Patent Description:
As well as complex lighting design and sound design, the modern touring music industry employs highly complex staging and set design in order to deliver engaging and entertaining shows, concerts or gigs. The staging may involve complex moving parts, for example in order to convey artists, musical equipment, lighting equipment or other stage equipment during the course of the performance.

It is common for even the most complex shows to be repeated in consecutive nights in different venues. Accordingly, there is a need for these complex staging systems to be rapidly assembled before the show, rapidly dissembled after the show and suitable for packing down in a compact manner for transport between venues, by road, air or boat.

In addition, even for large shows it is typical for a small number of staff to travel with the show to oversee the assembly, disassembly and packing down of the staging, with the bulk of the labour being carried out by locally-hired staff. The locally-hired staff are unlikely to be familiar with the specific staging set-up of the particular show and will have a very limited window of time to become familiar with the way in which the staging is to be assembled. This can be exacerbated in international touring, where the locally-hired staff may not speak the same language as the touring staff.

Accordingly, there is a need to provide stage equipment that supports the complex set design demanded by stage designers and artists, whilst being easy to assemble, dissemble and pack down.

It is an object of the invention to provide a scissor lift that overcomes at least some of the above-mentioned disadvantages, and any other disadvantages that may be apparent to the skilled reader from the description herein and/or their knowledge of traditional scissor lifts. It is a further object of the invention to provide a compact, lightweight scissor lift for use as part of a stage assembly.

The following documents disclose scissor lifts: <CIT>, <CIT> <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>. Document <CIT> shows a stage assembly according to the preamble of claim <NUM>, <CIT>.

According to the present invention there is provided an apparatus as set forth in the appended claims.

According to a first aspect of the invention there is provided a stage assembly comprising scissor lift comprising the features of claim <NUM>.

When used herein, the term "stage assembly" refers to a collection of components arranged to form a stage or other performance space, for use in a performance or event such as a concert, gig, corporate conference or other show. The components may comprise staging, platforms, decks, lighting, musical equipment and the like.

The rigid chain lifting system may comprise a pair of rigid chains.

The rigid chain lifting system may comprise an electric motor, preferably an AC servo motor, to extend and retract the rigid chain, preferably from a magazine. The motor may drive an axle, preferably via a gearing assembly, the axle comprising a chain gear portions arranged to engage the rigid chain. The axle may comprise a pair of chain gear portions arranged to engage a respective one of the pair of rigid chains. The gearing assembly may be a reduction gear head.

The rigid chain lifting system may comprise a safety brake, configured to be released upon supply of power to the electric motor and engaged upon cessation of the supply of power to the electric motor. The safety brake may be configured to engage a brake gear portion of the axle. The rigid chain lifting system may comprise a primary encoder, configured to determine the extent to which the rigid chain is deployed based on the motion of the motor. The rigid chain lifting system may comprise a secondary encoder, configured to determine the extent to which the rigid chain is deployed based on the motion of the axle. The rigid chain lifting system may be configured to engage the safety brake if the output of the primary encoder and secondary encoder indicate the rigid chain is deployed to a different extent.

The rigid chain lifting system may be disposed in the base portion of the scissor lift.

One or more, but preferably each, of the base portion, the top portion and the scissor arm assembly of the scissor lift may comprise aluminium. One or more, but preferably each, of the base portion, the top portion and scissor arm assembly of the scissor lift may be formed of aluminium.

The base portion of the scissor lift may be connected to the scissor arm assembly of the scissor lift with mechanical fasteners. The top portion of the scissor lift may be connected to the scissor arm assembly of the scissor lift with mechanical fasteners.

The base portion and/or top portion of the scissor lift may comprise components connected with mechanical fasteners. The scissor arm assembly may comprise components connected with mechanical fasteners. The top portion and/or base portion of the scissor lift may comprise a plate and a flange arranged around the edge of the plate. The top portion and/or base portion of the scissor lift may comprise a plurality of braces. The plate, flange and optionally the braces may be connected to each other by mechanical fasteners.

The scissor arm assembly of the scissor lift may comprise two parallel subassemblies. The scissor arm subassemblies may face each other. The scissor arm subassemblies may be spaced apart.

The scissor arm subassemblies may each comprise a pair of crossed arms connected at a pivot point, forming a scissor. The scissor arm subassemblies may each comprise a plurality of scissors connected to each other. The scissor arm subassemblies may each comprise two scissors, so as to form a double scissor. The scissor arm subassemblies may be symmetrical in a notional vertical plane extending through pivot points of the scissors. The or each rigid chain may be arranged between the scissor arm subassemblies, preferably on the notional vertical plane.

