GB2533649A

GB2533649A - Telescopic tube assembly

Info

Publication number: GB2533649A
Application number: GB1500071.4A
Authority: GB
Inventors: Lenihan Danny; Qinghao Mao
Original assignee: Three Legged Thing Ltd
Current assignee: Three Legged Thing Ltd
Priority date: 2015-01-05
Filing date: 2015-01-05
Publication date: 2016-06-29
Anticipated expiration: 2035-01-05
Also published as: GB2533649B; WO2016110684A1

Abstract

A telescopic tube assembly 1 comprises a first tube 10 and a second tube 20. The external geometry of the second tube 20 is adapted such that the second tube 20 fits within the first tube 10. The first tube 10 and the second tube 20 are axially slidable relative to each other. A fastening member 30 is slidably engagable to the second tube 20 and is operable in use to fix the position of the first tube 10 and the second tube 20 relative to each other. A lock 70 is slidably engagable to the first tube 10 and connectable to the fastening member 30. The lock 70 is adapted in use to secure the fastening member 30 to the first tube 10 so as to prevent the first tube 10 and second tube 20 becoming separated.

Description

Telescopic tube assembly

Field of the invention

The present invention relates to telescopic tubes. In particular, the present invention relates to telescopic tubes used as components of tripods and monopods.

Background

Tripods and rnonopods have leas that provide the support offered by a tripod or rnonopod. Commonly, these legs are telescopic, as this allows the volume taken up by the leg(s) to be reduced for storage and transport.

For a leg to be telescopic, a number of tubes f different diameters are arranged coaxially one inside the other. Each pair of tubes where one tube is located inside the other tube is coupled together by a fastening element, which, when operated by a used, is capable of holding the two tubes in position relative to each other.

An example of such a fastening element is a friction lock that is threaded to an outer tube within which another tube is axially fitted. The friction lock has an internal claw washer that fits between the outer tube and the respective inner tube of the pair of tubes.

The claw washer is a circumferentially compressible sleeve that sits slidably against the interior of the outer tube. On twisting of the fastening element, the sleeve is moved axially along the outer tube.

The outer tube has a change in the size of its internal diameter from a larger diameter at the end of the tube to which the fastening element is threaded, to a smaller diameter further inside the tube. By screwing the fastening element on to the outer tube, part of the sleeve is moved into a part of the outer tube with the smaller internal diameter causing the circumference of the sleeve to compress.

When the inner tube is inside the outer tube at this location, the sleeve is forced into contact with the inner tube due to the change in the internal diameter of the outer tube. This causes the sleeve to grip the inner tube due to friction between the two components. The amount of friction able to be applied is such that the inner tube is no longer able to move relative to the sleeve, thereby holding the outer tube and inner tube in place relative to each other.

To allow the tubes to move relative to each other again, the fastening element is unscrewed to remove the sleeve from the smaller diameter portion of the outer tube. However, this allows the inner tube to be removed from the outer tube, which is undesirable, as it means the tripod/monopod leg becomes disassembled.

It is known to use two shims keyed to the outside of the end portion of the inner tube to stop the leg becoming disassembled. The shims increase the size of the diameter of the inner tube, which means that the end portion of the inner tube cannot then pass through the sleeve, Further, the fastening element can become detached from the outer tube meaning the tubes are no longer coupled, and can still therefore become detached. This also means that the shims can fah off the inner tube and be lost 25 when the tubes are decoupled.

There is therefore a need for a more secure coupling of coaxial tubes in a telescopic leg of a tripod or monopod.

Summary of Invention

According to a first aspect, there is provided a telescopic tube assembly of a tripod or monopod, comprising: a first tube and a second tube, wherein the external Geometry' of the second tube is adapted such that the second tube fits within the first tube, the first tube and the second tube being axially slidable relative to each other; a fastening member slidably engagable to the second tube and operable in use to fix the position of the first tube and the second tube relative to each other; and a lock slidably engagable to the first tube and connectable to the fastening member, wherein the lock is adapted in use to secure the fastening member to the first tube so as to prevent the first tube and second tube becoming separated.

It is anticipated that such a telescopic tube assembly can be used as at least a part of a tripod, monopod, light stand, fishing pole, selfie stick (i.e. a pole to be held in use at one end by a user with a camera attached to an opposing end that is used to take pictures or video of the user), or any other assembly where the ability to telescopically extend the length of a tube or pipe is applicable and may be advantageous, Generally speaking, the telescopic tube assembly provides a lock that is able to couple to each of two tubes of a telescopic tube assembly to provide a secure link between the two tubes, whilst still allowing the tubes to move relative to each other.

Advantageously, by using the lock, the tubes cannot become separated by the user either inadvertently or without specifically acting to separate the tubes, which reduces the risk of a user damaging a component by disassembling the tube assembly, and reduces the risk of a component becoming lost. Generally, this makes the telescopic tube assembly more secure and improves the reliability and usability of the assembly.

As noted above, the telescopic tube assembly can be used as a part of a tripod or monopod, and may he particularly advantageous in such circumstances. This is because a tripod or monopod supports e.g. a camera by being able to withstanding primarily axial compression along its components. Using this telescopic tube assembly, the tripod or monopod is able to offer sufficient support along its length (as opposed to e.g. a fishing pole that must be able to primarily withstand lateral forces), whilst also ensuring the assembly is securely held together so that no component can become disconnected without specific action being taken to disassembly the assembly. This allows reliable repeatable use of the tripod or monopod with a reduced risk of damage or loss of a component of a telescopic part.

