GB2166649A

GB2166649A - A displaceable telescopic tripod

Info

Publication number: GB2166649A
Application number: GB8524914A
Authority: GB
Inventors: Sante Zelli; Salvatore Zelli
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-10-09
Filing date: 1985-10-09
Publication date: 1986-05-14
Also published as: GB8524914D0; FR2571471A1; DE3535962A1

Abstract

A displaceable telescopic tripod for lighting installations, such as for use in movie picture shooting comprising in combination telescopic elements 2 operated by double chain 27, 28 elevation and stiffening means, trolley means connected to a central element 6 of said tripod by parallelogram means 15, 16, 21 having a variable geometry, control and fastening means 19 slidably arranged on said central element 6 for controlling and fastening the position of said trolley means, drive 5 and transmission 29, 30 means provided for said double chain means and arranged respectively on the upper and lower end of said central element, and storage and guide means 10, 8 for said double chain means, said storage and guide means 10, 8 being parallel and external with respect to said central element 6. <IMAGE>

Description

SPECIFICATION A Displaceable Telescopic Tripod The present invention relates to a displaceable telesopic tripod for lighting installations, such as for use in movie picture shooting or the like. The invention concerns a tripod having telescopic elements controlled by a double chain, said tripod being provided with a system of parallelograms facilitating movement and assuring a correct orientation of the trolley.

The employment of telescopic support devices is well known in the art, and generally in the lighting field, such as in the movie picture shooting field, and other technical fields.

Such devices are operated either by ropes and pulley systems or by screws or by hydraulic systems.

The use of mechanical systems, such as ropes, pulleys, screws, causes high noise during the operations and, furthermore, it requires regular and careful maintenance in order to avoid breakdown of the mechanisms.

Moreover, the employment of hydraulic systems implies a complex assembly due to the overall dimensions and weight of the systems.

Furthermore, all of the kind of devices referred to above do not confer to the tripod, when the same is in the position of the maximum extension, an adequate bending stability adapted to equalise the moment caused by the loads applied at its free end, and consequently it limits the maximum height of employment.

This and other drawbacks are avoided or at least reduced by a device according to the present invention which consists of a tripod having telescopic elements by which the noise and stability problems are solved employing a double chain unit for controlling and supporting said telescopic elements, said device being integrated with wheels connected to the tripod by parallelogram systems.

The double chain unit employed in the device according to the present invention is disclosed in the Italian patent specification No. 1,057,915 and has been advantageously modified for adapting it to tripods of the above said kind.

The above said double chain unit operates as a thrust rod and it is characterised in that the single chain of the pair is identical to the other one and is derived from known chains, each one having a plurality of coupling plates on both side faces, said plates practically replacing the analogous side elements of the known chains.

Said double chain unit, when suitably joined in extension with one another, forms a rigid rod that operates as an elevation system for the extension of the tripod telescopic elements and acts in such a way that the bending stability of the device is remarkably increased making it possible to realise tripods reaching a height greater than that of the tripods at present known on the market.

By employing the above said chains, a positive transmission system in both movement direction is achieved, said system allowing the attainment of highly precise adjustments of the extensions of the tripod telescopic elements.

A development of the present invention provides a system having wheels to move the tripod, each one of said wheels being connected with the central element of the device according to the invention by means of a parallelogram having variable geometry, so as to allow the variation of the height of the tripod maintaining at the same time the wheels perpendicular to the ground, without substantial risk of instability of the device.

Therefore, a specific object of the present invention is to provide a displaceable telescopic tripod for lighting installations such as for movie picture shooting or the like, comprising in combination telescopic elements operated by double chain elevation and stiffening means, trolley means connected to a central element of said tripod by parallelogram means having variable geometry, control and fastening means slidably arranged on said central element for controlling and fastening the position of said trolley means, drive and transmission means for said double chain means and arranged respectively on the upper and lower end of said central element, and storage and guide means of said double chain means, said storage and guide means being parallel and external with respect to said central element.

According to a preferred embodiment of the present invention, said drive means are advantageously constituted by a manually operated winch or an electric motor.

Further according to the invention, said telescopic elements are provided at their one end, with locking means for increasing the stablity of the tripod.

Advantageously, orientation means for the lighting means are provided on the free end of said telescopic elements on which said lighting means are fastened.

