GB2396344A

GB2396344A - Telescopic camera crane arm and carrier control

Info

Publication number: GB2396344A
Application number: GB0229764A
Authority: GB
Inventors: Richard Arthur Lindsay
Original assignee: Vitec Group PLC
Current assignee: Videndum PLC
Priority date: 2002-12-20
Filing date: 2002-12-20
Publication date: 2004-06-23
Anticipated expiration: 2022-12-20
Also published as: WO2004056692A1; AU2003295112A1; GB2396344B; GB0229764D0

Abstract

A telescopic camera crane arm (10) has a carrier (12) for a camera at one end and a support (11) on which the arm is mounted adjacent the other end. The arm comprises a plurality of telescopically interengaging members which extend and retract in an axis extending lengthwise of the arm, including a base member (20) on the support, an intermediate member (23) and an outer member (29) on which the carrier is located, and a drive for moving the further members relative to the base member collectively to extend and retract the arm in said axis. The drive includes a telescopic lead screw (46) having interengaging threaded sections on the respective arm members which extend and retract with respect to one another but are constrained against relative rotation with respect to each other. A second lead screw 90 is supplied parallel to the first lead screw 46, that controls the tilt of the carrier (12) in order to maintain a uniform bearing while the arm is rotated in a vertical plane the screw 90 is actuated via mechanism 90,92,93,94,95.

Description

IMPROVEMENTS IN OR RELATING TO

TELESCOPIC CAMERA CRANE ARMS

This invention relates to telescopic 5 camera crane arms suitable for carrying television, video or cinematograph cameras. Television, video and cinematograph cameras are conventionally supported on 10 static tripods or movable pedestals depending on the circumstances in which they are to be used. They may also be mounted on telescopic or expendable arms, sometimes known as crane arms, where 15 access for the tripod or pedestal support is not convenient.

Our European Patent Specification No.

0725758 discloses, by way of example, a counter-balanced load carrier comprising a 20 multi-stage telescopic arm. One stage adjacent one end of the arm is mounted for rotation about a vertical axis on a mobile base and an end stage at the other end of the arm carries a support for a pan/tilt 25 mounting for a television, video or cinematograph camera. The respective stages of the arm are interconnected by a cable mechanism to extend and retract the stages of the arm together in a fixed 30 ratio and the arm has a counter-weight :.,, À.::

:... À..::

- 2 which is extended by the cable system in the opposite direction to the arm so that the arm remains counter-balanced throughout its range of movements. The 5 cable mechanism also acts on the camera support on the end of the arm to maintain the support horizontal throughout the range of tilting of the arm. A cable mechanism which controls both the 10 extension and retraction of the arm and also the tilt of the camera support is necessarily complex and any stretch in the cable system, which inevitably occurs, results in uneven movement in the 15 extension/retraction of the arm which invariably is reflected in the pictures transmitted/recorded by the camera.

It is an object of the present invention to provide an improved mechanism 20 for extending and retracting the arm without any backlash between respective sections of the arm.

This invention provides a telescopic camera crane arm having a carrier for a 25 camera at one end and a support structure on which the arm is mounted adjacent the other end, the telescopic arm comprising a plurality of telescopically interengaging members which extend and retract in an 30 axis extending lengthwise of the arm, the I:.,, À. a: : À.'.e '.':: ...

- 3 members including a base member mounted on said support structure, one or more intermediate members and an outer end member on which the carrier for the camera 5 is located, and drive means for moving the further members relative to the base member collectively to extend and retract the arm in said axis comprising a power driven telescopic lead screw having 10 telescopically interengaging threaded sections which can extend and retract with respect to one another but are constrained against relative rotation, the lead screw having threaded sections for the base and 15 intermediate arm members which are mounted for rotation but are constrained against axial movement on their respective arm members, the outer and each intermediate arm member having a nut to engage the 20 threaded section of the lead screw nearer the base member whereby the intermediate and outer end members of the arm extend and retract simultaneously with respect to their respective adjacent inner members 25 with rotation of the lead screw.

In one arrangement according to the invention the lead screw may have externally threaded hollow sections to telescope within one another which are of 30 progessively increasing diameter starting from the lead screw section on the base "'" i '2 ma" 2 2

- 4 \ member. According to a further feature of the invention the arm may be mounted on the support structure for movement in one or 5 more further axes.

