GB2619540A - A tripod with telescopic legs - Google Patents

Abstract

A tripod 10 comprised of at least three telescopic legs 13 disposed radially from a head bracket. Each leg includes a cassette housing 18 located at an end of the leg for facilitating coiling of a length of material 19 therewithin. An uncoiled length of the coliable material extends within the telescopic leg sections and is fixed at a distal end. A locking mechanism 17 engages against the coilable length to hold it in place, thereby holding the telescopic legs at a desired collapsed and/or expanded state. The coilable material is resistant to compression along its longitudinal length and may be akin to the spring steel used in a tape measure.

Description

A tripod with telescopic legs

Technical Field

The present invention relates to a tripod with telescopic legs, i.e. adjustable to different lengths. Such a tripod may be associated with a mounting device as used to stabilise a camera or other equipment.

Background to the invention:

Telescoping poles are used for many products, e.g. camera tripods, walking poles/sticks and tent poles, etc. A simple form of locking mechanism to hold an extended telescoping pole in place may employ a spring-loaded pin. Other solutions may employ a latching mechanism of some sort or clamp at each joint to fix the length of the pole. The latch is often a lever associated with a cam at an end of one section that applies force to an internally sliding/telescoping section to hold it in place or release it for relative sliding movement. Therefore, a pole with three telescopically arranged stages will require two locking mechanisms. Even further, a common tripod with three legs and two locking mechanisms on each will require six (6) locking mechanisms. Taller tripods often include additional telescoping stages where the number of locking mechanisms is equal to the number of stages minus one.

Summary of the Invention

The present invention seeks to provide an alternative construction for a telescopic leg locking mechanism, particularly for a tripod or implementable into other products that require extensible legs/poles. The invention seeks to reduce the number of locking mechanisms to, at most, one per pole/leg and to be conveniently accessible at the top of the leg and not, for example, part way down at the end of the first section.

The invention is embodied by a tripod according to claim 1, e.g. a mounting platform comprising three legs, that incorporates a locking mechanism with each leg to lock multiple stage telescoping sections to a set overall length (notably, in one form individual sections may move relative to each other) via a single locking mechanism at the upper end of the leg, that is most easily accessible by a user. In further forms, a single user operation may engage the locking mechanism for each leg in one movement. The tripod may include additional features to set the legs at different relative angles during deployment, i.e. as known from conventional tripods that can be set with legs wider apart for improved stability. Telescopic legs can take a number of forms, generally defined by a series of mutually sliding and connected parts, arranged coaxially or concentrically such that each successive stage fits within preceding stages. The configuration of stages may be directly concentric (i.e. about a central axis) or the sliding axis may be offset from the centre of the cross section.

The invention is enabled by incorporating a coilable length of material, such as spring steel or plastic equivalent, that is resistant to buckling along a longitudinal axis. In other words, when an extended length is locked in place, located within a telescopic pole, compression along its length is resisted. The coilable length can be locked in position at one end of the pole by a simple screw or other locking/latching means. In one form, the coilable length has a convex/concave/curved cross section to improve buckling resistance, in a similar way to a common retractable "tape measure" device.

A strip/tape (referred to herein as a "blade") of this type is strong in one direction of bending but weak in the opposite direction, such that it can be coiled. These properties are used to good advantage in a typical tape measure device which can be extended several meters and held relatively straight for a measurement to be made, yet can be coiled up into a neat package for storage.

When such a blade is used according to the invention to lock the length of a telescopic pole, and provided that it is prevented from twisting or bending, it will support a compressing force such as would hold the telescopic pole in an extended position and need only be locked in position at the end of the pole.

A particular solution for supporting the blade, as extended within telescopic pole sections, is to provide supporting members along the length, e.g. in practice at the end of each section.

The strength of the blade in compression resistance can be modified by altering the curvature, the thickness of the material and/or the width such that the invention can be scaled to suit larger or smaller applications. For example, a camera for shooting motion pictures or a machine gun is significantly heavier and needs more robust support than a domestic camera.