The lock may be secured to a loop or hook on the first tube. However typically; the lock is abutable against a stop on the first tube thereby limiting the movement of the lock relative to the first tube. This allows a significant range of motion of the lock, and makes assembly and manufacture more simple whilst ensuring the lock is securely retained on the first tube when assembled.

The lock may include a catch or some other means of engaging with the first tube. Typically though, the lock comprises a ring, an internal surface of which is slidable over the first tube, and wherein an end surface of Inc ring is abutable against the stop. This allows the lock to be engaged with the first tube by sliding it over an end of the tube, making assembly more simple and ensuring the shape of the lock is simple to manufacture.

The fastening member may be fitted within the first tube, or may be mounted or latched to the end of the first tube. Typically, the fastening member has a bore into which at least an end portion of the first tube is able to fit. This allows the fastening member to fit round the first tube thereby keeping the collapsed (i.e. unextended) length of the assembly to a minimum.

Of course, it would be possible for the fastening member to have a bore which fits a portion of the first tube other than an end portion should this be desirable. Here, the fastening member is usually located at an end portion of the first tube to maximise the combined axial length of the first and second tube when fully extended.

Whist the fastening member may be disengaged from the first tube (i.e. nave no direct engagement due to lack of direct contact between the fastening member and the first tube), typically, the fastening member is detachably engagable to the first tube. This means that the fastening member is directly coupled to each of the first and second tubes, allowing operation of the fastening member to be simple as no intermediate components are required.

The fastening member may be engagable to the first tube my means of a seal, 0-ring, catch or clasp. Typically however, the fastening member is threadable to the first tube. This provides a reliable and hardwearing engagement, and allows the fastening member to be operated by rotation with a minimal amount of force.

The fastening member may be threadable to a thread on an interior or exterior circumferential surface of the first tube. However, having the thread on the exterior of the first tube simplifies the manufacturing process.

The thread on the first tube may be integral with the tube, but typically, the assembly further comprises a threaded member that bears a thread, wherein the threaded member is attached to the first tube. Due to the thread, the threaded member is adapted to thread to the fastening member. Having the threaded member allows the first tube to be made of a material that may be unsuitable for threading (e.g. by using a threading tool to cut a thread on the tube), but which has other beneficial properties, such as being light, making each individual component easier to manufacture.

Of course, instead of the stop and the threaded member being separate components, the stop and threaded member may be a unitary component. This is achievable by threaded member having sufficient radial thickness to provide a surface against which the lock is able to abut. Using the threaded member as the stop is advantageous as it keeps the number of components to a minimum.

Once connected to the fastening member, the lock may be permanently attached to the fastening member. However typically, the lock is removably connectable to the fastening member. This allows the assembly to be disassembled for servicing, ensuring the telescopic functionality of the assembly can be maintained in good working order, extending the usable life of the tube assembly, The lock may be removable by hand, though typically, in use the lock is removable by use of a tool. This ensures that a user cannot inadvertently remove the lock from the fastening member. This is advantageous as it makes the assembly more secure when assembled.

The lock may be connectable to the fastening member by a latch, hook or push-fit connection. Typically, the lock is threadable to the fastening member This provides a hardwearing connection that allows for little relative movement of the parts when connected and is simple to manufacture.

When the lock is threadable to the fastening member, the lock may be securely connected to the fastening member by means of a lock washer (such as a nylon or fibre ring similar to those used in locknuts), thread-locking fluid, thread-locking tape, grub-screw or any other means for locking threads or by using a combination of material and geometries that ensure a high amount of friction between the lock and the fastening member.

The fastening member may be coupled to the second tube by a number of means. Typically, engagement of the fastening member with the second tube is provided by a flange formed of a single part on the exterior of the second tube, wherein the flange is abutable against the fastening member thereby preventing movement of the inner tube out of the outer tube through the fastening member. This establishes a coupling between the fastening member and the second tube.

The flange may be an integral part of the second tube. However typically, the flange is a separable component coupleable to the second tube. This allows the flange and the second tube to be made of different materials and simplifies the manufacturing process.

By using a single piece flange, should the second tube be detached from the first tube, the flange will be retained on the second tube. This means the flange is unlikely to fall off the second tube and get lost and is unlikely to become detached from the second tube when the telescopic tube assembly is assembled. This also means that the tube assembly is less likely to become jammed, making the telescopic function of the tube assembly more reliable.

The flange may be secured to the second tube in a number of ways, such as by gluing, Typically, the flange is keyable to the second tube. This is advantageous as it allows the flange to be installed on the second tube without the need for a separate joining component, such as an adhesive.

The flange may have a recess adapted to accept a projection on the second tube, but typically, the flange is keyable to the second tube by the flange being provided with at least one inwardly facing projection, each projection fitting into a bore in the second tube. This allows the second tube not to have any external projections, which would complicate the manufacture process of the second tube. Further, the allowable tolerances of the inwardly facing projections and the bore can be less stringent than for a projection on the second tube; as the flange will effectively "snap" onto the second tube rather than having to be fitted over the second tube projection(s). Moreover; this reduces the wear on the parts of the flange used to interact with the fastening member.