For example the arm may be mounted on the support structure for elevation about a horizontal axis and for stewing about a vertical axis.

10 In addition a mounting for a camera may be provided on the carrier at said one end of the arm, the mounting providing one or more further axes of movement for the camera with respect to the carrier.

15 More specifically the camera mounting may be a pan and tilt head providing movement of the camera in pan and tilt axes with respect to the carrier.

Additionally the pan and tilt head 20 may provide for movement about a further, roll axis to be parallel with the optical axis of the camera.

In any of the latter arrangements one or more of said further axes may have 25 powered drive means for generating movement in said axis.

Also in any of the latter arrangements control means may be provided for controlling the or each drive means, 30 the control means including transducer means for monitoring movement in one or a a i a

more of said axes and for driving one or more of said axes accordingly.

In one specific arrangement the drive means for extending and retracting the 5 telescopic arm may be controlled by transducers which monitor elevation and stewing of the arm with respect to the support structure to maintain said one end of the arm in a required vertical plane 10 throughout a range of elevation and stewing movement.

The arrangement may further include a manual control for controlling movement in the or each axis for which a powered drive 15 is provided.

By way of example the powered drive may be a variable speed powered drive and the manual control is arranged to vary the speed of the drive in the corresponding 20 axis. More specifically the manual control may comprise an arm movable against an increasing resistance from a neutral 25 position in opposite directions to provide forward and reverse movement in said axis, the extent of movement of the control from said neutral position determining the speed of movement in the axis.

30 In one specific arrangement the control member may be in the form of a : À....:e ... À À::

rocker switch having a neutral position and providing tilting movement to either side of the neutral position which is opposed by an increasing resistance in 5 each direction.

In a further arrangement according to the invention the manual control member may be fixed against movement and may have means responsive to an applied force in 10 opposing directions to vary the speed of a power drive in the corresponding axis of movement. For example the control member may have strain gauges for determining the 15 applied load in opposing directions for controlling the drive means.

In an alternative arrangement the or each powered drive may be controlled by a remotely operated servo mechanism.

20 In any of the above arrangements adjustable means may be provided on the base member of the arm to counter-balance the arm, said counterbalancing means being drivably connected to the lead screw 25 for adjustment with extension and retraction of the arm to maintain the arm in balance throughout the range of extension/retraction of the arm.

More specifically the counter 30 balancing means may comprise a counter balancing weight mounted on the base ..: a À À ' e..

7 - member of the arm to be extended and retracted on the opposite side of the tilt axis of the arm.

Also in any of the above arrangements 5 the carrier at the end of the arm may be mounted on the arm for tilt movement with respect of the arm about a horizontal axis and a control system may be provided for maintaining the carrier horizontal 10 throughout the range of tilt movement of the arm.

Thus the control system for maintaining the camera carrier horizontal may comprise a telescopic drive extending 15 through the arm to adjust the attitude of the support with respect to the arm and means responsive to tilting of the arm with respect to the base for operating the telescopic drive to the camera support to 20 adjust the attitude of the camera support with respect to the arm as the base member of the arm tilts with respect to the support for the arm.

In one particular arrangement the 25 means responsive to tilting of the arm may comprise interconnected links forming, with the arm and its mounting, a parallelogram linkage for transmitting a rotational input to said telescopic drive.

30 In any of the above arrangements the control system includes transducer means : Àe.....: Àe :e e.. À.:e

- 8 for measuring movement of the arm in one or more of the axes.

The following is a description of

5 some specific embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a front perspective view of a telescopically extendable arm 10 supported for tilting about a horizontal axis and rotation about a vertical axis adjacent one end and having a carrier for receiving a pan and tilt end for mounting a video camera at the other end, the arm 15 being partially cutaway to reveal operating mechanisms for extending/retracting the arm and controlling tilt of the carrier with tilting of the arm; 20 Figure 2 is a rear perspective view of the arm of Figure 1 further cutaway to show details of the mechanism for extending and retracting the arm; Figure 3 is an exploded view showing 25 a perspective of the component for extending and retracting the arm; and Figure 4 is a detailed view of part of the mounting supporting the arm for tilting about a horizontal axis.

