Abstract:
A recliner seat assembly for a passenger vehicle is disclosed. The recliner seat assembly includes a fixed supporting portion for supporting the assembly off a floor of the vehicle, a reclinable seat portion comprising a seat-pan and a back-rest, and a seat connecting device adapted for connecting the seat portion to the supporting portion. The connecting device includes a seat reclining mechanism adapted for allowing and controlling translational movement of the seat portion relative to the supporting portion between a first upright position and a second fully reclined position. The connecting device further includes a selectively operable, bi-directional motor adapted for driving the seat portion between the first and second positions. The seat reclining mechanism includes a guiding device for reclining the back-rest progressively rearwardly relative to the supporting portion as the seat portion is moved from the first upright position to the second fully reclined position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 10/774,244, filed Feb. 6, 2004, hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a novel seating system for a passenger vehicle, particularly an aircraft. The present invention also relates to a passenger accommodation unit for a vehicle, which accommodation unit is adapted to provide individual, self-contained seating and sleeping accommodation for a passenger. The accommodation unit of the present invention may be adapted for use on any passenger vehicle, including omnibuses, coaches, ferries and railway carriages, but is particularly suited for use on aircraft. The present invention also comprehends improvements in or relating to passenger seats for vehicles, particularly aircraft. 
       BACKGROUND OF THE INVENTION 
       [0003]    A conventional passenger seat for an aircraft comprises a back-rest and a seat-pan that are supported off the floor of the vehicle by means of a suitable supporting structure that is anchored to a pair of seat tracks in the floor. The seat defines a notional longitudinal seat axis, as viewed from the perspective of a passenger using the seat, and a plurality of such seats are adapted to be arranged in rows in a passenger accommodation cabin within the fuselage of an aircraft, each row extending transversely across the cabin, one behind another, with the notional seat axis of each seat substantially aligned with the longitudinal axis of the fuselage such that each seat faces forwards. Usually, the back-rest of the seat is capable of reclining from an upright position to a reclined position for the comfort of a passenger using the seat during the course of a flight. Some prior art passenger seats, particularly seats for use in business-class and first-class of sections of aircraft, where the pitch between adjacent rows of seats is greater than in an economy-class cabin, also comprise a leg-rest which is hinged to the front of the seat-pan and is capable of movement between a lowered or stowed position, in which the leg-rest depends from the seat-pan generally vertically towards the floor, and a raised or deployed position in which the leg-rest extends forwardly of the seat-pan to bear the passenger&#39;s legs off the floor. Thus, it is possible with conventional aircraft passenger seats to obtain a fair degree of comfort by reclining the back-rest and elevating the leg-rest, when fitted. 
         [0004]    Whilst the above-described arrangement of conventional aircraft passenger-seats is generally satisfactory for short-haul flights having a duration of up to three or four hours, it is not satisfactory for use on longer flights during which passengers typically wish to go to sleep. Even in the reclined position described above, a passenger using the seat remains in a general sitting position. Many passengers find it difficult to sleep properly, if at all, when sitting. In recent years there has been a significant increase in the number of passengers who regularly make long-haul flights, and there has been a trend in the art to devise passenger seats which allow passengers to adopt further reclined positions during the course of a flight to facilitate sleeping. This is particularly important for passengers who travel for business purposes for whom it is desirable that they arrive at their destinations feeling refreshed and alert. 
         [0005]    One possibility that has been disclosed in the art for increasing the degree to which an aircraft passenger seat can be reclined comprehends simply increasing the extent to which the back-rest can be reclined backwards and the leg-rest elevated. In the extreme, it is possible to form a substantially flat bed using such a technique in which the back-rest is reclined and the leg-rest raised, each to such an extent that they are disposed substantially co-planarly with the seat-pan and each other. A disadvantage of such a system is that the pitch between adjacent rows of seats must be increased substantially to accommodate the full height of a passenger. Whilst this is sometimes possible in the first-class area of an aircraft cabin, it is generally uneconomic for a business-class cabin. Furthermore, whilst it is possible to form a generally flat surface which is disposed substantially horizontally, the surface is still not ideal, because the foam or other padding on the seat is generally sculptured for use as a seat, whereas for a bed, it is desirable to have a substantially flat surface. 
         [0006]    GB 2326824 A discloses a seating unit for a first class aircraft cabin comprising a secondary seat positioned to face a primary seat, the secondary seat having a seating portion positioned to cooperate with a leg-rest of the primary seat to form a continuous, flat sleeping surface when the back-rest of the primary seat is reclined to a horizontal position. The seating unit defines a notional, longitudinal seat axis, and a plurality of such seating units may be arranged within the cabin side-by-side in a longitudinally offset relation with respect to the longitudinal axis of each seat, with each seating unit being oriented at an acute angle to the longitudinal axis of the aircraft fuselage, so as to define a generally triangular or trapezoidal space to the front or rear of each seating unit (according to whether the seating units face outwards or inwards relative to the cabin). The space is used to accommodate a counter-top to one side of an adjacent seating unit and optionally a cupboard or other storage space. The seating unit of GB 2326824 A has the advantage that by incorporating an additional, secondary seat in the flat sleeping surface together with back-rest, seating portion and leg-rest of the primary seat, it is possible to form a long sleeping surface which is able to accommodate comfortably passengers having a height of greater than 6 ft (1.83 m). However, the seating unit of GB 2326824 A represents an even greater overhead in turns of cabin space than the conventional system described above and, moreover, still suffers from the disadvantage that the seat cushioning is designed principally for use as a seat and not a bed. A disadvantage of the seat of GB 2326824 A is that it occupies a very large floor area within the cabin and, in view of its overall length, the seating unit of GB 2326824 A is wholly unsuitable for use in a business class section of an aircraft. 
         [0007]    WO 00/21831 A2 discloses a seating unit which can be converted into a bed for use principally in a business-class section of aircraft cabin. The seating unit of WO 00/21831 A2 comprises a pair of seats facing in opposite directions, each seat comprising a seating space for the seated body of an occupant and an extension space in which the legs of an occupant may be placed. The seats are positioned each side of a notional dividing axis with the seating space of one extending over the axis into the extension space of the other. When installed in an aircraft cabin, one of the seats faces substantially forwards and the other faces substantially aft. Each seat of the seating unit of WO 00/21831 A2 comprises a primary seat that is substantially the same as the primary seat of GB 2326824 A described above, but without a leg-rest, and a secondary unit spaced forwardly of the primary seat. Each seat thus comprises a primary seat having a reclinable back-rest and seat-pan and a secondary unit comprising an elevated pad which serves as a foot-rest. The primary seat can be reclined such that as the back-rest is reclined, the seat-pan moves forwardly to meet the secondary unit to form a continuous surface therewith which serves as a sleeping surface for a passenger. As with GB 2326824 A, the seating unit of WO 00/21831 A2 therefore has the advantage of providing a substantially horizontal sleeping surface for a passenger during long-haul flights. However, the seating unit of WO 00/21831 A2 is still extravagant in terms of the space available within a typical business-class cabin and also suffers from the disadvantage that when configured as a bed, each seat is unable to accommodate comfortably tall passengers. As with the other prior art seats described above, each of the seats of the seating unit of WO 00/21831 A2 also suffers from the disadvantage that the seat cushioning is not specifically designed for use as a bed surface, but is contoured for use principally as a seating surface. 
         [0008]    Another attribute of a passenger seat for use in a first-class aircraft cabin is a generous seat width. A further disadvantage associated with the seating unit of WO 00/21831 A2 is that in order to accommodate a maximal head count within a business class cabin, the seat width is reduced, which many passengers find to be uncomfortable. Whilst the seating unit of WO 00/21831 A2 has the undeniable benefit of providing a substantially flat sleeping surface for a passenger in-flight, its overall dimensions are such that passengers of above average height and/or weight find the accommodation somewhat cramped. Furthermore, privacy screens are provided between adjacent seating units which, in combination with the total number of seating units provided in the limited space afforded by a business class cabin, result in the cabin as a whole having a somewhat crowded appearance. 
         [0009]    FR 987559 A discloses a seating installation for public transport vehicles such as motor cars, auto buses and the like comprising a row of seats, each seat comprising a supporting structure for supporting the seat off the floor of a vehicle, a seat-pan and a back-rest. Said row defines an aisle between two adjacent seats. The seat-pan of one of the seats adjacent the aisle can be removed and slung in an inverted orientation between the supporting structures of the two seats adjoining the aisle to form an additional seat in the aisle. The back-rest of the one seat can then be rocked forwards into the space formerly occupied by the seat-pan to provide a replacement seat-pan for the one seat. The back-rest of the one seat thus has front and rear surfaces which can both serve as part of a seat. Optionally the entire row of seats could support a mattress to form a couchette. However, the installation of FR 987559 A is not suitable for use on a passenger aircraft where the aisles must be kept unobstructed at all times and, furthermore, a plurality of adjacent seats are used to provide support for a single couchette. Thus the installation of FR 987559 A is not able to provide one couchette per seat. 
         [0010]    JP 5-13838 A discloses a seating system for vehicles such as buses and trains comprising a plurality of seats. Each seat comprises a seat-pan and a back-rest that can rock between an upright position and a reclined position, and the seats are positioned within a cabin at an angle with respect to a centre-line of the cabin and face outwardly to define a generally triangular space between each seat and a wall of the cabin. Said space accommodates a box comprising a foot-rest for an adjacent seat. 
         [0011]    FR 647809 A discloses a seating system for a sleeping car in which a plurality of seats are arranged at an angle to the longitudinal axis of the sleeping car, facing inwardly to define a generally triangular space to the rear of each seat which is used to accommodate a small table for an adjacent seat. 
       SUMMARY OF THE INVENTION 
       [0012]    An embodiment of the present invention provides improved passenger accommodation for a business-class section of a passenger aircraft. In particular, an embodiment of the invention provides such accommodation which incorporates a flat sleeping surface of maximal length and preferably also of maximal width. 
         [0013]    Another embodiment of the present invention provides an improved passenger accommodation unit for a vehicle, particularly an aircraft, which accommodation unit is adapted to provide self-contained, individual seating and sleeping accommodation for a passenger, particularly for use in the business-class section of an aircraft where the pitch between adjacent rows of seats is typically in the range of 50-60 inches (1.27 to 1.52 metres). 
         [0014]    Yet another embodiment of the present invention provides a passenger accommodation unit which can be converted into a bed having maximal length to accommodate tall passengers, particularly those having height greater than 6 ft (1.83 metres). 
         [0015]    Yet another embodiment of the present invention provides a passenger accommodation unit for a vehicle having a seating surface which may be especially adapted for use as a seating surface and a bed surface that may be especially adapted for use as a bed surface. 
         [0016]    A different embodiment of the present invention provides a passenger accommodation unit which can be converted into a bed and which promotes or contributes to a first cabin ambience when configured as a seat and a second, different cabin ambience when configured as a bed. Thus, yet another embodiment of the invention provides a seating system for a vehicle cabin comprising a plurality of passenger accommodation units which can be converted into beds and which, when all or a majority of the units are configured as seats, gives the cabin a particular first overall visual appearance and, when all or a majority of the units are configured as beds, gives the cabin a second overall appearance or ambience. 
         [0017]    Yet another embodiment of the present invention provides a seating system for a passenger vehicle, particularly an aircraft, which optimises the use of space within a passenger cabin. 
         [0018]    Yet another embodiment of the present invention provides a seating system for a cabin of a passenger vehicle which has a substantially uncrowded appearance. 
         [0019]    Further embodiments of the invention will be apparent to those skilled in the art from the following description of the invention and specific embodiments of the invention. 
         [0020]    According to one embodiment of the present invention there is provided a passenger accommodation unit for a vehicle, particularly an aircraft, which is adapted to provide self-contained, individual seating and sleeping accommodation for a passenger, said accommodation unit comprising: supporting structure for supporting said assembly off the floor of a vehicle; one or more movable passenger-bearing, structural components; and means for connecting said movable, structural components to said structure such that said components can be selectively moved between a seat configuration, in which a plurality of passenger-bearing surfaces on said one or more of said structural, movable components or said supporting structure form a seat for the passenger, and a bed configuration, in which a plurality of said bearing surfaces are disposed substantially coplanarly and substantially contiguously to form a bed for the passenger; characterised in that at least one of said movable components is double-sided, comprising first and second opposite sides, one of said sides having a first seat surface that forms part of the seat in said seat configuration, and the other side having a second bed surface that forms part of said bed in said bed configuration. 
         [0021]    The double-sided, movable, structural component may comprise an internal, load-bearing diaphragm having first and second opposite faces and first and second outer cushioning layers adapted to be supported by said diaphragm on said first and second faces respectively. Thus, said one side of said double-sided movable component may, for example, carry a layer of foam padding having a contoured surface that is shaped for use as a seat component, and said other side may carry a layer of foam padding having a substantially flat surface for use as part of a bed. Said first side of said double-sided, movable component may have a first appearance that contributes to or promotes an overall cabin appearance that is suitable for a seating environment. For instance, said first surface may have a leather or simulated leather seat covering. Said second surface may have a visual appearance which contributes to or promotes an overall cabin ambience that is appropriate for a sleeping environment. Thus, said second surface may be upholstered in fabrics or other materials having an appearance that is usually associated with bedding materials. 
         [0022]    Preferably, said double-sided component is a back-rest component. Said back-rest component may be connected to the supporting structure such that it can be selectively pivoted between a first generally upright position, in which the first surface is arranged to form part of the seat, and a second prone position in which said second surface is arranged to form part of the bed. Preferably, the second bed surface of the back-rest component is generally horizontal in the second prone position. 
         [0023]    In some embodiments, one or more of said passenger-bearing surfaces may define a seat-pan. Said back-rest component may be connected to the structure such that, in the second prone position, the back-rest component overlays the seat-pan. Thus, in accordance with the present invention, said seat-pan may have a dedicated seating surface which is shaped and upholstered specifically for use as a seat. In the bed configuration, the seat-pan may be wholly or partially concealed by the back-rest component in the second prone position such that the seating appearance of the seat-pan is hidden by the back-rest. 
         [0024]    In some embodiments, said seat-pan may comprise one or more of said moveable components which are connected to said supporting structure for movement in a direction having a vertical component between an upper deployed position and a lower stowed position, and seat-pan moving means may be provided for moving the seat-pan from the upper deployed position to the lower stowed position when the back-rest component is moved from the upright position to the prone position. Thus, in said second prone position, the back-rest component may occupy the space that is normally occupied by the seat-pan in the upper deployed position, the seat-pan being displaced to its lower stowed position in the bed configuration. This feature of the invention allows the bed surface of the seat assembly to be provided at a relatively low-level off the floor of the vehicle to make it easy for a passenger to climb in to and out of the bed. 
         [0025]    In preferred embodiments of the present invention, one or more of said passenger-bearing surfaces comprise a bed extension surface, which bed extension surface is positioned or deployable to be positioned forwardly or rearwardly of the seat in said seat configuration. Said back-rest component may be connected to the structure such that in said prone position said second bed surface and said bed extension surface form a substantially continuous surface. Said bed extension surface may be positioned or may be deployable to be positioned forwardly of the seat-pan component such that, in the seat configuration, said bed extension surface may serve as a foot-rest. Said accommodation unit may therefore not have a leg-rest component that is connected to and deployable from the seat-pan. Thus, in place of such a conventional leg-rest, the accommodation unit of the present invention may include a separate foot-rest surface at a position spaced forwardly of the seat-pan. 
         [0026]    In some embodiments, one or more of said passenger-bearing surfaces may comprise a rear extension surface behind said back-rest component, and said back-rest component may be connected to the structure such that in said prone position said second bed surface and said extension surface are substantially coplanar. 
         [0027]    In some embodiments, said back-rest component may be spaced forwardly of said rear extension surface in said prone position, and a movable infill component may be provided that is connected to said structure such that it is movable between a stowed position and a deployed position, which infill component comprises a passenger-bearing infill surface that extends between said back-rest component and said rear extension surface when said infill component is deployed, such that said rear extension surface, infill surface and second bed surface form a substantially continuous surface, and means may be provided for moving the infill component from said stowed position to said deployed position when the back-rest component is moved from the upright position to the prone position. Said infill component may be mounted pivotably behind the back-rest component intermediate the rear extension surface, such that in the stowed position the infill component may be angled to the horizontal and, upon deployment, may be pivoted to the deployed position. Thus, in bed configuration, the bed may be constituted by a rear extension surface, an infill surface and a foot-rest surface as well as the second surface of the back-rest component. 
         [0028]    The bed in accordance with the present invention may have an overall length of at least 78″ (1.98 metres) and, in some embodiments, may have a length in excess of 85″ (2.16 metres). 
         [0029]    Preferably, said back-rest component is connected to the structure for selective movement between an upright position and a fully reclined position in which the back-rest component is rocked rearwardly relative to the upright position. In some embodiments, one or more of said movable components may comprise a seat-pan which is connected to the supporting structure such that it can be pivoted relative to the supporting structure between a first position and a second position, and means may be provided for pivoting the seat-pan progressively from the first position to the second position as the back-rest component is pivoted rearwardly from the upright position to the fully reclined position. 
         [0030]    It has been found surprisingly that a plurality of passenger accommodation unit according to embodiments of the present invention may be arranged within a business-class section of an aircraft cabin without significantly reducing the number of seats. Each seat defines a notional longitudinal axis that extends fore-and-aft relative to the normal manner of using the seat. It has been found that a maximal number of the passenger accommodation units according to the present invention may be accommodated within an aircraft cabin if each unit is arranged with its notional axis to subtend an angle in the range of 35 to 55° with the longitudinal axis of the aircraft. 
         [0031]    Thus, according to another embodiment of the invention, there is provided a seating system for a passenger vehicle, particularly an aircraft, comprising a plurality of seat units, each seat unit defining a notional longitudinal seat axis and comprising a supporting structure adapted for attaching the seat unit to a floor of a vehicle and means forming or being configurable for forming a seat comprising a seat-pan and a back-rest; characterised in that said seat units are arranged to form a column defining a notional longitudinal column axis, in which column said seat-units are arranged side-by-side in longitudinally offset relation at an acute angle to the notional column axis, thereby defining to the rear of each seat, each seat unit further comprising means forming or being configurable for forming a substantially flat bed, a major proportion of which bed is disposed forwardly of the position of the seat, which bed extends rearwardly into said space to extend the flat-bed. 
         [0032]    Preferably said space to the rear of each seat is generally triangular or trapezoidal. 
         [0033]    Said acute angle is typically in the range 30-60°, preferably 40-50°, e.g. 40°, 45° or 50°. Normally, the seat units are installed in an accommodation cabin of said vehicle, which cabin defines a notional longitudinal cabin axis. Said notional column axis may be substantially parallel to or subtend an acute angle with said cabin axis. Thus, within an aircraft cabin, seat units according to embodiments of the present invention may be positioned in a “herringbone” arrangement. 
         [0034]    Said seat units may be disposed adjacent a side wall of the vehicle and face inwardly. Preferably, said accommodation cabin comprises two opposing side walls, and a column of seat units may be positioned contiguously or closely adjacent to each wall such that each seat faces into the cabin, with an extension surface behind the back-rest of the seat disposed adjacent the wall. The seats may thus have their backs to the vehicle wall, giving the cabin as a whole an uncrowded appearance. 
         [0035]    Where cabin space permits, one or more additional columns of seat units may be provided towards the centre of the cabin. If it is possible to accommodate two central columns of seats in any given cabin, then preferably those columns are arranged generally back-to-back. 