Uppermost ends of uppermost arms of each scissor subassembly may be slidably attached to the top portion. The uppermost arms may each comprise a support arm, pivotally attached between the uppermost arms and the top portion. Lowermost ends of lowermost arms of each scissor subassembly may be slidably attached to the base portion. The lowermost arms may each comprise a support arm, pivotally attached between the lowermost arms and the base portion.

The scissor lift may comprise a plurality of bracing plates extending between the scissor arm subassemblies. The bracing plates may be configured to move to a nested configuration when the rigid chain is retracted. In the nested configuration, a lowermost of the bracing plates may form a bridge over the lifting system.

The top portion of the scissor lift may comprise a plurality of mounting points configured for the mounting of the platform thereto. Each mounting point may be adjustable in x, y and z directions.

The height of the scissor lift in a fully retracted state may be under <NUM>, preferably under <NUM>, more preferably under <NUM>, most preferably under <NUM>. The height of the scissor lift in a fully extended state may be at least <NUM>, preferably at least <NUM>, more preferably at least <NUM>, most preferably the height is <NUM>. The length of the base portion and/or top portion may be approximately <NUM>. The width of the base portion and/or top portion may be approximately <NUM>. The weight of the scissor lift may be under <NUM> ton, preferably under <NUM> ton, more preferably under <NUM> ton. The scissor may be operable to lift a load of at least <NUM> ton, preferably <NUM> ton.

The base portion of the scissor lift may comprise one or more wheels. The wheels may comprise casters. The wheels may be configured to be raised and lowered. The base portion of the scissor lift may comprise a plurality of support legs. The support legs may be configured to be raised or lowered.

The stage system may comprise an automation control system configured to remotely control the at least one scissor lift.

The passive scissor may not comprise a lifting system.

The passive scissor may be directly coupled to the scissor lift. The passive scissor may be coupled to the scissor lift via a further passive scissor.

The scissor assembly may comprise a single subassembly.

The passive scissor may comprise a plurality of mounting points configured for the mounting of the platform thereto. Each mounting point may be adjustable in x, y and z directions.

Preferable features of the scissor assembly of the passive scissor may be as defined above in respect of the scissor assemblies of the scissor lift of the first aspect.

The stage assembly may comprise a platform. The platform may be mountable to the top portion of the scissor lift. The platform may be mountable to top portion of the passive scissor. The platform may be mountable to both the top portion of the scissor lift and the top portion of the passive scissor.

The stage assembly may comprise a plurality of passive scissors. The stage assembly may comprise a plurality of scissor lifts. The or each scissor lift may be coupled to a plurality of passive scissors.

In the drawings, corresponding reference characters indicate corresponding components. The skilled person will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various example embodiments. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various example embodiments.

In overview, examples of the invention provide a scissor lift suitable for lifting a performer, props or other relatively lightweight stage equipment as part of a stage assembly, which employs a rigid chain lifting system. Further examples of the invention provide a passive, unpowered, scissor, which can be coupled to the scissor lift.

<FIG> show an exemplary scissor lift <NUM>. The lift <NUM> comprises a base portion <NUM>, which is arranged on the floor or another support surface in use, and a top portion <NUM>, upon which a load can be placed in order to be lifted.

The base and top portions <NUM>/<NUM> each take the form of substantially rectangular plate <NUM>/<NUM>, with a flange <NUM>/<NUM> extending around the periphery of the plate <NUM>/<NUM> so as to effectively define a tray. The flanges <NUM>/<NUM> extend towards each other. In other words, the flange <NUM> extends upwardly from the plate <NUM>, whereas the flange <NUM> extends downwardly from the plate <NUM>. In one example, the top and base portions <NUM>/<NUM> are formed from sheet metal (e.g. aluminium). In one example, the flanges <NUM>/<NUM> extend substantially orthogonally from their respective plate <NUM>/<NUM>.

As can be best seen in <FIG>, the top portion <NUM> comprises a plurality of braces <NUM>. In one example, the braces <NUM> comprise a pair of longitudinal braces 125a, extending in parallel between the short sides of the rectangular plate <NUM>, with cross braces 125b extending between the longitudinal braces 125a. Accordingly, the top portion <NUM> is prevented from flexing or distorting under load. The top portion <NUM> also comprises chain attachment points <NUM>, to which the chains <NUM> (discussed in detail below) are attached.

