GB2194730A - Extensible tripod - Google Patents

Abstract

A tripod has legs which have telescopically slidable sections (11, 12, 13, 14). A block (19) is provided at the join of two adjacent sections (11, 12) held in place by projections (19d, 19e, 19f) received in corresponding openings in the inner section (12) at the join. A boss-piece (16) is spring loaded into a pocket (19g) in the block (19) and projects through another opening in the inner section (12). In this position it holds the outer section (11) on the position corresponding to extension of the leg, but the outer section (11) can be released by pressing the boss-piece (16) into the pocket (19g) against the spring (20). Rings (21, 22) on the inner and outer sections abut to prevent play at the joins. The leg may terminate in a foot formed by a resilient hollow box in which the end of the leg is held, and which has a non-resilient inner surface against which the end of the leg abuts. <IMAGE>

Description

SPECIFICATION Extensible tripod The present invention relates to an extensible tripod used to support objects such as a photographic camera, a video camera or a telescope.

In a typical extensible tripod, each leg has two or more telescopic sections, each pair of adjacent sections forming an inner section and an outer section, the inner section being telescopically slidable in the outer section. It is usual for the inner sections to be provided with stoppers in the form of bosses consisting of boss-pieces spring-biased to project through the openings in each inner section so that the lower edges of the respective outer sections may be locked by or released from the boss-pieces of the adjacent inner sections to permit extension or contraction of the respective legs.

Fig. 7 of the accompanying drawings illustrates the join between the inner and outer section in a known extensible tripod of prior art and Fig. 8 of the accompanying drawings is a section taken along the line A-A in Fig. 7.

Figs. 7 and 8 illustrate a tripod with the legs extended, and show an outer section 1 in the form of a pipe connected to an inner section 2 also in the form of a pipe with a circumferential ridge 2a formed on an upper end of the inner section 2 along its outer periphery which engages with a circumferential groove 1a formed on a lower end of the outer section 1 along its outer periphery so as to prevent the inner pipe section 2 from falling out from the outer pipe section.

A pair of boss-pieces 4a,4b carried on opposite ends of a substantially V-shaped spring 3 are inserted from the interior into openings 2b,2c formed through the inner section 2 at symmetrical positions so that these bosspieces 4a,4b normally project through these openings under the biasing effect of the spring 3 and function as a stopper assembly.

The boss-pieces 4a,4b project through the openings as shown when the inner section 2 is in the position in which the groove la engages the ridge 2a and locks the outer pipe section 1 at its lower edge, holding the inner section 2 in its position with the legextended.

Depression of the boss-pieces 4a,4b into the openings against the action of the spring 3 enables the inner pipe section 2 to be slid into the outer pipe section 1 and therefore enables the-leg to be contracted.

This known tripod as mentioned above is usually provided at tips of the respective legs with feet 8 as illustrated by Fig. 10 of the accompanying drawings. The surface of each foot 8 which is to contact the earth or other surface on which the tripod is to rest, is made of spherical elastic material and provides various functions such as prevention of slippage, protection against the earth and absorption of vibration.

There are, however, three problems associated with this known tripod.

The first problem encountered is that the stopper assembly, consisting of the bosspieces 4a,4b and the spring 3, is mounted merely by inserting the boss-pieces 4a,4b through the openings 2b,2c of the inner section 2, respectively. Therefore, the bosspieces 4a,4b often fall out from the associated openings 2b,2c, as seen in Fig. 9 of the accompanying drawings. When this happens, the locking effect by the boss-pieces 4a,4b is lost and, in addition, restoration of the bosspieces 4a,4b to their normal condition is not easy.

The second problem is that the boss-pieces 4a,4b are circular in cross-section as viewed transversely of the sections 1,2 (see Fig. 7).

Hence, they bear against the lower edge of the outer section 1 in a point contact, resulting in damage not only to the lower edge of the outer section 1 but also to the bosspieces themselves during a long period of use under load.

The third problem is that the foot 6, mentioned above with reference with Fig. 10 cannot satisfactorily absorb the vibration of the respective legs, since this conventional foot 6 cannot stop vibration of the legs caused by flexion developed in the legs due to the weight of an object supported by the tripod in a short time, resulting in lack of precise support and, particularly when a heavy camera is supported, it is difficult to achieve accurate photography.

A fourth and final problem lies in that each joint is susceptible of a play. Certainly the groove la and the ridge 2a at the joint, reduce this, but differences in diameter between the inner and outer sections causes a mechanical play which, in turn, reduces the stability with which an object can be supported.

The present invention, in its various aspects, seeks to solve the problems discussed above.

In a first aspect of the present invention, a block is provided at the upper end of the inner section with a block, a radial pocket being formed in this block in alignment with an opening of the inner pipe section so that the boss-piece may be accommodated within this radial bore and resiliently-biased so as to project through said opening.

