross section of a leg of the ladder. Figure 1 1 is a side view of a cross section through a leg of the ladder.

Figure 12 is a side view of a cross section through a leg of a second embodiment of the ladder. Figure 13 is a side view of a leg of the ladder illustrating the deployment of a step.

Figure 14 is an illustration of the step locking mechanism of the ladder. Detailed Description of the Embodiments

[0024] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[0025] Referring to figure 1 , there is provided a ladder (101 ) in an unfolded form. The ladder comprises at least two elongate primary legs (102, 103) for supporting the ladder when in use. The legs may be hollow or of a C, U or other suitable cross section required to house further parts when in storage. It will be clear to one skilled in the art that a plethora of other cross section designs are available.

[0026] The ladder is further equipped with a crown (104) located at the top of the legs. The crown is fixed (105) to the legs such that the legs may rotate about the crown from a stowed position to a deployed position. The fixing illustrated here is of the hinge type, although it will be apparent to one skilled in the art that other alternative fixings may be used. [0027] Spaced apart down at least one of the legs are fixings (106) for steps such that the steps may be stowed within the leg and then unfold out when the leg is deployed. At least one other leg comprises attachments to receive the steps when deployed. [0028] Preferably the ladder is constructed from a lightweight and strong material such as aluminium. However it will be clear to one skilled in the art that a multitude of other suitable materials are available, including, but not exclusively, wood, polymers and other metals. [0029] Figure 2 illustrates the ladder of figure 1 in a deployed position.

[0030] The elongate legs (201 , 202) have both been rotated about the crown (203) in opposite directions to provide an "A" frame ladder arrangement. The steps (204) have been unfurled from the at least one leg (202) where the steps are stowed and the steps have been fixed to the leg with a step receiving fixing (201 ). The steps are of different lengths according to their location along the ladder, with the steps furthest from the crown having the greatest length in order to provide an "A" frame. [0031] It will be clear to one skilled in the art that a bend could be provided at a point in the legs such that the steps of constant length are provided. The resulting ladder would have largely parallel legs but terminate at a point at the crown reminiscent of an obelisk. [0032] The bend could be motile in order to facilitate compact storage of the ladder. [0033] Figure 3 illustrates the crown (301 ) to which the legs (302, 303) are adjustable fixed to. The crown consists of at least two leg attachments (304, 305). It will be apparent to one skilled in the art that only one leg must be adjustable attached, the second leg may be immobile relative to the crown.

[0034] Where a leg is mobile relative the crown, the crown is provided with a stop (306) such that the leg may only rotate to a predefined maximum angle in order to ensure a stable deployed ladder configuration is achieved. [0035] Figure 4 illustrates the stop (401 ) in action against the deployed legs

(402, 403). The legs have been rotated about their attachment points (404) relative to the crown (405). The legs are free to rotate up to the point where the stop engages with the top of the legs where upon the legs are unable to rotate further. [0036] Figure 5 illustrates one potential fixing method of a leg to the crown.

The crown (501 ) is equipped with a through hole (502) for engagement with a bolt (503).

[0037] The leg (504) is equipped with a corresponding socket (505) to engage with the leg. The socket comprises a through hole (506) to also accept a bolt to fix the leg and the crown together.

[0038] It will be apparent to one skilled in the art that the crown may comprise a socket which the leg attaches to instead. Furthermore, one skilled in the art will be aware that a number of suitable motile fixings are available, including but not exclusively sliding mechanisms, rivets and memory-shape metal.

[0039] Figure 6 depicts a cross section through a four-legged embodiment of the ladder. The four legs (601 , 602, 603, 604) are in a stowed position (605), with the steps (606) stacked "Russian-Doll" style within. [0040] The legs comprise an enclosed box portion (607) with engagement means (not shown) to receive the steps from an adjacent leg when in a deployed position. Each leg further comprises an open portion (608) in a C or U cross section where the steps are attached. The steps are rotatable about their attachments (not shown) such that the legs may move from a stowed position to an "in use" position. The legs sit, when in storage, within one another such that the ladder may fold down to a minimum size. It will be apparent to one skilled in the art that a folding ladder may still be achieved without the legs storing within each other, but it is preferable that such an arrangement is used.