Preferably, as in existing box section designs, the pole stages must be such as to prevent significant rotation of the poles with respect to each other. This is common practice to ensure the locks on a (for example) tripod are in line and reliable. It will be appreciated that any non-round (or round with a keyed surface) cross section shape may mitigate twisting of stages within a telescoping leg.

As mentioned, the use of a curved blade (like a tape measure blade) is a preferable solution as an internal/core support to remove the need for multiple locking means at each sliding leg joint. This results in a single locking point at one end (i.e. preferred at "top" end but, in principle, could be the bottom end where cassette serves as a foot) of each leg which can, if desired, be linked together to provide a single locking action for all the joints on all three legs. Each blade is fixed/anchored into its corresponding distal leg section (e.g. lowermost in the illustrated embodiment, but could be uppermost if the cassette is at the foot). Although, it is notable that the blade need not extend all the way to the ground contacting "foot" of the leg. Only the uppermost part of the lower leg requires connection, via the blade, to upper leg sections, because longitudinal strength is provided by the leg section (e.g. typicall a box section) itself.

Alternative forms could use a chain link solution (like a bicycle chain), which is also coilable and may resist longitudinal compression so long as constrained within a channel that prevents buckling. The coilable element may be arranged external of the telescoping leg, but it is expected that for most applications this would not be aesthetically or functionally advantageous.

In practice, since individual leg lengths may need individual adjustment in many cases, e.g. to adapt to uneven ground, in one form there may be a spring loaded lock on each leg so that each can be adjusted separately without having to operate the lock, but the lock then bites and prevents the leg collapsing when needed. Then, when collapsing the tripod for packing away, the locks can be released, e.g. all together so a user can cause collapse by pushing the top of the tripod downwards towards the ground to telescope each leg to its shortest dimension.

Ideally, the locking mechanism should permit a leg to telescope inwards if excess force is applied to prevent damage to the blade by buckling. In other words, in one form the locking mechanism has a force limit that can be exceeded to allow failure (collapse) without permanent damage to any part of the device.

In one form, the internal blade is supported at each leg joint to keep the lengths of blade between supports relatively short (e.g. 300 to 400mm, but varying dependent on application and scale). The support may be a block having a narrow aperture corresponding to the cross-sectional shape of the blade, e.g. a curved aperture/slit. When constrained through a block of this type, the blade is at its strongest buckling resistance. In any event, the blade is relatively strong in compression provided that the forces are contained to be along its length. As in a tape measure, the blade has poor resistance to force in a direction laterally into a trough of the curve, so that it is adapted for coiling into a spiral.

As mentioned, blade strength is dependent upon its material width, curvature and/or thickness. The curvature may be up to or beyond a semi-circle that can be coiled if a flattening mechanism is used between the coiled portion (flattened or shallow curve) and extended length (more curved cross section) to spread and flatten it for storage. The total length of the blade is generally determined by dimensions of the telescopic legs. In some forms the blade could be tapered.

When the tripod legs are collapsed, the supporting blade can be coiled into a cassette to minimise volume. In one form, the cassette may contain a constant force torque spring pulling the blade into the cassette (akin to tape measure device) to assist retraction of the blade and collapsing of the legs. Alternatively, the legs may telescope out by means of a user pulling them out and retracted by means of the user pushing them back in. In this way, adjustment is fully controlled by the operator. It is also noteworthy that a "coil" in the present context is any configuration where the tape-like material is to be housed within a reduced space compared to its fully extended length. A coil does not have to be round (e.g. could be elongate shape) but will generally include a material that overlaps itself in order to take up less space. The coil may be housed within the upper section of the leg itself.

A suitable cassette system may further prevent the blade from binding and stalling within the cassette (due to inherent radial uncoiling force of tape) by means of a spring-loaded guide which allows the effective diameter of the coiled blade to expand as it is pushed into the cassette.

In one form, to keep the legs rigid and not prone to looseness at the joints, the fit between the telescopic tubes should have a suitable minimum tolerance (i.e. minimal "play" or rattle between leg sections), but there should be some overlap (e.g. 100mm dependent on scale of application) at the joints when fully extended. Stops/abutments should be incorporated to facilitate the overlap and to prevent the tubes from simply pulling out of each other. The fit of the joints can be assisted by using a bearing material such as nylon or acetal for the blade support blocks and also using them as bearings inside the tubes. Bearings can also be added at the lower ends of the tubes.

