GB2585939A

GB2585939A - Chair

Info

Publication number: GB2585939A
Application number: GB1910693.9A
Authority: GB
Inventors: Jabez Marsh Fred
Original assignee: Accora Ltd
Current assignee: Accora Ltd
Priority date: 2019-07-26
Filing date: 2019-07-26
Publication date: 2021-01-27
Anticipated expiration: 2039-07-26
Also published as: GB201910693D0; GB2585939B

Abstract

A chair, such as a rise and recline chair, that has means 26 to move it across a floor, and two frames 10, 12 and an actuator 50 to move the seat relative to the frames. The seat has a first configuration in which the first frame 12 contacts the floor and the seat 4 is moved relative to the first frame, and a second configuration in which the second frame 10 contacts the floor and the seat 4 is moved relative to the second frame. The second and first frames may be raised from the floor in the first and second configurations, respectively. The actuator may be a linear actuator that alters the angle between the respective frames and the seat in the two configurations. The chair may be moved via castors, wheels or rollers, and may have a catch mechanism (82, figure 13), such as a hook and peg (84, 86, figure 13), to cause the chair to transition between the two configurations. The castors may be adjustable in height relative to the frame to which they are attached.

Description

FIELD OF THE INVENTION

This invention relates to chairs and in particular to chairs that have a rise and recline functionality.

BACKGROUND TO THE INVENTION

It is known in the art to provide chairs, such as arm chairs, with mechanisms that can lift the chair and can recline a backrest of the chair. These chairs are designed to help people with limited mobility to sit comfortably and to more easily sit down on and get up from the chair. In particular, known chairs are provided with a first mechanism that raises the height of at least a seat portion of the chair to enable a person to more easily get up from the chair. This first mechanism may also tilt the seat portion of the chair to assist the person into a standing position. Known chairs are also typically provided with a second mechanism that enables a person to recline the backrest of the chair.

Traditionally, in the UK at least, these types of chairs are referred to as rise and recline chairs.

The rise and recline mechanism of these chairs means that they are heavy and relatively bulky, this makes them difficult to move around, especially with the additional weight of a person sat in the chair. Accordingly, known chairs are provided with wheels or castors to enable the chair to be more easily moved. It is, however, undesirable for the chair to be able to move across the floor when the chair is moved into the raised configuration. It is known to provide a brake mechanism on the wheels or castors to prevent such movement.

It is an object of the present invention to provide a chair that has a more stable support structure when the chair is raised but which enables the chair to be easily moved across the floor when the chair is not raised. -2 -

SUMMARY OF THE INVENTION

An aspect of the present invention provides a chair frame comprising: a seat platform; a support frame; a base frame assembly including a base frame and means to facilitate movement of the chair across a floor; and an actuator configured to move the seat platform relative to the support frame 10 and the base frame, wherein the chair has a first state in which the base frame assembly is in a floor contacting position and the position of the seat platform relative to the base frame is variable and a second state in which the support frame is in a floor contacting position and the position of the seat platform relative to the support frame is variable.

When the base frame assembly is in a floor contacting position a part of the means to facilitate movement of the chair across a floor is preferably in contact with the floor on which the chair is standing.

Preferably the actuator is configured to move the seat platform between a recline position when the chair is in the first state and a rise position when the chair is in the second state.

In preferred embodiments the actuator is a linear actuator. Preferably the linear actuator travels through a first range of movement when the chair is in the first state and through a second range of movement when the chair is in the second state. The actuator may have a shorter length when the chair is in the first state and a longer length when the chair is in the second state.

The means to facilitate movement of the chair across a floor preferably comprises castors. -3 -

In preferred embodiments the chair frame further comprises a catch mechanism configured to cause the chair to transition between the first and second states.

The catch mechanism is preferably engaged with the support frame when the chair is in the first state and disengaged from the support frame when the chair is in the second state.

In preferred embodiments the catch mechanism comprises a hook connected to one of the base frame assembly and the support frame and a peg connected to the other 10 one of the base frame assembly and the support frame, the hook being engaged with the peg when the chair is in the first state.

In some embodiments the catch mechanism may comprise a hook connected to the base frame assembly and a peg connected to the support frame, and a lever preferably extends from the hook and is connected to the seat platform. The peg preferably extends from a connecting arm extending between the base frame and the support frame.

In preferred embodiments in the first state an angle between a plane of the seat platform and a plane of the base frame is variable. In preferred embodiments in the second state an angle between a plane of the seat platform and a plane of the support frame is variable.

