GB2244424A

GB2244424A - Adjustable supports

Info

Publication number: GB2244424A
Application number: GB9009481A
Authority: GB
Inventors: Colin Stanwell-Smith
Original assignee: Reckitt and Colman Fine Art and Graphics Ltd
Current assignee: Colart UK Ltd
Priority date: 1990-04-27
Filing date: 1990-04-27
Publication date: 1991-12-04
Anticipated expiration: 2010-04-27
Also published as: GB9009481D0; GB2244424B

Abstract

In a multi-legged stand each of the legs is pivotably attached to a common structural element and a strut individual to each leg is pivotably attached to its respective leg and to a sliding member individual thereto, retained with the structural element and slideably displaceable in the direction of the structural element. A clamp is provided for clamping the sliding members against displacement relative to the structural member. In practise the clamp can be released to release the sliding members, the structural member can then be located in a desired spacial position and the clamp is then re-secured, to secure the sliding members against displacement relative to the structural member, thus to fix the structural member in the desired spacial position. The stand is particularly a tripod and can be used in camera tripods, easels and outdoor stands for instruments, such as telescopes. <IMAGE>

Description

IMPROVEMENT5 TO ADJUSTABLE SUPPORTS This invention relates to an improved mechanism for multilegged adjustable stowable supports and in particular tripod supports.

Tripods and four-legged supports are used in many applications to support loads. This invention is particularly relevant to camera tripods, easels, outdoor stands for instruments such as telescopes and so on.

Collapsible tripods are useful for portable loads because compact storage is desirable during transport or when the tripod is not in use. By the provision of adjustment of the length of one or more frequently all of the legs, often by a telescopic arrangement, the height and attitude of the load can be changed. This is particularly useful out of doors, where the ground is often out of level or irregular.

Conventional tripods typically comprise three extendible legs joined by pivots at a combination joint and this simple arrangement allows a range of adjustment of height and compensation for non-horizontal ground and provides when locked a lightweight stable support which can alternatively be stowed in compact form.

Fig 1 shows a simple tripod of this type with telescopic legs.

The tripod has three legs 1, 2, 3 each having corresponding extensions 4, 5, 6 and typical pivots 7 at a joining piece 8. Each leg has a locking means 9 which fastens the telescopic action of the extensions 4, 5, 6.

It will be appreciated that to position the Joining piece 8 above the ground all three legs 1, 2, 3 have to be adjusted and locked in unique positions, requiring at least three locking operations and often an iteration of unlocking, sliding and locking operations.

In use the simple tripod just described can be inconvenient in that to achieve a given position all three legs need to be correctly adjusted. Altering the length of any one leg changes both the height and attitude of the junction point. It is desirable to contrive a support which offers the same range of adjustment and compact storage but with a single convenient adjustment means.

This invention provides a mechanism to achieve this.

According to the present invention there is provided an adjustable stand for supporting a load comprising an elongate structural member and thee or more legs, each with a strut, all controlled by a releasably lockable clamp which, when unlocked, allows at least one of the legs to pivot independently of another of the legs and which, when locket, prevents such pivoting so that the structural member will support loads, wherein each leg is pivoted at one Or its ends to the lower end of the structural member and one end of each strut is pivotally connected to its leg while the other end of each strut is slidable along the structural member.

Preferably the slidable end of each strut is pivotally connected to a lockable sliding element controlled by the clamp. These may be disposed in one or more grooves or channels in the structural member, or else the structural member may be hollow and the sliding elements disposed inside it.

The clamp may be operated by a lever, optionally provided with a ratchet. Alternatively, the clamp may comprise a lever having a cam face. More particularly, partially locking the clamp may allow at least one of the legs to pivot further before the clamp is locked completely.

At least two of the legs may be rigidly joined together.

In a preferred embodiment of the invention the legs are of commensurate length with the structural member and arranged so that they can be folded to lie alongside the structural member for storage. They may then be extended by rotating through an angle of between 90 degrees and about 150 degrees from this folded position, and the struts and locking means are arranged to fit within the length of the structural member when the legs are folded as described.

In a further preferred embodiment the rotation of the legs is assisted by springs so that the legs tend to extend themselves. The structural member can be used to support loads directly; for example a camera mounting point could be attached to the member. Further components can be added to the structural member.

In a further aspect of the present invention, there is provided an easel incorporating the adjustable stand. A tilting head can be added to the structural member to which a canvas-holder can be attached. The tilting head may be actuated by means of a handle which may be used as a carrying handle in the folded position.

The legs may be provided with anchoring means such as slidable pegs at their lower ends.

Embodiments of the invention will now be further described by reference to the drawings in which Fig 2 shows a stand in accordance with the present invention; Fig 3 shows a packed-up artists easel incorporating a variant of the stand; Fig 4 shows the same easel deployed in use; Fig 5 shows an enlarged cross-section on line V-V in Fig 4, with elevational details omitted for clarity; and Fig 6 shows an enlarged fragmentary detail of a further variant of the stand, viewed from the rear.

Referring to Fig 2 there is a fixed-length elongate structural member 20 having three legs 21, 22, 23 pivotally attached at the lower end of the structural member 20.