30 Referring firstly to Figure 1 of the drawings, there is shown a telescopically :.'...e..:.. :.. Àe -::-e

9 - extendable crane arm of hollow box-section form indicated generally at 10 supported adjacent one end in a mounting indicated generally at 11 and having an annular 5 carrier plate 12 mounted at the other end for receiving a conventional pan and tilt mounting for a video camera (not shown).

The carrier 12 has an encircling ring 13 for manual movement of the end of the arm.

10 The mounting 11 for the crane arm comprises a vertically extending hub 14 supported on a base (not shown) for slowing movement of the arm about a vertical axis 15. A frame 16 is mounted 15 on the hub 14 having a pair of upright side plates 17 joined by end plates 18.

The side plates have triangular shaped upper portions 19 between which the arm lo is mounted.

20 The telescopic crane arm comprises a succession of reducing crosssection slidably inter fitting members commencing with a base member 20. The base member is of hollow box-section and closed by an end 25 wall 21 at one end and is open as indicated at 22 at the other end. A first intermediate hollow box section member 23 of reduced cross-section compared with the base member 20 projects from the open end 30 22 thereof. Intermediate member 23 has an end wall 24 at one end and is open as À::..

......DTD: À.::. À.

- 10 indicated at 25 at the other end. A second intermediate hollow box section member 26 reduced in cross-section compared with member 23 extends from the 5 open end 25 of member 23 and has an end wall 27 and a open end 28. An outer end member 29 of reduced cross-section compared with intermediate member 26 extends from within the intermediate 10 member through the opening 28. The outer member has an end wall 29a at one end and the mounting 12 for the pan and tilt head for the camera is mounted at the outer end as will be described in detail below.

15 The side walls of base member 20 of the arm have laterally projecting bunions 30 which are received in bearings 31 (best seen in Figure 4 of the drawings) mounted in the upper appices of the triangular 20 side plate portions 19 to support the base member of the arm for elevation movement about a horizontal axis indicated at 32.

As can be seen from the drawings, the bunions are located approximately midway 25 along the side walls of the base member 20. To mount the intermediate member 23 for sliding movement into and out of the base member, the base member has pairs of 30 upper and lower rollers mounted on its side walls at the locations indicated at À, À À::

,......

:::::-:-e :.'.

- 11 33 and the side walls of the intermediate member have elongate guide tracks 34 T-

shaped in cross-section to engage and run between the rollers. The intermediate 5 member 26 is similarly mounted in intermediate member 23 and the end member 29 is similarly mounted in intermediate member 26 and like parts have been allotted the same reference numerals.

10 The drive mechanism for extending and retracting the intermediate and end members of the arm with respect to the base member will now be described with reference to Figures 2 and 3. The drive 15 mechanism comprises a telescopically extendable lead screw indicated generally at 40 having a plurality of telescopically engaged sections each formed with an acme-

type external thread. The lead screw 20 comprises a first, small diameter part 41 mounted for rotation with constraint against axial movement at one end in a mounting assembly indicated at 42 located in end plate 21. The lead screw part has 25 a pair of keyways 43 extending lengthwise of the lead screw at diametrically opposed locations and the other end of the lead screw has an annular bush 44 secured thereto to engage in the next lead screw 30 part. The lead screw part 43 is driven by a motor 45 mounted on a bracket 46 À À a À - À. À..

À À:::e

attached to the end wall 21. The motor has a stepped down belt drive 45a to a lay shaft 45b mounted below the motor. The lay shaft has a further stepped down belt 5 drive to the adjacent end of lead screw part 41 supported in the bearing 42.

The other end of the lead screw part engages in a lead nut 47 supported in a mounting plate 48 secured to the outer 10 side of end wall 24 of the intermediate member 23 of the arm. Thus rotation of the lead screw part 41 extends and retracts the intermediate member of the arm with respect to the base member 20.