         [0036]    Preferably each seat unit further comprises a foot-rest that is positioned forwardly of the seat. Said foot-rest can thus be used by an occupant of the seat to support his or her feet in-flight in an elevated position and/or by another passenger to sit on whilst visiting the occupant. Provided that such a foot-rest is provided, it has been found that passengers do not require the seat unit to incorporate a movable leg-rest as part of the seat-forming means. 
         [0037]    In some embodiments, each seat unit may further comprise a first privacy screen that is positioned forwardly of said foot-rest. 
         [0038]    Said seat forming means and said bed forming means may comprise one or more movable passenger-bearing elements which are selectively configurable to form, in a seat mode, at least part of the seat for a passenger or, in a bed mode, at least part of said flat bed, and advantageously the flat bed in the bed mode is disposed at substantially the same level as the seat-pan in the seat mode. 
         [0039]    Preferably, each seat unit optionally comprises a first, preferably fixed, passenger-supporting element in said space to the rear of the seat, which first passenger-supporting element is disposed substantially coplanarly with said one or more movable elements when said movable elements are configured in the bed mode and is adapted to form part of said flat bed. Said first passenger-supporting element may be generally triangular or trapezoidal. It will be appreciated that the first passenger-supporting element is only used by a passenger when the seat unit is arranged in the bed configuration, and accordingly the seat unit may be arranged such that the first passenger-supporting element extends into a lateral recess defined by the concave cabin side wall to maximise the use of space in the cabin. 
         [0040]    Advantageously, each seat unit optimally further comprises a second, preferably fixed, passenger-supporting element to one side of the seat, which second passenger-supporting element is disposed substantially coplanarly with said first passenger supporting element and is adapted to form part of said flat bed when the movable elements are configured in said bed mode, thereby to extend said flat bed laterally. Said second passenger-supporting element may be generally triangular or trapezoidal. Said first fixed element of one seat unit may be disposed substantially contiguously to the second fixed element of an adjacent seat unit, and said first and second elements may be divided from one another by a second privacy screen. Said first and second elements may occupy substantially all of the space to the rear of the seat. 
         [0041]    An embodiment of the present invention thus provides a seating system which is particularly suited for a business-class cabin of a passenger aircraft. The seating system of the present invention provides individual seat units having back-rests and seat-pans and optional foot-rests to allow passengers to rest their legs in an elevated position during a flight. Each seat unit is provided with self-contained means for forming a substantially flat bed, and the use of space within the cabin is optimised by positioning the flat bed to extend rearwardly behind the seat into a space defined by the arrangement of the seat units. Surprisingly, it has been found that in accordance with an embodiment of the present invention it is possible to provide flat beds within a business-class section of a passenger aircraft having a length of up to 7 ft (2.13 metres) without substantially sacrificing head-count. Furthermore, the applicants have found that the seat units of an embodiment of the present invention can be positioned to give the cabin a substantially uncrowded appearance. 
         [0042]    Said supporting structure may be manufactured from any suitable, aviation standard, lightweight material that is known to those skilled in the art and may be equipped with suitable anchoring means for anchoring the seat unit to seat tracks in an aircraft passenger cabin. Preferably, the supporting structure comprises a pallette or splinth which is adopted to be attached to said seat tracks. 
         [0043]    In accordance with another embodiment of the present invention there is provided a seat module for a passenger vehicle, said seat module comprising a seat portion, a foot-rest portion, a unitary supporting structure for supporting said seat portion and said foot-rest portion off the floor of the vehicle and attaching means for attaching said supporting structure to a pair of seat tracks in a floor of the vehicle; characterised in that said attaching means comprise two spaced fixings for fixing the supporting structure to one of the tracks of the pair at two spaced points and a single third fixing for fixing the supporting structure to the other track, thereby to provide a 3-point fixing between the seat module and the seat tracks; the arrangement being such that a plurality of said seat modules can be attached to a pair of seat tracks, one adjacent another, thereby to form a plurality of seat units, each seat unit comprising the seat portion of one module and the foot-rest portion of another, adjacent module. 
         [0044]    It has been found that the use of a 3-point fixing between a unitary seat supporting structure and a pair of seat tracks in accordance with the present invention allows the two seat tracks forming the pair a greater degree of flexibility to move relative to one another in the event of undue stresses being applied to the aircraft infrastructure such, for example, as in the event of an emergency or crash landing, thus reducing the likelihood of the structure becoming detached from the seat tracks at one or more of the fixing points under such conditions. 
         [0045]    According to yet another embodiment of the present invention there is provided a passenger seat assembly for a passenger vehicle, particularly an aircraft, which assembly is adapted to provide seating and sleeping accommodation for a passenger, said assembly comprising: 
         [0046]    a supporting structure adapted for supporting the assembly off the floor of the vehicle; 
         [0047]    a plurality of seat elements including a seat-pan element and a back-rest element, said back-rest element comprising first and second opposite sides, one of said sides having a first seat surface and the other side having a substantially flat second bed surface; 
         [0048]    one or more auxiliary accommodation elements connected to or forming part of said supporting structure and being positioned or being deployable to be positioned juxtaposed said seat, the or each auxiliary accommodation element having an auxiliary, substantially flat, passenger-bearing surface; and 
         [0049]    a seat movement mechanism adapted for connecting the seat elements to the supporting structure, said seat movement mechanism including a seat conversion sub-mechanism adapted to allow and control movement of the seat elements such that the seat elements can be selectively moved between a seat configuration adapted to provide a seat for the passenger and a bed configuration adapted to provide a bed for the passenger, the seat conversion sub-mechanism being adapted for controlling movement of the back-rest element such that said back-rest element is pivotable from a first upright position, in which said first seat surface of the back-rest element cooperates with said seat-pan element for forming the seat, to a second prone position in which the second bed surface is disposed substantially coplanarly and contiguously with one or more of said auxiliary passenger-bearing surfaces for forming the bed. 
         [0050]    Thus, in accordance with an embodiment of the present invention, a passenger seat assembly is provided having a plurality of moveable seat elements which are adapted to form a seat. The seat assembly can also be converted into a bed configuration in which the back-rest element and one or more of the auxiliary elements form a sleeping surface for a passenger. The embodiment is characterised in that the back-rest element has a first face that is specifically adapted for use as a seating surface and second opposite face that is specifically adapted for use as sleeping surface. 
         [0051]    Preferably, said seat movement mechanism is adapted to control movement of said seat-pan element and said back-rest element in relation to each other. Said seat conversion sub-mechanism may be adapted to control movement of said back-rest element such that as the back-rest element is moved from the first position to the second position said back-rest element rocks forwardly over the seat-pan element, and said back-rest element in the second prone position is superposed over the seat-pan element. Advantageously, therefore neither the seat-pan element nor the first seat surface of the back-rest element forms part of the bed surface in the bed configuration and may therefore be upholstered with materials especially suitable for use on a seat. Similarly the second bed surface of the back-rest is not used to form part of the seat in the seat configuration, and accordingly said bed surface may be upholstered in a manner especially suitable for use as a bed. Moreover, the materials used to upholster the seat elements used respectively in the seat configuration and bed configuration may be differently coloured and/or textured and/or patterned from one another so as to create a first ambience or a “mood” in an aircraft cabin when all or a majority of such passenger assemblies according to the present invention are configured in one of said configurations, and second different ambience or “mood” when all or a majority of the assemblies are configured in the other configuration. Said one face of the back-rest element may carry a layer of foam padding having a contoured first surface that is adapted to form a back-rest or part of a back-rest of a seat, and the other face may carry a layer of foam padding having a substantially flat second surface that is adapted to form part of the bed. 
         [0052]    Said seat conversion sub-mechanism may be adapted to control movement of the seat-pan element such that as the back-rest element is moved from the first upright position to the second prone position said seat-pan element is caused to move downwardly relative to the supporting structure. Thus, the bed surface of the seat assembly may be provided at a relatively low-level off the floor of the vehicle to make it easy for a passenger to climb in to and out of the bed. 
         [0053]    Preferably, suitable motor means are provided for automatically moving the back-rest element between the upright and prone positions and user-operable control means are provided for controlling operation of the motor means. 
         [0054]    Preferably said seat movement mechanism further comprises a seat reclining sub-mechanism which is adapted to allow said seat to be selectively reclined from an upright position to a fully reclined position, said seat reclining mechanism being adapted to control movement of the back-rest element such that as the seat is reclined from the upright position to the fully reclined position, said back-rest element is rocked rearwardly from the first upright position to a third fully reclined position. Said seat reclining sub-mechanism may advantageously be further adapted to control movement of said seat-pan element such that as the back-rest element is rocked rearwardly from the first upright position to the third fully reclined position said seat-pan element is caused to tilt rearwardly. Thus, in the fully reclined position, the back-rest element and seat-pan element may be respectively oriented to provide an ergonomically comfortable sitting position for a passenger using the seat assembly. Both the reclining action of the back-rest element and the tilting action of the seat-pan element may be motorised under the control of said user-operable control means. 
         [0055]    Preferably, one or more of said auxiliary accommodation elements are positioned or deployable to be positioned forwardly or rearwardly of the seat. In some embodiments, one or more of said auxiliary accommodation elements may comprise a foot-rest positioned or deployable to be positioned forwardly of said seat, and in said second position the second bed surface of the back-rest element may be disposed substantially coplanarly and contiguously with said foot-rest. 
         [0056]    One or more of said auxiliary elements may comprise a fixed, rear extension surface positioned rearwardly of the seat. In some embodiments, said seat assembly may further comprise a movable infill element, and said seat conversion sub-mechanism may be adapted to allow movement of said infill element between a lower, stowed position and a raised, deployed position in which said infill element extends substantially coplanarly and contiguously with said second surface of said back-rest element in said second prone position and said rear extension surface, thereby to form a substantially flat, extended bed surface. Said seat conversion sub-mechanism may be further adapted to control movement of said infill element such that said infill element is caused to moved from said stowed position to said deployed position when the back-rest element is moved from said first upright position to said second prone position. Said infill element may be pivotably connected to the lower end of the back-rest element, such that as the back-rest element is moved from the first position to the second position, the infill element is caused to move from the stowed position to the deployed position. 
         [0057]    Said seat conversion sub-mechanism may comprise a seat holding device that is pivotably connected to the supporting structure for rocking movement between a first seat position and second bed position. Said back-rest element may be mounted on the holding device, such that back-rest element can be pivoted from the first upright position to the second prone position by rocking the holding device from said first position to said second position, and releasable locking means may be provided for selectively locking the holding device in the first and second positions. In some embodiments, said seat holding device may comprise two opposing rocker plates. Said rocker plates may be interconnected by one or more torque tubes. 
         [0058]    Said seat-pan element may be pivotably mounted on the holding device, the arrangement being such that when the holding device is rocked from the first position to the second position, the seat-pan element is caused to move downwardly from an upper deployed position to a lower stowed position and the back-rest elements is caused to rock forwardly over the seat-pan element such that in the second prone position, the back-rest element overlays the seat-pan element. The seat-pan element may comprise a front end and a rear end relative to the back-rest element, and the seat-pan element may be pivoted to the holding device at or towards said rear end. 
         [0059]    Conveniently, the seat movement mechanism further comprises a seat-pan supporting device for supporting the front end of the seat-pan element. Said seat-pan supporting device may comprise a slideway disposed beneath the seat-pan element, a leg member having two opposing ends, one of said ends being pivotably connected to the front end of the seat-pan element, the other end being slidably engaged in said slideway, and a drag-strut connecting the other end of the leg member to the holding device, the arrangement being such that as the holding device is rocked from the first position to the second position, the drag-strut is moved to cause or allow said other end of leg-member to slide in the slideway, the slideway having a profile such that as the holding device moves from the first position to the second position, the leg member is moved downwardly, thereby causing or allowing the front end of the seat-pan element to move progressively downwardly. Said leg member may be pivoted to the seat-pan element at said one end and pivoted to said slideway at said other end. In some embodiments, the front end of the seat-pan element may be supported by two leg-members, each leg-member being slidably engaged in a respective slideway juxtaposed a respective lateral side of the seat. 
         [0060]    Preferably, the seat movement mechanism further comprises a seat reclining sub-mechanism adapted to allow said seat element to be selectively moved between an upright position and a fully reclined position, when said holding device is disposed in the first seat position. 
         [0061]    Said seat reclining sub-mechanism may comprise a curvilinear track attached to or formed in the holding device and having two opposing track-ends and a plurality of spaced track followers attached to said back-rest element, said track-followers being adapted to engage in and slide along the track, the track being configured such that as the track-followers slide along the track from one end to the other, the back-rest element is caused to rock progressively rearwardly from the first upright position to a third fully reclined position. Said seat reclining sub-mechanism may further comprise a selectively operable bi-directional driving means for translationally moving said back-rest element relative to the holding device, the arrangement being such operation of said driving means causes the track-followers to slide along the curvilinear track, thereby causing the back-rest element to rock progressively between said first and third positions. 
         [0062]    Advantageously, the driving means may comprise a linear actuator connected between the back-rest element and said holding device. A linear actuator such, for example, as a linear screw or ball screw may be stopped at any intermediate position between the first and third positions, thereby allowing the back-rest element to be reclined continuously between the first and third positions and to be stopped at any desired intermediate position. 
         [0063]    In some embodiments, said linear actuator may comprise a linear screw or ball screw fixedly secured to the holding device, a screw-engaging device pivotably connected to the back-rest element and a selectively operable bi-directional motor carried by said holding device for rotatably driving the linear or ball screw. Said seat-pan element may have a front end and rear end relative to the back-rest element, and said linear actuator may be pivotably connected between the holding device and the seat element, said linear actuator being attached to the seat-pan element at or towards said rear end for driving said seat-pan element progressively downwards relative to the supporting structure from a first upper position when the back-rest element is in said first upright position to a second lower position when the back-rest element is in said third fully reclined position, and said seat movement mechanism may further comprise a seat-pan supporting device for supporting the front end of the seat-pan element as the rear end of the seat-pan element is driven downwardly, thereby causing the seat-pan to tilt progressively rearwardly as the back-rest element rocks rearwardly. Thus, in the upright position, the back-rest element may be oriented substantially upright and the seat-pan element may be disposed generally horizontally. In the fully reclined position, the back-rest element is rocked rearwardly relative to the upright position, and the seat-pan element is tilted rearwardly relative to the upright position to form a comfortable lounge seat position. Preferably, the profile of the curvilinear track, the length and position of the linear actuator, the positions of the pivots between the linear actuator and the back-rest and seat-pan elements and the configuration of the seat-pan supporting device are such that as the seat is progressively reclined from the upright position to the fully reclined position, it moves through a series of predetermined, ergonomically comfortable seating positions. Intermediate said predetermined positions, the profile of the curvilinear track, etc., may be determined by interpolation. In some embodiments, the linear actuator may be connected to the back-rest element through a lost motion device to allow a small degree of relative translational movement between the seat-pan and back-rest elements in order to allow the back-rest and seat-pan elements to adopt the aforesaid ergonomically comfortable positions. 
         [0064]    Said seat conversion sub-mechanism may comprise a selectively operable bi-directional actuator for locking said holding device between said first seat position and said second bed position. Said actuator may comprise a four-bar double-rocker linkage, said linkage comprising a rocker and coupler link connected intermediate said holding device and said rocker, and selectively operable bi-directional rotary drive means for operating said rocker, the arrangement being such that operation of the rocker causes rocking of said holding device between said first and second positions. Said rotary drive means may comprise a motor, a worm-gear and a worm-wheel, wherein the worm-wheel is fixedly secured to the rocker. A worm-gear/worm-wheel device is a non-reversible device, and advantageously, therefore, undue forces applied to the holding device, for example, in the event of a heavy passenger sitting heavily into the seat, are not transmitted through the worm-gear/worm-wheel device to the motor. Furthermore, the rotary drive means are locked in said first and second positions. 
         [0065]    However, in order to allow the holding device to be rocked manually when desired between said first and second positions, for example, in the event of a failure of said motor or of the power supply in an aircraft cabin, the worm-gear may be disengageable from the worm-wheel. 
         [0066]    Said actuator may be attached to the supporting structure of the seat assembly beneath said seat elements. Said holding device may comprise two spaced side members disposed respectively to opposing sides of the back-rest element. Said coupler link may be connected to the side members below the pivot point between the holding device and said supporting structure. 
         [0067]    The present embodiment thus provides a passenger seat assembly for use on a vehicle, particularly an aircraft, in which a back-rest element is mounted on a supporting structure such that it can be reclined rearwardly from an upright position to a reclined position for passenger comfort and can be pivoted forwardly to a substantially horizontal prone position over the top of a seat-pan element. The seat-pan element and a first surface of the back-rest element are upholstered in a manner suitable for use as a seat. The second reverse surface of the back-rest element however is adapted for use as a bed surface. The seat may comprise one, and preferably two, fixed or deployable the auxiliary extension surfaces behind and/or in front of the seat, and the back-rest element is pivoted to the support structure such that, when pivoted to the second prone-position, it meets one of the extension surfaces to form a substantially continuous surface therewith. A moveable infill element may be provided to fill-in the space between the back-rest element and the other extension surface where provided. The seat assembly of the present invention can thus be converted from a seat into a bed which is capable of accommodating even tall passengers. 
         [0068]    Advantageously, the seat assembly of the invention may be oriented at an angle of between 35 and 55°, preferably 40 to 50°, relative to the longitudinal axis of an aircraft cabin such that an extension surface behind the back-rest element extends into a recess defined by a typical concave aircraft cabin interior wall. Whilst the area of the cabin juxtaposed the concave cabin wall is not suitable, and has insufficient headroom, to accommodate the back-rest element in the upright position, it can be used in accordance with the present invention to accommodate the rear extension surface which forms part of the bed surface in the bed configuration. The extension surface(s), infill element and second surface of the back-rest element are preferably upholstered with foam padding or any equivalent material specifically for use as a bed. Thus, the bed surface of the seat assembly of the present invention may have a substantially flat surface which is oriented substantially horizontally when deployed. 
         [0069]    It will further be appreciated that when the seat assembly is arranged in the seat configuration, with the back-rest element upright, the rear extension surface behind the seat is substantially concealed and forms a useful storage space. Conveniently, the storage space can be used for storing bedding materials which are required only when the seat assembly is converted into the bed configuration. For example, the storage space defined by the rear extension surface behind the back-rest element can be used for storing a duvet and/or a blanket and one or more pillows. Advantageously, such bedding materials may be concealed when the seat assembly is in the seat configuration, giving the cabin an overall tidy appearance. When the seat assembly is converted into the bed configuration, the back-rest element is rocked forwardly over the top of the seat-pan element to reveal the rear extension surface and to allow easy access to the bedding materials stored on the rear extension surface which can be manually deployed on the bed surface. 
         [0070]    According to yet another embodiment of the present invention there is provided a recliner seat assembly, particularly for use on a vehicle such, for example, as an aircraft, comprising a fixed supporting portion adapted for supporting the assembly of a floor of the vehicle, a reclinable seat portion comprising a seat-pan and a back-rest and seat connecting means adapted for connecting said seat portion to said supporting portion, said connecting means including a seat reclining mechanism adapted for allowing and controlling movement of said seat portion between a first upright position and a second fully reclined position and selectively operable, bi-directional motor means adapted for driving said seat portion between said first and second position; wherein said seat reclining mechanism comprises a non-reversible linear actuator connected between said motor means and said seat portion. 