Brief description of the drawings

Figure 1 illustrates an overview of a tripod, with legs extended, according to one aspect of the invention; Figure 2 illustrates a close up view of a tripod head unit/platform; Figure 3 illustrates an internal view of a coiling/locking mechanism for a telescopic leg according to an aspect of the invention; Figure 4 illustrates an overview of a tripod, with legs collapsed and pivoted inwards for compactness/carrying/storage; Figure 5 illustrates a close up view of a support block component; Figure 6 illustrates a close up view of an extended telescopic leg; Figure 7 illustrates an underview of a collapsed tripod according to an alternative embodiment with linked locking mechanisms; Figure 8 illustrates an overview of a collapsed tripod according to an alternative embodiment with linked locking mechanisms; Figure 9 illustrates an internal view of a coiling/locking mechanism for a telescopic leg according to the alternative aspect of the invention; Figure 10 illustrates an underneath view of a tripod with legs extended according to the alternative embodiment.

Detailed description of the invention

The following description presents exemplary embodiments and, together with the drawings, serves to explain principles of the invention. However, the scope of the invention is not intended to be limited to the precise details of the embodiments or exact adherence with all features, since variations will be apparent to a skilled person and are deemed also to be covered by the description. Indeed, the present disclosure may separately define a number of discrete inventions. Terms for components used herein should be given a broad interpretation that also encompasses equivalent functions and features. In some cases, several alternative terms (synonyms) for structural features have been provided but such terms are not intended to be exhaustive.

Descriptive terms should also be given the broadest possible interpretation, e.g. the term "comprising" as used in this specification means "consisting at least in part of" such that interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. Directional terms such as "vertical", "horizontal", "up", "down", "upper" and "lower" are used for convenience of explanation usually with reference to the illustrations and are not intended to be ultimately limiting if an equivalent function can be achieved with an alternative dimension and/or direction.

The description herein refers to embodiments with particular combinations of steps or features, however, it is envisaged that further combinations and cross-combinations of compatible steps or features between embodiments will be possible. Indeed, isolated features may function independently as an invention from other features and not necessarily require implementation as a complete combination.

Figure 1 illustrates a general external view of a tripod 10 having features according to the invention. The tripod includes a hub or head 11 that provides several radially arranged bracket/mounts 12 from each of which a leg 13 can be located for pivoting movement about a pin 14. In the known way, pivoting is usually enabled by an interference fit or by abutment between two positions. The illustrated view of Figure 1 shows an extended standing position where legs are spaced apart at a set distance to achieve a stable configuration for a device (not seen) to be mounted to the head 11. The tripod will be free standing and maintain the device at a stable elevation. Each leg 13 of tripod 10 has four sections, arranged for sliding/telescoping extension, resulting in three effective joints/transitions 15 along the total length, terminating in a ground contacting foot 16.

More detail of the head 11 is seen in Figure 2, particularly where a locking lever 17 is visible adjacent a cassette 18, at the uppermost end of each leg where it is pivotally mounted to bracket 12 via pin 14. Locking lever 17 is the effective single release mechanism for extension and collapse or each telescoping leg 13, shown in more detail by Figure 3. Figure 4 simply shows an appearance of the tripod 10 in collapsed form where the ground contacting foot 16 has been pushed to its closest position relative to head 11.

According to Figure 3, where the cassette 18 is shown removed from mount 12 and with a cover displaced, a coiled blade 19 is visible, coiled about a central boss 20 (for accommodating pivot pin 14 and not needed for coiling around unless associated with a retracting spring) and extending a straightened length through a support block 21 into a leg 13 (not shown in Figure 3). At one wall of the cassette, lock lever 17 is pivotally mounted and biased to push the blade 19 inwardly against a support surface 31 for locking it in place.