In this manner, the boss-piece is prevented from accidentally falling out from the opening of the inner pipe section.

Additionally, a planar locking surface of the boss-piece adapted to bear against the lower edge of the outer pipe section may be formed so that both the lower edge of the outer pipe section and the boss-piece itself are protected against damage even after use of a long period.

In a second aspect there is provided a resili ent box adapted for planar contact with the earth, within which there is defined a space permitting the inserted tip of the leg to float therein. A disc of hard material may be provided on the inner bottom of the box against which the inserted tip of the leg bears. The tip of the leg inserted through an opening formed in an upper wall of the box may be provided with a member preventing the tip from slipping out. A foot having this arrange ment effectively absorbs vibration of the leg since the tip of the leg comes in contact with the disc of hard material on the inner bottom of the box over a small area.

In a third aspect, there is provided a first ring of e.g. sheet metal on the inner periphery of the outer pipe section and a second ring of e.g. sheet metal around the upper end of the inner pipe section, respectively.

The first sheet metal ring may then slide along the outer periphery of the inner section and the second sheet metal ring slides along the inner periphery of the outer section so that, after the leg has been extended with the inner section being pulled out, these first and second sheet metal rings between both pipe sections function to eliminate play which could otherwise oecur at the join and thereby to improve the mechanical stability of the tripod.

An embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows, partially in section, a tripod leg in accordance with the present invention; Fig. 2 shows a detail of the join between two leg sections of the leg of Fig 1; Fig. 3 is a sectional view along the line B B in Fig. 2; Fig. 4 is a perspective view of a ring suit able for use in the join of Fig. 2; Fig. 5 is a perspective view of a block and part of a leg section, in accordance with the present invention; Fig. 6 shows a sectional view of a foot and leg end according to the present invention; Fig. 7 shows a view, corresponding to Fig.

2, of a known join, and has already been de scribed; Fig. 8 shows a sectional view along the line A-A in Fig. 7; Fig. 9 shows a sectional view corresponding to Fig. 8, but with the stoppers displaced from the correct position; and Fig. 10 is a sectional view of a known foot and leg end, and has already been described.

Referring first to Figs 1 and 2, a tripod has -three legs, each having four sections 11 to 14 in the form- of interconnected telescopic pipes.

A stopper assembly is provided at each pipe joint and the tip of the leg is provided with a foot 15. Also illustrated in Fig. 1 are respective boss-pieces 16,17,18 of the respective stopper assembly.

Considering the interconnection of pipe sections 11 and 12, section 11 forms an inner pipe section telescopically received into section 11 forming an outer pipe section. Similarly, section 13 forms an inner pipe section received into section 12 forming an outer pipe section, and such relationship is true also for the pipe sections 13,14.

Referring now to Figs. 3 to 5, a solid block 19 of hard plastics material is provided within e.g. section 11 adjacent its join with section 12.

As is best seen in the perspective view of Fig. 5, the block 19 is in the form of a body from.which projects a pair of parallel arms.

One side of the body 19a and end surfaces 19b,19c of the respective parallel arms define symmetrical convex portions accommodated within the inner periphery of the inner pipe section 12 and these convex portions have respective stepped projections 19d,19e,19f formed integrally therewith. The convex side 1 9a of the body 19 has a rectangular pocket 1 9g within which the bosspiece 16 and an associated coil spring 20 are located.

The boss-piece 16 is a small rectangular block having an oblique tip 16a and a shoulder 1 6b formed midway of the block. To fit the block 19 into the inner pipe section 12, the boss-piece 16 and the coil spring 20 are first placed into the pocket 199 of the block 19, and then the block 19 is inserted into the inner pipe section 12 through the end thereof, with the boss-piece 16 held depressed into the pocket 19g.

During this insertion, pressure is exerted on the peripheral wali of the inner pipe section 12 and thereby this pipe section is slightly deformed so that the stepped projections 19d,19e,19f are forcibly received into the inner pipe section 12 and then these stepped projections 19d,19e,19f may be fitted into associated mounting openings 12a,12b,12c, respectively in the inner pipe section 12.

Once the block 19 has been positioned in this manner, the tip 16a of the boss-piece 16 projects through an opening 12d in the inner pipe section 12, which opening is aligned with the pocket 1 9g, under the biasing effect of the coil spring 20 and its stepped shoulder 1 6b locks it into position due to its abutment against the edge of the opening 12d.

The size of the stepped projections 19d,19e,19f are chosen so that they are flush with the outer periphery of the inner pipe section, when these stepped projections are fitted into the associated mounting openings. If they project above the outer periphery of the pipe section by a small amount, the excessive material may be machined away. First and second sheet metal rings 21,22, being corrugated rings as illustrated in Fig. 4 and made of synthetic resin or metallic material, are provided at the join. The first sheet metal ring 21 is located at the lower end of the outer pipe section along its inner periphery and the second sheet metal ring 22 is located at the upper end of the inner pipe section 12 along its outer periphery. These rings may be fitted into circumferential grooves formed in the respective pipe sections or secured by adhesive to the associated pipe sections.It should be noted here that the first and second sheet metal rings are not necessarily corrugated, but may have embossed or smooth surfaces.