As can be seen in <FIG> and <FIG>, the top portion <NUM> furthermore comprises a plurality of mounting points <NUM>. The mounting points <NUM> are connectable to a platform (not shown) or other piece of staging. The mounting points <NUM> protrude upwards from an upper surface 120a of the top portion <NUM>. In one example, the top portion <NUM> comprises four mounting points <NUM>, distributed at corners of a notional rectangle on the upper surface 120a. The structure of the mounting points <NUM> will be described in more detail below. Additionally or alternatively, the top portion <NUM> may also be provided with a plurality of holes (e.g. tapped holes) to which a platform may be attached. In some examples, the holes may serve as the attachment point for the mounting points <NUM> to the top portion <NUM>. Accordingly, a user may choose whether to employ the mounting points <NUM> or to directly couple a platform to the holes. The holes may also be configured to receive lifting pins, to assist in the handling of the lift <NUM>. In one example, the holes extend into a profile (i.e. a block of material) arranged on the underside of the top portion <NUM>. The profile is for example formed of steel or aluminium.

As can be best seen in <FIG>, the base portion <NUM> comprises four longitudinal braces <NUM>, extending in parallel between the short sides of the rectangular plate <NUM>.

In one example, the base portion <NUM> comprises a plurality of caster wheels <NUM>, for example <NUM> caster wheels arranged proximate to the corners of the base portion <NUM>. The casters <NUM> may be recessed from the underside of the base portion <NUM>, such that only a portion of each wheel protrudes from the underside of the plate <NUM>. In one example, the base portion <NUM> comprises a plurality of support legs <NUM>. The support legs <NUM> are configured to be lowered down from the lower surface of the base portion <NUM>, so as to raise the base portion <NUM>. Accordingly, the wheels <NUM> become disengaged from the floor, thus preventing the base portion <NUM> from moving during use. In addition, the support legs <NUM> may be individually adjusted in order to allow the base portion <NUM> to be levelled. Alternatively or additionally, the wheels <NUM> can be raised and lowered, either to level the base portion <NUM> in its wheeled configuration, or to disengage the wheels <NUM> from the floor in favour of the support legs <NUM>.

The lift <NUM> further comprises a scissor assembly <NUM> that comprises pair of scissor subassemblies 130a, 130b, which extend between the top portion <NUM> and the base portion <NUM>. The scissor subassemblies 130a/b are spaced apart, and are formed proximate to the longer edges or the rectangular plates <NUM>/<NUM>. The scissor subassemblies <NUM> are parallel, and disposed to face each other (i.e. they are adjacent). Accordingly, the scissor subassemblies 130a/b are symmetrical in a notional vertical plane disposed between the subassemblies 130a/b, equidistant the assemblies 130a/b. Each scissor subassembly <NUM> comprises a first, lower scissor <NUM> and a second, upper scissor <NUM>, so that the assemblies 130a/b each take the form of a double scissor.

Each scissor <NUM>/<NUM> comprises a pair of crossed arms <NUM>, rotatably connected at a pivot point <NUM> located at the meeting point of the arms <NUM>.

The lower ends of the arms <NUM> of lower scissors 131a/b are slidably attached to the base portion <NUM>. The arms <NUM> of lower scissors 131a/b are also connected to the base portion <NUM> by virtue of secondary support arms <NUM>. The arms <NUM> are pivotally connected to the lower scissor arms <NUM> at a position approximately <NUM> /<NUM> of the way along their extent from the base portion <NUM>. The arms <NUM> are also pivotally connected to the base portion <NUM> at a hinging point <NUM> between the sliding attachment points of the arms <NUM>.

The attachment between the lower scissor 131a/b and the base portion <NUM> is best understood with reference to <FIG> and <FIG>. As can be seen therein, the base portion <NUM> comprises tracks <NUM>, each track <NUM> being arranged to receive a wheel <NUM> formed on the end of the arms <NUM> so as to support the sliding motion of the end of the arm <NUM> with respect to the base portion <NUM>. Furthermore, the hinging portion <NUM> takes the form of a bar arranged to extend through apertures formed on the end of the support arms <NUM>.