Each of the legs 21, 22, 23 is pivotally attached towards its upper end to a strut 24. The upper end of each strut 24 has an pivot 25 which attaches it to a sliding element 26. Each of the three sliding elements 26 is slidable along the elongate structural member 20 in a groove, within a single clamp 27 which is lockable by a lever 28. 'When the clamp 27 is unlocked the sliding elements 26 are free to slide and thus each leg 21, 22, 23 can be rotated on its pivot. en the clamp 27 is locked the sliding elements 25 are fixed, thereby fixing the position of the upper ends of the struts 24 so that the legs cannot rotate on their pivots on the structural member 20. The clamp 27 may interact with the sliding elements 26 and/or the lever 28 by means of a ratchet.

The effect of this mechanism is that, when the clamp 27 is unlocked, the top of the structural member 20 can be grasped and manoeuvred through a continuous range of spatial positions while the distal ends of the legs 21, 22, 23 remain in contact with the ground. When the desired position is found, the clamp 27 may be locked after which the stand will support loads. Ideally the clamp 27 will be constructed so that locking it by means of the lever 28 initially fixes just two of the sliding elements 26 so that the third leg 23 may be further adjusted before fixing the remaining sliding element 26. The third leg 23 can be constructed as two legs rigidly joined together.

The stand may be constructed from various load-bearing materials such as wood, metal, plastic resins or combinations of these. One preferred combination uses extruded aluminium tubes for the various elongate members and plastic moulded parts, which are strongly attached to said tubes, for the pivots and sliding components.

Referring to Figs 4 and 5 a hollow central elongate structural member 40 has three pivoted legs 41, 42, 43 each of which has slidable pegs 44, 45, 46 for anchoring in soft ground. Struts 47, 48, 49 act as already described. A lever 50 locks and unlocks sliding elements 59 disposed in a channel 60 in the rear of the structural member 40, in the manner already described. A support rod 51 is attached to the structural member 40 and supports two pivoted boxes 52, 53 which can be used for storage of consumables and so on.

A tilt pivot 54 is attached to the top of the structural member 40 actuated by a handle 55. A board carrier 56 can tilt and slide when the handle 55 is set in an unlocked position. Brackets 57, 58 are used to support canvases and the like and can lockable slide on the carrier 5S.

Referring to Fig 3 the handle 55 can be used to carry the folded assembly in which the boxes 52, 53 are rotated to a stowed position, while the legs 41, 42, 43 are folded beside the structural member 40. The lower bracket 57 can be arranged to form a foot so that the folded assembly stands by itself.

Referring to Fig 6 the three sliding elements 51 (shown in fragmentary section) are again disposed in a channel 62 in the rear of the structural member 63. The clamp comprises an S-shaped lever 64 with a cam face 65 adjacent to the sliding elements 61 so that, when it is moved doufnwardly from the unlocked position te the locked po3iticn, the cam face 55 Initially fixes the central sliding element 61a. The two side legs 66, 67 may then be further adjusted before fixing the two outer sliding elements 61 b, 61c.

Claims

1. An adjustable stand for supporting a load comprising an elongate structural member and three or more legs, each with a strut, all controlled by a releasably lockable clamp which, when unlocked, allows at least one of the legs to pivot independently of another of the legs and which, when locked, prevents such pivoting so that the structural member will support loads, wherein each leg is pivoted at one of its ends to the lower end of the structural member and one end of each strut is pivotally connected to its leg while the other end of each strut is slidable along the structural member.

2. An adjustable stand as claimed in claim 1, wherein the slidable end of each strut is pivotally connected to a lockable sliding element controlled by the clamp.

3. An adjustable stand as claimed in claim 2, wherein the sliding elements are disposed in one or more grooves or channels in the structural member.

4. An adjustable stand as claimed in claim 2, wherein the structural member is hollow and the sliding elements are disposed inside it.

5. An adjustable stand as claimed in any one of the preceding claims, wherein the clamp is operated by a lever.

6. An adjustable stand as claimed in claim 5, wherein the clamp is provided with a ratchet.

7. An adjustable stand as claimed in any one of claims to ! herein the clamp comprises a lever having a cam face.

8. An adjustable stand as claimed in any of claims 5 to 7 wherein partially locking the clamp allows at least one of the legs to pivot further before the clamp is locked completely.

9. An adjustable stand as claimed in any one of the preceding claims, wherein at least two of the legs are rigidly joined together.

10. An adjustable stand as claimed in any one of the preceding claims, wherein the legs are of commensurate length with the structural member and can be folded te lie alongside the structural member for storage.

11. An adjustable stand as claimed in claim 1C, wherein the legs can be extended from the folded position by rotating through an angle between 90 degrees and about 15C degrees from the folded position.

12. An adjustable stand as claimed in claim 10 or claim 11, wherein the struts fit alongside the structural member in the folded position.

13. An adjustable stand as claimed in any one of claims 10 to 12, wherein the extension of the legs from the folded position is assisted by springs.

14. An adjustable stand as claimed in any one of the preceding claims, wherein the structural member has further support components attached thereto.

15. An easel incorporating an adjustable stand as claimed in claim 14.

16. An easel as claimed in claim 15, wherein the structural member has a tilting head attached thereto.

17. An easel as claimed in claim 16 incorporating an adjustable stand as claimed in claim 10, wherein the tilting head is actuated by means of a handle which may be used as a carrying handle when in the folded position.

18. An easel as claimed in any one of claims 15 to 17, wherein the legs are provided with anchoring means.

19. An easel as claimed in claim 18, wherein the anchoring means comprise slidable pegs at the lower ends of the legs.

20. An adjustable stand substantially as described herein with reference to and as illustrated in Fig 2 or Fig 6 of the accompanying drawings.

21. An easel substantially as described herein with reference to and as illustrated in Figs 3, 4 and 5 of the accompanying drawings.