WO2000043709A1

WO2000043709A1 - Improvements in or relating to tripod stands

Info

Publication number: WO2000043709A1
Application number: PCT/GB2000/000136
Authority: WO
Inventors: Richard Arthur Lindsay
Original assignee: Vitec Group, Plc
Priority date: 1999-01-19
Filing date: 2000-01-19
Publication date: 2000-07-27
Also published as: JP2002535576A; GB2361180A; AU3063700A; CN1344358A; GB2361180B; GB0118021D0

Abstract

The disclosure relates to a tripod stand for supporting equipment such as a TV camera or the like comprising a mounting (10) for the equipment having a central axis and three telescopic legs (17, 18) extending from the mounting, the legs having head ends (40) pivotally attached to the mounting at locations equi-spaced around said central axis of the mounting to allow the legs to fold together in a closed position and outwardly to an erect position in which they diverge in tripod form from the mounting, and foot ends (50, 51) to engage the ground or other surface on wich the stand is to be used. Each leg comprises a plurality of slidably engaged interlocking channel section members (17, 18, 19) facing outwardly of said axis to extend and retract with respect to one another. One of said members (17) is being pivotally attached to the mounting to swing between said folded and erect positions and each of the further members having menas (35, 45, 48) to lock the member in any position of extension/retraction with respect to the adjacent member nearest said mounting to vary the stand height.

Description

IMPROVEMENTS IN OR RELATING TO TRIPOD STANDS

This invention relates to tripod stands and is particularly, although not exclusively, applicable to stands for equipment such as TV cameras or the like-

Tripod stands for TV or video cameras comprising a camera mounting and three telescopic legs each having a head end pivotally attached to the mounting at locations equi-spaced around the mounting to allow the legs to fold together in a closed position and outwardly to an erect position in which they diverge in tripod form from the mounting and a foot end to engage the ground are well known. Our European Patent No. 0, 541,579B discloses one form of such a stand in which each leg comprises an upper member consisting of two parallel tubes joined at their upper and lower ends by cross pieces, the upper cross piece being pivotally attached to the camera mounting for the legs to fold between an inner packed position and an outer erected position. A central member of the leg also comprises a pair of parallel tubes spaced to slide between the tubes of the upper member and, again joined by cross pieces at their upper and lower ends. The tubes of the central member extend slidably in bores in the lower cross piece of the upper member and the upper cross piece of the central member is slidably engaged on the tubes of the upper member. A locking device is provided on the upper cross piece of the central member to lock the central member in any position of extension with respect to the upper member. A bottom member of the leg comprises a single tube slidably engaged in a bore in the lower cross piece of the central member having a cross piece at its upper end which slidably engages with the tubes of the central member and a foot at its lower end. A locking device is provided on the lower cross piece of the central member to lock the lower member in any position of extension with respect to the central member. With the leg members fully retracted the lower cross-piece of the central member abuts the lower cross-piece of the upper member and the foot of the bottom member abuts the cross-piece of the central member. It is not possible to retract the bottom and central members wholly into the upper member so that the legs cannot be made as compact as would be desirable .

Furthermore, operators prefer that the locking device for each extendable leg member is located on that member rather than a non-moving member so that a leg can be released and extended one handed rather than requiring a lock to be released on a non-moving member and then the moving member to be adjusted in a separate operation.

To obviate the latter disadvantage, this invention provides a tripod stand for supporting equipment such as a TV camera or the like comprising a mounting for the equipment having a central axis and three telescopic legs extending from the mounting, the legs having head ends pivotally attached to the mounting at locations equi-spaced around said central axis of the mounting to allow the legs to fold together in a closed position and outwardly to an erect position in which they diverge in tripod form from the mounting, and foot ends to engage the ground or other surface on which the stand is to be used, each leg comprising a plurality of slidably engaged interlocking channel section members facing outwardly of said axis to extend and retract with respect to one another, one of said members being pivotally attached to the mounting to swing between said folded and erect positions and each of the further members having means to lock the member in any position of extension/ retraction with respect to the adjacent member nearest said mounting to vary the stand height.

In the preferred arrangement the members from the mounting end to the foot end are of successively reduced cross-section, each successive member along the leg from the mounting end to the foot end being slidably engaged in the previous member.

