An adjustable telescopic support

DESCRIPTION

Technical field of the invention

The present invention relates to an adjustable telescopic support, particularly but not exclusively for supporting video and photographic equipment, of the type including the features mentioned in the preamble of the main claim. Background art In the construction of supports for photographic equipment, such as monopods or tripods having telescopic legs, it is desired that the legs (and/or the central column of the support) should be telescopically adjustable without offering substantial resistance in the lengthening direction but should be subject to automatic locking, which can be released manually, in the opposite direction, that is to say, that of contraction. In practice, it would be desirable for the operator to be able to position the tripod with minimum force, even with one hand, and for the legs to lock automatically under the load they support.

A support of that type is known, for example, from US 5,575,448 which belongs to the same Applicant. The support described in that document is provided with a locking device which comprises a beaker-like formation fitted to one of the tubular elements, with a tapered seat in which are engaged two limbs projecting from a contractible collar capable of being clamped on the other tubular element in order to be locked thereon in a loading direction and to be unlocked in the opposite direction.

That device achieves the desired result of automatic locking of the telescopic elements in the loading direction but does have some disadvantages. A first disadvantage is caused by the decidedly large space requirement of the device which, especially in a photographic tripod, is hardly consistent with the requirements of compactness typical of the sector. A second disadvantage is caused by the complicated nature of the system for manually unlocking the device when it is desired to contract the telescopic rod to which it is fitted. Disclosure of the invention The technical problem underlying this invention is that of providing an adjustable telescopic support which is designed structurally and functionally to enable all of the disadvantages discussed with reference to the mentioned prior art to be overcome. In the context of this problem, an important object of the invention is to provide a support, the locking device of which is suitable for being fitted on tubular elements produced from various materials.

Another object of the invention is to provide a support which can be readily operated with one hand. This problem is solved and these objects are achieved with an adjustable telescopic support according to the invention which is produced in accordance with the claims which follow. Brief description of the drawings

The features and advantages of the invention will emerge more clearly from the detailed description of some preferred embodiments thereof which are illustrated by way of non-limiting example with reference to the appended

drawings in which :

- Figure 1 is a view in longitudinal section of a first embodiment of a support according to the invention;

- Figure 2 is an exploded perspective view of the support of Figure 1; - Figure 3 is a sectioned view of a second embodiment of the support of this invention;

- Figure 4 is a sectioned view of a third embodiment of the support of this invention;

- Figure 5 is a sectioned view on an enlarged scale of the detail indicated by the arrow V of Figure 4;

- Figure 6 is a partial sectioned view of a variant of the support of Figure 4;

- Figure 7 is an exploded perspective view of a further embodiment of the invention;

- Figure 8 is a view in axial section of the embodiment of Figure 7; - Figure 9 is a sectioned view taken on the line IX-IX of Figure 8.

Best modes for carrying out the invention

In Figures 1 and 2, 1 indicates generally a portion of a support, such as a portion of a leg of a tripod or monopod for optical, photographic or video- photographic equipment. The support 1 can, however, equally well be used for other purposes.

The support comprises a first and a second tubular element 2, 3 which are internal and external, respectively, and which can be slid telescopically one inside the other. The tubular elements are guided one inside the other and can be locked in any relative position by means of a locking device 5 fitted between them.

The locking device 5 comprises a first sleeve 6 fitted and locked by a portion

7 thereof on one end of the external tubular element 3 and having, on its inside, a frustoconical seat 8 on which a covering 9 is fitted and held in a suitable recess. A shoulder 10 abutted by the corresponding end of the tubular element 3 is formed between the seat 8 and the portion 7. The seat

8 is thus fitted on the tubular element 3 and may be produced, together with the sleeve 6, with a material which is the same as or different from the material of the tubular element 3.

On its outer surface, the sleeve 6 has an annular enlarged portion 11 on which a series of cam profiles 12 are formed, each having a ramp 13 terminated by a portion 14 which extends circumferentially. A second sleeve 15 is fitted slidably on the first sleeve 6. The second sleeve 15 has, for each cam profile 12, a cam-follower appendage 16 projecting radially inwards and is acted on by a spring 17 which is active in the direction of arrow F in Figure 1 between a shoulder 18 formed by the enlarged portion 11 and an annular plug 19 fitted on the second sleeve 15. The second sleeve 15 also has, on the side remote from the plug 19, a collar 20 which is resiliently contractible owing to the provision of notches 21 and which is fitted on the internal tubular element 2 to surround it completely. The collar 20 is secured in abutment against the second sleeve 15 by means of a bayonet coupling 21a. The latter has, on the outside, a frustoconical shell surface 22 which engages in the seat 8 of the first sleeve with the interposition of the covering 9. The covering 9 preferably has a coefficient of friction which is lower, with respect to the surface of the collar 20, than the coefficient of friction between the internal surface of the collar

20 and the external surface of the tubular element 2, so that the collar can be moved with respect to the seat 8 more readily than with respect to the tubular element 2. The covering 9 is fitted on the seat 8 in the form of a frustoconical ring composed of a sheet-form plasties material having a low coefficient of friction.