Each bore in the second tube may be a blind bore, through typically, each bore is a through-bore. This simplifies the manufacturing process of the second tube as each bore, or the bores can be drilled in the tube without needing to limit the depth to which any one bore is drilled.

The flange may be keyed to the interior of the first tube. This allows the flange to restrict relative rotation between the first tube and the second tube about their common axis.

The flange may be keyed to the first tube by the first tube having being adapted to fit a keyway located on the flange. However typically, the flange is adapted to fit a keyway located axially along the interior of the first tube. This keeps the shape of the flange more simple and reduces the chances of the keyway being worn away by relative circumferential movement of the flange and first tube over time, as the first tube typically is made of more hardwearing material than the flange.

The flange may have an axial channel shaped to accept the keyway. The channel may be a recess in the flange: but is typically as circumferential break in the flange. This makes the flange simpler to manufacture.

An end of the channel may be bevelled. This makes it easier to assemble the tube assembly as the bevelled ends allow the flange to self-centre on the keyway of the first tube.

The first tube may have a transition from a larger internal dimension at an end of the first tube where the fastening member is located to a portion of the first tube with a smaller internal dimension. This allows a wider opening to the tube to make axial insertion of the second tube axially into the first tube easier. When the tubes are e.g. circular, the dimension may be the diameter.

The transition may be a tapered transition, through typically, the transition is a step transition. This makes the transition easier to produce as it can either be drilled or formed of two separate parts of the first tube.

For example, the smaller internal dimensioned portion may be the interior of the first tube, and the larger internal dimension may be formed by the threaded member attached to the first tube. This may form an internal end portion of the first tube with a larger dimension and another portion (i.e. a portion further inside the first tube) with a smaller internal dimension.

The fastening member may be coupleable to the second tube in a number of ways, such as by mounting or clipping to the second tube. Typically, the fastening member has a sleeve situated between the first tube and the second tube. This provides a means of slidably coupling the fastening member to the second tube, as the sleeve is able to fit around the second tube whilst also fitting within the first tube. This thereby provides a coupling between the first tube and the second tube, whilst allowing the two tubes to move axially relative to each other.

The sleeve is typically formed from a plastic material, such as nylon or vinyl. Of course, the sleeve may be any other suitable material.

The fastening member may be operable to move the sleeve between a first position, in which at least a part of the sleeve is located between the second tube and the first tube smaller internal dimension portion, and a second position, in which the whole sleeve is located outside of said smaller internal dimension portion. In this case, when in the first position, the sleeve is adapted to grip the first tube and the second tube thereby fixing the first tube and the second tube in position relative to each other, and when in the second position, the first tube and second tube are axially moveable relative to each other. This allows the fastening member to grip the second tube without the risk of deforming the first or second tube, which may be the case with other types of friction lock, Further, when this arrangement is used, should an attempt be made to push the second tube axially into the first tube, the amount of frictional force applied increases as the sleeve is pulled further into the smaller internal dimension portion by the frictional contact between the sleeve and the second tube. This may be the case when a compression force is applied axially along the assembled tube assembly.

The telescopic tube assembly may include one or more other tubes, each with an external geometry adapted to allow it to fit within the second tube, or within a tube fitted within the second tube, or with an internal geometry adapted to allow it to fit around the first tube, or around a tube fitted around the first tube, This allows more tubes to be used, extending the maximum possible length of the tube assembly.

Each tube may be linked by a fastening member as described above to a tube that fits axially inside or outside the respective tube, allowing a number of tubes to be securely connected together to form a telescopic tube assembly.

Each tube may be a cylinder, such as a right circular or polygonal cylinder (e.g. a triangle, square, hexagon or an irregular polygon).

According to a second aspect, there is provided a tripod or monopod comprising an assembled telescopic tube assembly according to any combination of the features described above. In the case of a tripod, a telescopic tube assembly in accordance with the first aspect may be provided as one, each of two or most preferably each of the three legs of the tripod. This allows the leg(s) of the tripod or monopod to be telescopic whilst also being securely held together. It would of course be possible to use a telescopic tube assembly in accordance with the first aspect for one leg or each of the two legs of a bipod.

According to a third aspect, there is provided a telescopic tube assembly according to the first aspect, wherein the telescopic tube assembly forms at least a part of: a monopod log, or at least one leg of a tripod, or a central column of a tripod, or a pole, or a horizontal beam, or a light stand, or a selfie stick.

Brief description of figures

An example of a telescopic tube assembly is described in detail below, with reference to the accompanying figures, in which: Figure 1 shows a sectional view of part of an assembled telescopic tube assembly; Figure 2 shows an exploded sectional view of part of the telescopic tube assernbly; Figure 3 shows a sectional view of part of the assembled telescopic tube assembly in a fixed length configuration; Figure 4 shows a sectional view of part of the assembled telescopic tube assembly in a variable length configuration; Figure 5 shows a sectional view of a pad of a fastening member of the telescopic tube assembly; Figure 6 shows a partial exploded view of a telescopic tube assembly, Figure 7 shows a perspective view of a flange; and Figure 8 shows an end view of the flange.