15 The lead screw part 40 projects through plate 24 to engage in the next part 50 of the lead screw located in intermediate member 23 of the arm. The lead screw part 50 is of a larger diameter 20 than lead screw part 41 and has a bore into which the lead screw projects, the bushing 44 at the end of lead screw part 41 supporting the lead screw part for sliding movement with respect to lead 25 screw part 50. One end of the lead screw part 50 is supported for rotation but is restrained axially in the bearing assembly 51 mounted on end plate 24 of the intermediate arm member. The bearing 30 assembly includes an annular sleeve 52 encircling the end of the lead screw part .. 2. À2,.2.:'.' '

50 and having inwardly projecting splines 53 which project through slots 54 in the end of the lead screw part 50 and engage in slots 43 in the first lead screw part 5 41. Thus lead screw part 50 is engaged to rotate with lead screw part 41 but is free to slide axially with respect to the first lead screw part as the intermediate member 23 extends and retracts with respect to 10 the base member 20.

Lead screw part 50 has four axial slots 55 extending the length of the lead screw part at equi-spaced locations around the lead screw part and an annular bearing 15 56 is mounted at the other end of the lead screw part.

The other end of lead screw part 50 engages in a lead nut 57 located in a mounting 58 and secured to end plate 27 of 20 the second intermediate member 26. The lead screw part 50 projects through end plate 27 to engage in the final lead screw part 60 located in intermediate member 26 of the arm. The lead screw part 60 is 25 again hollow having a bore to receive the lead screw part 50, the bearing 56 at the end of lead screw part 50 supporting the lead screw part for axial sliding movement with lead screw part 60.

30 A sleeve 61 is mounted on the outer end of lead screw part 60 and has four À * À À:. À:

À À À....

:::::- * À a À À À.

À

inwardly projecting splines 62 at spaced locations around the inner periphery of the sleeve which extends through slots 63 in the end of the lead screw part and 5 engage in the slots 55 of lead screw part 50. Thus lead screw part 60 is locked to rotate with lead screw part 50 to move axially with respect to part 50. The sleeve 61 secured to the end of lead screw 10 part 60 is supported in the bearing assembly 64 located in a mounting plate 65 on the inner side of end wall 27 to support the lead screw part 60 for rotation but against axial movement with 15 respect to the end wall 27. The other end of lead screw part 60 has an annular bush 66 secured therein.

The lead screw part 60 engages in a lead nut 70 secured to the end plate of 20 the outer member 29 of the arm. An elongate guide tube 71 is mounted in the arm between the end plate and an intermediate plate 72 in the arm to receive the lead screw part 60, the tube 25 having a bore in which the bush 66 at the end of lead screw part 60 is slidable.

Thus the intermediate and outer members of the telescopic arm are extended and retracted together by rotation of the 30 telescopic lead screw in one or the opposite direction. Since all of the lead À, À '. À::

. ' À À:e:

- 15 screw sections move together rather than in sequence, the possibility of vibration caused by one arm member reaching the end of its travel with respect to an adjacent 5 arm member and which could be detected by the camera at the end of the arm is avoided. A further feature of the arm is an automatic levelling mechanism for the 10 carrier 12 at the outer end of the arm.

The end of the arm has a head 70. The carrier is supported on a pair of spaced lugs 71 pivotally mounted on the head 70 on a mounting shaft 72. Thus the 15 telescopic shaft indicated at 80 extends through the arm parallel and above the lead screw 40 comprising sections for each part of the arm of increasing diameter from the base member 20 to the outer end 20 member 29. The section of the spline shaft for each arm member is mounted in a bearing in the end plate for that member.

The other end of each spline section is slidably engaged in the next spline 25 section along the arm so that together the spline sections provide a telescopic drive on the base member of the arm to the outer member of the arm. At the outer member of the arm, the spline shaft has a gear 30 connection to the carrier 12 to tilt the carrier about its horizontal axis with : a, À a À À a À::::...

À

- 16 rotation of the shaft. At the base member of the shaft, the spline shaft extends through the end wall 21 and there is a gear drive connection to a shaft 90 5 mounted in a bracket 91 on the end plate 21. The ends of the shaft 90 carry gears 92 which mesh with quadrant gears 93 mounted on a parallel shaft extending 10 across the end member 20. A link 24 is fastened to one end of the further shaft and is in turn connected by a link 95 to a pivotal mounting 96 on side plate 19. The links thus form a parallel linkage with 15 the plate 19 and end member 20 so that as the arm tilts about the horizontal axis 32, the segmental gears 93 are rotated which in turn rotate gears 92 to the turn shaft 91 and, through the gear drive, the 20 splined shaft 80. The gear arrangements at the respective ends of the arm are arranged so that as the arm is tilted about the axis 32, the carrier 12 remains horizontal. 25 Referring now to Figure 4 of the drawings, the shaft 30 on which the arm tilts has a tooth wheel mounted on the shaft on the inside of plate 19 which drives through a tooth belt 101, an 30 encoder 102 mounted on a support bracket 103. Other encoders are provided for À a - À '

À À À a.

monitoring stewing and elevation movement of the arm and also pan and tilt movement of the camera mounting head as follows.