         [0071]    Said non-reversible linear actuator may comprise a lead screw drive or a ball screw drive or any other, equivalent, non-reversible device. The use of such a non-reversible actuator for driving the seat portion between the first upright and second fully reclined positions has the advantage that unduly strong or sudden forces applied to the seat portion are not transmitted to the motor, thereby reducing the risk of damage to the motor and thus prolonging its life. For example, in the event that a heavy passenger drops suddenly into his or her seat portion, thus applying a sudden, strong force to the seat portion, that strong force is not transmitted through the non-reversible linear actuator to the motor means. 
         [0072]    The linear actuator may comprise a linear screw or ball screw attached to one of said supporting portion (or a part connected thereto) and said seat portion and a screw-engaging device attached to the other of said seat portion and said supporting portion (or a part connected thereto). In some embodiments, the linear actuator may be connected to the seat-pan for driving the seat-pan along a predetermined linear path between a first position and a second position relative to the supporting portion. 
         [0073]    Said seat-pan may have a front end a rear end relative to the back-rest, and the linear actuator may be pivotably connected to the seat-pan at or towards the rear end and may be arranged for driving the rear end of the seat-pan downwardly as its moves from the first position to the second position. Said seat reclining mechanism may further comprise a supporting device for supporting the front end of the seat-pan as the rear end of the seat-pan is driven downwardly, thereby causes the seat-pan to tilt rearwardly as the back-rest rocks rearwardly. 
         [0074]    The linear actuator may alternatively or additionally be connected to the back-rest for driving the back-rest translationally between a first upright position and a second reclined position. Said seat reclining mechanism may further comprise a guiding device for rocking said back-rest progressively rearwardly relative to the supporting portion as the back-rest is moved from the first upright position to the second fully reclined position. Said guiding device may comprise a curvilinear track attached to the supporting portion or a part connected thereto and a plurality of spaced track-followers attached to the back-rest, said track-followers being adapted to engage in and slide along said track. 
         [0075]    Advantageously, the linear actuator may be pivotably connected to the seat-pan and may be pivotably connected to the back-rest through a lost-motion device to allow relative pivoting and translational movement between the seat-pan and the back-rest in order to allow a degree of freedom of movement between the back-rest and seat-pan to allow those seat components to adopt a plurality of relative, predetermined, ergonomically comfortable positions. 
         [0076]    In yet another embodiment of the present invention there is provided a seat having a reclinable back-rest, said seat comprising a fixed supporting portion adapted for supporting the seat off the floor, a seat portion comprising a reclinable back-rest and seat connecting means adapted for connecting said seat portion to said supporting portion, said connecting means including back-rest reclining mechanism adapted for allowing and controlling movement of the back-rest between a first upright position and a second fully reclined position; wherein said back-rest comprises a first lower back-rest member having an upper end and a second upper back-rest member that is superposed on said back-rest member and is pivotably connected at or towards the upper end thereof in such a manner as to transmit translational movement therebetween, and wherein said back-rest reclining mechanism comprises first and second elongate guide tracks attached to the supporting portion or a part connected thereto, said first track having two opposing track-ends, a plurality of first spaced track-engaging follower members attached to the first back-rest member and adapted to engage and slide in first said track and a second track-engaging follower member attached to the second back-rest member or a part connected thereto and adapted to engage and slide in said second track, said first track being curvilinear such that as the first track-engaging follower members slide along the first track from one end to the other, the back-rest member is caused to rock progressively relative to the supporting portion between the first upright position and the second fully reclined position, and said second track having a profile such that as said second track-engaging follower member is caused to slide along said second track, the second back-rest member is caused to rock progressively with respect to the first back-rest member. 
         [0077]    Advantageously therefore, the upper and lower back-rest members may have different relative dispositions in the upright and fully reclined positions. Furthermore, the relative dispositions of the upper and lower back-rest members may be adjusted continuously between the upright and fully reclined positions. Preferably, in the first upright position, the upper and lower back-rest members are disposed substantially co-planarly to one another to form a generally flat back-rest surface. In the second fully reclined position, the upper and lower back-rest members may subtend an obtuse angle such that the lower back-rest member is inclined at a greater angle to the vertical than the upper back-rest member. The lower back-rest member may thus form a lumbar support for a person using the seat. 
         [0078]    Said back-rest reclining mechanism may comprise a rocker lever having two arms which subtend an obtuse angle, which rocker lever is pivoted to the first back-rest member at a point intermediate said two arms, one of said arms carrying said second track-engaging follower member, and a connecting lever having two opposite ends, one of said ends being pivoted to the other arm of said rocker lever and the other end being fixedly secured to the second back-rest member; the arrangement being such that as the second follower member is caused to slide along said second track, the rocker lever is caused to rock about its pivot to the first back-rest member, thereby causing said connecting lever to pivot about its pivot to the other arm of the rocker lever, thereby causing the second back-rest member to pivot about its pivot to the first back-rest member. Said back-rest reclining mechanism may further comprise means for limiting movement of the rocker lever and/or connecting lever. 
         [0079]    Said seat connecting means may further comprise a selectively operable bi-directional linear actuator connected between the supporting portion or a part connected thereto and said back-rest for moving the back-rest translationally relative to the supporting portion, the arrangement being such that as the back-rest is caused to move translationally relative to the supporting portion, the first follower members on the first back-rest member are caused to slide progressively along the first track, thereby causing the back-rest to rock progressively between the first upright and second fully reclined positions. 
         [0080]    Said seat portion generally comprises a seat-pan. Said linear actuator may be connected to the seat-pan for moving said seat-pan along a predetermined linear path from between a first position and second position. Said linear actuator may be pivotably connected to the seat-pan. Advantageously, the linear actuator may be pivotably coupled to the back-rest by a lost motion device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0081]    Following is a description by way of example only with reference to the accompanying drawings of embodiments of the present invention. 
           [0082]    In the drawings: 
           [0083]      FIG. 1  is a sectional, schematic plan view of a front portion of an aircraft fuselage showing a seating system in accordance with the present invention comprising a plurality of individual seat units. 
           [0084]      FIG. 1A  is an enlarged view of part of  FIG. 1  showing three adjacent seat units. 
           [0085]      FIG. 2  is an isometric view of the three adjacent seat units of  FIG. 1A . In  FIG. 2 , one of the seat units is shown in an upright seating configuration, another is shown in a reclined seating configuration, and the third is shown in a bed configuration. 
           [0086]      FIG. 2A  shows a portion of a supporting structure of an individual seat unit of the kind shown in  FIG. 2 , with the movable seat elements removed. 
           [0087]      FIG. 3  is a schematic side elevation of a first passenger seat assembly for a vehicle in accordance with the present invention, shown in an upright seating configuration. 
           [0088]      FIG. 4  is another schematic side elevation of the first passenger seat assembly of  FIG. 3 , shown in a fully reclined seating configuration. 
           [0089]      FIG. 5  is yet another schematic side elevation of the first seat assembly of  FIGS. 3 and 4 , shown in a bed configuration. 
           [0090]      FIG. 6  is an isometric view of part of the first seat assembly of  FIGS. 3 to 5  in the upright seating configuration, with the seat upholstery removed. 
           [0091]      FIG. 6A  is a side elevation of a back-rest component forming part of the first seat assembly of  FIG. 6 . 
           [0092]      FIG. 6B  is an isometric view of the back-rest component of  FIG. 6A . 
           [0093]      FIG. 7  is another isometric view of the part of the first seat assembly shown in  FIG. 6 , with the seat assembly in the fully reclined seating configuration. 
           [0094]      FIG. 8  is yet another isometric view of the part of the first seat assembly of  FIGS. 6 and 7 , with the seat assembly in the bed configuration. 
           [0095]      FIG. 9  is an isometric view of part of a seat movement mechanism of the first seat assembly of  FIGS. 3 to 8 , shown in the bed configuration. 
           [0096]      FIG. 10  is a side elevation of the part of the seat movement mechanism of  FIG. 9 , shown in the seating configuration. 
           [0097]      FIG. 11  is another side elevation of the part of the seat movement mechanism of  FIGS. 9 and 10 , shown in the bed configuration. 
           [0098]      FIG. 12  is an enlarged isometric view of part of the seat movement mechanism of  FIGS. 9 to 11 . 
           [0099]      FIG. 13  is an isometric view of part of a seat reclining sub-mechanism of the first seat assembly of  FIGS. 3 to 8 . 
           [0100]      FIG. 14  is an isometric view of part of a seat conversion sub-mechanism of the first seat assembly of  FIGS. 3 to 8 , shown in the bed configuration. 
           [0101]      FIG. 15  is another isometric view of the part of the seat conversion sub-mechanism of  FIG. 14 , shown in the seat configuration with a worm-screw removed from a corresponding worm-gear to allow manual movement of the seat conversion sub-mechanism between the seat and bed configurations. 
           [0102]      FIG. 16  is an enlarged, sectional side elevation of part of the seat conversion sub-mechanism of  FIGS. 14 and 15 . 
           [0103]      FIG. 17  is a sectional, schematic plan view of another seating system in accordance with the present invention. 
           [0104]      FIG. 18  is an isometric view of a passenger accommodation unit in accordance with the present invention, shown in a seat mode. 
           [0105]      FIG. 19  is an isometric view of the passenger accommodation unit of  FIG. 18  in a bed mode. 
           [0106]      FIGS. 20A-20C  show schematically in side elevation the interconversion of the passenger accommodation unit of  FIGS. 18 and 19  between the bed mode and the seat mode. 
           [0107]      FIG. 21A  is a schematic, isometric view of the passenger accommodation unit of  FIGS. 18 and 19 , showing a passenger using the seat in the seat mode. 
           [0108]      FIG. 21B  is a schematic, isometric view of the passenger accommodation unit of  FIGS. 18 and 19 , showing a passenger using the seat in the bed mode. 
           [0109]      FIG. 22  is an isometric view of an another accommodation unit in accordance with the present invention shown in a seat mode. 
           [0110]      FIG. 23  is an isometric view of the passenger accommodation unit of  FIG. 22 , shown in a bed mode. 
           [0111]      FIG. 24A  is a schematic, isometric view of the passenger accommodation unit of  FIGS. 22 and 23 , showing a passenger using the seat in the seat mode. 
           [0112]      FIG. 24B  is a schematic, isometric view of the passenger accommodation unit of  FIGS. 22 and 23 , showing a passenger using the seat in the bed mode. 
           [0113]      FIG. 25  is an isometric view of a variant of the passenger accommodation unit of  FIGS. 22 and 23 , which comprises a sliding seat-pan. 
           [0114]      FIGS. 26A-26C  show schematically in side elevation different positions of the sliding seat-pan. 
           [0115]      FIG. 27  is an isometric view showing a further variant of the passenger accommodation unit of  FIGS. 22 and 23 . 
           [0116]      FIG. 28  is a schematic, sectional plan view of the upper and lower decks of a front portion of an aircraft fuselage, showing yet another seating system in accordance with the present invention as applied to the upper and main decks of a Boeing® 747-400 aircraft. 
           [0117]      FIG. 29A  is a schematic side elevation of a second passenger seat assembly according to the present invention, which seat assembly is shown in a dining position. 
           [0118]      FIG. 29B  is a schematic side elevation of the second passenger seat assembly of  FIG. 29A , shown in an intermediate reclined position. 
           [0119]      FIG. 29C  is a schematic side elevation of the second passenger seat assembly of  FIGS. 29A and 29B  in a fully reclined position. 
           [0120]      FIG. 30A  is a schematic side elevation of the second passenger seat assembly of  FIGS. 29A to 29C  in another intermediate conversion position. 
           [0121]      FIG. 30B  is a schematic side elevation of the seat assembly of  FIGS. 29A to 29C  and  FIG. 30A  in a bed configuration. 
           [0122]      FIG. 31  is a schematic plan view of yet another seating system comprising a plurality of passenger assemblies in accordance with the present invention. 
           [0123]      FIG. 32  is a schematic plan view of yet another seating system comprising a plurality of passenger seat assemblies according to the present invention. 
           [0124]      FIG. 33A  is a schematic side elevation of a third passenger seat according to the present invention, which seat assembly is shown in a seat configuration. 
           [0125]      FIG. 33B  is a schematic side elevation of the third seat assembly of  FIG. 33A , shown in an intermediate position. 
           [0126]      FIG. 33C  is a schematic elevation of the third assembly of  FIGS. 33A and 33B  in a bed configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0127]    A passenger aircraft generally comprises a hollow, spindle-shaped fuselage having a front end and a rear end. A front end portion  12  of a typical aircraft fuselage  10 , which is disposed towards the front end  11 , is shown in  FIG. 1  of the accompanying drawings, by way of example. Said fuselage  10  defines a longitudinal aircraft axis indicated by the chain-dot-line A-A in  FIG. 1  between the front and rear ends, and the fuselage  10  tapers towards the front end  11  to form a nose portion  15 . 
         [0128]    The fuselage  10  accommodates many of the functions and facilities of the aircraft, including one or more passenger accommodation cabins  20 ,  21 . The number and size of the passenger cabins  20 ,  21  provided on a given aircraft depends on the space available within the fuselage for passenger accommodation and on the desired configuration of the passenger accommodation. The present invention is not limited to the use of any particular shape, size or number of passenger cabins. However, in  FIG. 1 , which is given by way of example only, two cabins  20 ,  21  are shown in the front portion of the fuselage  12 , a first cabin  20  being located within the nose portion  15  of the aircraft, and a second cabin  21  being disposed behind the first cabin  20 , with a utilities area  22  being provided between the two cabins  20 ,  21 . Said utilities area  22  may include a galley  23  and one or more passenger toilets  24  as shown in  FIG. 1 . 
         [0129]    As shown in  FIG. 1 , an aircraft passenger cabin  20 ,  21  is generally defined by two opposing surface portions  26 ,  28  of the interior surface of the fuselage  10 . Said opposing surface portions  26 ,  28 , in effect, constitute opposing side walls of the cabin  20 ,  21 . The cabin  20 ,  21  also comprises a floor or deck  30  which is supported by suitable infra-structure (not shown) within the fuselage and a ceiling (also not shown) that extends between the opposing side walls above the floor  30 . Said opposing side walls  26 ,  28  are usually lined with a plurality of pre-fabricated, composite panels to give the interior of the cabin attractive appearance and to provide thermal insulation between the cabin  20 ,  21  and the outside of the aircraft. 
         [0130]    Embedded within the floor  30 , the infra-structure of the fuselage  10  comprises a plurality of pairs of seat tracks  32 ,  34  of the kind well known to those skilled in the art and indicated in  FIG. 1  by dotted lines. Each seat track pair is substantially linear and comprises a pair of substantially parallel tracks for fixedly securing to the aircraft infra-structure a plurality of seats or other fixtures. Generally, an aircraft passenger cabin  20 ,  21  comprises two outer pairs of seat tracks  32 , each being disposed adjacent a respective one of the two opposing cabin side walls  26 ,  28 . Where space permits, a cabin  20 ,  21  may also include one or more central pairs of seat tracks  34  disposed intermediate the outer seat track pairs  32 . As shown in  FIG. 1 , the first cabin  20  comprises a single central pair of seat tracks  34 , whilst the second cabin  21  comprises two juxtaposed central pairs of seat tracks  34 . Typically, a central seat track pair  34  extends substantially parallely to the longitudinal aircraft axis A-A. Where a passenger cabin  21  is positioned towards a central portion of the fuselage  10 , away from the front and rear ends of the aircraft, such, for example, as the second cabin  21  in  FIG. 1 , the opposing side walls  26 ,  28  of the cabin  21  extend substantially parallely to the longitudinal axis A-A of the aircraft, and the outer seat track pairs  32  follow the line of the side walls  26 ,  28  and thus also extend substantially parallely to the longitudinal aircraft axis A-A. However, towards the nose portion  15  of the aircraft, the opposing side walls  26 ,  28  are arcuate and converge towards the front end  11 . Accordingly, in such cases, the outer seat track pairs  32  are angled with respect to the longitudinal aircraft axis A-A to subtend an acute angle therewith. 
         [0131]    Each cabin  20 ,  21  accommodates a plurality of seat units  40 . As shown in  FIG. 1 , within each cabin  20 ,  21  the seat units  40  are arranged to form a plurality of columns  29  as described in more detail below. Each column  29  is fixedly secured to a respective pair of seat tracks  32 ,  34  and extends substantially parallely thereto to define a notional column axis indicated by the lines B-B in  FIG. 1 . As shown in  FIG. 1 , the first cabin  20  comprises two columns  29  of seat units  40 , each of said columns  29  being fixedly secured to a respective one of the outer pairs of seat tracks  32 . As the outer pairs of seat tracks  29  in the first cabin  20  are inclined with respective to the longitudinal axis A-A of the aircraft, the notional column axis B-B of each of the columns  29  of seat units  40  in the first cabin also subtends an acute angle with the longitudinal aircraft axis A-A. The second cabin  21  comprises two outer columns  29  of seat units  40  and two mutually juxtaposed central columns  29  of seat units  40 . Each of the outer columns  29  is attached to a respective one of the outer pairs of seat tracks  32 , and each of the central columns  29  is attached to a respective one of central pairs of seat tracks  34 . As described above, the central pair of seat tracks  34  extends substantially parallely to the longitudinal aircraft axis A-A, and accordingly each of the central columns  29  of seat units  40  also extends substantially parallely to the longitudinal aircraft axis A-A. In the second cabin  21 , each of the outer pairs of seat tracks  32  also extends substantially parallely to the longitudinal aircraft axis A-A, and accordingly each of the outer columns  29  of the second cabin  21  extends substantially parallely to the aircraft axis A-A. 
         [0132]      FIGS. 1A and 2  show three adjacent seat units  40  forming part of one of the columns  29  of  FIG. 1 . Each seat unit  40  comprises supporting structure  42  for attaching the seat unit to the floor  30 . Said supporting structure  42  may be fabricated in any suitable manner known to those skilled in the art, but preferably comprises a load-bearing, aerospace grade steel sub-frame (not shown), clad with one or more shaped composite panels. Each seat unit  40  has a front end  51 , a rear end  52  and two opposing sides  53 ,  54 . Juxtaposed the rear end  52 , the supporting structure  42  comprises a seat housing  43  as shown in  FIG. 2A  which defines a substantially cuboidal recess  44 . To the rear of said recess  44 , the supporting structure  42  defines a first, substantially flat, generally triangular surface  47  which, when the seat unit  40  is installed in a cabin  20 ,  21 , extends generally parallely to the floor  30  of the cabin  20 ,  21 , but at a slight incline thereto, as described in more detail below. Juxtaposed a first side  53  of the seat unit  40 , the supporting structure  42  defines a second substantially flats generally triangular surface  48  which is substantially co-planar with the first surface  47  and, in some embodiments, as shown in  FIGS. 2 and 2A , may be substantially contiguous with the first surface  47 . Each of said first and second surfaces  47 ,  48  is sufficiently strong to support at least part of the weight of a passenger. Said second surface  48  has a first concave lateral edge  45  which extends from a front end of the seat housing  43  outwardly and rearwardly to a point  46  intermediate the front end of the housing  43  and the rear end  52  of the seat unit  40 . Said first and second surfaces  47 ,  48  define a substantially linear second lateral edge  49  which extends rearwardly and inwardly from said point  46  to the rear end  52  of the seat unit. Said first and second surfaces  47 ,  48  thus extend to the rear and one side of the cuboidal recess  44  and define the upper extent of said recess  44 . Said first and second surfaces  47 ,  48  are supported at a predetermined height off the floor  30  of the cabin  20 ,  21  by the supporting structure  42 . 