The upper ends of the arms <NUM> of the upper scissors 132a/b are slidably attached to the top portion <NUM> in a similar manner, as can be seen in <FIG>, which shows the underside of the top portion <NUM>. In particular, the support arms <NUM> of the upper scissors <NUM> are connected to hinging point <NUM>, and wheels <NUM> of the arms <NUM> of the upper scissors <NUM> are received in tracks <NUM>.

The upper ends of the arms <NUM> of the lower scissor <NUM> are pivotally connected to the lower ends of the arms <NUM> of the upper scissor <NUM> at pivot points <NUM>.

In one example, the upper and lower scissors <NUM>/<NUM> are of the same size, and thus each scissor subassembly 130a/b, and thus the scissor assembly <NUM> as a whole, is symmetrical about a notional vertical line extending perpendicularly to the surface of the plates <NUM>/<NUM> and through the pivot points <NUM> of the scissors <NUM>,<NUM>. In addition, in one example the pivot point <NUM> may be located substantially equidistant from the ends of the arms <NUM>. Accordingly, each scissor subassembly 130a/b may also be symmetrical about a notional horizontal line extending through the pivot points <NUM> of the scissors <NUM>,<NUM>.

At least one of, but preferably all of, the base portion <NUM>, the top portion <NUM> and the scissor assembly <NUM> are formed of a lightweight material, preferably a lightweight metal, for example aluminium. Alternatively or in addition, at least one of, but preferably all of, the base portion <NUM>, the top portion <NUM> and the scissor assembly <NUM> are formed by mechanical fastening. In other words, the flanges <NUM>/<NUM>, plates <NUM>/<NUM>, braces <NUM>/<NUM>, arms <NUM>/<NUM> are attached to each other by nuts and bolts, or other suitable mechanical fasteners. Accordingly, the lift <NUM> as a whole is not welded, save for in respect of the construction of minor components such as the caster wheels <NUM>. Avoiding using welding prevents the warping of components (e.g. during fabrication due to the sheet metal being affected by heat), ensuring that the lift <NUM> can be precisely manufactured and operated.

The lift <NUM> further comprises a rigid chain lifting system <NUM>. The rigid chain lifting system comprises a pair of rigid chains <NUM>. The rigid chains <NUM> act as the lifting mechanism of the lift <NUM>, taking the place of traditional hydraulic rams or the like.

One end of each chain <NUM> is connected to the underside of the top portion <NUM>, and the other end of the chain is retained in a magazine <NUM> attached to the base portion <NUM>. The chains <NUM> are movable between a retracted position, in which a substantial portion of each chain <NUM> is retained in the magazine <NUM> attached to the base portion <NUM>, and an extended position, in which the chains <NUM> extend substantially vertically between the base portion <NUM> and the top portion <NUM>. The structure of the chains <NUM> is such that the vertical chain is substantially rigid, so that it is able to support the weight of the top portion <NUM> and any load placed thereupon. Accordingly, the extension/retraction of the chain raises/lowers the top portion <NUM> between a lowermost or retracted position and an uppermost or extended positon. The scissor assembly <NUM> is able to effectively act as a guide only, rather than being substantially load-bearing, because the weight is supported by the chains <NUM>. In one example, the chains <NUM> are SERAPID® chains, such as SERAPID® LinkLift <NUM> chains.

The rigid chain lifting system <NUM> will now be explained in more detail with reference to <FIG>. As can be seen therein, the lifting system <NUM> comprises the magazines 152a/b for retaining respective rigid chains 151a/b in a substantially horizontal configuration. The system <NUM> further comprises a motor <NUM>, gearing assembly <NUM> and axle <NUM>.

The axle <NUM> extends across the base portion <NUM> in a direction between the two longer edges of the plate <NUM> at a position approximately equidistant the short edges of the plate <NUM>, though it will be understood that axle <NUM> need not be precisely equidistant from the short edges. Gearing portions comprising teeth (not shown) are formed at respective ends of the axle <NUM>, which engage with respective rigid chains 151a/b. Accordingly, rotation of the axle <NUM> drives the chains <NUM> between the extended and retracted positions. Furthermore, the use of a common axle for both chains <NUM> ensures the chains <NUM> are driven synchronously.

The motor <NUM> is configured to drive the axle <NUM>. The motor <NUM> may drive the axle <NUM> via the gear assembly <NUM>, as discussed below. However, it will be understood that in other examples the motor may drive the axle <NUM> directly. In one example, the motor <NUM> is an AC servo motor, driven by mains power received at port 153a. The servo motor delivers its maximum torque with a very low lag, which allows for precise control of the lift <NUM>. This is highly advantageous in performance applications, in which the motion of the lift <NUM> must be synchronised with the music, the motion of other equipment and lighting effects.