Further drive motors may be provided 5 for moving the arm in said axes of stewing and elevation and for moving the camera in pan, tilt and roll. A microprocessor operated control system is provided for linking the one or more transducers to the 10 one or more motor drives as required. The microprocessor control system may include programs for moving the arm and/or the pan and tilt head for the camera in accordance with a predetermined program or programs.

15 For example the extension of the arm may be controlled in accordance with elevation and stewing of the arm so that the camera moves through a predetermined locus or path by extension and retraction of the 20 arm. More specifically the camera may be restrained to move in a vertical or horizontal line with elevation/slewing of the arm or may be constrained to move in a vertical plane with elevation/slewing of 25 the arm.

The power drive for the arm may also be controlled by a manually operable member which may be in the form of a tillable arm or rocker switch having a 30 neutral position and forward and reverse directions with progressively increasing : 2 ' -'. '

spring resistance and providing progressively increasing velocity of movement of the respective component of the structure in either direction.

5 Instead of a moving control arm, a fixed control member can be provided arranged to act on strain gauges connected in a control system to respond to force applied to the control member. Pressure 10 on one side of the member causes the corresponding drive to move in one direction and on the other side to move in the opposite direction, the velocity being in proportion to the pressure applied to 15 the arm. For example, the carrier 12 may incorporate strain gauges acted on by the encircling ring 13 in a similar manner to that disclosed in our Euro(UK) Patent No. 0704039 to control the drive motor for 20 extending and retracting the crane arm.

Other forms of interface can be used including a remote control system having a joystick or joysticks for controlling movement of the arm and/or pan and tilt 25 head in the respective directions provided by the power driven axes.

A control system including a microprocessor is provided for controlling movement of the arm. In particular 30 extension and retraction of the arm may be controlled in accordance with a :.. À:..:..

Àe Àa.

À À À À À À

À À À À ÀÀ

e À-e

predetermined programme with rotation of the arm about the axis 15 with tilting of the arm about the axis 32.

.. À À À À..DTD: e. À. À À À À . À.....

... À À. À..DTD:

Claims

- 20 CLAIMS

1. A telescopic camera crane arm having a carrier for a camera at one end and a 5 support structure on which the arm is mounted adjacent the other end, the telescopic arm comprising a plurality of telescopically interengaging members which extend and retract in an axis extending 10 lengthwise of the arm, the members including a base member mounted on said support structure, one or more intermediate members and an outer end member on which the carrier for the camera 15 is located, and drive means for moving the further members relative to the base member collectively to extend and retract the arm in said axis comprising a power driven telescopic lead screw having 20 telescopically interengaging threaded sections which can extend and retract with respect to one another but are constrained against relative rotation, the lead screw having threaded sections for the base and 25 intermediate arm members which are mounted for rotation but are constrained against axial movement on their respective arm members, the outer and each intermediate arm member having a nut to engage the 30 threaded section of the lead screw nearer the base member whereby the intermediate À. À À À

. ... Be. À.. I. À.

. À À... .

À. À À À

À À....

- 21 and outer end members of the arm extend and retract simultaneously with respect to their respective adjacent inner members with rotation of the lead screw.

2. A camera crane arm as claimed in claim 1, wherein the lead screw has externally threaded hollow sections to telescope within one another which are of 10 progessively increasing diameter starting from the lead screw section on the base member.

3. A camera crane arm as claimed in 15 claim 1 or claim 2, wherein the arm is mounted on the support structure for movement in one or more further axes.

4. A camera crane arm as claimed in 20 claim 3, wherein the arm is mounted on the support structure for elevation about a horizontal axis and for stewing about a vertical axis.

25

5. A camera crane arm as claimed in claim 3 or claim 4, wherein a mounting for a camera is provided on the carrier at said one end of the arm, the mounting providing one or more further axes of 30 movement for the camera with respect to the carrier.