         [0133]    At the second side  54  of the seat unit  40 , the seat housing  43  comprises an upstanding arcuate screen  60  having a convex rear portion  61  which extends from the rear end  52  of the seat unit  40  to a rear end of the cuboidal recess  44  and a generally linear front portion  62  which extends between the front and rear ends of the recess  44 . Said rear convex portion  61  has a curvature in plan view as shown in  FIG. 1A  which corresponds to the curvature of the first concave lateral edge  45  of the second surface  48 . Said screen  60  extends substantially higher than the first and second surfaces  47 ,  48  and serves as a privacy screen for a passenger using the seat unit  40 , around the rear end  52  and second side  54  of the seat unit  40 . 
         [0134]    Juxtaposed the front end  51  of the seat unit  40 , the supporting structure  42  comprises an ottoman which extends upwardly from the floor  30  and has a substantially flat upper surface  66 . Said upper surface  66  is adapted to carry a cushion  67  having a thickness such that the cushion  67  is disposed substantially co-planarly with the first and second surfaces  47 ,  48 . Said ottoman  65  is sufficiently strong to support the weight of a passenger such that the ottoman  67  can be used as an auxiliary seat if desired. Said supporting structure  42  further comprises a relatively small, auxiliary privacy screen  68  around the front end  51  of the seat unit  40 . 
         [0135]    Said cuboidal recess  44  receives a plurality of moveable passenger-bearing elements which are connected to the supporting structure by a seat movement mechanism described in more detail below. Said moveable passenger-bearing elements comprise a seat-pan  71  and a back-rest  72 . The seat movement mechanism allows the passenger-bearing elements to be selectively configured to provide a seat for a passenger, as shown in the centre and right-hand seat units  40  of  FIG. 2 , or a bed as shown in the left-hand seat unit  40  of  FIG. 2 . In the seat configuration, the moveable passenger-bearing elements  71 ,  72  are selectively movable between an upright or dining position as shown in the right-hand seat unit  40  of  FIG. 2  and a reclined or lounge position as shown in the centre seat unit  40  of  FIG. 2 . 
         [0136]    Said moveable passenger-bearing elements  71 ,  72  are attached to the supporting structure  42  through the seat movement mechanism such that, in the seat configuration, the seat-pan  71  is accommodated within the cuboidal recess  44  of the housing  43 , and the back-rest  72  extends upwardly from the recess  44  to the rear of the seat-pan  71  and extends transversely between the first and second sides  53 ,  54  of the seat unit  40 . As perceived by a passenger using the seat unit  40 , therefore, the seat unit  40  defines a notional longitudinal seat axis which extends between the front and rear ends  51 ,  52  of the seat unit  40  and is indicated in  FIG. 1A  by the dashed line C-C. 
         [0137]    In the fully upright position, the seat-pan  71  is disposed substantially at the same level as the first and second surfaces  47 ,  48  of the housing  43  and is spaced rearwardly of the ottoman  65 , such that the cushion  67  provides a foot-rest for a passenger using the seat unit  40 . In the reclined position, the back-rest  72  is reclined rearwardly relative to its position in the upright position, and the seat-pan  71  is tilted slightly rearwardly to provide an ergonomically comfortable lounge seating position. Again, in the lounge position, the cushion  67  of the ottoman  65  provides a foot-rest for the passenger. 
         [0138]    Said back-rest  72  comprises a front surface  73  and a rear surface  74 . In the upright and reclined positions the front surface  73  of the back-rest cooperates with the seat-pan  71  to form the seat for the passenger. In the bed configuration, as shown in the left-hand seat unit of  FIG. 2  the back-rest is rocked forwardly relative to the seat unit and is partly accommodated within the cuboidal recess  44  such that the rear surface  74  of the back-rest  72  is substantially co-planar with the first and second surfaces  47 ,  48  and with the cushion  67  of the ottoman  65 . The rear surface  74  of the back-rest  72  is also substantially continuous with the second surface  48  and cushion  67  in the bed configuration. The seat movement mechanism includes a moveable infill element  76 , as shown in  FIG. 1A , which is moved from a stowed position to a deployed position when the seat is converted from the seat configuration to the bed configuration. In the bed configuration, the infill element  76  is disposed intermediate and substantially co-planarly and contiguously with the rear surface  74  of the back-rest  72  and said first surface  74 . In the bed configuration, the seat unit  40  thus provides an extended bed surface for the passenger, the bed surface being extended rearwardly of the seat by the first surface  47 , laterally of the seat by the second surface  48  and forwardly of the seat by the cushion  67  of the ottoman  65 . 
         [0139]    With reference to  FIGS. 1 and 1A , the seat units  40  within each column  29  are attached to the respective pair of seat tracks  32 ,  34  such that the notional longitudinal seat axis C-C of each seat unit  40  subtends an acute angle with the notional longitudinal column axis B-B, and the seat units  40  are arranged side-by-side in longitudinally off-set relation to each other such that each seat unit  40  defines a generally triangular or trapezoidal space  36  to the rear of each seat  71 ,  72 . Said seat units  40  are arranged within the column  29  such that the convex portion  61  of the privacy screen  60  of one seat unit  40  abuts substantially contiguously on the first concave lateral edge  53  of another adjacent seat unit  40 . As best seen in  FIG. 1A , the space  36  to the rear of the seat  71 ,  72  of each seat unit  40  is thus occupied by the first surface  47  of one seat and the second surface  48  of the other adjacent seat, said first and second surfaces  47 ,  48  of the one and other seat units  40  respectively being divided from one another by the privacy screen  60  of the one seat unit  40 . The space  36  behind each seat  71 ,  72  is thus used to extend the length of the bed surface  47 ,  48 ,  67 ,  74 ,  76  provided by the seat unit  40  in the bed configuration rearwardly of the seat  71 ,  72  into said space  36 . 
         [0140]    The acute angle at which the seat units  40  within a column  29  are oriented relative to the notional column axis B-B depends on the desired cabin layout. However, typically, the acute angle subtended by the notional seat axis C-C of each is seat unit  40  and the column axis B-B is in the range of 30° to 60°, preferably 40° to 50°, for example about 40° as shown in  FIG. 1 . The seat units  40  may be oriented to face inwardly or outwardly with respect to the cabin  20 ,  21 . In the first cabin  20  of  FIG. 1 , it can be seen that each of the outer columns  29  is disposed adjacent a respective of one of the opposing side walls  26 ,  28 , and the seat units  40  within each column  29  face inwardly. The second lateral edges  49  of the seat units  40  in each column  29  are substantially co-linear to form an elongate column outer edge which extends juxtaposed the side wall  26 ,  28  of the cabin  20 . As a result of the curvature of the side walls  26 ,  28  in the first cabin  20 , there is a small gap  27  between the outer column edge and each side wall  26 ,  28 , and usually the gap  27  is filled using suitable infill panels of the kind well known to those skilled in the art. 
         [0141]    In the second cabin  21 , the seat units  40  of each outer column  29  also face inwardly and forwardly relative to the cabin  21 . It will be seen from  FIG. 1  that as the side walls  26 ,  28  of the second cabin  21  are substantially less curved than the side walls  26 ,  28  of the first cabin  20 , the second edges  49  of the seat units  40  are disposed closer to the sidewalls  26 ,  28  than in the first cabin  20  and thus there are no or substantially no gaps between the outer column edges of the seat units and the opposing cabin side walls  26 ,  28 . The seat units  40  of the two central columns  29  of the second cabin  21  also face forwardly, but are oriented to face outwardly with respect to the cabin  21 . The two central columns  29  are arranged back-to-back such that the second linear edge  49  of each seat unit  40  in one central column  29  is disposed substantially contiguous a corresponding second linear edge  49  of another seat unit  40  in the other central column  29 . As with the columns  29  of the first cabin  20 , however, the seat units  40  of the columns  29  of the second cabin  21  are arranged such that to the rear of each seat  71 ,  72 , the seat unit  40  defines a generally triangular or trapezoidal space  36  which is occupied by the first surface  47  of one seat unit  40  and the second surface  48  of another adjacent seat unit  40 . 
         [0142]    A privacy screen may be provided between the two central columns  29  said screen may comprise a movable portion member intermediate each pair of corresponding seats  40  in the two central columns  29 , said position member being selectively movable automatically between a deployed position, in which said position member effectively forms a privacy shield between the two seats  40  of the pair, and a stowed and retracted position, in which the position member is removed, such that passengers using the two corresponding seats do not have any boundaries between them in either the bed mode or the seat mode. 
         [0143]    It has been found that the seating system in accordance with the present invention allows each seat unit  40 , in the bed configuration, to provide a bed surface for a passenger having a length of at least 80 inches (2.032 metres) with a pitch between adjacent seat units  40  within each column  29  of 50 to 60 Inches (1.27 to 1.52 metres). In some cases, it is possible to provide an overall bed length in the bed configuration in excess of 85 inches (2.16 metres) with such a pitch. 
         [0144]    It will be appreciated that when the movable passenger-bearing elements  71 ,  72  of a seat unit  40  in accordance with the present invention are disposed in a dining or lounge seat configuration as shown in  FIG. 2 , the space  36  to the rear of the seat  71 ,  72  is concealed by the upright or reclined back-rest  72 . The space  36  thus provides a useful storage space which, in particular, can be used for storing bedding materials such as pillows, blankets, duvets and the like when the seat unit  40  is being used as a seat. Such bedding materials can be stored within the space  36  behind the seat  71 ,  72  such that the bedding materials are supported by the first surface  47  to the rear of the seat  71 ,  72 . When a passenger wishes to go to sleep, the moveable passenger-bearing elements  71 ,  72 ,  76  can be selectively moved to the bed configuration as shown in  FIG. 2 , thus exposing the space  36  to the rear of the seat  71 ,  72  allowing easy access to bedding materials stowed therein. With the moveable seat elements  71 ,  72 ,  76  in the bed configuration, the extended bed surface provided by the seat unit  40  can be manually made-up with the bedding materials by a passenger or flight attendant to provide a fully made bed for the passenger. 
         [0145]    In the seat configuration, a first passenger using the seat unit can sit on the seat formed by the seat-pan  71  and back-rest  72 , and a second passenger who might wish to visit the first passenger can sit on the auxiliary seat provided by the ottoman  65 . 
         [0146]    As shown in  FIG. 1A , the second surface  48  of the seat unit  40  carries a hinged arm rest  75  which is hinged to the supporting structure  42  for swinging movement in the plane of the second surface  48  between a stowed position as shown in  FIG. 1A  in which the arm rest  75  extends substantially parallely to the second linear edge  49  and a deployed position (not shown) in which the arm rest  75  extends substantially parallely to the notional seat axis C-C between the front and rear ends of the cuboidal recess  44  juxtaposed the seat formed by the seat-pan  71  and back-rest  72 , so that a passenger using the seat may rest one of his or her arms on the arm rest  75 . Alternatively, the arm rest  75  may be stored within a recess (not shown) formed in said surface  48  and means may be provided for translationally moving the arm-rest vertically between a stored position, in which said arm rest is accommodated within said recess, flush with said head surface  48 , and a deployed position in which said arm-rest protrudes from the recess to provide an arm rest for an occupant of the seat. This alternative has the advantage that in the stored position, the arm-rest does not impinge on the available surface area provided by the head surface  48 . Another fixed arm rest (not shown) may be carried by the screen  60 . 
         [0147]    The seating system in accordance with the present invention thus comprises a plurality of self-contained seat units  40  which each provide individual seating and sleeping accommodation for a passenger. Within each column  29 , it will be seen that the screen  60  to the second side  54  of one seat unit  40  and the screen  60  of another adjacent seat unit  40  disposed juxtaposed the first side  53  of the one seat unit  40  define a partially enclosed, private space for a passenger using the one seat unit  40 . 
         [0148]    Each seat unit  40  in accordance with the present invention comprises a seat housing  43  and an ottoman  65 , which ottoman  65  is spaced forwardly of the seat housing  43 . However, the seat units  40  of the present invention as described above may be conveniently manufactured by integrating the seat housing  43  of one seat unit  40  with the ottoman  65  of another adjacent seat unit  40 . Thus, the supporting structure  42  forming the seat housing  43  of the one seat unit  40  may be integral with the supporting structure  42  forming the ottoman  65  of the other adjacent seat unit  40 . Thus, the seating system in accordance with the present invention may be constituted by a plurality of seat modules  80  as shown in  FIG. 1A , each module  80  comprising the seat housing  43  and moveable seat elements  71 ,  72 ,  76  of one seat unit  40  and the ottoman  65  of another adjacent seat unit  40 . By attaching a plurality of said seat modules  80  to a pair of seat tracks  32 ,  34  in a cabin  20 ,  21 , a plurality of seat units  40  can be assembled, each unit  40  comprising the seat housing  43  of one module and the ottoman  65  of another adjacent module  80 . 
         [0149]    Each seat module  80  is attached to a seat track pair  32 ,  34  at three points as shown in  FIGS. 1 and 1A . In particular, each seat module  80  is attached to one seat track of the pair  32 ,  34  at two spaced points  38  and to the other seat track of the pair  32 ,  34  at a single point  39 . Each seat module  80 , may be attached directly to the seat track pair  32 ,  34  or, alternatively, the supporting structure  42  of each module  80  may comprise a plinth or palette (not shown), which plinth or palette is attached to the seat tracks  32 ,  34 . In either case, the supporting structure  42  or plinth or palette is attached to the seat tracks  32 ,  34  using foot fixings of the kind well known to those skilled in the art. The use of a three-point fixing  38 ,  39  for attaching a seat module  80  to a seat track pair  32 ,  34  has been found to be advantageous over a conventional four-point fixing. In particular, it has been found that a three-point fixing allows a greater degree of flexibility between the two seat tracks of a pair  32 ,  34 , thus allowing the two seat tracks to move or flex relative to one another in the event of an emergency landing or crash with a reduced risk of the seat modules  80  becoming detached from the seat tracks  32 ,  34 . 
         [0150]    The configuration of each seat unit  40 , and the arrangement of the seat units  40  within a cabin in accordance with the present invention, allows the occupant of each seat unit  40  easily to gain access to the seat unit  40  from the aisle and vice versa. 
         [0151]    A first passenger seat assembly in accordance with the present invention is shown in  FIGS. 3 to 5 . Said first passenger seat assembly can suitably be used to form a seat unit  40  of the seating system described above with reference to  FIGS. 1 ,  1 A,  2  and  2 A. However, those skilled in the art will appreciate that the seating system in accordance with the present invention is not limited to the use of the seat assembly of  FIGS. 3 to 5 . Generally the seating system described above can comprise any seat unit  40  which defines a notional, longitudinal seat axis C-C and comprises a supporting structure  42  for supporting the seat unit off the floor  30  of a vehicle, means  71 ,  72  forming or being configurable for forming a seat comprising a seat-pan  71  and a back-rest  72  and means  47 ,  48 ,  67 ,  74 ,  76 , forming or being configurable for forming a substantially flat bed, a major proportion of which bed is disposed forwardly of the position of the seat, which bed extends rearwardly behind the seat for extending the flat bed. 
         [0152]    In  FIGS. 3 to 5 , parts of the first passenger seat assembly which correspond to parts of the seat unit  40  of  FIGS. 1 ,  1 A,  2  and  2 A are indicated by the same reference numerals, with the addition of a preceding numeral “1”. 
         [0153]    The first passenger seat assembly  140  in accordance with the present invention has a front end  151 , a rear end  152  and two opposing sides  153 ,  154 . The seat assembly  140  comprises a supporting structure  142  for fixedly securing the seat assembly  140  to seat tracks embedded in the floor  130  of a vehicle and for supporting the seat assembly  140  off the floor  130 . Any suitable foot fixings of the kind known to those skilled in the art can be used for securing the supporting structure  142  to a pair of seat tracks. Whilst the first passenger seat assembly  140  of  FIGS. 3 to 5  is particularly suitable for use on a passenger aircraft, it can also be suitably used on other forms of passenger vehicles such, for example, as trains, coaches and water-borne craft, including passenger ships and ferries and hovercraft. 
         [0154]    Said supporting structure  142  comprises a seat housing  143  disposed generally towards the rear end  152  of the assembly  140  and an ottoman unit  165  disposed generally towards the front end  151  of the assembly  140 . Said seat housing  143  defines a generally rectilinear or cuboidal recess  144  which is open at its upper end  201  and front end  202  and closed at its rear end  203  by a substantially vertically extending rear wall  204  and at each side by two spaced opposing, substantially vertically extending side walls  205 ,  206 . In  FIGS. 3 to 5 , only one of the sidewalls  205  is visible. To the rear of the recess  144 , the seat housing  143  defines a substantially flat first upper surface  147 , and intermediate one side of the recess  144  and one side  153  of the assembly, the housing  143  further defines a substantially flat second upper surface  148  which is substantially coplanar, and may also be substantially continuous, with the first surface  147 . Said first and second upper surfaces  147 ,  148  are sufficiently strong to support at least part of the weight of a passenger using the seat assembly  140 . 
         [0155]    Said ottoman unit  165  is spaced forwardly of the seat housing  143  and has a substantially flat upper surface  166  which carries a cushion  167  having a flat upper surface  169  which is substantially coplanar with the first and second upper surfaces  147 ,  148  of the seat housing  143 . Said ottoman unit  165  is also sufficiently strong to support the weight of a passenger and can be used as an auxiliary seat. 
         [0156]    Each of said side walls  205 ,  206  of the recess  144  carries a rotary bearing  222 . Said rotary bearings  222  are aligned with one another to define a transverse axis which extends transversely across said recess  144  generally parallely to the floor surface  130 , but at a slight incline thereto as described in more detail below. Said rotary bearings  222  are disposed at a height above the floor surface  130  approximately mid-way between the floor surface  130  and the first and second upper surfaces  147 ,  148 . Said rotary bearings  222  are also positioned generally rearwardly within the recess  144  towards the rear wall  204 . Each of said rotary bearings  222  receives a respective, laterally-extending trunnion  221  of a seat movement mechanism  220  as shown in  FIGS. 6 to 8  in which the supporting structure  142  is omitted for clarity. 
         [0157]    Each trunnion  221  is attached generally centrally to a substantially flat, outwardly-facing surface  226  of a respective, generally lenticular rocker plate  223 . Each rocker plate  223  has a substantially linear first edge  224  and an opposing arcuate second edge  225 .  FIGS. 9 to 11  comprise detailed views of the rocker plates  223 . Each rocker plate has an upper end  228  and lower end  229 , and the two rocker plates  223  are fastened together by means of a generally cylindrical, transversely extending first torque tube  230  having two opposing ends  231 ,  232 . Each end  231 ,  231  of the torque tube  230  is connected to an inner face  227  of a respective one of the rocker plates  223  juxtaposed the lower end  229 . The first torque tube  230  thus serves to unite the two rocker plates  223  which define a recess  235  intermediate their respective opposing inner faces  227 . The united rocker plates  223  are thus capable of rocking movement relative to the seat housing  143  about the trunnions  221  connected to the rotary bearings  222 . 