Detailed description

The telescopic tube assembly referred to herein is portable, and may be assembled by hand (i.e. without the use of tools, such as powered tools). The main purpose of the telescopic tube assembly is to be able to withstand a compression force applied primarily axially along its length (although the assembly can also withstand a certain amount of force applied radially as well). As such, the telescopic tube assembly can be used as at least a part of e.g. a fishing pole, but will usually be used in an area where a rigid assembly would be advantageous, such as a stand.

The example of a telescopic tube assembly described below refers to use of the assembly as a component of a tripod or monopod, in particular to a leg of a tripod or monopod. However, the assembly described can be used in other applications where the functional aspect of the assembly (namely being telescopic whilst ensuring all the components are able to be coupled together securely so that no component can inadvertently be removed from the assembly) is able to be applied. This means that in a field where the functionality of the telescopic tube assembly would work, the assembly can be used.

In the field of tripods and rnonopods, the telescopic tube assembly can be used for any part where it is desirable that the length of the part is extendable. For example, this may be a leg, central column (i.e. a column supported by the tripod legs that is used to support a head joint and/or camera) or any other part. Such a part may also be removable from the tripod or monopod, such as a leg or central column of a tripod that is removable so that it may be used as a monopod.

In the wider photographic and motion picture fields, the telescopic tube assembly may be used as; or as a part in, a light stand; a horizontal beam (for example. from which a light may be hung), a pole or a selfie stick.

In order to prevent two coaxial tubes of different diameters in a telescopic leg of a tripod Of monopod from becoming separated in use, an assembly holding the two tubes together is needed. However, to ensure that it is possible manufacture and assemble the telescopic leg, and that the leg is able to function in a telescopic manner, it is difficult to irremovably couple the two tubes directly to each other without conducting the manufacturing the leg components in an assembly configuration. This is difficult to achieve where the components may be sourced from a number of different suppliers, or the manufacturing techniques of the various components are incompatible.

As a result of this, we have developed the telescopic leg assembly of a tripod or monopod, an example of which is shown in Figure 1. This shows part of a telescopic leg 1 of a tripod or monopod with all the constituent parts fitted together.

As can be seen in Figure 1, the leg has a first tube 10 (hereinafter referred to as the outer tube), and a second tube 20 (hereinafter referred to as the inner tube), each of which are (circular) cylinders. The tubes are also rigid. In the arrangement shown, the tubes share a common central axis, although, strictly, it is not necessary for them to do so.

Each tube may be made of steel, aluminium, carbon-fibre, carbon-fibre reinforced polymer or any other material suitable for use in tripod or monopod legs. For example, in the use of a photographic application, they must be of sufficient strength to support the entire "weight" of a camera and lens and may be required to support other articles as well or instead The total supportable mass could be up to 5kg and preferably up to 10kg per leg, and more preferably up to 50kg per leg, although the maximum mass each leg can support may be much greater, such as up to about 100kg, or even up to about 200kg, To enable the leg to be telescopic, the outer tube 10 has a minimum internal diameter that is larger than the maximum external diameter of the inner tube 20. This means that the inner tube is able to slide axially relative to the outer tube into and out of the outer tube (indicated by the arrow 11 in Figure 1).

Example diameters of the tubes are a minimum internal diameter of about 0.5cm to a maximum internal diameter of about 10.0cm, and are usually in the range of about 2.0cm to about 6.0cm, such as between about 4 Ocrn and about 5.0cm. The external diameters will be in a comparable range, but will be slightly larger than any particular internal diameter due to the thickness of each tube, which may in the range of about 0.5mm to about 10.0mm, preferably about 1.0mm.

Although the entire length of each of the outer tube and the inner tube is not shown in the figures, the tubes are approximately the same length. This means that when the leg is collapsed, the respective lengths of the tubes allows the entire length of the inner tube to fit within the outer tube. As an example, each tube may have a length of about 10.0cm to about 200,0cm, and preferably about 10.0cm to 100.0cm or about 10.0cm to 50.0cm, although more preferably, each tube will have a length of about 15.0cm to 30.0cm.

VVhen the leg is in a collapsed state (i.e. the inner tube is located inside the outer tube with a minimum amount of the inner tube projecting axially out of the outer tube), the outer tube and inner tube may be described as being concentric due to the shared central axis.

In order to enable the leg to support weight when the tubes are in any arrangement other than when the inner tube 20 is slid as far inside the outer tube 10 as possible, a means of restricting the relative axial movement of the tubes is needed. This is achieved by use of a fastening member 30.

The fastening member 30 has a sleeve 40 that is connected to the remainder of the fastening member by an end piece that takes the general form of a ring. The sleeve is fitted within the outer tube 10 and between the outer tube and the inner tube 20. The sleeve is therefore formed around the inner tube, which is located through a bore in the sleeve when assembled.

The sleeve 40 is connected to a collar 32. The collar is annular, having an axial bore through its centre. This allows the collar to be coaxial with, and to connect around, the outer tube 10.

The collar 32 is attached to one end of the outer tube 10, and the inner tube 20 is able to fit through the collar and the sleeve 40, and is able to slide axially relative to the outer tube, the collar and the sleeve. This arrangement of the collar provides a user accessible component, movement of which causes the sleeve to move.