The second sleeve 15 can be rotated manually with respect to the first sleeve 6 in order to move the cam-follower appendages 16 between the circumferential portion 14, in which the collar is locked with respect to the seat 8 in a non-operative position in which the tubular elements 2, 3 are free to slide with respect to each other, and the ramp 13, in which the collar is urged by the spring 17 into an operative position in the seat 8 in order to lock the tubular elements 2, 3 with respect to each other. The spring 17, the cam profiles 12 and the cam-followers 16 therefore constitute actuator means between the sleeve and the external tubular element in order to move the collar 20, by means of the sleeve, between the operative and non-operative positions identified above. It should be mentioned that, in that position, a load acting in the direction tending to insert the first tubular element 2 more deeply into the second tubular element 3 tends to drive the collar 20 further into the seat 8, increasing the resilient contraction of the collar and the resulting locking force in respect of the tubular elements 2, 3. Conversely, an urging in the opposite direction tends to move the collar 20 axially with respect to the seat 8 in the direction of compression of the spring 17, thus freeing the relative sliding between the tubular elements 2, 3. Referring now to Figure 3, a second embodiment of the invention is

generally indicated 30. Details analogous to those just described are indicated by the same reference numerals.

In this embodiment 30, the seat 31 for accommodating the contractible collar 32 is formed by flaring at the corresponding end of the external tube 3. It will be appreciated that the material of the seat and the material of the tubular element are in that case identical.

The cam profile 12 in this case comprises a front cam 33 formed at the corresponding end of the external tube 3 by fitting an annular element 34 to the mouth of the seat 31. The annular element 34 is locked in rotation on the tubular element 3 by the engagement of a tooth 35 in a corresponding recess 36. One (or more) projection(s) 37 from the second sleeve 38 is (are) provided as (a) cam-follower appendage(s).

In the embodiment of Figure 4, which is generally indicated 40, the cam- follower appendage is formed by a peg 41 placed radially in the sleeve 42 and projecting inside the same in such a manner as to engage a cam profile 43 formed by producing a slot in the external tube 3. The sleeve 42 may (Figure 6) or may not (Figure 5) be provided with a spring 17 so that the cam and the cam-follower can, if necessary, be the only means actuating the locking device. In this case too, as in the remaining embodiments, details analogous to those of the previous Figures are marked by the same reference numerals.

With reference to Figures 7 to 9, a further embodiment of the invention is generally indicated 70. A sleeve 71 is fitted and secured to the external tubular element 3 in a manner completely analogous to the sleeve 6 of the first embodiment. Like

the latter, the sleeve 71 has the seat 8, complete with the covering 9, and also the shoulder 10. Also completely the same except for structural details is the collar 20 which is terminated by a flange 71a abutted by a collar- carrying member in the form of an annular element 72 having two diametric appendages 73 projecting radially outwards and acting as cam-followers. The appendages 73 are accommodated in respective opposite openings 74 formed longitudinally in the sleeve 71. A tilting element 75 is pivoted about a transverse axis 80 by means of respective pins 76 in corresponding seats 77 formed in the sleeve 71 at the base of the openings 74. The collar is moved in the seat 8 against the force of a spring 79 by means of cam profiles 81 with which the cam-follower appendages 73 cooperate and which are formed on the element tilting about the pivot axis 80. The spring 79 tends to place the collar 20 in the seat 8 in an operative position of locking the tubular elements and it is held in a recess 82 of the sleeve 71 by means of a screw plug 83.

By tilting the element 75 about the axis 80, either the tubular elements are released, in order to adjust the relative extension thereof, when the cam profiles 81 act on the cam-follower appendages 73 in order to disengage the collar from the seat 8, or they are locked, when the cam profiles 81 allow the spring 79 to place the collar in the seat 8.

The invention thus solves the problem set and achieves numerous advantages over traditional supports. These include the compactness of the locking device between the tubular elements and the locking efficiency which is proportional to the load acting on the support. Another important advantage is the fact of being able to adapt the invention to supports whose

telescopic tubular elements are constructed with various materials, which may or may not be suitable for undergoing flaring machining.