A cam action at an end of lever 17, in the illustrated form, configures the device to allow the blade 19 to be pulled in an extending direction, but automatically locks in a retracting/shortening direction. When a distal end of lever 17 is pressed by a user, the pushing force is released, thereby freeing blade 19 to be extended more easily further out from cassette 18, or pushed longitudinally to coil more of its length into cassette 18 about boss 20. In the illustrated form, the lever 17 is used to release a locking mechanism rather than cause locking, but another configuration could be arranged, e.g. where a user actively engages lever 17 to cause locking and disengagement releases the blade 19. A bias (i.e. resilient spring element or the like) may be applied or not, dependeng on the required effect.

Figure 3 further shows a spring biased guide, e.g. a curved element 32, keyed in place to move laterally against a wall of the coil to mitigate "binding" of the spring loaded blade 19. Such a feature is necessary in the illustrated form of the invention because, without it, material 19 would tend to coil during retraction of the telescopic leg and naturally expand itself against walls of cassette housing 18 and/or against successive coils, causing it to cease before a full retraction of the telescopic stages is possible. Element 32 provides an urging force against coil 19 to counter its natural expansion and guide it into a tighter configuration, and/or enabling gradual expansion of the coil as the leg is retracted.

A support block 21 (as seen in Figure 3) is integrally formed (or may be separate component) with the cassette and press fitted into the uppermost (i.e. with largest cross sectional area) section of leg 13. Corresponding support blocks 21, which may incorporate abutment to prevent telescoping sections from complete withdrawal, are stationed at each joint 15. Detail of a support block is shown by Figure 5, where an aperture 22 is visible corresponding to a curved cross section of blade 19. Aperture preferably has a uniform cross section to support the curve of blade 19 and mitigate any tendency to buckle which, in turn, may cause a partial retraction of an extended leg 13. Aperture 22 may include a finger 23 that "points" to the inner curve shape corresponding to blade 19 for support thereof or the aperture itself may be a slot matching the cross section of relatively thin spring steel tape.

The dimensions of support 21 are determined dependent on which tube section it is associated with. For example, the cross-sectional area of tube sections of the telescoping legs 13 get progressively smaller toward ground contacting foot 16. Supports 21 must also get progressively smaller (width and length) to match the box section of each stage of leg 13.

Figure 6 illustrates detail of a joint 15 of leg 13, shown as a box section with an optional bearing material 24 to facilitate sliding. Within the box section, at the uppermost distal end, support 21 is located internally (i.e. not visible) to provide support to blade 19 as mentioned above.

Figures 7 to 10 illustrate a form of the invention where the three locking mechanisms are linked to provide for a single action to engage/disengage the locking actions of each leg. In this embodiment, a lever 25 extends from a dial 26 underneath head 11, intended for simultaneous engagement and/or disengagement of all blades 19 within respective cassettes 18 in one action. Furthermore, in this or other forms, the blade coil may be biased to extend (or retract) its substantive length such that activation of lever 25 causes the legs to "pop" out or in, in one movement.

The view of Figure 8 shows above head 11, where lever 25 is visible and also a series of abutments 27 moulded with an external wall of cassette 18 to delimit radial extension (opening angle) of legs 13.

Figure 9 shows an internal view of a cassette 18, similar in function to that of Figure 3, except where a sub lever 28 engages from below to act on a cam 29 for implementing a pressing force to the surface of coiled blade 19 and pinch it in place. As described above, a guide 32 provides a means of keeping the coil diameter from touching walls of the cassette.

Figure 10 shows an underneath view where rotatable dial 26 can be seen to have indents 30, each for receiving a sub-lever 28 of a leg locking mechanism (within cassette 18). In this way, when main lever 25 is turned, actuating dial 26 to turn about a central axis, the indents 30 act upon sub levers 28 to switch between first and second positions, in turn engaging or disengaging internal element 29 depending on the required configuration.

Further alternative configurations are possible to those described above, to achieve an equivalent function. For example, the locking mechanism may not be friction based and could implement a series of holes along the blade that engage with a toothed wheel (cog) having a ratchet paul to prevent return retraction/movement.