         [0158]    The arcuate edge  225  of each rocker plate  223  is pivotably connected towards its lower end  229  to one end  242  of a link  241  through a suitable pin joint. The other end  243  of the link  241  is pivotably connected to one end  244  of a rocker arm  245 . As shown in  FIGS. 14 and 15 , the other end  246  of the rocker arm  245  is fixedly secured juxtaposed a respective end  251 ,  252  of a second rotatable torque tube  250 . At one end  251 , the second torque tube  250  is rotatably supported within a hollow worm-gear casing  260 . At the other end  252 , the second torque tube  250  is rotatably mounted in a bearing  253  supported by the second side wall  206  of the recess  144 . 
         [0159]    Said worm-gear casing  260  has a substantially flat bottom surface  261  and defines a generally cylindrical interior cavity  262  which accommodates the bearing for the one end  251  of the second torque tube  250 . Said one end  251  of the second torque tube  250  is fixedly secured coaxially to a worm-gear  271  which is accommodated within said cavity  262 . The casing  260  has an upper wall  263  which is partially cut-away as shown at  264  to expose the teeth of the worm-gear  271 . Said casing  260  is fixedly secured to the supporting structure  142  of the first seat assembly  140  within a recess (not shown) within the first side wall  205 , beneath the second upper surface  148  at the rear of said recess  144 , juxtaposed the rear wall  204 . 
         [0160]    The upper wall  263  of said casing  260  is formed with a generally upwardly extending lug  265 , and a generally cylindrical worm-screw housing  273  is hinged to said lug  265  for movement between an engaged position as shown in  FIG. 14  and disengaged position as shown in  FIG. 15 . Said worm-screw housing  273  is shaped such that in the engaged position, the housing  273  mates with the upper wall  263  of the worm-gear casing  260 . As shown in  FIG. 15 , the worm-screw housing  273  is cut-away as shown at  274  to allow the teeth of the worm-gear  271  to extend into the interior of the worm-screw housing  273 . As shown in  FIG. 16 , the worm-screw housing  273  accommodates a worm-screw  270  which is rotatably mounted between two opposing thrust-bearings  272 . Said worm-screw  270  is rotatably coupled via a coaxial spindle  275  to an electric motor  280  having a motor housing  281  which is fixedly secured to the worm-screw housing  273 . As shown in  FIG. 16 , the motor housing  281  is connected to the worm-gear casing  260  through two links  282 ,  283  which form a “break-link” device. One of said links  282  is pivoted to the motor housing  281  at one end  284  and to a first end of the other link  283  at the other end  285 . A second end  286  of said other link  283  is pivoted to the worm-gear casing  260 . Said one link  282  is substantially larger than the other link  283  and, in the engaged position, the three pivot points  284 ,  285 ,  286  are co-linear such that the pivot point between the second end of the other link  283  and the worm gear casing  260  is disposed intermediate the pivot point  284  of the one link  282  to the motor housing  281  and the pivot point  285  between the two links  282 ,  285 , such that the worm-screw housing  273  is prevented from disengaging the worm-gear casing  260 . Said one link  282  can be selectively rotated clockwise as shown in  FIG. 16 , causing the other link  283  also to rotate clockwise, “breaking” the alignment of the three pivot points  284 ,  285 ,  286 . The worm-screw  273  can then disengage from the worm-gear, allowing the rocker arms  245  to rotate freely about the axis defined by said second torque tube  250 , the links  282 ,  283  serving to limit the extent to which the worm-screw housing  273  can be disengaged from the worm-screw casing  260 . Alternatively, instead of the break-link device, the worm-screw housing  273  could be releasably secured to the worm-gear casing  260  by means of a removable bolt, for example. 
         [0161]    As shown in  FIG. 9 , the inner face  227  of each rocker plate  223  is fabricated with an elongate, substantially linear recess  301  which is substantially rectilinear in cross-section and extends substantially parallely to said first edge  224  from a lower end  302  juxtaposed the lower end  229  of the rocker plate  223  to an upper end  303  at a point intermediate said upper and lower ends  228 ,  229  of the plate  223 . As shown in  FIGS. 3 to 5 , said elongate recess  301  accommodates a linear screw  304  having upper and lower ends  305 ,  306  as shown in  FIG. 13 . In some embodiments, ball screws or any other suitable, non-reversible linear actuator devices may be used instead of the two linear screws. At its upper end  305 , each linear screw  304  is rotatably mounted in a bearing  307 , which is fixedly secured to the rocker plate  223  at the upper end  303  of the recess  301 . The lower end  306  of each linear screw  304  is accommodated within a gear casing  310  which is fixedly secured to the inner face  227  of the respective plate  223 . (In  FIG. 13 , one of the gear casings  310  is omitted to reveal the detail at the lower end  306  of the linear screw  304 ). Said lower end  306  is supported by a rotary bearing  308  within the gear casing  310  and is rotatably coupled through a bevel gear  311  to a respective end  313 ,  314  of a rotary drive shaft  312 . At one end  314 , the drive shaft  312  is connected through a pair of interengaging pinions  315 ,  316  to a stepper motor  318  that is mounted to the gear casing  310  such that operation of the motor  318  causes rotation of the shaft  312  and thus rotation of the linear screws  304 . 
         [0162]    Each linear screw  304  carries a nut  320  comprising a shaped body  321 . Said body  321  is generally T-shaped in cross section and comprises a substantially rectilinear slider portion  322  which is shaped to form a close, but free-sliding fit within the linear recess  301  formed in the inner face  227  of the respective rocker plate  223 . Said slider portion  322  accommodates the linear screw  304  therein and comprises internal formations (not shown) for engaging the screw  304 . Said body  321  further comprises a pair of opposing wing portions  324 , each of which has a substantially flat outer face  325 , the outer faces  325  of the two wing portions  324  being substantially co-planar to one another. The body  321  has a substantially flat inner face  326 . With the slider portion  322  inserted in the linear recess  301  of the respective rocker plate  223 , the outer faces  325  of the wing portions  324  lie closely adjacent the inner face  227  of the rocker plate  223 . 
         [0163]    With reference to  FIG. 6 , each of said nuts  320  is connected through a gimbal joint  329  to a respective lateral side edge  331 ,  332  of a structural diaphragm  330  forming part of a seat-pan element  171  which is disposed in the recess  235  intermediate the two opposing rocker plates  223 . Said diaphragm  330  may comprise a light-weight, moulded composite panel or a perforated aluminium sheet. Said seat-pan element  171  has a rear end  333  and a forward end  334 , said gimbal joints  329  being fitted to the diaphragm  330  towards said rear end  333  to allow the front end  334  of the seat-pan element  171  to be tilted upwards or downwards relative to the rear end  333  which moves less relative to the rocker plates  223 . Said seat-pan element  171  includes suitable cushioning and upholstery which is supported by the diaphragm  330  to provide a comfortable seating surface for a passenger using the seat assembly  140 . (The cushioning and upholstery is omitted in  FIGS. 6 to 8  for clarity). 
         [0164]    Juxtaposed the front end  334 , the diaphragm  330  is pivotably connected to an upper end  341  of a depending lever  342 . The other end  343  of the lever  342  is pivotably connected to a slider  345  which is slidably retained in an elongate, substantially linear slideway  350  that is fixedly secured to a respective one of the side walls  205 ,  206  of the seat housing  143  within said recess  144 . As best seen in  FIG. 3 , each slideway  350  is oriented at an angle relative to the floor surface  130  such that the slideway  350  extends forwardly and upwardly within the recess  144  between an upper end  351  and a lower end  352 . Said other end  343  of the lever  342  is also pivotably connected to a lower end  354  of a drag strut  355 , said drag strut  355  having an upper end  356  that is pivotably connected to the first linear edge  224  of the respective rocker plate  223  juxtaposed the lower end  229  of the rocker plate  223 . 
         [0165]    With reference to  FIG. 9 , the inner face  227  of each rocker plate  223  is also formed with an elongate arcuate track  360  which extends juxtaposed the second arcuate edge  225  between an upper end  361  juxtaposed the upper end  228  of the plate  223  and a lower end  362  juxtaposed the lower end  229  of the plate  223 . Intermediate the linear recess  301  and arcuate track  360 , the inner face  227  of each plate  223  is also formed with a short linear slot  365  which extends from an upper end  366  juxtaposed the upper end  361  of the track  360  to a lower end  367  juxtaposed the upper end  303  of the linear recess  301 . As best seen in  FIG. 3 , the linear slot  365  is angled with respect to the linear edge  224  of the plate  223  such that as the slot extends downwardly from the upper end  366  to the lower end  367 , it extends inwardly of the plate from the linear edge  224  towards the arcuate track  260 . It can also be seen that the arcuate track  360  and linear slot  365  diverge from one another from their respective upper ends  361 ,  366  towards their respective lower ends  362 ,  367 . 
         [0166]    The arcuate track  360  on each rocker plate  223  receives slidably two spaced friction blocks  371  that are fixedly secured to the outer surface  372  of a respective lower side member  373  of a lower back-rest element  374  as shown in  FIGS. 6A and 6B . Said lower back-rest element  374 , together with an upper back-rest element described in more detail below, forms a back-rest component  172 . Each lower side member  373  is generally L-shaped having an upper end  375 , a lower end  376  and a substantially linear rear edge  377 . At said lower end  376 , each lower side member  373  comprises an enlarged foot portion  378  having a forwardly protruding nose  379 . Each lower side member  373  has a substantially linear front edge  381  which extends between said upper end  375  and said enlarged foot portion  378  at a slight angle relative to the rear edge  377 . As shown in  FIGS. 6A and 6B , one of the friction blocks  371  on each lower side member  373  is mounted to said outer face  372  at the lower end  376  of the side member  373  at an angle of about 45° to the rear edge  377 . Said other friction block  371  is mounted to said outer face  372  juxtaposed said rear edge  377  at a point intermediate said upper and lower ends  375 ,  376 . The other friction block  371  also subtends an angle with the rear edge  377 , but that angle is less than the angle subtended by the one friction block  371  and the rear edge  377 . 
         [0167]    Intermediate the two lower side members  373 , the lower back-rest element  374  comprises a substantially flat diaphragm  385  which is spaced inwardly of both said front and rear edges  377 ,  381  to form rear and front lower recesses  386  and  387  respectively. Like the seat diaphragm  385  may comprise a moulded composite panel or a perforated metal sheet of the kind well-known in the manufacture of aircraft seats. 
         [0168]    The outer face  372  of each side member  373  is further formed with a generally rectilinear, shaped cavity  390  having a peripheral side wall  391 . Said cavity  390  is covered by a cover plate  380  (omitted in  FIGS. 6A and 6B  for clarity) which is fixedly secured to the outer face  372  of the side member  373 . Said cavity  390  accommodates a generally triangular rocker lever  392  having an upper limb  393  and a lower limb  395 . The rocker lever  392  is pivoted substantially centrally to the side member  373  at its obtuse apex  396 . The lower limb  395  is provided at its extremity with an outwardly directed pin  397 , and the upper limb  393  is formed at its extremity with a lug  398 . The rocker lever  392  is thus capable of rocking about said pivot  396  with corresponding rocking movement of the upper and lower limbs  393 ,  395 . Movement of the rocker lever  392  is limited by the side wall  391  of the cavity  390  such that the upper limb  393  can rock between one position as shown in  FIGS. 6A and 6B  in which the lug  398  is disposed fully forwardly and another position (not shown) in which the upper arm  393  is disposed fully rearwardly. 
         [0169]    The pin  397  on the lower limb  395  is slidably received in the linear slot  365  formed in the inner face  227  of the respective rocker plate  223 . As best seen in  FIG. 3 , the lower back-rest element  374  extends upwardly of the rear end  333  of the seat-pan element  171  and is pivoted at its upper end  375  to said upper back-rest element  394 . Said upper back-rest element  394  comprises two spaced upper side members  402  and a substantially flat upper diaphragm  403  which extends between said upper side members  402 . Each of said upper side members  402  has a substantially linear rear edge  404  and a substantially linear front edge  405 , and said upper diaphragm  403  is spaced inwardly of both said rear and front edges  404 ,  405  to define front and rear upper recess  406  and  407  respectively. The lower and upper front recesses  387 ,  407  accommodate cushioning that is specifically designed to form a comfortable back-rest surface which, in conjunction with the cushioning on the seat-pan element  171 , forms a dedicated seat surface for a passenger. The back-rest cushioning is upholstered to match the upholstering on the cushioning on the seat-pan element  171 . The cushioning and upholstery of the upper and lower back-rest elements have been omitted in  FIGS. 6 ,  6 A,  6 B,  7  and  8  for clarity. The upper and lower rear recesses  386 ,  406  define a substantially continuous recess which receives a substantially flat cushion or mattress suitable for forming a bed surface. Again this is omitted in  FIGS. 6 ,  6 A,  6 B,  7  and  8  for clarity. In particular, however, the back-rest cushioning provided in the upper and lower front recesses  387 ,  407  may have a different style or colour of upholstery from the rear cushion or mattress. Furthermore, the cushioning provided on the front and rear surfaces respectively of the back-rest component may have different degrees of resilience as appropriate for seating and bedding purposes. 
         [0170]    Each of said upper side members  402  has an upper end  409  and a lower end  411 . Each upper side member  402  is pivotably connected to the upper end  375  of the respective lower side member  373  at  410  intermediate said upper and lower ends  409 ,  411 , such that each upper side member  402  extends downwardly from the pivot point  410  to form a leg portion  412  having a generally U-shaped cut-out  414  at said lower end  411 . Said U-shaped cut-out  414  slidably accommodates the lug  398  formed on the upper limb  393  of the respective rocker lever  392  for transmitting rocking movement of said arm  392  to the upper side member  402 . Thus, rocking movement of the rocker lever  392  about its central pivot point  396  causes corresponding rocking movement of the upper back-rest element  394  about the pivot point  410  between the upper and lower back-rest elements. 
         [0171]    With reference to  FIG. 3 , the nose  379  of each lower side member  373  is connected through a lost motion device  420  to one of the wing portions  325  on the nut  320  mounted on the linear screw  304  of the respective rocker plate  223 . Each lost motion device  420  comprises a pin attached to the respective wing portion  325  at  328 , which pin is received in a short slot formed in the nose  379  of the lower side member  373 . 
         [0172]    With reference to  FIGS. 9 to 12 , the arcuate edge  225  of each rocker plate  223  is formed towards the upper end  228  with a protruding lug  431  which is pivotably connected to one end  433  of an arm member  432  which arm member  432  terminates remote from the lug  431  in another end  434 . The two arm members  432  carry a transverse infill diaphragm member  440  which carries a generally rectilinear in-fill cushion  442  having an upper surface  443 . 
         [0173]    Juxtaposed the lug  431 , the outer face  226  of each rocker arm  223  carries a small dog-leg member  450  which is pivoted to the rocker plate  223  at  451  between the lug  431  and the lower end  229  of the plate  223 . Said dog-leg member  450  has a first limb  452  provided with a hook  453  at its extremity and a second limb  454  provided with a cam follower  455 . Each arm member  432  has an outwardly extending holding pin  456 , and the outer surface  226  of each rocker plate  223  is formed with an outwardly extending stop pin  457  which is positioned between the pivot point  451  and the arcuate edge  225  of the plate  223 . The dog-leg member  450  is freely rotatable about the pivot  451 , and the stop pin  457  serves to limit clockwise rotation of the dog-leg member  450  of the plate  223  as shown in  FIGS. 9 to 12 . (The stop pin on the other rocker plate  223  limits counter-clockwise movement of the corresponding dog-leg member  450 ). 
         [0174]    The cam follower  455  on the second limb  454  of the dog-leg member  450  engages a cam  460  (see  FIGS. 8 and 12 ) formed on the respective sidewall  205 ,  206  of the recess  144  for controlling movement of the dog-leg member  450 . 
         [0175]    As shown in  FIG. 3 , the first seat assembly  140  as hereinbefore described can be arranged in a upright seat configuration in which the rocker arms  245  extend forwardly relative to the rotary shaft  50  within the recess  144  and the links  241  are substantially co-linear with the rocker arms  245  such that the united rocker plates  223  are oriented in a seat configuration as shown in  FIGS. 3 ,  4 ,  6 ,  7 , and  10  in which the linear edge  224  of each rocker plate  223  extends upwardly and rearwardly within the recess  144 , with the arcuate tracks  360  on the two rocker plates  223  extending generally downwardly and forwardly within the recess  144 . As the links  241  and rocker arms subtend an angle of 180° to form a compression strut in the seat position, any loads applied to the rocker plates  223  are applied lineally to the second torque tube  250  and no rotational force is applied to the worm-gear  271 . Advantageously, the seat conversion sub-mechanism of the seat assembly is capable of withstanding large forward forces, without the need for any additional disengageable mechanical coupling, such as a shoot-bolt, between the seat movement mechanism and the supporting structure. In the upright seating configuration, the nuts  320  are disposed at the upper ends  305  of their respective linear screws  304  as shown in  FIG. 13 , and the lower ends  343  of the levers  342  are disposed at the upper ends of the slideways  350  such that the seat-pan element  171  is disposed substantially horizontally within the recess  144 , with the upper surface of the seat-pan cushioning at approximately the same level as the first and second upper surfaces  147 ,  148  on the seat housing  142  and the upper surface  169  of the cushion  167  on the ottoman  165 . The friction blocks  371  on the lower side members  373  of the lower back-rest element  374  are disposed at the upper ends  361  of the arcuate tracks  360  on the rocker plates  223 , and the pins  397  on the rocker levers  392  are disposed at the upper ends  366  of the linear slots  365  on the rocker plates  223 . Accordingly, the upper limbs  393  of the rocker levers  392  are disposed fully forwardly within their respective cavities  390 , such that the upper back-rest element  394  is substantially co-linear with the lower back element  373 . 
         [0176]    In the upright position of  FIG. 3 , the dog-leg members  450  on the rocker plates  223  are disengaged from the respective cam members  460 , and the arm members  432  are disposed, as shown in  FIG. 10 , in a stowed position with the in-fill cushion  442  disposed generally beneath the first upper surface  147  of the seat housing  143 . In the upright position, the cushioning  408  on the upper and lower back-rest elements  373 ,  394  forms an ergonomically comfortable seat with the cushioning on the seat-pan element  171 . 
         [0177]    In the upright position, the seat defined by the seat-pan element  171  and back-rest element  172  is generally suitable for dining. The ottoman unit  165  is spaced forwardly of the seat-pan element  171  and may be used as a foot-rest for the passenger. 
         [0178]    From the upright position of  FIG. 3 , the seat assembly may be reclined to a fully reclined position as shown in  FIG. 4  as follows. Upon operation of the stepper motor  318 , the linear screws  304  on the rocker plates  223  are caused to rotate. As the nuts  320  are restrained from rotation with the linear screws  304 , the nuts are driven translationally along the linear screws  304  towards the lower ends  302  of the recesses  301  formed in the opposing inner faces  227  of the rocker plates  223 . As the nuts  320  are driven downwardly, the rear end  333  of the seat-pan element  171  is also driven downwardly relative to the front end  334  which is supported by the levers  342 . The rear end  333  of the seat-pan element  171  is thus driven downwardly causing the seat-pan element to tilt rearwardly about the pivot between the upper ends  341  of the levers  342  and the front end  334  of the seat-pan diaphragm  330 . As the linear screws  304  extend downwardly and forwardly within the recess  144 , the seat-pan element  171  is also driven forwardly, which forwards movement is accommodated by forward rocking of the levers  342  about the pivots between the lower ends  343  of the levers  342  and the sliders  354  in the respective slideways  350 . 