The motor <NUM> comprises a dynamic brake, which is operable to hold the axle <NUM> in a fixed position. In addition, the motor <NUM> comprises a primary encoder (not shown), which is operable to sense the extent to which the chains <NUM> have been extended or retracted based on the operation of the motor <NUM>.

The motor <NUM> is positioned transverse to the axle <NUM> at the opposite side of the axle to the magazines 152a/b, and thus the gearing assembly <NUM> is arranged between the motor <NUM> and the axle <NUM> in order to convert the drive of the motor <NUM> to rotate the axle <NUM>. In one example, the gearing assembly <NUM> comprises a helical bevel gear, and acts as a reduction gear head.

In one example, the rigid chain lifting system <NUM> comprises a safety brake <NUM>. The safety brake <NUM> is arranged to, when activated, interfere with a further gearing portion of the axle <NUM>. For example the safety brake <NUM> may be a substantially cylindrical body, which surrounds the further gearing portion, and which comprises projections configured to mesh with the gearing portion upon activation of the brake <NUM>. Accordingly, the activated safety brake <NUM> prevents the rotation of the axle <NUM>, thereby fixing the position of the top portion <NUM> with respect to the base portion <NUM>. In one example, the safety brake <NUM> is arranged at one end of the axle <NUM>.

The safety brake <NUM> is configured to permit the rotation of the axle <NUM> upon receipt of power. In other words, in its default, unpowered state, the brake <NUM> prevents rotation of the axle <NUM>, and thus motion of the chains <NUM>. The rigid chain lifting system <NUM> is configured such that, when power is supplied to activate the motor <NUM> and move the chains <NUM>, power is also provided to the safety brake <NUM> to permit rotation of the axle <NUM>. When power ceases to be applied to the motor <NUM> (e.g. because the lift is in its desired position), and therefore also the safety brake <NUM>, the safety brake <NUM> is activated thereby securely holding the platform in position.

The rigid chain lifting system <NUM> further comprises a limit encoder assembly <NUM>. The limit encoder assembly <NUM> is connected to the axle <NUM> by virtue of a belt assembly 157a, and accordingly is able to sense the rotation of the axle. The limit encoder assembly <NUM> fulfils two functions. Firstly, it acts as a secondary encoder, configured to sense the extent to which the chains have been extended or retracted based on the rotation of the axle <NUM>. The rigid chain lifting system <NUM> is configured to compare the output of the primary encoder and the secondary encoder, for example using suitable software/hardware controller (not shown). If the output of the primary encoder and secondary encoder does not match (i.e. the encoders do not agree that the same amount of chain <NUM> has been deployed from the magazine <NUM>), it is indicative of an error and the power is cut, thereby activating the safety brake <NUM>.

In addition, the limit encoder assembly <NUM> acts as a limit switch, automatically stopping the motor <NUM> when the chains <NUM> are either fully extended (and so the lift <NUM> is fully extended) or fully retracted (and so the lift <NUM> is fully retracted).

In one example, the controller is configured to control the motor <NUM> in order to raise/lower the lift, in response to a control signal. The control signal may be received via cables connected to a port 153b of the motor. It will however be understood by those skilled in the art that other means of delivering the control signals are possible, including via wired or wireless communication links.

In one example, the lift <NUM> is configured to receive the control signal from a suitable automation control system (<NUM>, <FIG>, such as an automation control console.

As can be best seen in <FIG> in one example there is provided a system <NUM> comprising the automation control system <NUM>, which is configured to control one or more scissor lifts <NUM>. The automation control system <NUM> may also be arranged to control various other stage equipment <NUM>.

In one example, the lift <NUM> further comprises a plurality of bracing plates <NUM> extending between corresponding locations on the respective scissor subassemblies 130a/b. In particular, bracing plates <NUM> are arranged on each scissor <NUM>/<NUM> at each side of the pivot point <NUM>, to give a total of <NUM> plates. The plates <NUM> ensure that the scissor subassemblies 130a/b remain in their parallel, spaced apart configuration during operation of the lift <NUM>. In one example, the bracing plates <NUM> are made of a stronger material than the scissor assembly <NUM>, such as steel. The plates <NUM> are mechanically fastenable to the arms <NUM>.