In either of the above arrangements the locking means may comprise an elongate element on each of said further members extending lengthwise of the member adjacent the inner side of one side wall thereof and engageable with the outer side of a further member slidable thereon, the element being rotatably mounted on the member at the ends thereof about an axis extending lengthwise of the member between a position in which the further member is free to slide with respect to member and a position in which the locking element effects a jamming engagement between the side walls of the members to lock the member together.

In the latter arrangement the locking element on each of said further members may be arranged to pass through an over centre position as it approaches locking engagement of the leg member with the adjacent member to hold the locking element in said locking engagement therewith.

In any of the preceding arrangements means may be provided for removing lateral play between adjacent leg members parallel to the pivot axis.

More specifically the means for removing play between adjacent leg members may comprise elongate cams mounted on said one member and successive members along the leg up to the penultimate member to act on the overlapping part of the next member along the leg to remove play between the members .

According to a further feature of the invention, the cross-sections of the members are such that the flexural axis of each leg is aligned with the point at the foot end of the leg where reaction from the ground acts on the leg so that lateral loads on the leg generally parallel to the axis about which the leg pivots with respect to the mounting do not cause twisting of the leg.

In the latter case the member at the head end of each leg may have a double channel section providing channel forms facing to either side of the leg, the channel section to one side of the leg receiving the next channel member slidably engaged therein and the channel section of the other side of the leg being formed to position the flexural axis of the leg to extend through the point of reaction load at the foot end of the leg as aforesaid.

In either of the above mentioned arrangements the foot end of each leg may have an angled foot member attached thereto to engage the ground, the foot member being attached to the leg so that load applied to the foot acts on the foot end of the leg through the flexural axis of the leg in the direction parallel to the pivot axis of the leg with the mounting. Also, the sections of the leg members may be such that the flexural axis of the legs intersect the respective pivot axes of the legs on the mounting.

According to a further feature, the sections of the leg members are such that the flexural axis of the legs intersect the respective pivot axes of the legs on the mounting.

In a further construction according to the invention, the locking means may comprise elongate clamping means projecting from one side wall of a channel to engage on the opposite side of an outer channel and means are provided to extend and contract the clamping means to lock and release the channels.

For example, the clamping means may comprise an elongate clamping member and an elongate driving member acting on the clamping member with longitudinal movement in one direction to extend the clamping member into clamping engagement with the side wall of the adjacent channel and in the opposite direction to release the clamping action.

More specifically, the elongate driving member may have a series of shallow saw-shaped teeth spaced along its length engageable with corresponding saw- shaped teeth on the clamping member such that movement of the driving member in one direction displaces the clamping member away from the side wall of its associated channel into clamping engagement with the side wall of the adjacent channel.

In one particular arrangement, the elongate clamping member and the elongate driving member may have further interengaging means which cause the clamping member to be positively withdrawn from clamping engagement with movement of the driving member in said opposite direction.

In a preferred construction according to the invention, said channel member on which the clamping means are mounted may have an elongate side channel extending the length of the side wall in which the clamping member and cam member are mounted.

In the latter arrangement, guide means may be provided for guiding the driving member linearly along the channel to displace the clamping member outwardly of the channel with movement in one direction and to allow the clamping member to retract into the channel with movement in the opposite direction.

It is further preferred that means are provided for pre-adjusting the position of the clamping member in relation to the driving member to minimise movement before the clamping member acts on a side wall of a further channel.

Preferably the driving member for each channel is displaced along its respective channel by an operating device at one end of the channel.

More specifically the operating device may comprise a lever rotatably mounted about an axis extending transversely to the leg at said one end and inter connected to the cam member to displace the cam member with rotation of the lever.

The following is a description of some preferred embodiments of the invention, reference being made to the accompanying drawings in which:

Figure 1 is a perspective view of a tripod stand for a TV or video camera in accordance with the invention;

Figure 2 is a sectional view through one leg of the stand;

FIG. 3 is a perspective view of a further form of camera tripod stand in accordance with the invention in fully collapsed form;

FIG. 4 is a perspective view of the stand at Figure 3 in fully erected form;

FIG. 5 is an elevation view of one leg of the stand shown partially extended;

FIGS. 6 to 9 show upper portions of a channel section in perspective having an elongate clamping arrangement extending lengthwise of one side of the channel for clamping respective channel sections together, the clamping arrangement being operated by a pivoting bell crank lever and associated mechanism shown in its release position in Figures 6 and 8 and in the locked position in Figures 7 and 9;