         [0179]    The front end  334  of the seat-pan element  171  therefore moves downwardly slightly in the recess  144 , but not to the same extent as the rear end  333  of the seat-pan element  171 . Movement of the sliders  354  rearwardly along the slideway  350  is prevented by the drags struts  355  between the sliders  354  and the rocker plates  223 . 
         [0180]    Forwards and downwards movement of the nuts  320  also causes corresponding movement of the back-rest element  172  which is connected to the nuts  320  through the lost motion devices  420  on the noses  379  of the lower back-rest elements  373 . Movement of the back-rest component  172  causes the friction blocks  371  to slide in their respective arcuate tracks  360  on the opposing inner faces  227  of the rocker plates  223  from the upper ends  361  of the tracks  360  towards the lower ends  362 . The relative orientation of the friction blocks  371  as described above and the curvature of the tracks  360  have the result that, as the friction blocks  371  slide along the tracks  360 , the lower back-rest element  373  is caused to rock rearwardly as shown in  FIG. 4  from the upright position of  FIG. 3  to a fully reclined position as shown in  FIG. 4 . 
         [0181]    Contemporaneously, the pins  397  on the rocker levers  392  are caused to slide along the linear slots  365  on the rocker plates  223 . As each linear slot  365  diverges from the corresponding arcuate track  360  on the same rocker plate  223 , the upper limb of each rocker lever  392  is caused to rock rearwardly in the respective cavity  390 . Rearwards movement of the upper limbs  393  of the rocker levers  392  causes the upper side members  402  of the upper back-rest element  394  to rock forwardly relative to the lower back-rest element  373 . As the back-rest component  172  is driven forwardly and downwardly by movement of the nuts  320 , the upper back-rest element  394  rocks progressively further forwards relative to the lower back-rest element  373  until the rocker levers  392  engage the side walls  391  of the respective cavities  390 , preventing further forwards rocking of the upper back-rest element  394 . The relative positions and profiles of the recesses  301 , tracks  360  and slots  365  formed on the two rocker plates  223  are carefully calculated to ensure that as the seat reclines from the upright position of  FIG. 3  towards the fully reclined position of  FIG. 4 , the seat-pan element  171  and upper and lower back-rest elements  374 ,  394  move through a plurality of predetermined, ergonomically comfortable positions. 
         [0182]    The stepper motor  318  can be controlled such that the nuts  320  can be stopped at any intermediate position between the upper and lower ends  305 ,  306  of the linear screws  304 . Thus, movement of the seat defined by the seat-pan element  171  and upper and lower back-rest elements  374 ,  394  can be halted in any intermediate position between the upright position of  FIG. 3  and fully reclined position of  FIG. 4 . The angle subtended by the upper and lower back-rest elements  374 ,  394  in a reclined position has the effect that the lower back-rest element  374  advantageously provides lumbar support for a passenger using the seat assembly  140 . 
         [0183]    The linear screws  304  are non-reversible linear actuator devices, and thus the seat assembly of the present invention has the added advantage that forces applied to the seat-pan element  171  or back-rest component  172  cannot be transmitted through the nuts  320  and linear screws  304  to the motor  318 . This has the advantage that sudden and/or strong forces applied to the moveable seat elements  171 ,  374 ,  394  are not “seen” by the stepper motor, thus reducing the risk of damage to the stepper motor  318 . 
         [0184]    A particular feature of the first seat assembly  140  as hereinbefore described is that it can be converted from the upright position of  FIG. 3  to a bed configuration as shown in  FIG. 5 . In order to convert the seat assembly  140  from the upright configuration to the bed configuration, the motor  280  is operated to cause rotation of the worm-screw  270 . With the worm-screw housing  273  in the engaged position on the worm-gear casing  260 , rotation of the worm-screw  270  causes corresponding rotation of the worm-gear  271  and thus rotation of the second torque tube  250 . Rotation of the torque tube  250  in turn causes rotation of the rocker arms  245  from a seat position as shown in  FIG. 15  to a bed position as shown in  FIG. 14 . 
         [0185]    With reference to  FIGS. 3 and 5 , rotation of the rocker arms  245  rearwardly causes the links  241  to rock the rocker plates  223  forwardly about the trunnions  221 . Rocking of the rocker plates  223  forwardly within the recess  144  causes the lower back-rest member  374  to rock forwardly about the trunnions  221 . The gimbal joints  329  between the seat-pan element  171  and the nuts  320  also rotate about the trunnions  222 , and rocking of the rocker plates  223  causes the drag struts  355  to pull the sliders  354  at the lower ends  343  of the levers  342  rearwardly and downwardly along the slideways  350  from the upper ends  351  of the slideways towards the lower ends  352 . The front and rear ends  334 ,  333 , of the seat-pan element  171  are thus caused to descend within the recess  144 , such that the back-rest component  172  rocks forwardly over the seat-pan element  171  as shown in  FIG. 5 . 
         [0186]    In the bed configuration of  FIG. 5 , the seat-pan element  171  is disposed in a lower stowed position within the recess  144 , and the cushioning or mattress in the lower and upper rear recesses  386 ,  406  of the back-rest component  172 , is disposed substantially co-planarly with the upper surfaces  147 ,  148  of the seat housing  143  and of the cushioning  167  on the ottoman unit  165 . It can also be seen from  FIG. 5  that the upper and lower back-rest elements  374 ,  394  are dimensioned such that in the bed configuration, the upper ends  409  of the upper side members  402  meet the ottoman unit  165  such that the cushioning or mattress on the rear surface of the backrest component  172  forms a substantially continuous surface with the cushion  167  on the ottoman unit  165  and with the second upper surface  148  on the seat housing  143 . Advantageously, the upper end  409  of the upper back-rest element  394  may engage a formation (not shown) on the ottoman unit  165 , such that in the bed configuration part of the load applied to the back-rest component  172  is borne in part by the ottoman unit. The engagement of the rocker levers  392  with the side walls  391  of their respective cavities on the lower side members  374  of the lower back-rest element  373  serves to lock the upper and lower back-rest elements  373 ,  394  together to prevent buckling of the back-rest component  172  under load in the bed configuration. 
         [0187]    Movement of the rocker plates  223  from the seat position to the bed position also raises the arm members  432  carrying the in-fill cushioning  443  within the recess  144 . In the seat position as shown in  FIG. 10 , the dog-leg members  450  are disengaged from the cams  460  formed on the side surfaces  205 ,  206  of the recess  144  and can pivot freely about the pivot points  451 . As mentioned above, however, movement of the dog-leg members  450  is limited by the stop pins  457 . 
         [0188]    As the rocker plates  223  are rocked forwardly towards the bed configuration of  FIG. 5 , the holding pins  456  on the arms  432  become trapped behind the hooks  453  on the first limbs  452  of the dog-leg members  450 . As the rocker plates  223  move towards the bed configuration, the cam followers  455  engage the cams  460 , thus locking the dog-leg members  450  in place, trapping the holding pins  456  behind the hooks  453 . 
         [0189]    As best seen in  FIG. 5 , the arm members  432 , cushioning members  442 , holding pins  456 , dog-leg members  450  and cams  460  are shaped and positioned such that, in the bed configuration, the upper surface  443  of the in-fill cushioning member  442  fills a space between the lower end  376  of the lower back-rest element  374  and the forward end of the first upper surface  147  of the seat housing  143 . The upper surface  443  of the in-fill cushioning member  442  is disposed substantially continuously and substantially co-planarly with the cushioning or mattress on the rear of the back-rest component  172  and the first upper surface  147  to form an extended, substantially flat bed surface. 
         [0190]    The supporting structure  142  of the seat assembly  140  is configured such that, in flight, with the floor surface  130  at an angle of about 1-3° to the horizontal, the bed surface provided by the seat assembly of the present invention is disposed substantially horizontally relative to Earth. In other words, the seat assembly  140  of the present invention compensates for the slight incline of the aircraft in flight. 
         [0191]    Advantageously, the worm-gear, worm-screw assembly  271 ,  270  is non-reversible, and so in the bed and seat configurations, the motor  280  does not “see” undue forces applied to the rocker plates  223 . In other words, undue or sudden forces applied to the rocker plates  223  are not transmitted through the worm-gear/worm-screw assembly to the motor  280 . 
         [0192]    The first passenger seat assembly  140  as hereinbefore described is equipped with user-operable controls mounted conveniently to the supporting structure  142 . Said controls comprise means for operating the stepper motor  318 , for selectively moving the seat-pan and back-rest moveable elements  171 ,  374 ,  394  between the upright position of  FIG. 3  and the fully reclined position of  FIG. 4 , and for operation of the motor  280  for converting the moveable elements  171 ,  374 ,  394  between the upright seat configuration of  FIG. 3  and the bed configuration of  FIG. 5  in which the moveable back-rest elements  374 ,  394  cooperate with the fixed auxiliary elements of the supporting structure  142 , i.e., the ottoman unit  165  and first and second upper surfaces  147 ,  148  of the seat housing  143  to form an extended, substantially flat bed for the passenger. Said controls comprise control circuitry for ensuring that if a passenger attempts to convert the seat assembly  140  from the seat configuration to the bed configuration when the seat is in a reclined or fully reclined position, the stepper motor  318  is first operated to return the moveable seat elements  171 ,  374 ,  394  to the fully upright position before the motor  280  is operated to convert the seat into the bed configuration. In the event of a failure of the motor  280  or of the aircraft cabin power supply, the seat assembly  140  can be returned to the upright position of  FIG. 3  by breaking the break-link device  282 ,  283  as described above and manually rocking the rocker arms  245  forwardly to the seat position of  FIG. 15   
         [0193]    The first passenger seat assembly  140  in accordance with the present invention as hereinbefore described thus provides self-contained, individual seating and sleeping accommodation for a passenger. 
         [0194]      FIG. 17  shows another seating system in accordance with the present invention comprising a plurality of first passenger seat assemblies  140  of the kind hereinbefore described with reference to  FIGS. 3 to 16 . In  FIG. 17 , an aircraft fuselage  510  encloses a passenger accommodation cabin  520  at a position rearwardly of a nose portion  515  of the fuselage  510 . As in the case of the seating system of  FIG. 1 , the accommodation cabin  520  of  FIG. 17  is defined by two opposing interior surface portions  526 ,  528  of the fuselage  510 , a floor surface or deck  530  supported within the fuselage  510  on suitable supporting infrastructure (not shown) and a ceiling (also not shown). The infrastructure includes a plurality of pairs of seat tracks  532 ,  534  which are embedded in the floor surface  530 . The cabin  520  of  FIG. 17  includes two outer pairs of seat tracks  532 , each extending juxtaposed a respective one of the opposing surface portions  526 ,  528  of the fuselage  510  and a single, central seat track pair  534 . Each of the seat track pairs  532 ,  534  extends substantially parallel to a longitudinal aircraft axis defined by the fuselage  510  and indicated in  FIG. 17  by the chain dot line A-A. 
         [0195]    The seat assemblies  140  are attached to the seat tracks  532 ,  534  to form a plurality of columns  529 . Each column  529  is fixedly secured to a respective one of the seat track pairs  532 ,  534  and defines a notional, longitudinal column axis indicated by lines B-B in  FIG. 17 . Each seat assembly  140  defines a notional, longitudinal seat axis, indicated by lines C-C in  FIG. 17 , which subtends an angle of about 49° to the notional column axis B-B. The seat assemblies  140  attached to the outer seat track pairs  532  face forwardly and inwardly within the cabin  520 . The seat assemblies  140  attached to the central pair of seat tracks  534  form two groups  537 ,  538 . A forward group  537  of seat assemblies  140  attached to the centre seat track pair  534  face forwardly and to one side of the cabin  520 , whilst a rear group  538  face forwardly and to the other side of the cabin  520 . 
         [0196]    As in  FIG. 1 , within each column  529 , the seat assemblies of  FIG. 17  are arranged side-by-side in a longitudinal off-set relation to one another so as to define a generally triangular or trapezoidal space  536  to the rear of each seat assembly  140 , behind the back-rest component  172  when the seat assembly  140  is in the seat configuration. As described above, each seat assembly  140  is self-contained, capable of providing an individual, extended flat bed having a length of at least 80″ (2.02 metres) for a passenger, and the arrangement of seat assemblies  140  in accordance the seating system of  FIG. 17  allows the seat assemblies  140  to be accommodated within the cabin  520  at a pitch of about 50 to 60″ (1.27-1.52 metres). Thus, a plurality of seat assemblies  140  in accordance with the present invention, each providing an individual bed of at least 80″ (2.032 metres) length, can be accommodated within a typical business class cabin of a passenger aircraft. 
         [0197]    The interior surface of an aircraft fuselage  510  is concave in vertical cross-section, and thus within the cabin  520  of  FIG. 17 , each of the opposing interior surface portions  526 ,  528  of the fuselage  510  defines a lateral recess at each side of the cabin  520 . Advantageously, this lateral recess is occupied by the first and second passenger-supporting auxiliary surfaces  147 ,  148  of each seat assembly  140  attached to one of the outer seat track pairs  532 . The first and second supporting surfaces  147 ,  148  form part of the extended flat bed surface provided by each seat assembly  140  in the bed configuration and, whilst the lateral recess has insufficient head room to accommodate the full height of the seat in an upright or reclined seating configuration, its use to accommodate part of the extended bed surface for which the headroom requirement is less represents an efficient use of the space available within the cabin. 
         [0198]    In accordance with the present invention, the upholstery used to dress the seat-pan element  171  and cushioning  408  provided on the back-rest elements  374 ,  394  of each seat assembly  140  may be selected such that when all or a majority of the seat assemblies  140  of the seating system of  FIG. 17  are arranged in a seating configuration, the cabin has a first particular appearance and/or ambience which is suitable for dining and/or lounging. The bedding materials provided for dressing the cushions provided in the lower and upper rear recesses  386 ,  406  on the back-rest component  172  may have patterns and/or colourways which are particularly appropriate for a sleeping environment. In particular, the style of the bedding materials may be selected such that when all or a majority of the seat assemblies  140  of the seating system of  FIG. 17  are in the bed configuration, the cabin  520  may have a different second appearance or ambience which is more “restful” than the first appearance and is more appropriate for a sleeping environment. 
         [0199]    With reference to  FIGS. 18 and 19  of the accompanying drawings, a passenger accommodation unit in accordance with another embodiment of the present invention comprises a shell assembly  610  that is assembled from two half-shells  610   a ,  610   b . The accommodation unit is adapted to be positioned in a passenger cabin of an aircraft in juxtaposition with at least one neighbouring seat  610 ′, and the two half-shells  610   a ,  610   b  are similar to one another such that each forms a part of two adjacent seats. Each half-shell  610   a ,  610   b  is manufactured as a single piece from a suitable aircraft-grade, light-weight structural material. 
         [0200]    The shell  610  of each accommodation unit comprises a curved, upright rear screen  612  and an opposing, upright, curved front screen  614  which are interconnected by a generally linear side wall  616  to form an enclosed passenger space  618 . 
         [0201]    Said shell  610  comprises a bottom edge  611  which defines a plane and is provided with a plurality of suitable fixings (not shown) for attaching the accommodation unit to the seat tracks in the aircraft cabin. In some embodiments the unit may be adequately secured to the seat tracks using three such fixings. 
         [0202]    Said shell  610  provides a suitable supporting structure for a seat  620  which comprises a seat-pan  622 , a back-rest  624  and a backrest extension  626  (see  FIGS. 20A-20C ). In particular, the shell  610  of the accommodation unit comprises an under-seat-pan  628  (see  FIG. 19 ) that is disposed adjacent to the rear screen  612  and has a generally flat, horizontal upper surface that serves to support the seat-pan  622 . Said seat-pan  622  is pivoted to the under-seat-pan  628  at its forward edge  623 , and the backrest, which normally rests in a generally upright position against the internal surface of the rear screen  612 , is pivoted at its lower end  625  to the rear end of the seat-pan. Said backrest extension  626  is permanently fixed to the internal surface of the rear screen  612  at a position above and substantially contiguous to the upper edge of the backrest  624  in its normal position as described above. 
         [0203]    Said enclosed passenger space  618  further comprises a pedestal  640  that is supported above the cabin floor on the shell  610  adjacent the front screen  614 . Optionally, said pedestal  640  may be height-adjustable in any convenient manner known to those skilled in the art. 
         [0204]    Behind the rear screen  612 , the shell  610  of the seating unit is shaped to define a hollow foot-box  630  (see  FIGS. 21  A and  21 B). In  FIGS. 18 and 19 , the foot-box  630 ′ of the neighbouring seat is shown. Said foot-box  630  includes an internal, generally horizontal shelf which is positioned at substantially the same vertical level as the under-seat-pan  628 , and an aperture  629  is formed in the rear screen  612  of the shell  610  immediately behind the backrest  624  in its normal position to allow access to the interior of the foot-box  630 . 
         [0205]    Said foot-box comprises a first side wall  632  which forms part of the interconnecting side wall  616  of the shell  610  of the neighbouring unit and is oriented substantially parallel to the notional longitudinal axis of the unit. The foot-box  630  further comprises a second opposing side wall  634  that subtends an acute angle with the notional, longitudinal axis of the unit, such that the foot-box has a generally triangular or trapezoid shape in plan view. In  FIGS. 18-21  of the drawings, the foot-box of the accommodation unit has a generally triangular shape, but the foot-box could be truncated with an end wall between the two side walls  632 ,  634  to form a trapezoidal shape. Alternatively, where the seat is intended to be positioned juxtaposed a wall, the first side wall  632  may be omitted such that the first lateral side of the foot-box is open. The foot-box  630  terminates below the upper edge of the rear screen  612  with a generally flat top wall  636 . Said top wall  636  is formed with a generally triangular, flat portion  638  which serves as a drinks side-table for the neighbouring unit. 
         [0206]    As shown in  FIG. 19 , the upper surfaces of the shelf within the foot-box  630  and the under-seat-pan  628  are cushioned with thick padding or support a mattress portion  652 . Similarly, the underside of the seat-pan  622  and the rear side of the backrest  624  are cushioned. 
         [0207]    In a “seat mode” the seat-pan  622  and backrest  624  are positioned normally as shown in  FIGS. 18 ,  20 A and  21 A, such that a passenger may sit on the seat. However, when the passenger wishes to go to sleep, he or she may get up from the seat and manually pull the back-rest  624  away from the rear screen  612 . The back-rest  624  will pivot relative to the seat-pan  622 , and continued pulling of the back-rest  624  will cause the rear end of the seat-pan  622  to lift upwardly away from the under-seat-pan and pivot about its front edge  623  as shown in  FIG. 20B . The seat-pan  622  and back-rest  624  can be manipulated as shown in  FIGS. 20C and 21B  to provide a substantially flat and continuous sleeping surface in which the front side of the back-rest  624  is supported on an upper surface of the pedestal  640 , the joints between the back-rest  624 , seat-pan  622  and under-seat-pan  628  locking in the flat position as shown in  FIG. 20C  to form a “bed mode”. The passenger may then lie is down on the flat surface with his or her head towards the front screen  614 . By removing the back-rest  624  from the rear screen  612 , the aperture  629  through the shell  610  is exposed, allowing the passenger to extend his or her lower legs through the aperture into the foot-box  630 . In the bed mode, the cushioned upper surfaces of the shelf and under-seat-pan  628  and the underside of the seat-pan  622  and rearside of the back-rest  624  may be fitted with suitable bed linen such as sheets and blankets, and a pillow for the passenger may be placed on the rear of the back-rest  624 . The surfaces of the unit used in the bed mode may be upholstered and dressed differently from those used in the seat mode. When all of a majority of the units in the a cabin are in one or other of the modes, a particular ambience can be created within the cabin. 