[0041] As such, in order for the legs to unfold correctly they are of decreasing step width, such that the broadest step (609) is most rearward when stowed, and the narrowest step (610) foremost when stowed. When the ladder is deployed this means that the broadest step is located at the top of the ladder (closest to the crown) and the narrowest step at the bottom of the ladder (furthest from the crown). Advantageously, this arrangement provides increased stability for a user as they ascend the ladder. As their position becomes more precarious, the steps increase in breadth and provide increased stability and reassurance to the footing of a user.

[0042] The steps are of a C or U cross section, although it will be apparent to one skilled in the art that I shaped steps may also be used along with other suitable configurations. [0043] The C and U style configurations are advantageous in that they provide the step with extra strength and increased load bearing capacity.

[0044] The cross section of the step may be unequal, with one edge (61 1 ) longer that another (612) with the foot plate (613) of the step at an angle that is inclined away from the centre (614) of the deployed ladder, such that a user, when on the deployed ladder naturally leans in towards the centre of the ladder. This minimizes the potential of a user slipping off a step. [0045] Fixing means (615) may also be provided between the legs in order to facilitate easy stowing of the ladder. For example, each leg may be equipped with magnets (615) such that each adjacent leg is equipped with a complementary magnet. As such an attractive force is created that holds the legs together when in the stowed position. It will be apparent to one skilled in the art that other temporary fixing means are available such as, but not exclusively, Velcro™, string, zip-ties, and mechanical catches. [0046] Figure 7 shows a partially deployed 4 legged embodiment of the ladder (701 ). The ladder may also function with different numbers of legs. Two narrow legs are the minimum required to form a ladder suitable for climbing. (A stable two legged ladder that may stand up without the support of an external item such as a wall, may be achieved by using very broad or triangular legs, however such an embodiment is not preferred due to the increased size of the device which has a detrimental impact on easy storage.) Three narrow legs are the minimum required number of legs to form a ladder that may stand alone unaided. The erect ladder would take the form of a tetrahedron. [0047] The ladder depicted in figure 7 forms a square based pyramid when erect. It is equipped with feet (702), which may be capped with a soft material to prevent damage to the substrate upon which the ladder is placed. Once possible material could be rubber or any other suitable plastic. [0048] The four legs (703, 704, 705, only three visible) are deployed, rotated relative to the crown (706) about their fixings (707) until they top of each leg engages with the stop (708) located on the cap (706).

[0049] Each step (709) is unfolded from their respective storage location in each leg and engages with the corresponding adjacent leg (710). Such engagement may comprise a hook for latching onto a lip. The location of the hook or lip can be on either the step or the leg. It will be apparent to one skilled in the art that other engagement means are available.

[0050] The legs are further equipped with temporary binding means (71 1 ) (such as but not exclusively magnets) to facilitate easy storage of the ladder. The temporary binding means prevent a leg deploying when in transit or when the ladder is being maneuvered into position. Preferably the temporary fixing means is located towards the bottom to the ladder away from the crown to minimize any lever effect which may facilitate the disengagement of the temporary fixing means. As such the legs should not deploy at a time not desired by a user.

[0051] Advantageously, the four legged embodiment provides a very stable ladder. A second person is not required to hold the base of the ladder as required in the prior art. As steps are provides on all four faces of the square based pyramid multiple users may climb each face safely and work independently or cooperate effectively together.

[0052] A pair of such ladders may also form a stable platform to work off if a solid substrate (such as but not exclusively, a scaffolding plank or aluminium platform) is placed between two corresponding steps from each ladder.

[0053] Figure 8 provides a plan view of the crown (801 ) of the four legged embodiment of the ladder. As such it takes the form of a cross shape comprising 4 wings (802, 803, 804, 805) where each leg may be attached to each wing using by way of non-limitative example, nuts and bolts (806). If the legs are generally square, then each wing of the crown may engage at the centre point of each square, preferably such that the legs may stack neatly together to take up the minimum surface area providing a compact ladder when folded up. [0054] Figure 9 illustrates the ladder of figure 8 in a deployed position. Each of the steps (901 ) are deployed from the leg in which they are stored and affixed to the appropriate corresponding leg (902, 903, 904, 905). The stable square base of this embodiment is visible in this conformation with the crown (906) located at the centre of the square base.

[0055] In other embodiments, the crown may be constructed such that each leg may rotate to a different degree, or where the legs are of unequal length. As such a non-central crown (offset relative to the centre of the base) may be achieved when the ladder is deployed. Such an embodiment may be advantageous in designing a folding ladder to access awkward spaces. [0056] Figure 10 depicts a cross section through the lower part of a deployed ladder leg. The leg (1001 ) in equipped with a rubberized foot (1002) to prevent marking of a substrate on which the ladder is placed.