FIGS. 10 and 11 show the upper end of the channel section of Figures 6 to 9 in side view with the bell crank lever in its respective locked and released positions ;

FIGS. 12 and 13 are further perspective views of the upper end of the channel section with the bell crank lever for operating the locking mechanism omitted;

FIG. 14 is a planned view of the channel section of Figures 12 and 13; FIG. 15 is a perspective view of the elongate clamping member and corresponding driving member shown separated for clarity;

FIG. 16 is a longitudinal sectional view through the clamping and driving members showing the clamping member in its retracted position with respect to the driving member; and

FIG. 17 is a similar view showing the clamping member extended by the driving member.

Referring firstly to Figure 1 of the drawings, there is shown a tripod form stand for a TV or video camera comprising a mounting 10 adapted to receive and support the camera. The mounting has a generally circular form and has three equi-spaced recesses or sockets around its periphery in which the upper ends of extendable legs 12 are hinged about pivot axes, one of which is indicated at 13, to allow the legs to be folded inwardly to a stowed position and outwardly to an erect position to a tripod form to support the stand on the ground or other surface on which it is to be used.

Referring now to Figure 2 of the drawings, one of the legs is shown in fully retracted form comprising an upper member 17 of generally I-beam cross section form to provide channel sections 18, 19 on either side thereof, an intermediate channel section member 20 slidably engaged in the channel 18 of the upper member and a lower channel section member 21 slidably engaged in the channel section of the intermediate member.

The upper end of the intermediate member 20 has a crosspiece 22, the ends of which project beyond the sides of member for a purpose which will become apparent below. The lower end of member 20 has a similar cross-piece. Both cross-pieces are shaped or cut-away to allow passage of the upper and lower channel section members as the leg extends and retracts as described above.

The channel 18 of the member 15 has convergent side walls 23 between which the intermediate leg member 20 is located and held captive laterally whilst being free to slide longitudinally. The inner side of one wall of the channel 18 has a concave recess 24 and the adjacent side wall 25 of the intermediate channel member has a corresponding concave recess 26. An elongate dual scroll shaped cam element 27 extends between the side wall 25 and the side wall 23 engaging in the recesses 24 and 26 to provide a pivot axis for the intermediate member 18 with respect to the upper member 15 and to provide lateral adjustment of the intermediate member across the upper member by rotationally adjustment of the cam element to remove lateral play between the members .

The cam element is mounted at its upper and lower ends for rotational adjustment in the ends of the crosspieces at the upper and lower ends on one side of the intermediate member 17. On the other side of the channel, the inner face of side wall 23 is formed with an angled recess 30 having a rounded apex 31 and the adjacent side wall 32 of the intermediate leg member has a similar angled recess 33 with a concave apex 34. A triangular section elongate braking element 34 has apices 36,37 engaged between the apices 31,34 respectively. The braking element is pivotally mounted at its upper and lower ends on the crosspieces at the upper and lower ends on the other side of the intermediate member of the leg. A lever is attached to the braking element at its upper end to rotate the brake element to lock and release the upper and intermediate channel members together, as described below.

The brake element 35 is released by turning the member in an anti-clockwise direction drawing the intermediate channel member out of the upper channel member until a side of the triangular member bears against the outermost face 30a of the inside angled recess of the channel sidewall 21. In this position, the intermediate member is free to slide with respect to the upper member for extension and traction as required. When the intermediate member has reached the required position, the locking member is rotated clockwise to draw the intermediate member into the upper channel member. Eventually, the apex of the triangular member and apex 34 of the intermediate channel pass "over centre" through the dotted line 40 and reach a stable position just beyond "over centre" in which one side of the triangular member is supported against further rotation into the channel by a stop (not shown) between the bottom wall of the intermediate channel member and bottom wall of the upper channel member.

The cam element 25 has been previously adjusted so that in this position the braking member, intermediate channel member and rotary cam member are held compressed between the side walls of the channel to lock the intermediate member against movement. Similar arrangements are provided on the bottom channel member to remove play and provide a locking engagement with the intermediate member.