         [0208]    By positioning the accommodation unit at an angle of about 40-50 degrees, preferably about 45 degrees, to the direction of travel of the aircraft, a full bed length of up to 7 ft (2.13 metres) may be provided for the passenger, and at the same time, a side-table  638  is also provided of generous proportions, of the kind normally associated with first-class accommodation. As with the seat units  40  of  FIGS. 1-2  and the seat assembly of  FIGS. 3-5 , the accommodation unit of  FIGS. 18-21  is configured to compensate for the bed mode, the accommodation unit in accordance with the present invention provides a substantially horizontal sleeping surface. 
         [0209]    Another passenger accommodation unit in accordance with the present invention is illustrated in  FIGS. 22-27 . Many of the elements of the unit of  FIGS. 22-27  are similar to corresponding elements of the unit of  FIGS. 18-21  described above. Accordingly, for clarity, such elements are referred to by the same reference numerals plus 100. Thus, by way of example, whilst the rear screen of the unit of  FIGS. 18-21  is referred to by numeral  612 , the rear screen of the unit of  FIGS. 22-27  is referred to by numeral  712 . 
         [0210]    Thus, as shown in  FIG. 22 , the other passenger accommodation unit comprises a shell  710  which is formed from two half shells  710   a  and  710   b . Said shell  710  comprises a rear screen  712  and a front screen  714  that are interconnected by an interconnecting side wall  716 . Behind the rear screen  712 , the shell comprises a hollow foot-box  730  having opposing side walls  732  and a top wall  736  which includes a substantially flat, horizontal portion  738  that serves as a drinks side-table for a neighbouring seat. 
         [0211]    The shell  710  of  FIGS. 22-27  is mounted on a plinth  760 . Said plinth  760  is manufactured from a suitable aircraft grade, light-weight, structural material, typically the same material as the shell  710 , and has a planar bottom wall  762  which is fitted with suitable fixings (not shown) for fixing the plinth substantially to the seat tracks. 
         [0212]    Said plinth  760  is formed with a recess  764  which is defined by an upstanding side wall  763  having an inwardly directed, upper rim  765 . Said recess  764  extends from the front screen  714  under the entire seat into the foot-box  730  which is positioned at floor level. The recess  764  accommodates a mattress or similar cushioning or padding suitable for forming a bed for a passenger. Said recess is shaped to compensate for the slight incline of the aircraft in flight such that said mattress is substantially horizontal. Juxtaposed the front screen  714 , the shell  710  carries a movable pedestal  740  which is movable on a substantially vertical axis between a lower deployed position as shown in  FIGS. 22 and 24A  and a raised, stowed position as shown in  FIG. 24B . Whilst various mechanisms for achieving such movement of the pedestal will be apparent to those skilled in the art, an example of a suitable mechanism would be inter-engaging runners fitted on the inner surface of the front screen  714  and on the pedestal  740 . Suitable means are provided for locking the pedestal  740  in the upper and lower positions. 
         [0213]    Said shell  710  defines a personal passenger space  718  which accommodates a seat  720  comprising a seat-pan  722  and a backrest  724 . Said backrest  724  is permanently fixed to the inner surface of the rear screen  712 , whilst the seat-pan is pivoted at its rear edge  723  to the inner surface of the rear screen  712  for movement between a deployed position as shown in  FIGS. 22 and 24A  and a stowed position as shown in  FIGS. 23 and 24B . In the deployed position the front edge  725  of the seat-pan  722  is supported by inwardly directed protrusions  752  formed on the shell  710  which constitutes supporting structure for the seat assembly  720 . 
         [0214]    Beneath the seat-pan  722 , the rear screen  712  of the shell  710  is formed with an aperture  729  to allow access from the passenger space  718  into the interior of the foot-box  730 . Said mattress extends beneath the seat assembly  720  through the aperture  729  into the foot-box  730 . 
         [0215]    Intermediate the seat-pan  722  and pedestal  740 , the recess  764  is covered by a removable false floor panel  770  which is made from a suitable aviation standard, load-bearing material. Said false floor panel  770  is preferably connected to said interconnecting side wall  716  for movement between a deployed position as shown in  FIG. 22  and a stowed position in which the panel  770  extends substantially vertically and lies contiguous the side wall  716 . Securing means are provided for securing the panel in the stowed position. 
         [0216]    Juxtaposed the seat-pan of a neighbouring unit, the first side wall  732 ′ of the foot-box is formed with an external recess  733 ′ which is provided with an upholstered shelf  735 ′ at the same level as the seat-pan  722  of the neighbouring unit to provide a lateral extension of said seat-pan  722 . 
         [0217]    The accommodation unit  720  can thus be selectively manipulated between a “seat mode” as shown in  FIGS. 22 and 24A  in which the seat-pan  722  is deployed and a “bed mode” as shown in  FIGS. 23 and 24B  in which the seat-pan  722  is pivoted upwardly about its rear edge  723  to lie flat against the inner surface of the backrest  724  in the stowed position. In the bed mode, the removable false floor panel  770  can be moved to the stowed position, and the pedestal  740  raised from its lower position to its raised position thereby to expose the mattress within the recess  764  of the pedestal  760 . Raising the seat-pan  722  to its stowed position facilitates access to the foot-box  730  and provides a more spacious personal space  718  within the shell  710  in the bed mode. 
         [0218]    Thus, in the seat mode as shown in  FIG. 24A , a passenger may sit on the seat provided by the unit  720  and, if desired, may rest his or her feet on the pedestal  740  in its lower position. If the passenger desires to go to bed, then he or she may stand up and lift the seat-pan  722  to its stowed position as shown in  FIG. 24B . The pedestal  740  may be raised to its elevated position and the false floor panel  770  may be removed. The passenger may then lie down on the mattress within the recess  764  with his or her head towards the front panel  714  and his or her lower legs extending into the foot-box  730 . By orienting the unit at an angle of about 40-50 degrees, for example about 45 degrees to the direction of travel of the vehicle, an overall bed length of up to about 7 ft (2.13 metres) may be provided. The front screen  714  serves to protect the passengers&#39; head whilst asleep, and the pedestal  760  provides a step-up into the passenger&#39;s personal space which many passengers find is attractive. The shell above the foot-box may be shaped to provide a lateral seat extension  735  for the seat-pan  722  of a neighbouring seat and a generously proportioned occasional side-table  738  for use by the neighbouring seat. 
         [0219]    In a variant of the other accommodation unit of  FIGS. 22-24 , the seat-pan  722 , instead of pivoting about its rear edge  723  to lie flat, in its stowed position, against the front surface of the backrest  724  may be arranged to slide relative to the shell  710  between a forward position as shown schematically in  FIG. 26A  and a retracted position as shown in  FIGS. 25 and 26C . In the retracted position, the seat-pan  722 , or at least a major proportion of the seat-pan  722  may be accommodated within the foot-box  730  at a position vertically spaced above the mattress. Various mechanisms suitable for achieving such sliding movement of the seat-pan  722  will be self-evident for those skilled in the art, for example linear bearings provided on the interior surfaces of the shell  710  adjacent to the seat-pan  722 . Advantageously, the sliding mechanism may be provided with one or more detents (not shown) for selectively halting movement of the seat-pan  722  in at least one intermediate position such as that shown in  FIG. 26B . Thus, in the fully extended position, as shown in  FIG. 26A , the unit may be configured ergonomically for relaxing, whilst in the intermediate position as shown in  FIG. 26B , the unit may be configured to provide a more upright passenger position which is suitable, for example, for dining or working. In the fully retracted position, the seat-pan  722  is substantially stowed to allow access to the foot-box  730  when the seat is in bed mode. 
         [0220]    Another variant of the accommodation unit of  FIGS. 22-24  is shown in  FIG. 27  in which the removable false floor panel  770  is hinged to the interconnecting side wall  716  for movement between a deployed position in which it lies generally horizontally over the recess  764  to protect the mattress and a stowed position as shown in  FIG. 27  in which it lies flat in a substantially vertical orientation against the interconnecting side wall  716 . The underside  772  of the false floor panel  770  may be upholstered with suitable cushioning, such that together with the mattress  764 , it provides a sofa-like arrangement; a passenger may sit sideways on the mattress  764  in the bed mode with his or her back-resting against the underside  772  of the panel  770 . 
         [0221]    Yet another seating system in accordance with the present invention is illustrated in  FIG. 28 . The particular system of  FIG. 28  is designed specifically for use on the upper and lower decks of a Boeing 747-400® aircraft, but the system may be adapted for use on any passenger aircraft, particularly in a business class cabin. The seating system of  FIG. 28 , on each of the upper and lower decks, comprises a plurality of passenger accommodation units  800  in accordance with the present invention, for example the accommodation units of  FIGS. 18-21  or  FIGS. 22-27 . Each of said units  800  is positioned juxtaposed a cabin side wall  810  and is oriented at an angle of about 40-50 degrees, preferably about 45 degrees, to the longitudinal direction of the juxtaposed side wall  810 , with the rear of the unit towards the wall  810 , such that the seat faces generally inwardly of the cabin. By orienting units  800  to face inwardly, the cabin is given a less crowded appearance as compared with a cabin in which seats are aligned substantially fore-and-aft. Each unit has a generally triangular or trapezoidal extension box or space  830  between the rear of the unit and the juxtaposed cabin side wall  810 . Generally, the walls of an aircraft cabin are concave on the interior, and accordingly the extension box or space  830  of each unit  800  extends into the concave recess defined by the wall to optimise the use of space in the cabin. Each unit  800  comprises means adapted to provide a bed as described above which extends into the extension box or space to maximise the available bed length. 
         [0222]    In some aircraft floor plans, there may also be sufficient space to dispose one or more units towards the centre of the cabin, as shown for the lower deck of the Boeing® 747-400 in  FIG. 28 . In that embodiment, two central lines of units are provided in which each unit is oriented at an angle of about 45 degrees to the direction of travel of the aircraft. The central units  800  are arranged in pairs, with each seat facing generally forwardly and outwardly of the cabin, such that the two units of each pair diverge from one another in the forwards direction and define a generally quadrilateral space behind the units in front of the pair of units behind. Said quadrilateral space  840  accommodates an extension box or space associated with each unit  800  in order to provide an extended bed length for each unit. Where each unit  800  comprises a hollow foot-box of the kind described above with reference to  FIGS. 18-21  and  FIGS. 22-27 , the top wall of each foot-box may be adapted to provide a convenient side-table or other furniture means for another unit. 
         [0223]    With reference to  FIGS. 29A to 29C , a second passenger seat assembly  900  for a passenger vehicle such, for example, as an aircraft, in accordance with the present invention comprises a fixed, supporting structure, generally indicated by reference numeral  910  for supporting the seat assembly of the floor F of the vehicle. Said supporting structure  910  comprises means suitable for attaching the seat assembly to the floor. For instance, where the seat assembly  900  is to be installed on aircraft, said supporting structure  910  typically comprises one or more fixings for attaching the seat assembly to seat tracks of the kind commonly found in the floor of an aircraft cabin. As with the seat units  40  of  FIGS. 1-2  or the first seat assembly of  FIGS. 3-5 , the supporting structure of the second seat assembly  900  may comprise a plinth or palette (not shown) for attachment to said seat tracks. Said supporting structure  910  further comprises two elevated, passenger-supporting members  912 ,  914 , each of which has a generally flat, substantially horizontal upper surface (subject to compensation for the slight incline of the aircraft in flight). Said passenger supporting members  912 ,  914  are spaced apart to define a cavity  916  within the supporting structure. 
         [0224]    Said supporting structure  910  can be made of any suitable, aircraft grade structural materials known to those skilled in the art. Said supporting structure may be generally skeletal or may comprise one or more solid walls. Typically, said supporting structure is made from a light-weight composite material, but the aforementioned fixings for securing the supporting structure to seat tracks in an aircraft or other floor may comprise one or more reinforcing beams or plinths of light steel or aluminium. 
         [0225]    Said cavity  916  accommodates a passenger seat, generally indicated by reference numeral  920 . Said passenger seat  920  is generally supported by the supporting structure  910  and comprises a back-rest element  922  and a seat-pan element  924 . Said back-rest and seat-pan elements  922  and  924  are connected to the supporting structure  910  by a seat movement mechanism, generally indicated by reference numeral  930 . 
         [0226]    Said seat movement mechanism  930  comprises two similar, irregularly shaped, polygonal plates  932  that are mounted to either side of the seat  920 . It will be appreciated that as  FIGS. 29A to 29C  are side elevations, only one of said plates  932  can be seen. Each polygonal plate  932  is formed with a generally linear, elongate slot  934  juxtaposed one edge  935  of the plate. Juxtaposed an opposing edge  936 , said plate  932  carries two spaced, inwardly directed lugs  937 . A straight line between lugs  937  subtends an acute angle with said linear slot  934 . Juxtaposed a further edge  939  of said plate  932 , which further edge extends generally transversely between said one and opposing edges  935 ,  936 , said plate  932  is connected to one end of a two part linkage device  940 . Said linkage device  940  comprises a first member  941  that is pivotally connected to said plate  932  and a second member  942  that is pivotally connected at one end to first member  941  to form a “knee” joint  943  and is connected at another end to a fixed pivot point  944  on said supporting structure  910 . 
         [0227]    Said seat movement mechanism comprises means for linking the seat-pan to the back-rest such that the lower end of the back-rest remains contiguous to the rear end of the seat-pan, whilst allowing said seat-pan and back-rest to pivot relative to each other. 
         [0228]    Said linear slot  934  has upper and lower extremities  954 ,  955  and accommodates slidingly a lug member  951  that protrudes from the respective side of the seat-pan  924 . Juxtaposed its forward end  925 , said seat-pan  924  is pivotally connected to each side, at pivot point  952 , to one end of a linear strut  961 . Said linear strut  961  is pivotally connected at its other end  962  to a carriage member (not shown) that is connected to the supporting structure  910  beneath the seat-pan  924 . Said carriage member is movably mounted to the supporting structure  910  such that the carriage member can move between an upper position corresponding to  FIGS. 29A  to  29 C and lower position corresponding to  FIGS. 30A and 30B . Suitable biasing means such, for example, as springs, gas struts or the like, are provided for biasing the carriage member into the upper position. Selectively releasable mechanical locking means are also usually provided for locking the carriage means member in its upper position. 
         [0229]    Said linear strut  961  is rockably mounted to the carriage member such that it can rock between a generally upright position as shown in  FIG. 29A  and a forwardly reclined position as shown in  FIG. 29C . 
         [0230]    Said spaced lugs  937  on the polygonal plate  932  engage in a curvilinear track  971  that is fixedly secured to the respective side of the backrest  922 . As can be seen from  FIGS. 29A to 29C  and  30 A to  30 B, said curvilinear track  971  is conveniently formed in an elongate plate member  972  that is attached to the side of the back-rest. Said curvilinear track  971  has upper and lower extremities  973 ,  974  respectively. 
         [0231]    With reference to  FIG. 29A , when said seat  920  is disposed in an upright or “dining” position, the two-part linkage device  940  is an extended configuration such that the first and second members  941 ,  942  are generally co-linear with one another, and both of said first and second members  941 ,  942  extend generally upwardly and forwardly from said pivot point  944 . Said plate  932  extends rearwardly of its point of attachment to the first link member  941  and is oriented such that said linear slot  934  extends upwardly and rearwardly. The back-rest portion  922  is in an upright position, and the spaced lugs  937  are disposed at the lower extremity of the curvilinear track  971 . The seat-pan is oriented substantially horizontally, (in flight) and the lug  951  is disposed at the upper extremity  954  of the linear slot  934 . The carriage member (not shown) is disposed in its upper position as described above, and the rockable linear strut  961  is oriented generally vertically. The seat-pan  924  is thus positioned rearwardly within the cavity  916  between the two passenger supporting members  912 ,  914 . 
         [0232]    Said seat-pan  924  has an upper surface  926  that is suitably upholstered for use as a seating component. Similarly, said back-rest element  922  has a front surface  923  that is suitably upholstered as a seating component. Preferably, the forward surface  923  of the back-rest element is dressed to match the upper surface  926  of the seat-pan element  924 . One of said passenger supporting members  914  is positioned forwardly of the seat  920  and serves as a fixed leg-rest portion  928 . Said leg-rest portion  928  has an upper surface  929 . 
         [0233]    Said linear strut  961  is operably connected to a selectively operable locking motor drive (not shown) which is capable of driving the strut  961  to rock about its upper end  962 , as described above, between the upright position of  FIG. 29A  and the forwardly inclined position of  FIG. 29C . Suitable user controls (not shown) are provided in the seat assembly to enable a passenger using the seat to operate said locking drive. 
         [0234]    Said back-rest portion  922  has a rear surface  921  that is generally planar. Said rear surface  921  is spaced from the passenger supporting member  912  by a small gap  913  when the seat is upright as shown in  FIG. 29A . Said rear surface  921  carries a mattress portion (not shown) for use as part of a bed, which mattress portion is attached to the rear surface  921  of the backrest portion  922  such that when the back-rest is upright, the mattress portion does not detach. Said passenger supporting member  912  also has an upper surface  911  which carries a mattress portion. A movable infill passenger supporting member  915  is pivotally connected to a forward, transverse edge  917  of said passenger supporting member  912 . Said infill member  915  is generally rectilinear and has an upper surface  918  which has a generally flat upper surface  918  which carries a mattress portion (not shown). Said infill member  915  is slidably connected to the rear surface  921  of the back-rest element  922 . As seen in  FIG. 29A , in the upright position, the infill member  915  extends generally upright between the fixed passenger supporting member  912  and the back-rest element  922  of the seat  920  in said gap  913 . 
         [0235]    In addition to the locking drive motor for driving the linear strut  961 , a further selectively operable motorised drive is provided for rocking the second link member  942  of said two-part linkage device  940  rearwardly about the fixed pivot point  944 . Said second link member  942  comprises a rearwardly extending knuckle portion  945  (see  FIG. 30A ) for connection to said other drive motor (not shown). 
         [0236]    Said user controls may also be adapted to operate said mechanical locking means to release the seat-pan from its upper position simultaneously with operation of said second drive. 
         [0237]    When the seat is upright as shown in  FIG. 29A , the seat may be reclined by operating the locking drive motor to rock the linear strut  961  forwardly about its other end  962 , whilst the carriage member (not shown) supporting the linear strut  961  is retained in its upper position. By rocking the linear strut  961  forwardly, the seat-pan element  924  of the seat is pulled forwardly within the cavity  916 , and the lug  951  slides along said slot  934  from said upper extremity  954  towards said lower extremity  955 . Forward movement of the seat-pan also causes the lower end of the back-rest  922  to move forwardly. The back-rest portion is constrained to move along a predetermined path by the engagement of the lugs  937  within the curvilinear track  971 . The track  971  is shaped to cause the back-rest  922  to recline rearwardly progressively as the seat-pan moves forward. 
         [0238]    As the seat is reclined, the lugs  937  move along said curvilinear track  971  through an intermediate position as shown in  FIG. 29B  and two of the lugs  937  abut the upper extremity  973  of the curvilinear track  971 , at which point no further movement of the seat is possible, and the seat is in a reclined or “lounge” position as shown in  FIG. 29C . It will be appreciated that the locking action of the locking drive motor allows the seat to be stopped and locked at any desired intermediate position between the two extreme positions represented by  FIGS. 29A and 29C . 