As can be best seen in <FIG>, the bracing plates <NUM> are substantially trapezoidal in cross-section. Each bracing plate <NUM> comprises an upper plate <NUM>, angled side plates <NUM> extending obliquely downward from the upper plate <NUM> towards the arms <NUM>, and flanges <NUM> connecting the side plates <NUM> to the arms <NUM>. Accordingly, once installed, the upper plate <NUM> is parallel to, yet stands proud of, a notional plane extending between the point at which the flanges <NUM> connect to the arms <NUM> of the respective subassemblies 130a/b. In certain examples (e.g. as shown in <FIG>), the braces <NUM> comprise cutaway portions.

As can be best seen in <FIG>, the bracing plates <NUM> are configured to move to a nested configuration when the lift <NUM> is at its lowermost, fully retracted, position. In other words, the width of the upper plates <NUM> (i.e. in the direction between the arms <NUM>) progressively increases from a lowermost bracing plate <NUM> to an uppermost bracing plate <NUM>, so that when the lift <NUM> is in its lowermost position, each bracing plate <NUM> is nested within the bracing plate <NUM> immediately above it. Furthermore, in the lowermost position, the lowermost of the bracing plates <NUM> forms a bridge over the lifting system <NUM>. This allows for a low-profile base portion <NUM>, thus decreasing the overall height of the lift <NUM> in its fully retracted position.

Turning now to <FIG>, the detailed structure of the mounting portion <NUM> will be discussed. The mounting portion <NUM> comprises a base portion <NUM>, which is fixed to the upper surface 120a of the top portion <NUM> by virtue of a fastening means such as bolts 162a, washers 162b and nuts 162c. Stud portion <NUM>, which comprises a plate 163a and a threaded projection 163b upstanding from the plate 163a, is disposed on top of base portion <NUM>. Bolts <NUM> extend downwardly through elongate slots 163c formed in the stud portion <NUM> at either side of the projection 163b, then through elongate slots 161a formed in the base portion <NUM>, before being received in sliding blocks <NUM>. The sliding blocks <NUM> are retained in a channel <NUM> under the base portion <NUM>, which permits motion of the blocks <NUM> in the direction of the slot 161a. The elongate slots 163c and 161a are substantially orthogonal to one another.

When the bolts <NUM> are loosened, the stud portion <NUM> is permitted to slide with respect to the base portion <NUM> in a first direction in the horizontal plane (i.e. an x direction), guided by the slots 163c. In addition, the stud portion <NUM> is also permitted to move in a second direction in the horizontal plane, orthogonal to the first direction (i.e. a y direction), guided by the slots 161a. When the bolts <NUM> are tightened, the stud portion <NUM> becomes fixed with respect to the base portion <NUM>.

In addition, the mounting portion <NUM> comprises a pair of locknuts <NUM>, threadable onto the projection 163b. The lower locknut 167a is threaded onto the projection 163b, a platform or other staging (not shown) is mounted to the projection 163b (for example by extending through an aperture sized to allow passage of the projection 163b but not the locknut 167a), and then the upper locknut 167b is threaded onto the projection 163b, sandwiching the platform between the locknuts.

The position of the lower locknut <NUM> may be adjusted (i.e. by threading it a longer or shorter distance along the extent of the projection 163b), thereby permitting adjustment of the position of the platform in a vertical plane, orthogonal to the x and y planes (i.e. a z direction).

In one example, the overall dimensions of the scissor lift <NUM> are as follows. The base portion <NUM> and top portion <NUM> are <NUM> wide and <NUM> long. The lift <NUM> in its fully extended state is approximately <NUM> from the upper surface 121a of the top portion <NUM> to the lower surface of the base portion <NUM>. The lift in its fully retracted state is <NUM> from the upper surface 121a of the top portion <NUM> to the lower surface of the base portion <NUM>. In one example, the lift <NUM> weighs <NUM>, and is rated for a <NUM> safe working load.

In use, the scissor lift <NUM> is wheeled into position on caster wheels <NUM>. Subsequently, the support legs <NUM> are deployed or the wheels <NUM> are raised to fix the lift <NUM> in positon. Power and control cables are then connected to the ports 153a/b. A platform (not shown) may be mounted to the mounting points <NUM>. In some examples, however, the top surface 120a of the top portion <NUM> functions as the deck/platform, and so no additional platform is mounted to the lift <NUM>.