The lower end of the bottom channel member has a foot attached to it for engaging the ground or other surface on which the stand is to be used. The upper channel member 17 is, as indicated above, of I- section, and the cross-sections depths and wall thickness of all of the channels are such that the flexural axis of each of the channel members are coincident, that is are in alignment lengthwise of the leg. Thus the flexural axis about which the leg bends in lateral movement extends the location where the foot is attached to the bottom end of the leg and also through the pivot axis at the upper end of the leg. Thus, lateral side loads on the leg do not tend to twist the leg.

The components of the leg may be formed from carbon fibre reinforced plastics or may be high strength aluminium alloy extrusions. The bottom member of each leg is shown as a channel section to provide visual uniformity with the intermediate and upper members but it will be readily appreciated that since the bottom member does not have a member nested with it, it is not in fact necessary for it to be of open channel form. Instead, it could be of closed tubular form or, indeed, solid section.

Reference will now be made to the further embodiment shown in Figures 3 to 5 and like parts have been allotted the same reference numerals to those of the first embodiment.

As described in our earlier application, each extendable leg 12 of the tripod comprises an upper outwardly facing channel section member 17 having a pivot moulding 40 secured to the upper end thereof with integral moulded trunnions 41 projecting on either side of the moulding to engage in corresponding sockets on either side of a recess in the mounting 10. The lower end of the member 17 has a guide moulding 42 secured thereto which has an open front 43 to allow the next channel section member 18 to slide into and out of the upper member 17. The adjustment cam 27 described in our earlier application is rotatably mounted at its upper and lower ends in mouldings 40 and 42 respectively and lies immediately inside side wall 17a of upper member 17. The cam 27 is engageable with the outer side of the next channel section member 18 of the leg where it projects into the upper member 17, as described in our previous application.

Channel section member 18 is closed at its upper end by a moulding 45 secured thereto and at its lower end by a guide moulding 46 similar to moulding 42.

Again, moulding 46 has an open front 47 to allow the next channel section member 19 to pass through.

An adjustment cam 27 as described earlier is mounted at its ends in the mouldings 45 and 47 of member 18 adjacent the side wall 18a of the member similar to the mounting of the cam 27 in the upper member 17. An elongate brake member 35 extends lengthwise of the member 18 and is rotatably mounted at its upper end in moulding 45 and its lower end 46 on the outer side of side wall 18b of the member to engage the inner side of side wall 17b of the upper member. The brake member is rotated by a moulded lever 48 attached to its upper end between a locked position in which the lever 48 lies flush with the member 18 and the brake member provides a jamming engagement between the side walls 17b and 18b of the members 17 and 18 respectively and a release position in which the member extends outwardly of the leg 18 and the member 18 is free to slide with respect to member 17, as described in our previous application. The cam 27 is pre-adjusted to take up excess slack between the members 17 and 18 and to provide the correct amount of play between the members for smooth sliding movement in the release position and positive locking between the members in the jamming position.

The final innermost member 19 of the leg is constructed similarly to the intermediate member 18 except that instead of having an open lower moulding 46, it has a foot moulding 50 secured thereto with a projecting pin 51 to dig into the ground or other surface on which the tripod is to be used. The member 19 has a braking member 35 pivotally mounted adjacent the outer side of sidewall 19a of the member in the upper and lower mouldings of the member and operated by a lever 52.

As can be seen in the arrangement of Figure 1, when the leg members 18 and 19 are fully retracted into upper member 17, the respective brake levers of the two members 48 and 52 lie side by side at the top of the leg flush with the pivot moulding 40. To extend one of the leg members, the appropriate lever 48 or 52 is rotated to its release position and is used to slide the leg member outwardly to reach the required position of extension. The lever is then returned to its locking position. Thus, each leg member can be extended with respect to its adjacent member by a single handed movement rather like the action of a trombone slide.

Referring now to the further arrangement illustrated in Figures 6 to 17, the upper channel section 20 of the leg has an outwardly open side channel 60 closed at its lower end by an end wall not shown and open at its upper end as indicated at 61. The side channel contain an elongate clamping member 62 and a corresponding elongate driving member 63 located behind the clamping member in the channel. The driving member 63 is of T-shaped cross-section and the rear part of the side channel is a corresponding T-shaped cross-section so that the driving member is constrained to rise and fall in the channel.