The collar 32 has an axial length of between about 1.0cm and about 15.0cm, but will usually have an axial length of between about 2.0cm and about 5,0cm.

To improve a users ability to grip the collar in use, the collar can have a textured portion round its circumference. The textured portion (shown in Figure 6) is a shaped rubber cover 50, which has a sufficient axial length to be gripped by a user, but could take a different form. Sometimes the collar does not have a cover. For example, a cover would not necessarily be used when the collar is a cast alloy, such as aluminium alloy ADC12, or a machined alloy, such as aluminium alloy T6061.

Another alternative is for the collar to have plastic moulded onto it, such as nylon (e.g. PA66). This is moulded onto the collar making it immovable. As the cover will then be a thermal insulator, this means that, should the assembly be used in cold conditions, the collar will feel less cold to the touch.

The collar 32 has a bore through its centre. The internal wall of the collar has a thread that is engagable to a threaded member 60, which is threaded on an outer surface, connected to the end of the outer tube 10.

The threaded member 60 is shown in Figure 1 between the collar 32 and the sleeve 40. The interaction of the thread on the collar with the threaded member allows the collar to have a threaded engagement with the outer tube and to be axially moveable (as indicated by the arrow 13 in Figure 1) over the outer tube by rotation of the collar relative to the threaded member (and therefore the outer tube).

The threaded member 60 is fixed to the end of the outer tube 10, which effectively lengthens the outer tube. As at least part of the threaded member fits around the exterior of the outer tube; the threaded member has a larger internal diameter than the outer tube and, due to the screw thread; has a larger outer diameter as well.

A lock 70 is fitted around the outer tube 10 and is axially slidable over, and able to rotate about the common central axis relative to the outer tube.

The lock 70 is annular; and has a smaller internal diameter than the external diameter of the threaded member 60, meaning that the lock is unable to pass over the threaded member. As such, the lock is fitted onto the outer tube before the threaded member, or is fitted from an opposing end of the outer tube to the end to which the threaded member is connected.

The lock 70 is connectable to the fastening member 30 to form an end piece on the collar 32. The lock and the collar have cooperative threads. Once the lock is connected to the fastening member, it is unable to be removed without the use of a tool; such as a wrench, screwdriver or Allen key. This is due to the use of a locking washer (not shown) on the lock, or locking-fluid or locking-thread (not shown) installed between the threads.

The lock 70 has a bore (not shown) orientated primarily radially therethrough. The bore extends radially inwardly from the outer surface of the lock, and may be a through-bore into an inner surface of the lock. The bore allows part of a cooperative tool such as a pin or pole to be inserted into the bore This tool can then be used as a lever to axially rotate the lock relative to the fastening member to remove the lock from the fastening member.

The tool may also, or alternatively, provide a purchase for a user to enable them to grip the lock 70 to remove it from the fastening member 30. This is useful because the lock can have a smooth surface, which a user will find difficult to grip once the lock is screwed tight onto the fastening member.

The tool can also be used to thread the lock 70 onto the fastening member. However, usually the lock will be threaded to the fastening member without the use of a tool (i.e. the lock will be threaded to the fastening member by hand and is screwed tight by hand).

When the lock 70 is connected to the fastening member 30, the fastening member can be rotated about the common axis of the leg, and yet it cannot be removed from the outer tube 10. This is because the lock, when moved away from the outer tube; will abut the end of the threaded member 60, which may be the end of the thread or may be a blank portion of the threaded member.

To limit the amount of movement of the fastening member 30 onto the outer tube 10, the connection between the collar 32 and the sleeve 40 will abut the other end of the threaded member 60 from the end abutable by the lock. This occurs when the fastening member is screwed far enough onto the threaded member. This is achieved by the axially movement caused by screwing the fastening member onto the threaded member bringing an inside surface (not shown) of this connection into contact with an end surface of the threaded member.

In order to prevent the inner tube 20 from being removed from the outer tube 10 through the threaded member 60 and the fastening member 30, the end part of the tube is formed as a flange section that has an internal diameter that is the same as the inner tube 10, The external diameter of the flange section is greater than the inner tube, arid is sufficiently large not to fit into the bore of the sleeve 40. The flange portion can be integral with the inner tube or can be a separate component The flange portion is provided by an end of the inner tube 10 located inside the outer tube when assembled and a flange 22 formed around said end of the inner tube. The flange increases the size of the diameter of the end of the inner tube so that the external diameter of the flange is larger than the internal diameter of the sleeve 40 of the fastening member.

The flange 22 is keyed to the interior of the outer tube 10 by an elongate keyway 12 on the interior of the outer tube, the keyway running axially along an inner surface of the tube 12. As the flange is coupled to the inner tube 20, this limits circumferential rotation of the inner tube and the outer tube relative to each other.

Figure 2 shows the telescopic leg assembly laid out in a disassembled arrangement along the common central axis A-A. Note that some of the components are shown partly in section for illustrative purposes.

From Faure 2, it can be seen that the lock 70 is annular with a generally shaped cross-section. It is of course possible to use other shapes, and the exact shape of the lino may be varied. For example, Figure 6 shows that one corner of the "L" is bevelled. Naturally, the degree of variation can be greater than just having a bevelled corner.