In order to raise the lift <NUM>, a control signal is sent to the motor <NUM>, driving the motor <NUM> to turn the axle <NUM> (e.g. via gearing assembly <NUM>) in a direction that drives the chains <NUM> out of their respective magazines <NUM>. As the links of the chains <NUM> move into a vertical configuration, they become rigid and so move the top portion <NUM> upwards and away from the base portion <NUM>. During the motion of the chains <NUM>, power is also supplied to the safety brake <NUM>, such that it permits rotation of the axle <NUM>. When the top portion <NUM> is in its desired position, the motor <NUM> deactivates and the safety brake <NUM> engages, thereby preventing motion of the chains <NUM> and holding the top portion <NUM> in position.

In order to lower the lift <NUM>, a control signal is sent to the motor <NUM>, driving the motor <NUM> to turn the axle <NUM> in the opposite direction, thereby driving the chains into their respective magazines. When a platform is mounted to the top portion <NUM>, each mounting point <NUM> allows for adjustment in the x/y/z directions, thereby facilitating levelling of the platform. Alternatively, in the absence of a platform the mounting points <NUM> may be discarded and support legs <NUM> used to level the lift <NUM> instead.

In order to transport the lift <NUM>, the lift <NUM> is fully retracted, whereupon it can be loaded into a container or lorry in a configuration that occupies minimal space.

Turning now to <FIG>, there is shown an exemplary passive scissor <NUM>. The passive scissor <NUM> comprises a base portion <NUM>, which is arranged on the floor or another support surface in use, and a top portion <NUM>, upon which a load can be placed in order to be lifted. The passive scissor <NUM> further comprises a scissor assembly <NUM>, which extends between the top portion <NUM> and the base portion <NUM>.

In one example, the structure of the scissor assembly <NUM>, and the means by which it couples to the top and base portions <NUM>/<NUM> are the same as or similar to one of the scissor subassemblies 130a/b of the scissor lift <NUM>. The base portion <NUM> comprises support legs <NUM> the same as or similar to the support legs <NUM> of the scissor lift <NUM>. The top portion <NUM> comprises mounting portions <NUM>, the same as or similar to the mounting portions <NUM> of the scissor lift <NUM>. Accordingly, for clarity, the description of these elements is not repeated.

In one example, the passive scissor <NUM> has the same length (e.g. <NUM>) as the scissor lift <NUM>. However, the passive scissor is substantially narrower (e.g.<NUM> wide).

In use, the passive scissor <NUM> is coupled to a scissor lift <NUM>, such that the rise and fall of the scissor lift <NUM> also causes the rise and fall of the passive scissor <NUM>.

Example stage assembly arrangements comprising scissor lifts <NUM> and passive scissors <NUM> will now be discussed with reference to <FIG>.

<FIG> shows a stage assembly 2000A in schematic plan view. The assembly 2000A comprises a scissor lift 100A and a passive scissor 200A. A long side of the passive scissor 200A is attached to one of the short side edges of the scissor lift 100A, so as to form a T shape. Each of the passive scissor 200A and scissor lift 100A may comprise apertures to receive mechanical fastenings for securing the devices to one another. For example, the flanges of top and base portions of each device may comprise apertures. It will be understood that the flanges may be provided with a plurality of apertures disposed at differing locations around the flanges, so as to facilitate coupling the passive scissor 200A and scissor lift 100A to one another, and to numerous other accessories, in various ways.

The scissor lift 100A and passive scissor 200A support a platform 300A. As the scissor lift 100A rises and falls, the passive scissor 200A directly coupled thereto rises and falls. Accordingly, the passive scissor 200A effectively provides a means for stabilising the platform 300A, and transmitting the lifting motion of the lift 100A to a wider area.

<FIG> shows an example stage assembly 2000B, similar to the stage assembly 2000A of <FIG>. However, in this example, four passive scissors 200B-<NUM>, <NUM>-B2, 200B-<NUM>, 200B-<NUM> are coupled to the scissor lift 100B. Two of the passive scissors 200B-<NUM>, 200B-<NUM> are coupled to the short side of the scissor lift 100B, such that their long sides abut the short side. Accordingly, the overall width of the area supported is larger than in the stage assembly 2000B. In addition, two further passive scissors 200B-<NUM>, 200B-<NUM> are respectively coupled to opposing longer sides of the scissor lift 100B. In particular, each passive scissor 200B-<NUM>, 200B-<NUM> is arranged such that approximately half of its longitudinal extent coincides with the scissor 100B, thus extending the overall length of the area supported by the stage assembly 2000B.