The clamping and driving member 62, 63 are best illustrated in Figures 15 to 17 to which reference will now be made. The clamping member 62 has an elongate front wall providing an elongate clamping face 64, side walls 65 and is open at the rear. Integral saw-shaped teeth 66 are formed in the clamping member spaced at regular intervals along the member between the side walls.

The driving member 63 has corresponding saw- shaped teeth 67 spaced apart down its length to engage with the teeth 66 of the clamping member between the side wall 65 of the clamping member.

As indicated earlier, the lower end of the side channel 60 is closed by an end wall and a grub screw is mounted in the wall to adjust the vertical position of the clamping member 62 with respect to the driving member 63 so that the clamping member can be preset close to the closing side of the outer channel section within which the channel 20 engages to be clamped and released to the outer channel as described below. The driving member 63 has slot 68 on its rearward side adjacent the top of the driving member to be engaged by a mechanism for raising and lowering the driving member as described later.

Referring to Figures 16 and 17, a number of the teeth 67 on the clamping member are replaced angle ribs 69 on one side 65 of the member. The ribs engage in angle slots 70 in the sides of corresponding teeth on the driving member 63. When the driving member 63 is forced downwardly, interaction of the ratchet teeth forces the clamping member 62 laterally as shown in Figure 17 to clamp with the adjacent side channel of the next channel section member. When the clamping member is lifted, the interaction of the ribs 69 in the slots 70 and causes the clamping member 62 to be retracted as shown in Figure 16.

The operating mechanism for causing the driving member 63 to be raised and lowered with respect to the side channel 60 to release and clamp the clamping member 62 will now be described.

A housing for enclosing the operating mechanism (which has been omitted for the sake of clarity) formed integrally with the top end of the channel section 20. The housing supports a laterally extending shaft 71 for rotation about a horizontal axis extending laterally of the channel section. A triangular section block or prism 72 is moulded on the shaft 71 to rotate therewith at one apex of the prism adjacent to the upper open end of the side channel 60. A crank pin mounted on a second apex of the prism 73 is slidably mounted in the slot 68 at the upper end of the driving member 63. As the block rotates with the shaft 71, the driving member 63 is raised and lowered in the side channel. The shaft 71 also has an integrally formed crooked arm 74 spaced to one side of the prism 72.

The housing also supports a bell crank operating lever 75 on a pivot 76. One part of the lever 77 projects from the housing for raising and lowering the lever about the pivot 76 as shown in Figures 10 and 11. The other part of the lever comprises spaced cheeks 78 between which a roller 79 is rotatably supported. The roller engages a side of the prism 72 as the lever is pivoted between its stowed position shown in Figure 10 and its release position as shown in Figure 11 to pivot the prism between its upright position in Figure 10 in which the drive member 63 is in its lower position to extend the clamping member 62 into engagement as described previously and in the release position shown in Figure 11 in which the prism is rotated with the spindle 71 to lift the side member 63 and thereby release the clamping action of the clamp 62.

To ensure that the prism rotates to lift the drive member 63, the spindle carrying the roller 79 on the bell crank lever projects on the inner side of the channel 17 to engage over the crook shaped arm 74 to drive the arm downwardly as the bell crank lever 77 is lifted as best seen in Figures 6 and 11.

A similar mechanism is provided at the other end of the next channel section 21 down the leg with the operating mechanism disposed laterally so that when - li ¬

the channel sections are fully stowed, the operating mechanisms lie adjacent one another.

The legs of the tripod are extended and retracted in a similar manner to that described above to erect, adjust or collapse the tripod as required.

Claims

1. A tripod stand for supporting equipment such as a TV camera or the like comprising a mounting for the equipment having a central axis and three telescopic legs extending from the mounting, the legs having head ends pivotally attached to the mounting at locations equi-spaced around said central axis of the mounting to allow the legs to fold together in a closed position and outwardly to an erect position in which they diverge in tripod form from the mounting, and foot ends to engage the ground or other surface on which the stand is to be used, each leg comprising a plurality of slidably engaged interlocking channel section members facing outwardly of said axis to extend and retract with respect to one another, one of said members being pivotally attached to the mounting to swing between said folded and erect positions and each of the further members having means to lock the member in any position of extension/retraction with respect to the adjacent member nearest said mounting to vary the stand height.