Furthermore, according to the invention, said trolley means may comprise three wheels disposed at a 1200 angle, each of said wheels being provided with parallelogram means.

In a preferred embodiment of the tripod according to the invention, said parallelogram means comprise, respectively, first and second arms pivoted, at one end, to said sliding means, and, at the other end, in the same pivoting point, to the wheel, a third arm arranged upwardly and parallel with respect to said first and second arm, and having its ends pivoted, respectively, to said sliding means and said wheel, a fourth arm pivoted, at one end, to said central element, and, at the other end, to the same point where said third arm is pivoted to the wheel.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of one embodiment of a device according to the invention; Fig. 2 shows a schematic view of the double chain unit of the device according to the present invention; Fig. 3 shows a partial view, partially cutaway, of the device according to the present invention; Fig. 4 shows a second schematic view of the double chain unit of the device according to the invention; Fig. 5 shows a sectional view taken aloing the lines AA and BB of Fig.4; 4; and Fig. 6 is a sectional view taken along the line CC of Fig.5.

Fig. 1 shows a tripod 1 comprising telescopic elements 2 at the free end of said tripod 1, a device 3 for the fastening and a device (not shown) for the orientation of a lighting group.

A locking device 4 is provided on each one of said elements 2, with the exception of the last one on which the lighting group is fastened.

The double chain unit (see Fig. 2) is operated by a winch 5 and is rigidly connected to said last element. Starting from said fastening point of the double chain unit with said element 2, said double chain extends within a central element 6, in which the two chains are coupled with one another, till a separation group arranged within a housing 7, as it will be disclosed hereafter with reference to the drawings.

After the separation, each of said chains extends at first within external storage and guide elements 10 to return pinions (not shown) arranged within a housing 9, and then downwardly within internal storage and guide elements 8.

The motion from the winch 5, which is provided with a gear (not shown), is transmitted to the double chain unit by a chain 32 (see Fig. 3) housed in a shaft 11 and buy a return pinion arranged in a housing 12.

The wheels 13 are connected to the tripod 1 by parallelogram systems generally indicated by the reference numeral 14.

Each parallelogram 14 comprises two arms 15 and 16, pivoted, at points 17 and 18, to a sliding element 19 slidably arranged on the central element 6, and, at point 20, to the wheel 13, and arm 21, parallel to said arms 15 and 16, pivoted in points 22 and 23, respectively, to the element 19 and to the wheel 13, and a sloping arm 24 that is, in its turn, pivoted in points 23 and 25, respectively, to the wheel 13 and to the upper end of said central element 6.

Acting on a lever 26, the position of the wheels 13 can be adjusted withoutjeopardising the stability of the tripod 1.

Fig. 2 shows the manner of coupling the single elements 27 and 28 of the double chain unit.

Said elements 27, 28 are coupled in the zone where they are engaged with the sprocket wheels 29 and 30, and they are subsequently separated along the guide 31. Then they engage again the sprocket wheels 29 and 30 by which they are conveyed upwards along the element 10 (see Fig. 1).

The chain 32, by which the motion is transmitted from the winch 5 to the sprocket wheels 29 and 30, is shown in Fig. 3.

The transmission of the motion is shown in greater detail in Figs. 4 and 5. The two sprocket wheels 29 and 30 are provided, each one, with two sets of teeth 33 and 34, the first ones engaging with one another while the second ones engage said elements 27 and 28 of the double chain for coupling them with one another.

The teeth 33 of the sprocket wheel 29 further engage with a pinion 35, said pinion transmitting to said teeth 33 the motion of the winch 5 and the chain 32.

The coupling of said sprocket wheels 29 and 30 by the teeth 33 is provided in order to avoid that the load acts only one one of said sprocket wheels 29 and 30.

The pinion 35 is fastened on a shaft 36, the axis of which is arranged parallel with respect to those of said sprocket wheels 29 and 30.

During assembly, a bushing 37 is mounted on said shaft 36 before the pinion 35. Said bushing 37 locks one end of a spring 39 by the insertion of a dowel within the housing 38.

The pinion 35 is, subsequently, fastened to the bushing 37 by a key inserted into a housing 40.