. .. À. . À À.

........CLME: À À À. À. À

ee À -

- 22

6. A camera crane arm as claimed in claim 5, wherein the camera mounting is a pan and tilt head providing movement of the camera in pan and tilt axes with 5 respect to the carrier.

7. A camera crane arm as claimed in claim 6, wherein the pan and tilt head also provides for movement about a further 10 roll, axis to be parallel with the optical axis of the camera.

8. A camera crane arm as claimed in any of claims 3 to 7, wherein one or more of 15 said further axes has powered drive means for generating movement in said axis.

9. A camera crane arm as claimed in any of claims 3 to 8, wherein control means 20 are provided for controlling the or each drive means, the control means including transducer means for monitoring movement in one or more of said axes and for driving one or more of said axes 25 accordingly.

10. A camera crane arm as claimed in claim 9, wherein the drive means for extending and retracting the telescopic 30 arm is controlled by transducers which monitor elevation and stewing of the arm À À À.

À > À À À À

. À À.e À .. ....

À e e.

À À À -

with respect to the support structure to maintain said one end of the arm in a required vertical plane throughout a range of elevation and stewing movement.

11. A camera crane arm as claimed in any of claims 3 to 10, wherein a manual control is provided for controlling movement in the or each axis for which a 10 powered drive is provided.

12. A camera crane arm as claimed in claim 11, wherein the powered drive is a variable speed powered drive and the 15 manual control is arranged to vary the speed of the drive in the corresponding axis.

13. A camera crane arm as claimed in 20 claim 12, wherein the manual control comprises an arm movable against an increasing resistance from a neutral position in opposite directions provide forward and reverse movement in said axis, 25 the extent of movement of the control from said neutral position determining the speed of movement in the axis.

14. A camera crane arm as claimed in 30 claim 13, wherein the control member is in the form of a rocker switch having a À À see À e e e À À À see e À Àe. a À e e a e À e e- À e À e-e

- 24 neutral position and providing tilting movement to either side of the neutral position which is opposed by an increasing resistance in each direction.

15. A camera crane arm as claimed in claim 11, wherein the manual control member is fixed against movement and has means responsive to an applied force in 10 opposing directions to vary the speed of a power drive in the corresponding axis of movement.

16. A camera crane arm as claimed in 15 claim 15, wherein the control member has strain gauges for determining the applied load in opposing directions for controlling the drive means.

20

17. A camera crane arm as claimed in any of the preceding claims, wherein the or each powered drive is controlled by a remotely operated servo mechanism.

25

18. A camera crane arm as claimed in any of the preceding claims, wherein adjustable means are provided on the base member of the arm to counter-balance the arm, said counter-balancing means being 30 drivably connected to the lead screw for adjustment with extension and retraction À À eve e ::::.:.:::

À À À À e À À À e Àe.

- 25 of the arm to maintain the arm in balance throughout the range of extension/retraction of the arm.

5

19. A camera crane arm as claimed in claim 18, wherein the counterbalancing means comprises a counter-balancing weight mounted on the base member of the arm to be extended and retracted on the opposite 10 side of the tilt axis of the arm.

20. A camera crane arm as claimed in any of the preceding claims, wherein the carrier at the end of the arm is mounted 15 on the arm for tilt movement with respect of the arm about a horizontal axis and a control system is provided for maintaining the carrier horizontal throughout the range of tilt movement of the arm.

21. A camera crane arm as claimed in claim 20, wherein the control system for maintaining the camera carrier horizontal comprises a telescopic drive extending 25 through the arm to adjust the attitude of the support with respect to the arm and means responsive to tilting of the arm with respect to the base for operating the telescopic drive to the camera support to 30 adjust the attitude of the camera support with respect to the arm as the base member À.....

... ..........CLME: À À À À À:

À À À - À

À À. À

of the arm tilts with respect to the support for the arm.

22. A camera crane arm as claimed in 5 claim 21, wherein the means responsive to tilting of the arm comprise interconnected links forming, with the arm and its mounting, a parallelogram linkage for transmitting a rotational input to said 10 telescopic drive.

23. A camera crane arm substantially as described with reference to and as illustrated in the accompanying drawings.

... ........CLME:

........CLME:

... ...CLME: À. -. ..

À À. À