2. A tripod stand as claimed in claim 1, wherein the members from the mounting end to the foot end are of successively reduced cross-section, each successive member along the leg from the mounting end to the foot end being slidably engaged in the previous member.

3. A tripod stand as claimed in claim 1 or claim 2, wherein the locking means comprise an elongate element on each of said further members extending lengthwise of the member adjacent the inner side of one side wall thereof and engageable with the outer side of a further member slidable thereon, the element being rotatably mounted on the member at the ends thereof about an axis extending lengthwise of the member between a position in which the further member is free to slide with respect to member and a position in which the locking element effects a jamming engagement between the side walls of the members to lock the member together.

4. A tripod stand as claimed in claim 3, wherein the locking element on each of said further members is arranged to pass through an over centre position as it approaches locking engagement of the leg member with the adjacent member to hold the locking element in said locking engagement therewith.

5. A tripod stand as claimed in any of the preceding claims, wherein means are provided for removing lateral play between adjacent leg members parallel to the pivot axis.

6. A tripod stand as claimed in claim 5, wherein the means for removing play between adjacent leg members comprise an elongate cam mounted on said one member and successive members along the leg up to the penultimate member to act on the overlapping part of the next member along the leg to remove play between the members .

7. A tripod stand as claimed in any of the preceding claims, wherein the cross-sections of the members are such that the flexural axis of each leg is aligned with the point at the foot end of the leg where reaction from the ground acts on the leg so that lateral loads on the leg generally parallel to the axis about which the leg pivots with respect to the mounting do not cause twisting of the leg.

8. A tripod stand as claimed in claim 7, wherein the member at the head end of each leg has a double channel section providing channel forms facing to either side of the leg, the channel section to one side of the leg receiving the next channel member slidably engaged therein and the channel section of the other side of the leg being formed to position the flexural axis of the leg to extend through the point of reaction load at the foot end of the leg as aforesaid.

9. A tripod stand as claimed in claim 7 or claim 8, wherein the foot end of each leg has an angled foot member attached thereto to engage the grounds, the foot member being attached to the leg so that load applied to the foot acts on the foot end of the leg through the flexural axis of the leg in the direction parallel to the pivot axis of the leg with the mounting.

10. A tripod stand as claimed in any of claims 7 to 9, wherein the sections of the leg members are such that the flexural axis of the legs intersect the respective pivot axes of the legs on the mounting.

11. A tripod stand as claimed in claim 1, wherein the locking means comprise elongate clamping means projecting from one side wall of a channel to engage on an adjacent sidewall of an outer channel and means are provided to extend and contract the clamping means to lock and release the channels.

12. A tripod stand as claimed in claim 11, wherein the clamping means comprise an elongate clamping member and an elongate driving member acting on the clamping member with longitudinal movement in one direction to extend the clamping member into clamping engagement with the side wall of the adjacent channel and in the opposite direction to release the clamping action.

13. A tripod as claimed in claim 12, wherein the elongate driving member has a series of shallow saw- shaped teeth spaced along its length engageable with corresponding saw-shaped teeth on the clamping member such that movement of the driving member in one direction displaces the clamping member away from the side wall of its associated channel into clamping engagement with the side wall of the adjacent channel.

14. A tripod as claimed in claim 12 or claim 13, wherein the elongate clamping member and the elongate driving member have further interengaging means which cause the clamping member to be positively withdrawn from clamping engagement with movement of the driving member in said opposite direction.

15. A tripod as claimed in any of claims 11 to 14, wherein said channel member on which the clamping means are mounted has an elongate side channel extending the length of the side wall in which the clamping member and cam member are mounted.

16. A tripod as claimed in claim 15, wherein guide means are provided for guiding the driving member linearly along the channel to displace the clamping member outwardly of the channel with movement in one direction and to allow the clamping member to retract into the channel with movement in the opposite direction.

17. A tripod as claimed in any of claims 12 to 16, wherein means are provided for pre-adjusting the position of the clamping member in relation to the driving member to minimise movement before the clamping member acts on a side wall of a further channel.

18. A tripod as claimed in any of claims 11 to 17, wherein the driving member for each channel is displaced along its respective channel by an operating device at one end of the channel.

19. A tripod as claimed in claim 18, wherein the operating device comprises a lever rotatably mounted about an axis extending transversely to the leg at said one end and inter connected to the cam member to displace the cam member with rotation of the lever.