<FIG> shows an example stage assembly 2000C comprising two scissor lifts 100C-<NUM>, 100C-<NUM> and two passive scissors 200C-<NUM>, 200C-<NUM>. Each passive scissor 200C is arranged to connect the short edges of the two lifts 100C. Accordingly, the lifts 100C act in tandem and greater stability is provided.

It will be appreciated that these are merely exemplary arrangements, and that more or fewer passive scissors <NUM> and scissor lifts <NUM> may be deployed in various configurations, depending on the size and weight of the load to be lifted. Although the examples above comprise a single platform <NUM>, it will be understood that multiple platforms <NUM> can be used.

Various modifications within the scope of the invention will be apparent to those skilled in the art. For example, each scissor assembly could comprise a single scissor, or more than two scissors. The scissor lift may comprise more than two scissor subassemblies. In other examples, the scissor subassemblies need not be disposed in parallel or adjacent to one another. Whilst the examples shown comprise base portions and top portions of matching dimensions, it will be understood that these may differ in dimensions. It will be understood that in some examples, one or more the components (e.g. base portion, top portion, scissors) may be formed of or comprise steel or other heavier metals, in addition to, or instead of, aluminium. In further examples, the top and/or bottom portions <NUM>/<NUM> may comprise access panels or hatches, for cable management and to facilitate access to the rigid chain lifting system <NUM>. For example a hatch may be provided on the top plate <NUM>.

The above-described scissor lift provides an advantageously lightweight and compact lift. The use of a rigid chain lifting system means that the scissors are provided for guidance rather than applying load, and thus can be fabricated from lighter, less strong material. In addition, the use of an AC servo motor allows for precise control of the lift, allowing for synchronous movement of multiple lifts during performances. In addition, the lift is fabricated substantially without welding, ensuring that the components do not warp during manufacturing and facilitating easy repair and fabrication.

In addition, the above-describe scissor lift can be operated in conjunction with one or more passive scissors, utilising the lifting power of the scissor lift to stably lift loads of differing sizes and shape. The scissor lift and passive scissors are advantageously modular, and can be deployed in many different configurations depending on the requirements of the show.

Advantageously, the scissor lift and passive scissors retract into a highly compact arrangement, thereby saving on travel costs.

Claim 1:
A stage assembly comprising:
a scissor lift (<NUM>) comprising:
a base portion (<NUM>) configured to be supported on a floor or other support surface;
a top portion (<NUM>) configured to support a platform (<NUM>);
a scissor arm assembly (<NUM>) connecting the base portion (<NUM>) and the top portion (<NUM>), the scissor arm assembly (<NUM>) comprising two subassemblies (130a, 130b) each subassembly comprising at least one pair of crossed arms (<NUM>) connected at a pivot point (<NUM>) to form a scissor (<NUM>, <NUM>);
a rigid chain lifting system (<NUM>) comprising a rigid chain (<NUM>) connecting the base portion (<NUM>) and the top portion (<NUM>), wherein the scissor lift (<NUM>) is configured such that extension and retraction of the rigid chain (<NUM>) causes the top portion (<NUM>) to rise and fall with respect to the base portion (<NUM>);
and characterized by
a plurality of bracing plates (<NUM>) extending between corresponding locations on the respective subassemblies (130a, 130b), the bracing plates (<NUM>) each comprising an upper plate (<NUM>) and angled side plates (<NUM>) extending obliquely downward from the upper plate (<NUM>) towards the arms (<NUM>) of the respective scissor arm subassemblies, and flanges (<NUM>) connecting the angled side plates (<NUM>) to the scissor arm subassemblies (130a, 130b);
wherein the width of the upper plates (<NUM>) in a direction between the arms (<NUM>) of the respective scissor arm subassemblies progressively increases from a lowermost bracing plate to an uppermost bracing plate, so that when the lift (<NUM>) is in a lowermost position, each bracing plate is nested within the bracing plate immediately above it;
wherein the uppermost arms (<NUM>) of each subassembly (130a, 130b) comprise a support arm (<NUM>) pivotally attached between the respective uppermost arm (<NUM>) and the top portion (<NUM>), and wherein at least one of the lowermost arms (<NUM>) of each subassembly (130a, 130b) comprise a support arm (<NUM>) pivotally attached between the respective lowermost arm (<NUM>) and the base portion (<NUM>).