The invention may find application in products other than tripods. For example, a cassette/housing as described above may be incorporated into the handle of a walking stick which can be extended (e.g. via a trigger in substitute of lever 17) to a required length. The leg may further feature a shock absorption characteristic desirable in walking sticks. Shock absorption may be enabled by controlled buckling of the internal tape element and/or spring bias in the coil inside the cassette. In either case, the telescopic construction is resilient to return to its user-set length.

In this configuration, an aspect of note defines a walking stick in the form of a telescopic leg, comprising a plurality of tubular parts, arranged to mutually slide relative to one another, so as to move between a collapsed and expanded state; a housing located at an end of the leg for facilitating coiling of a length of material therewithin; a coilable length of material resistant to compression longitudinally along its length, having a distal end extending away from the housing coincident with the plurality of concentric tubular parts and fixed with a concentric tubular part most distant from the housing; a locking mechanism comprising an engagement element to engage against the coilable length and hold said coilable length longitudinally in place, thereby holding the plurality of concentric tubular parts at a desired collapsed and/or expanded state. The housing may be ergonomically moulded like a handle, wherein the locking mechanism is actuated by a trigger. A shock absorption mechanism may be implemented such as by enabling controlled buckling of the tape when exceeding a threshold of force applied longitudinally to the tape. The tape, being resilient, would then spring back to its set length. Alternatively, or in addition, the shock absorber may be a spring-loaded additional telescoping part within the ground contacting telescope section or handle end.

As a summary of the above disclosure, the invention may be embodied by a tripod comprised of at least three telescopic legs disposed radially from a head bracket. Each leg includes a cassette housing located at an end of the leg for facilitating coiling of a length of material therewithin. An uncoiled length of the coliable material extends with (and/or within) the telescopic leg sections and is fixed at a distal end. A locking mechanism (17, 29, 31) engages against the coilable length (19) to hold it in place, thereby holding the telescopic legs at a desired collapsed and/or expanded state. This is possible by virtue of the buckle/compression resistant nature of the coilable material, which may be akin to the spring steel used in a tape measure.

Claims (6)

1. Claims: 1.
2. A mounting device, comprised of at least three telescopic legs disposed radially from a head bracket, each leg comprised of: a plurality of telescoping tubular parts, arranged to slide relative to one another, so as to move between a collapsed and expanded state; a housing located at an end of the leg for facilitating coiling of a length of material therewithin; a coilable length of material resistant to compression longitudinally along its length, having a distal end extending away from the housing coincident with the plurality of tubular parts and fixed with a tubular part most distant from the housing; a locking mechanism comprising an engagement element to engage against the coilable length and hold said coilable length longitudinally in place, thereby holding the plurality of tubular parts at a desired collapsed and/or expanded state. 15 2.
3. 3.
4. 4.
5. 5.
6. 6.The mounting device according to claim 1, further comprising a support element mounted with at least one of the plurality of tubular parts, including an aperture corresponding to and receiving a cross section of the coilable length of material.The mounting device according to claim 1 or 2, wherein the coilable length is comprised of a tape, e.g. of spring steel or plastic equivalent.The mounting device according to any preceding claim, wherein the plurality of tubular parts are each non-round cross sections of diminishing cross sectional area to prevent relative rotation.The mounting device according to any preceding claim, wherein a cross section of the coilable length is curved.The mounting device according to any preceding claim, wherein a straight uncoiled length of the coilable length is housed within the plurality of tubular parts.The mounting device according to any preceding claim, wherein the engagement element is actuated by a lever.The mounting device according to any preceding claim, wherein the engagement element is or incorporates a screw.The mounting device according to any preceding claim, wherein a locking mechanism of each leg is simultaneously actuatable by an actuator at the head bracket, thereby simultaneously engaging and/or disengaging each engagement element.The mounting device according to any preceding claim, further comprising an urging element for providing a force against the coilable length when in a coiled state.The mounting device according to any preceding claim, wherein a locking mechanism of each leg is simultaneously actuatable by an actuator at the head bracket, thereby simultaneously engaging and/or disengaging each engagement element.The mounting device according to any preceding claim, wherein each interface between tubular parts is supported by a linear bearing to facilitate sliding movement and mitigate looseness at joints. 7. 8. 9. 10. 11. 12.