Although the stopper assembly has been described above with respect to the joint between the pipe sections 11,12, similar stopper assemblies are provided at the other pipe joints.

The foot 15 provided on the tip of each leg comprises, as illustrated in Fig. 6, an elastic box 1 5a made of hard rubber or similar material and adapted for planar contact with the earth, a space 15b within the box 15a for receiving the end of the inserted leg 14 and a disc 15c of hard material on the inner bottom surface of the box 15a.

The tip of the leg 14 is inserted through the upper opening of the elastic box 15a of the foot 15 and the latter is prevented by a flange 14a provided around the tip of the leg from slipping off said tip of the leg.

The hard disc 1 sic may be made of relatively hard material such as ceramics or metal and the tip of each leg contacts with the hard disc 15c at a point P when the legs are opened. Such point contact is surprisingly advantageous in effective absorption of vibration propagated from the foot in contact with the earth to the leg itself.

The tripod constructed as has been described hereinabove according to the present invention may offer advantageous effects as will now be discussed.

(1) The block, supporting the boss-piece, may be reliably secured to the inner pipe section by a plurality of stepped projections, avoiding the accidental slippage of the bosspiece which has often occurred in the arrangement of prior art.

Also when the locking surface of the bosspiece adapted to bear against the lower edge of the outer pipe section is planar, the area of contact is increased, protecting both the pipe section and the boss-piece against damage during a long period of use. It should be understood that the number of said blocks serving to fix the block in place is not limited to three but may be more or less than three, with a corresponding number of mounting openings formed through the inner pipe section. The block may also be fixed in place by adhesive, instead of the stepped projections.

Although the surface of the boss-piece along which the latter bears against the lower edge of the outer pipe section is preferably planar, the rest of the boss-piece may have various configurations.

(2) The foot may rapidly absorb vibration of the associated leg and may thereby reduce deterioration in the precision of support due to vibration of the leg, regardless of the conditions of use.

This shoe is adapted to be detachably mounted on the tip of each leg and may be carried or stored separately.

(3) The use of first and second sheet metal rings may provide a packing, a spring and a cushion between the outer pipe section and the inner pipe section, improving the precision of the joint therebetween.

Accordingly, extension and contraction of the tripod can be smooth and stabilized even after a long period of use in contrast with the known tripod in which an inconvenient play often develops after such a long period of use.

As will be clear from the aforegoing description, the present invention is highly efficient in practice particularly when realised as the extensible tripod comprising two or more sectioned pipes.

Claims (10)

1. A tripod in which each leg has a plurality of telescopically joined sections forming an inner and an outer section at each join, there being a stopper assembly at each join having a block received in the inner section and a boss-piece mounted in the block, there being an opening in the inner section through which the boss-piece is resiliently biased, whereby an end of the outer section is held in a predetermined position by abutment of the end against the boss-piece and is releasable from that predetermined position by movement of the boss-piece against its resilient biasing.

2. A tripod according to claim 1, wherein the bosspiece is mounted in a pocket in the block.

3. A tripod according to claim 1 or claim 2, wherein the block has a plurality of fixed projections received in corresponding openings in the inner section, thereby to locate the block in the inner section.

4. A tripod according to any one of the preceding claims, wherein the surface of the boss-piece which abuts against the outer section, when the outer section is in its predetermined position, is planar.

5. A tripod according to any one of the preceding claims, wherein the end of each leg extends through an aperture in a hollow resilient foot, there being a flange on the leg within the foot of a size greater than the aperture, to prevent removal of the foot from the leg.

6. A tripod according to claim 5, wherein there is a bearing surface of non-resilient material within the foot against which the end of the leg abuts.

7. A tripod according to any one of the preceding claims, wherein rings are provided within the inner and outer sections at each join, which rings abut each other when the outer section is in the predetermined position.

8. A tripod in- which the end of each leg extends through an aperture in a hollow resilient foot, there being a flange on the leg within the foot of a size greater than the aperture, to prevent removal of the foot from the leg, and there being a bearing surface of nonresilient material within the foot against which the end of the leg abuts.

9. A tripod in which each leg has a plurality of telescopically joined sections forming an inner and an outer section at each join, there being releasable means for holding the outer section in a predetermined position relative to the inner section, wherein rings are provided within the inner and outer section at each join, which rings abut each other when the outer section is in the predetermined position.

10. A tripod substantially as herein described with reference to and as illustrated in Figs. 1 to 5 of the accompanying drawings.