The general shape of the lock 70 allows it to have an innermost internal surface 72 that is slidable over the exterior of the outer tube 10 to engage the outer tube.

The lock then has a second internal surface 74 on which a thread (not shown) is located. The second internal surface has a larger diameter than the innermost internal surface 72 so that it is able to thread to the outside of the collar 32 of the fastening member 30. The lock could of course thread to the inside of the collar if these components were modified accordingly, with the aim being that they may be threaded together.

Figure 2 also shows the keyway 12 on the inside of the outer tube 10. This is formed as a projection from the interior 14 of the outer tube towards the common central axis A-A, and has a rectangular cross-section.

The keyway 12 extends to the end of the nterior 14 of the outer tube 10, and is not continued on the interior 62 of the threaded member 60. In part, this is because of the difference in diameter between the interior of the outer tube and the interior of the threaded member.

An end portion of the threaded member 60 overlaps with an end portion of the outer tube 10 so that the two components can form a single joined component.

As detailed above, the internal diameter of the threaded member 60 is larger than the external diameter (of the combined outer tube 10 and the threaded member 60) of the outer tube 10 to allow the threaded member to fit onto the outer tube. As can be seen in Figure 2, this difference causes a step transition in the diameter at the interface 16 between the end of the outer tube, and the threaded member.

The keyway 12 of the outer tube 10 fits in a corresponding channel 220 in the flange 22, which is coupleable to the inner tube 20. The channel is formed simply by a break in the circumference of the flange, such that it has a "0" cross-section rather than an "0" cross-section.

The flange 22 is itself keyable to the inner tube 20 by at least one inwardly facing projection. Whilst other forms of projection can be used, here, the projection is a highly oblate (circular or elliptical) cylinder 224 (see Figures 7 and 8) that fits within a bore 24 through the inner tube. The cylinder 224 effectively forms a localised circumferential plateau region projecting inwardly from the inner surface of the flange 22. In use, the inward projection from the flange 22 holds the fiance to the inner tube.

The sleeve 40, which is a separate component from the collar 32, is formed of a "claw washer" 42 and a radial flange 44 The claw washer fits inside the outer tube 10 and has a bore through which the inner tube 20 is locatable, whilst the radial flange is engagable with a groove (not shown) on an interior 322 of the collar 32. When the sleeve is engaged with the collar, this forms the fastening member 30.

The claw washer 42 is a (circular) cylinder, having flexible walls such that its diameter may be modified. The diameter is variable as the claw washer is circumferentially compressible. This is achieved by having axial slits 420 in the cylinder of the washer.

The slits 420 extend axially along the cylinder from either end, and have a circumferential width as well as an axial length. Whilst most of the slits (including all those shown) do not extend the entire length of the cylinder, all the slits enhance the flexibility of the cylinder walls. Having slits that only extend along part of the length of the cylinder allows each end of the claw washer to be circumferentially compressed independently if wanted, There are an equal number of slits 420 that extend along the cylinder from each end of the cylinder This allows each end of the washer 42 to adopt a similar modified diameter when compressed.

There is also a slit (not shown) that runs the entire length of the cylinder. This allows the axially central portion of the washer to be evenly compressed. It would be possible to have just this slit, as this would allow uniform circumferential compression of the washer 42, which is desirable is some cases, such as when inserting the sleeve 40 into the collar 32, The radial flange 44 projects radially outwardly from the claw washer 42. This may be from an end of the claw washer, or may be from the exterior of the claw washer at a location along its length, To ensure the sleeve is circumferentially compressible, the flange also has a radial slit 440 circumferentially aligned with each axial slit 420 with which the flange circumferentially overlaps. This allows the flange to compress circumferentially with the claw washer.

There is little resistance to relative circumferential rotation of the flange relative to the collar 32 when the radial flange 44 is engaged with the groove in the collar. This means that the sleeve 40 is able to rotate relative to the collar.

To protect at least a portion of the sleeve 40 when it is engaged with the collar 32, the collar has an end 320 formed of a radially inward projection. Of course, part of the sleeve, such as an end of the claw washer 42, may extend past the projection to be flush with the end of the collar or may extend further.

The interior 322 of the collar 32 has a threaded portion (not shown) that is configured to cooperate with the threaded member 60. This allows the fastening 15 member to be engaged with the threaded member and thereby engaged with the outer tube 10.

Figure 3 shows the telescopic leg in an assembled arrangement with the outer tube 10 and the inner tube 20 held in a fixed position relative to each other.

As is explained above, the relative circumferential rotation of the tubes is restricted by the flange 22, as it is keyed to the keyway 12 and coupled to the inner tube 20.

The relative axial movement of the tubes is prevented by means of the fastening member 30. Due to the threaded engagement of the collar 32 with the threaded member 60, the fastening member is able to be twisted to screw it (further) on to the outer tube. This moves all the components of the fastening member axially relative to the outer tube.

The axial movement of the fastening member 30 forces the sleeve 40 from the larger diameter section inside the threaded member 60 into the smaller diameter section inside the outer tube 10 of the overall tube defined by the threaded member and the outer tube.

As the fastening member 30 is screwed (further) on to the threaded member 60, Vie claw washer 42 of the sleeve 40 is deflected radially inwardly at the step transition 14, circumferentially compressing the end of the claw washer that is forced into the smaller diameter portion by the axial movement of the fastening member 30 as a whole.