         [0239]    When a passenger using the second seat assembly  900  in accordance with the present invention wishes to go to sleep, the seat assembly can be converted into a bed. The passenger operates the user controls to release the seat-pan from its upper position and to cause the second motorised actuator to rock the second link member  942  of the linkage device  940  rearwardly about said pivot point  944  as shown in  FIG. 30A . As the second link member  942  is rocked rearwardly, the knee joint between the first and second link members  941 ,  942  is broken allowing the first link member  941  to rock forwardly and downwardly about the knee joint  943  which, in turn, causes the polygonal plates  932  to rock forwardly and downwardly, thereby causing the back-rest element of the seat  920  to move forwardly within the cavity  916  and to pivot forwardly from its upright position. As the back-rest element  922  pivots forwardly, it pushes downwardly on the seat-pan portion  924  which is thus caused to move downwardly on said carriage member (not shown) against the action of the biasing means. Continued rearward movement of the second linkage member  942  causes the polygonal plates  932  and back-rest element  922  to move downwardly towards the floor F of the vehicle until, as shown in  FIG. 30B , the rear surface  921  of the back-rest element  922  is disposed substantially horizontally (in flight) and co-planarly with the passenger supporting members  912 ,  914 . The linkage member  940 , polygonal plate  932 , curvilinear tracks  971  and lugs  937  are arranged such that in the bed configuration as shown in  FIG. 30B , the upper end of the back-rest element  922  abuts the rear edge of the forward passenger supporting member  914  to form a continuous surface therewith. Suitable, releasable locking means are provided for locking the back-rest  922  in the end position. 
         [0240]    Furthermore, as seen most clearly in  FIG. 30A , as the back-rest element  922  rocks forwardly and moves translationally forwards within the cavity  916 , the infill and member  915  slides along the rear surface  921  of the back-rest element and is caused or allowed to pivot forwardly until, as shown in  FIG. 30B , when the back-rest element is disposed substantially horizontally, the infill member  915  forms a bridge between the passenger supporting member  912  and the rear surface  921  of the back-rest element  922 , such that the upper surfaces  911 ,  918 ,  921  of the passenger supporting member  912 , infill member  915  and back-rest element  922  are substantially co-planar and form a continuous surface. It will be appreciated that the mattress portions carried by the passenger supporting member  912 , infill member  915  and rear surface  921  of said back-rest  922  form an elongate mattress for the passenger to sleep on. Furthermore, the upper surface  929  of the passenger supporting member  914  forwardly of the seat  920  may also carry a mattress portion which further extends the bed formed by the seat in the bed configuration of  FIG. 30B . The seat assembly in accordance with the present invention allows a continuous bed surface to be formed having a length of at least 78-80 inches (1.98-2.032 metres). In some cases, the bed formed by the upper surfaces  911 ,  918 ,  921 ,  929  of the passenger supporting members  912 ,  914 , infill member  915  and rear surface  921  of the back-rest element  922  may have a length in excess of 85 inches (2.16 metres). 
         [0241]    In order to return the seat assembly  900  to a seat configuration, the second motor drive is actuated to rock the second link member  942  of the two part linkage device  940  forwardly about said fixed pivot point  944 , thereby causing the first link member  941  to rock rearwardly which, in turn, causes the polygonal plates  932  to rock rearwardly and move upwardly, restoring the back-rest element  922  progressively to its upright position. As the back-rest element  922  returns to the upright position, the seat-pan element  924  is allowed to return to its upper position on the carriage member (not shown) under the influence of said biasing means (also not shown). When the seat-pan is returned to its upper seat position, the mechanical locking means are automatically re-engaged to retain the seat in its upper position. 
         [0242]    As will be appreciated from inspection of  FIGS. 29A to 29C , the upper surface  911  of said passenger supporting member  912  and upper surface  918  of said infill member  915 , when the seat assembly is configured in a seat configuration, form a convenient recess  980  to the rear of the seat  920 . Said recess  980  is at least partially concealed from view by the back-rest portion  922  of the seat  920 . Thus, said recess  980  may be used for a storage, for example of bedding materials such as pillows, duvets, and the like. When the seat assembly is moved to the bed configuration of  FIG. 30B , the bedding materials can be easily accessed by a passenger and deployed upon the bed surface that is formed by the components of the seat assembly as described above. 
         [0243]    A further advantage of the passenger seat assembly  900  as hereinbefore described is that the front surface  923  of said back-rest element  922  and upper surface  926  of the seat-pan element  924  can be upholstered and covered specifically for use as seating components. Thus, for example, the back-rest element and seat-pan element  922 ,  924  may carry foam padding layers that are sculpted particularly for use as seating members. The texture, patterns and/or colourways of the upholstery and dressing materials used for covering the front surface  923  of the back-rest element and upper surface  926  of the seat-pan element may be selected specifically for use as seating materials. Conversely, the mattress portions carried by the passenger supporting member  912 , infill member  915  and rear surface  921  of back-rest element  922  may be specifically adapted for use as bedding materials. Thus, interior sprung mattress portions or foam padding layers may be used which are specifically shaped for maximum passenger comfort when the seat is used as a bed. In particular, the materials and fabrics used to dress the mattress portions may have textures, colours, etc. that are particularly suitable for use as bedding materials. The bedding materials used to dress the mattress portions and the materials used to dress the seating portions of the seat assembly may have quite different appearances from one another. However, as will be appreciated, when the seat is configured for use as a seat, the bedding materials are largely concealed by the back-rest element  922 , leaving visible only those parts of the seat that are used actually form part of the seat. Similarly, when the seat is reconfigured for use as a bed, the front surface of the back-rest element and upper surface of the seat-pan element are substantially concealed from view, leaving visible only the bedding materials comprising the mattress portions on the passenger supporting component  912 , infill member  915  and rear surface  921  of the back-rest element  922 . 
         [0244]    Where a plurality of passenger seat assemblies in accordance with the present invention are installed in a vehicle cabin, for example, on an aircraft, they can be used to give the aircraft cabin two different visual appearances or ambiances according to whether a majority of the seat assemblies are disposed in a bed configuration or a seat configuration. Thus, during a daytime flight, or during a daytime portion of a long haul flight, a majority of passenger seat assemblies may be arranged in a seat configuration as per one of  FIGS. 29A to 29C . The bedding materials will be substantially concealed, leaving visible only the seating surfaces of the assemblies. The seat assemblies may, of course, be dressed in any desired design, but, for example, seat assemblies may be upholstered and dressed to give the cabin the appearance of a private members club environment. For instance, the upper surface  926  of the seat-pan element  924  and front surface  923  of the back-rest element  922  may be upholstered in leather. During a night-time flight or during the night-time portion of a long haul flight, a majority, or all, of the seat assemblies may be configured in a bed configuration as per  FIG. 30B , in which case, the seating portions of the assemblies will be substantially concealed, leaving visible only the bedding materials carried by the upper surfaces  911 ,  918 ,  921 ,  929  of the passenger supporting members  912 ,  914 , infill member  915  and back-rest element  922 . The materials used to dress the mattress portions may have a significantly “softer” appearance than the materials used to dress the reverse seating side of the back-rest element  922 , in order to give the passenger cabin an attractive, restful ambiance that is appropriate for sleeping. 
         [0245]      FIGS. 31 and 32  show respectively two different seating systems, each comprising a plurality of seat assemblies of the kind hereinbefore described with reference to  FIGS. 29-30 . In  FIG. 31 , an aircraft cabin is defined inter alia by two opposing curvilinear walls  1001 ,  1002 . As is well known to those skilled in the art, each of said walls  1001 ,  1002  is generally concave on its internal surface. Juxtaposed each of said walls  1001 ,  1002  is provided a column  1029  of passenger seat assemblies  900  in accordance with the present invention. Each seat assembly  900  defines a notional longitudinal axis indicated by reference numeral  1012  in respect of a representative one of the seat assemblies  900 . The seat assemblies  900  are oriented at an acute angle with respect to the adjacent cabin wall  1001 ,  1002 .  FIG. 31  also shows, in juxtaposition with wall  1001 , a notional “forwards” axis  1014 . It will be appreciated that towards the front of the aircraft, the “forwards” axis  1014  may not, in fact, be oriented precisely forwards with respect to the direction of travel of the aircraft, but is oriented substantially parallel to the fore-aft direction of the adjacent side wall  1001 , ignoring the slight curvature of that side wall  1001 . Each of said passenger seat assemblies  900  is oriented to define an angle α of about 40° between the notional, longitudinal axis  1012  of the seat assembly and the notional “forwards” axis  1014  of the aircraft cabin. Each seat assembly is positioned such that the passenger supporting member  912  is disposed adjacent the juxtaposed cabin wall  1001 ,  1002 , such that the passenger supporting member  912  extends into the recess defined by the concave nature of said side wall  1001 ,  1002 . The seat  920  is positioned facing forwardly and inwardly with respect of the cabin, and a low privacy screen  927  is formed around the forward end of the passenger supporting member  914 , so as to define a personal passenger space around each seat assembly. By positioning each seat assembly such that the passenger supporting member  912  extends into the recess defined by the concave side wall  1001 ,  1002 , maximum use is made of the space available in the aircraft cabin. As will be appreciated, the passenger supporting member  912  is only used by a passenger when the seat is arranged in a bed configuration, and thus, full-height head room is not required above passenger supporting member  912 . 
         [0246]    Suitable privacy screens may be provided between adjacent seats, and as shown in  FIG. 31 , a space  1015  adjacent each seat assembly and behind the passenger supporting member  912  of the neighbouring seat assembly may be used to provide a seat-height surface for use as a cocktail table or the like. 
         [0247]    Where cabin space permits, one or more central columns  1030  of seat assemblies  900  may be installed in addition to columns of seat assemblies  900  juxtaposed the cabin walls  1001 ,  1002 .  FIG. 31  shows a cabin installation in which two central columns of seat assemblies  1030  are installed. Within each central column  1030 , the seat assemblies  900  are arranged, as described above, at an acute angle to the fore-aft axis of the aircraft cabin. The seat assemblies  900  are also arranged in rows of two and, within each row, the seat assemblies are arranged back-to-back so that the passenger supporting members  912  of adjacent seats within the same row are disposed contiguously to one another and, when the seats are in a seating configuration, are substantially concealed from view by the juxtaposed back-rest elements of the seat  920 . 
         [0248]      FIG. 32  shows a seating system suitable for a different aircraft comprising three columns  1129 ,  1130  of seat assemblies  900 , comprising two columns  1129  that are disposed respectively juxtaposed the two longitudinal walls  1101 ,  1102  of the cabin and a single, central column. As with the installation shown in  FIG. 31 , the seat assemblies  900  in each column  1129 , juxtaposed one of the cabin walls  1101 ,  1102  are oriented such that the seats face forwards and inwards with respect to the cabin. The seat assemblies within the central column  1130  are also arranged to face forwards and to one side. Each seat assembly defines an acute angle β of about 49° between the notional longitudinal axis  1112  of the seat assembly  900  and the fore-aft axis  1114  of the cabin. 
         [0249]      FIGS. 33A to 33C  show a third passenger seat assembly according to the present invention. For components of the third seat assembly of  FIGS. 33A to 33C  that are similar to corresponding components of the assembly of  FIGS. 29A to 29C  and  FIGS. 30A and 30B , corresponding reference numerals are used, but with the prefix “12” instead of “9”. Thus, the supporting structure  1210  of the third seat assembly of  FIGS. 33A to 33C  corresponds to supporting structure  910  of the second seat assembly of  FIGS. 29A to 29C . 
         [0250]    The third seat assembly according to  FIGS. 33A to 33C  comprises a supporting structure generally indicated by reference numeral  1210 , for supporting the assembly off the floor F of a vehicle floor such, for example, as the floor of an aircraft cabin. Similar to the second seat assembly of  FIGS. 29 and 30  described above, the third seat assembly of  FIGS. 33A to 33C  comprises two elevated, auxiliary passenger-supporting elements  1212 ,  1214  that are spaced apart and oppose one another to form a cavity  1216  within the supporting structure. Said cavity  1216  accommodates a seat generally indicated by reference numeral  1220 , which seat comprises a back-rest element  1222  and a seat-pan element  1224 . Said seat-pan element  1224  has a forward end  1225  and a rear end  1223  and is pivoted at its rear end  1223  to a lower end  1226  of the back-rest element  1222 . Said seat-pan element  1224  is movably connected to the supporting structure  1210  by a seat movement mechanism (not shown) which allows the seat-pan element  1224  to move substantially vertically within the cavity  1216  between an upper position as shown in  FIG. 33A  and a lower position as shown in  FIG. 33C . Suitable biasing means are provided (not shown) for biasing the seat-pan element  1224  into the upper position and selectively operable locking means are provided for locking the seat-pan  1224  in the upper position. 
         [0251]    Said back-rest element  1222  is pivoted to said supporting structure  1210  at a fixed pivot point  1230 . Said back-rest element  1222  has a rear surface  1221  which comprises an extension portion  1231  at the lower end  1226  of the back-rest element  1222 , which extension portion  1231  extends downwardly beyond the fixed pivot point  1230  when the back-rest element  1222  is in an upright position. 
         [0252]    The upper surface of the seat-pan element  1224  and front surface of the back-rest element  1222  are upholstered and covered with materials that are specifically designed for use as seating materials. The passenger-supporting element  1214  is spaced forwardly of the seat  1220  and can be used as a foot-rest element  1228  when the seat  1220  is in an upright position as shown in  FIG. 33A . The passenger-supporting element  1212  is disposed behind the back-rest element  1222  and separated therefrom by a small gap  1213 . 
         [0253]    Said rear surface  1221  of the back-rest element  1222  is generally flat and carries a first mattress portion (not shown) which is designed and dressed specifically for use as a bedding component. Said passenger-supporting element  1212  has an upper surface  1211  which also carries a mattress portion. The back-rest  1222  and passenger-supporting element  1212  define a recess  1280  behind the back-rest  1222  which can be used for storage of bedding materials such as pillows, duvets, rugs, blankets and the like. An advantage of the third passenger seat assembly according to the present invention is that when the back-rest is in the upright position as shown in  FIG. 33A , the recess  1280  is concealed from view, thus tidily hiding any bedding materials stored in the recess. 
         [0254]    Said back-rest element  1222  is pivotable from an upright position in  FIG. 33A  about said fixed pivot point  1230  to a bed position as shown in  FIG. 33C . Said back-rest element  1222  and said pivot point  1230  are designed, with the passenger-supporting elements  1212 ,  1214 , such that, in the bed position, the rear surface  1221  of the back-rest element  1222  is disposed contiguously to both of said passenger-supporting elements  1212 ,  1214  to form a generally flat, substantially continuous surface therewith. In the bed configuration of  FIG. 33C , the second mattress portion carried by the upper surface  1211  of the passenger-supporting element  1212  and the first mattress portion carried by the rear surface  1221  of the back-rest element  1222  abut or nearly abut one another to form an elongated bed on which a passenger using the seat may sleep. The upper surface  1229  of the passenger-supporting element  1214  also forms an extension surface to be bed. As to with the first and second seat assemblies described above, in accordance with the third seating assembly, it is possible to form a bed having a total “point-to-point” length of at least 78-80″ (1.98-2.032 cm) and, in some cases, at least 85″ (2.16 cm). 
         [0255]    Movement of the back-rest element  1222  between the upright and bed positions of  FIGS. 33A and 33C  may be motorised (not shown) and suitable user-operable controls (also not shown) may be provided adjacent the seat  1220  to enable a passenger to control operation of the seat. When the seat is in the upright position as shown in  FIG. 33A , the locking mechanism may be removed thereby releasing the seat-pan from its upper position, and operation of the motor drive causes the back-rest element  1222  to rock forwardly about said fixed pivot point  1230 . As the back-rest element  1222  rocks forwardly, it abuts on the seat-pan element  1224 , pushing the seat-pan element  1224  downwardly in the cavity  1216 , against the action of the aforementioned biasing means. 
         [0256]    In the bed position as shown in  FIG. 33C , the seat-pan element  1224  is completely concealed by back-rest element  1222 . Thus, as with the first and second seat assemblies described above, the front surface of the back-rest element  1222  and upper surface of the seat-pan element  1224  may be covered with materials to give a completely different visual appearance and cabin ambience from those materials used to dress the bedding parts carried by the rear surface  1221  of the back-rest element  1222  and upper surface  1211  of the passenger-supporting element  1212 . When the back-rest element  1222  is upright, the seating surfaces of the back-rest element  1222  and seat-pan element  1224  are visible, whilst the bedding surfaces of the rear surface  1221  of the back-rest element  1222  and upper surface  1211  of the passenger-supporting element  1212  are concealed. On the other hand, when the seat is in the bed configuration of  FIG. 33C , the seat surfaces of the back-rest element  1222  and seat-pan element  1224  are concealed, whilst the bedding surfaces  1221  and  1211  are visible. 
         [0257]    In accordance with a particular aspect of the second and third seat assemblies of the first described above, therefore, the back-rest element  922 ;  1222  has a first seating surface  923 ;—which forms part of a seat with the upper surface  926 ;—of the seat-pan  924 ;  1224  and an opposite bed surface  921 ;  1221  which is adapted to form part of the bed with one or more other auxiliary passenger-supporting elements  912 ,  914 ;  1212 ,  1214 . 
         [0258]    The passenger seat assembly in accordance with the present invention is thus particularly advantageous because it allows a long bed to be provided for a passenger in an aircraft cabin or other vehicle which capable of accommodating comfortably even very tall passengers having a height greater than 78-80″ (1.98-2.032 cm) at a minimal seat pitch. By positioning a seat assembly, in accordance with the present invention, juxtaposed a concave cabin wall, with the rear passenger supporting element  912 ;  1212  disposed adjacent said cabin wall, it is possible to use efficiently the available space within the cabin. In a seat configuration, the back-rest element  922 ;  1222  forms a recess  980 ;  1280  with the rear passenger-supporting element  912 ;  1212  which can used to conceal tidily bedding materials such as rugs, blankets, pillows, etc. The seat and bedding surfaces of the back-rest element  922 ;  1222  can be given respectively different visual appearances such that in a cabin installation comprising a plurality of seat assemblies according to the present invention, a first cabin ambience can be obtained when all or a majority of the seat assemblies are disposed in the seat configuration, and a second, different, ambience can be obtained when all or a majority of the seats are disposed in the bed configuration. Furthermore, the seat and bedding surfaces can be respectively adapted specifically for use for their given purposes. Thus, for example, the seating surface of the back-rest element  922 ;  1222  may be provided with foam padding or the like which is sculpted particularly for use as a seating component, whilst the bedding surface of the back-rest portion can be equipped with a mattress portion or other comfortable, resilient layer that is shaped specifically for use as a bed component. Another advantage of the seat assembly in accordance with the present invention is that, in the bed configuration, the seat-pan element  924 ;  1224  is completely or substantially concealed by the back-rest element  922 ;  1222 , such that the appearance of the materials used to cover the seat-pan element does not spoil the appearance and ambience afforded by the bedding materials. Preferably, the seat assembly in accordance with the present invention comprises a leg-rest portion  928 ;  1228  spaced forwardly of the seat  920 ;  1220  and, in the bed configuration, the leg-rest element forms part of an extended bed surface.