Since the weight of a charge would act on the extended tripod 1 and would show a tendency to rotate the pinion 35 so asto lowerthetripod 1 towards its rest position, at the opposite end of the shaft 36 it is provided with a rotation locking device, which is well known to those skilled in the art and schematically shown in Fig. 6, said device substantially consisting of an outer ring 41, two rollers 42 and an inner ring 43.

The outer ring 41 is rigidly connected with the housing 12 by screws 44, the inner ring 43 being rigidly fastened on the shaft 36 by dowels 45.

The chain 32 acts on a pinion 46 rigidly connected with a cap 47 which is in turn secured on the shaft 36. Said pinion 46 has the same number of teeth as the pinion actuated by the winch 5 so that the transmission ratio of chain 32 is 1:1.

The other end of the spring 39 is coupled to said cap 46 by a dowel inserted into an opening 48.

The spring 39 must have a radial clearance for allowing the locking and loosening around the shaft 36.

When the tripod 1 is extended, the chain 32 acts on the upper end of the spring 39 and thus locks the same around said shaft 36. In this condition, the rotation locking device is released so that the shaft 36 may rotate even if the spring 39 is locked.

In the extended position of the tripod 1, said rotation locking device avoids that the telescopic elements descend towards the lowered position.

Thus, only when the winch 5 is actuated, may said telescopic elements be lowered, putting the rotation locking device into its inoperative position and loosening the spring 39.

The present invention has been disclosed according to some specific embodiments of the same, but it is to be understood that modifications and changes can be introduced into the same by those skilled in the art without departing from the scope of the invention.

Claims

1. A displaceable telescopic tripod suitable for.

lighting installations such as, for movie picture shooting or the like, comprising telescopic elements operated by a double chain elevation and stiffening means, trolley means connected to a central element of said tripod by parallelogram means having variable geometry, control and fastening means slidably arranged on said central element, for controlling and fastening the position of said trolley means, drive and transmission means for said double chain means and arranged, respectively, on the upper and lower end of said central element, and storage and guide means for said double chain means, said storage and guide means being parallel and external with respect to said central element.

2. A displaceable telescopic tripod according to claim 1, in which said drive means are constituted by a winch.

3. A displaceable telescopic tripod according to claim 1 or 2, in which a vertical chain for the transmission of motion is provided between said drive means and said transmission means of said double chain means.

4. A displaceable telescopic tripod according to claim 3, in which said transmission means consist of a first pinion engaged with said chain, a second pinion mechanically connected to said first pinion, and a first and second sprocket wheel provided, respectively, with two coaxial tooth arrangements, the outer most ones of which engage with one another and the inner most ones engage, respectively, with one of the elements of said double chain means, the outer most toothing of one said first and second sprocket wheels being further engaged with said second pinion.

5. A displaceable telescopic tripod according to claim 4, in which said first and second pinions are connected by a shaft, having an axis parallel with respect to the axis of said first and second sprocket wheels, on which said second pinion is provided, and a spring is provided on said shaft and rigidly fastened, at one end to said second pinion by means of a bushing, and, at the other end, to a cap rigidly fixed to said first pinion and externally coaxial with respect to said shaft.

6. A displaceable telescopic tripod according to claim 5, in which a rotation locking device is provided on said shaft at the end opposite to that on which said second pinion is provided.

7. A displaceable telescopic tripod according to any one of the preceding claims, in which said telescopic elements are provided, at one of their ends, with locking means.

8. A displaceable telescopic tripod according to any one of the preceding claims, in which orientation means for lighting means are provided on the free end of said telescopic means on which said lighting means are fastened.

9. A displaceable telescopic tripod according to any one of the preceding claims, in which said trolley means comprise three wheels disposed at a 1200 angle, each of said wheels being provided with parallelogram means.

10. A displaceable telescopic tripod according to any one of the preceding claims, in which said parallelogram means comprise, respectively, first and second arms pivoted, at one end, to said sliding means, and, at the other end, in the same pivoting point, to the wheel, a third arm arranged upwardly and parallel with respect to said first and second arm, and having its ends pivoted, respectively, to said sliding means and said wheel, a fourth arm pivoted, at one end, to said central element, and, at the other end, to the same point where said third arm is pivoted to the wheel.

11. A displaceable telescopic tripod substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.