This causes the deflected end of the claw washer 42 to be pushed into contact with the exterior of the inner tube 20 whilst also being in contact with the interior of the outer tuber 10. This causes the sleeve 40 to grip the inner tube due to friction between the claw washer and the inner and outer tubes. This is sufficient to hold the inner and outer tube in place relative to each other. The frictional forces applied may be sufficient to withstand an axial compression force applied to the assembly by a mass of up to about 20kg, preferably up to about 50kg and possibly up to about 100kg or about 200kg.

By restricting the reiative circumferential rotation of the tubes, it will be more difficult to move the tubes axially relative to each other. This is because the tubes cannot be twisted relative to each other, which may be an easier way for a user to overcome the frictional forces.

Figure 4 shows the telescopic leg in an assembled arrangement with the outer tube 10 and the inner tube 20 axially moveable relative to each other. This is indicated by the arrow 11 in the figure.

For the tubes to be freely axially moveable relative to each other, no part of the length of the sleeve 40 can be located within the smaller diameter inside the outer tube 10. This causes the grip of the sleeve on the inner tube 20 to be released, the inner tube thereby being slidable through the sleeve.

When the fastening member 30 is unscrewed from the threaded member 60 by a certain amount (this may be completely unscrewed so that the fastening member has no direct engagement with the threaded member, or when the fastening member is only partially unscrewed, so still has some direct engagement with the threaded member), an internal end surface (not visible in Figure 4, but visible in Figures 1 to 3 and 5 as element 76) of the lock 70 abuts an end of the threaded member. This prevents further axial movement of the fastening member away from the outer tube, making the fastening member irremovable from the threaded member; and therefore from the outer tube, as the lock cannot move axially past the threaded member.

The lock 70 also assists in ensuring that the inner tube 20 cannot be removed from the outer tube 10, thereby ensuring that once assembled, the telescopic leg cannot be disassembled without the use of a tool to remove the lock from the fastening member 30. This is because an end surface 226 of the fiance 22 coupled to the inner tube abuts an end of the claw washer restricting its axial movement past the sleeve 40. Due to the lock, this retains the coupling between the outer tube and the inner tube.

Due to the variability in the diameter of the claw washer 42, i, may be possible for the flange 22 to slip inside the internal perimeter of the claw washer. In this circumstance, the flange is prevented from passing all the way through the claw washer by the radial flange 44 that gives the sleeve 40 a smaller maximum internal diameter at the point where the radial flange is connected to the claw washer than the external diameter of the flange.

The amount of axial movement permitted by the lock can be any predetermined amount. We have found that permitting the collar to be rotated (unscrewed) about the common axis by half a full turn (so through 180 degrees) or a quarter of a full turn (so through 90 degrees) from an end of the thread on the threaded member closest to the lock, there is sufficient axial movement of the fastening member to release the tubes to be freely moveable axially relative to each other. As such, it is possible to position the lock relative to the collar to only allow sufficient axial movement of the collar for a half or quarter turn in either direction (i.e. clockwise or anti-clockwise) of the collar on the threaded member. This keeps the amount of possible axial movement of the fastening member to a minimum, thereby keeping the coupling between all the components as secure as possible.

Figure 5 shows the fastening member 30 and lock 70 when engaged with each other. This shows that, in this arrangement, the lock is engaged at one end of the collar 32 of the fastening member.

Due to the general shape of the lock 70, the innermost surface 72 and the internal surface 76 of the lock form a rim around the end of the collar that has a smaller diameter than the interior 322 of the collar that engages with the threaded member. This is what prohibits the removal of the fastening member From the outer tube when the leg is assembled.

The sleeve 40 is also engaged to an end of the collar 32. This engagement is provided by the radial flange 44. The sleeve can be engaged with the collar at other locations, but, in this case, the sleeve is engaged to an opposing end of the collar to the end to which the lock 70 is engaged. This means that the radial flange of the sleeve fits just inside the end 320 of the collar with the radially inward projection.

Figure 6 shows the coupling between the threaded member 60, the collar 32 of the fastening member 30 and lock 70 in a disassembled arrangement.

The threaded member 60 is shown on the end of the outer tube 10 within which an end of the inner tube 20 is located.

The collar 32 has a shaped rubber cover 50 to assist a user in screwing or unscrewing the collar from the threaded member.

The collar 32 is engagable with the threaded member 60 by an internal thread as described above. The collar also has an external thread 324 that is able to engage with a cooperative thread inside the lock 70. Once the lock is screwed on to the collar, it is only able to be unscrewed through use of a tool due to increased friction at the threaded engagement between the lock and the collar meaning that a user is manually unable overcome the increases friction to remove the lock without assistance.

Figures 7 and 8 show the flange 22. This is a "shim' in the shape of a retaining ring The shape of the flange allows it to hold itself to a tube when the flange is not held in place by any other component, such as when the telescopic leg is being assembled.

The flange 22 has a channel 220 formed axially along its length as described above. The ends of this channel have bevels 222. These allow the flange to self-centre on the keyway inside the outer tube into which it is pushed during assembly of the leg.