[0057] The foot may be provided with a level adjusting device (1003). This device may be used to adjust the ladder leg length to provide a sure footing, preventing the ladder from wobbling when deployed upon an uneven substrate.

[0058] Such a leveling device may take the form of a circular disc (1004) connected to a screw (1005), which when turned engages with a thread in the foot or leg. The turning of the screw in one direct causes the disc to protrude from the base of the leg allowing the leg length to be adjusted. Rotation of the disc in a second, opposite direction causes the disc to return to a stowed position.

[0059] It will be apparent to one skilled in the art that other leveling means may be utilised.

[0060] The leg is also shown having a step (1006) engaged. The step is attached to an adjacent leg, such that when stowed, the step is stored in the adjacent leg (not shown). When the step is deployed and engaged with the leg (1001 ), a lip (1007) on the step hooks over a slot (1008) in the leg providing support to the step ready for use. [0061] Figure 1 1 depicts how the bottommost step (1 101 ) (furthest from the cap) is rotate ably attached to a leg (1 102). The step in this figure is deployed and is in a substantially perpendicular position to the length of the leg. A through bolt (1 103) is used to attach the step to the leg. However it will be apparent to one skilled in the art other attachments may be used.

[0062] Spacers (1 104) are used to ensure the step is restricted to a fixed position within the leg and as such the step may not move laterally across the width of the leg. Such a spacer may, but not exclusively, be a washer or nylon sleeve. The sleeve or washer may facilitate the easy rotation of the step, and may suitably function as a lubricant.

[0063] Figure 12 depicts the attachment of other steps (1201 ) to a leg (1202) of the ladder. The step is any of the steps above the bottom most step (the step depicted in figure 12 is closer to the crown than the step depicted in figure 1 1 ). The step in this figure is deployed and is in a substantially perpendicular position to the length of the leg.

[0064] A pair of bolts (1203, 1204) are used to rotatably attach each side of the step to the leg. As such there are two complementary rotatable connections between the step and the leg. A single connection may be used but it will be apparent to one skilled in the art that at least two connections provide a more secure step attachment. [0065] A "straight through" connection may be used, however this is not a preferred embodiment as it would present a barrier to a subsequent step residing within the present step. This would prevent the ladder from adopting an optimum stowed volume (minimum volume). The use of a connection means that allows the centre of the step to be hollow allows other steps to reside within that step when stowed. [0066] Spacers (1205, 1206) are used to ensure the step is restricted to a fixed position within the leg and as such the step may not move laterally across the width of the leg. Such a space may, but not exclusively, be a washer or nylon sleeve. The sleeve or washer may facilitate the easy rotation of the step, and may suitably function as a lubricant.

[0067] Figure 13 depicts the deployment of a step (1301 ) from a leg (1302) (or vice versa, the stowing of a step into a leg). The step rotates about its leg attachment point (1303) from a deployed, substantially horizontal position relative to the substrate upon which the ladder is placed, to a stowed position wherein the step resides within the leg.

[0068] Figure 13 also depicts the end of the leg, and shows how the end may be chamfered (1304) with a foot (1305) attached to allow the leg to present a substantially horizontal face to the substrate upon which the ladder is placed to ensure a stable footing. It will be apparent to one skilled in the art that other designs of leg end may be employed.

[0069] Figure 14 shows a step (1401 ), deployed from the leg to which it is attached (not shown) about to be engaged with an adjacent leg (1402). In this embodiment, the step comprises a lip (1403) to be engages with an aperture(1404) on the adjacent leg. The aperture is appropriately just large enough to allow the step to engage. [0070] The aperture comprises a tooth (1405) located to the rear of the aperture (closest to the centre of the deployed ladder). As such the length of the aperture plus the tooth is sufficiently longer than the step, that the tooth over hangs the step when the step is deployed and presents a barrier to the accidental disengagement of the step.

[0071] The tooth is located towards the rear of the leg (closest to the centre of the deployed ladder) such that a user, when placing their foot on the exterior of the step ready to climb the ladder, naturally pushes the step towards the centre of the ladder, ensuring that the step engages with the tooth ensuring that the step will not disengage when in use. [0072] It will be apparent to one skilled in the art that other suitable step disengagement means may be used, such as but not limited to, sprung fixing pins, wedges and screws.