The flange 22 has two radial projections 224 formed on the inside of the flange 22. These fit into apertures in the wall of the inner tube to ensure the flange is securely coupled to the inner tube when assembled. There can of course be fewer or more projections.

The flange may be made from nylon or some other plastic. Irrespective of the material from which the flange is made, the benefit of using the flange (namely enabling the inner tube to be retained within the fastening member whilst also holding itself to the inner tube) is achievable without the use of the lock In other words, the flange can be used without also using the lock. This also applies to the lock, which can be used without also using the flange.

Other tubes can be connected inside the inner tube or outside the outer tube to extend the length of the telescopic leg. Each tube may be connected to a coaxial tube of a smalier or larger diameter (or comparable dimension) using a friction lock similar to the fastening member and the lock described.

The telescopic leg described herein will usually be used for photographic or motion picture tripods or monopods, including those used to support equipment other than cameras, such as lights, reflectors, and/or monitors. However, as mentioned above the disclosed telescopic tube assembly can be used in other fields.

Claims

CLAIMS1. A telescopic tube assembly, comprising: a first tube and a second tube, wherein the external geometry of the second tube is adapted such that the second tube fits within the first tube, the first tube and the second tube being axially slidable relative to each other; a fastening member slidably engagable to the second tube and operable in use to fix the position of the first tube and the second tube relative to each other: and a lock slidably engagable to the first tube and connectable to the fastening member, wherein the lock is adapted in use to secure the fastening member to the first tube so as to prevent the first tube and second tube becoming separated.
2. The telescopic tube assembly according to claim 1, wherein the lock is abutable against a stop on the first tube thereby limiting the movement of the lock relative to the first tube.
3 The telescopic tube assembly according to claim 2, wherein the lock comprises a ring, an internal surface of which is slidable over the first tube, and wherein an end surface of the ring is abutable against the stop.
4 The telescopic tube assembly according to any one of claim 1, claim 2 or claim 3, wherein the fastening member has a bore into which at least an end portion of the first tube is able to fit.
5. The telescopic tube assembly according to any one of the preceding claims, wherein the fastening member is detachably engagable to the first tube.
6. The telescopic tube assembly according to claim 5 wherein the fastening member is threadable to the first tube.
7 The telescopic tube assembly according to claim 6, further comprising a threaded member that bears a thread, wherein the threaded member is attached to the first tube.
8. The telescopic tube assembly according to any one of the preceding claims, wherein the lock is removably connectable to the fastening member.
9. The telescopic tube assembly according to claim 8, wherein in use the lock is removable by use of a tool.
10. The telescopic tube assembly according to any one of the preceding claims, wherein the lock is thmadable to the fastening member.
11. The telescopic tube assembly according to any one of the preceding claims, wherein engagement of the fastening member with the second tube is provided by a flange formed of a single part on the exterior of the second tube, wherein the flange is abutable against the fastening member thereby preventing movement of the inner tube out of the outer tube through the fastening member.
12. The telescopic tube assembly according to claim 11, wherein the flange is a separable component coupleable to the second tube.
13. The telescopic tube assembly according to claim 12, wherein the flange is keyable to the second tube.
14. The telescopic tube assembly according to claim 13, wherein the flange is keyabie to the second tube by the flange being provided with at least one inwardly facing projection, each projection fitting into a bore in the second tube.
15. The telescopic tube assembly according to claim 14, wherein each bore is a through-bore.
16 The telescopic tube assembly according to any one of claims 11 to 15, wherein the flange is keyed to the interior of the first tube.
17. The telescopic tube assembly according to claim 16, wherein the flange is adapted to fit a keyway located axially along the interior of the first tube.
18. The telescopic tube assembly according to claim 17, where the flange has an axial channel shaped to accept the keyway.
19. The telescopic tube assembly according to claim 18, wherein an end of the channel is bevelled.
20. The telescopic tube assembly according to any one of the preceding claims, wherein the first tube has a transition from a larger internal dimension at an end of the first tube where the fastening member is located to a portion of the first tune with a smaller internal dimension.
21. The telescopic tube assembly according to claim 20, wherein the transition is a step transition.
22. The telescopic tube assembly according to claim 20 or claim 21, wherein the fastening member has a sleeve situated between the first tube and the second tube.
23. The telescopic tube assembly according to claim 22, wherein the fastening member is operable to move the sleeve between a first position, in which at least a part of the sleeve is located between the second tube and the first tube smaller internal dimension portion, and a second position, in which the whole sleeve is located outside of said smaller internal dimension portion, wherein when in the first position, the sleeve is adapted to grip the 'first tube and the second tube thereby fixing the first tube and the second tube in position relative to each other, and when in the second position, the first tube and second tube are axially moveable relative to each other
24. A telescopic tube assembly substantially as described herein, with reference to and as illustrated in the accompanying drawings.
25.A tripod or monopod comprising an assembled telescopic tube according to any one of the preceding claims.
26.A tripod or monopod substantially as described herein, with reference to and as illustrated in the accompanying drawings.
27.A telescopic tube assembly according to any one of claims 1 to 23, wherein the telescopic tube assembly forms at least a part of: a monopod leg, or at least one leg of a tripod, or a central column of a tripod, or a pole, or a horizontal beam, or a light stand, or a selfie stick.