Preferably in the first state the support frame is not in a floor contacting position and in the second state the base frame assembly is not in a floor contacting position.

In some embodiments the chair frame may further comprise a stop surface configured to retain the hook in a fixed position relative to the base frame when the chair is in the second state.

In preferred embodiments the chair frame further comprises a height adjustment mechanism permitting a distance between a plane of the base frame and a floor contacting plane of the means to facilitate movement of the chair across a floor to -4 -be adjusted.

Preferably the height adjustment mechanism comprises a mounting plate including a plurality of gaps and a support plate having a tooth, the tooth being engageable in each of the gaps, and the mounting plate being attached to the base frame and the support plate being attached to the means to facilitate movement of the chair across a floor.

In preferred embodiments the means to facilitate movement of the chair across a 10 floor comprises castors, and an arm preferably extends from the support plate and a castor is attached to the arm by a spindle, and the spindle is engageable with the arm to secure the castor to the arm in two different and opposite directions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a chair frame according to a preferred embodiment of the invention, with the chair in a neutral seating position; Figure 2 is a further perspective view of the chair frame of Figure 1 in the neutral position; Figure 3 is a perspective view of the chair frame of Figure 1, with the chair in a rise position; Figure 4 is a further perspective view of the chair frame of Figure 3 in the rise position; Figure 5 is a perspective view of the chair frame of Figure 1, with the chair in a tilted or reclined seating position; -5 -Figure 6 is a further perspective view of the chair frame of Figure 5 in the reclined position; Figure 7 is a side view of the chair frame of Figure 1 in the neutral position; Figure 8 is a side view of the chair frame of Figure 3 in the rise position; Figure 9 is a side view of the chair frame of Figure 5 in the reclined position; Figure 10 is a perspective view of a part of the chair frame of Figure 1 in the neutral position; Figure 11 is a perspective view of a part of the chair frame of Figure 5 in the reclined position; Figures 12a and 12b are perspective views of a part of the chair frame of Figure 3 in the rise position; Figure 13 is a detail view of a preferred catch mechanism of the chair frame of Figure 1, with the chair in the neutral position; Figure 14 is a further detail view of the preferred catch mechanism of Figure 13; Figure 15 is a detail view of a preferred catch mechanism of the chair frame of Figure 3, with the chair in the rise position; Figure 16 is a further detail view of the preferred catch mechanism of Figure 15; Figure 17 is a detail view of a preferred catch mechanism of the chair frame of Figure 5, with the chair in the reclined position; Figure 18 is a further detail view of the preferred catch mechanism of Figure 17; -6 -Figure 19 shows a preferred castor assembly of the chair frame of Figure 1; Figure 20 shows another preferred castor assembly of the chair frame of Figure 1; and Figure 21 is a further view of the castor assembly of Figure 20.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A chair frame 2 according to a preferred embodiment of the present invention is shown in Figures 1 to 9. The chair frame 2 comprises a seat platform 4, a backrest frame 6, a footrest frame assembly 8, a base frame assembly 10 and a support frame 12. To form a complete chair 14 according to the present invention one or more seat cushions (not shown) are supported by the seat platform 4, one or more backrest cushions (not shown) are connected to the backrest frame 6 and one or more footrest cushions (not shown) are connected to the footrest frame assembly 8. One or more covers (not shown) may extend over and cover the seat, backrest and footrest cushions, as well as parts of the seat platform 4, backrest frame 6, footrest frame assembly 8 and base frame assembly 10, such that minimal parts of the chair frame are exposed in use.

The footrest frame assembly 8 may include an actuator 16 configured to raise and lower a footrest in a known manner. A further actuator 18 may be connected to the backrest frame 6 to enable a backrest to be reclined relative to the seat of the chair 14. In particular the backrest actuator 18 may be configured to adjust an angle between the backrest frame 6 and the seat platform 14.

It will be appreciated that in normal use the chair 14 will be standing on a floor or other suitable surface. In the following description, references to upwardly and in an upward direction refer to directions away from the surface or floor on which the chair 14 is standing in its usual orientation in use. References to rear or rearwardly refer to locations closer to and/or in a direction towards the backrest of the chair 14. References to front or forwardly refer to locations further from and/or in a direction -7 -away from the backrest of the chair 14. Accordingly, in normal use a user will sit on an upward facing surface of a seat cover and their back will rest against a forward facing surface of a backrest cover.

The chair frame 2, and therefore the chair 14, is moveable between three positions.

In a first position, shown in Figures 1, 2 and 7, the chair 14 is in a neutral position. In this position the seat platform 4 is substantially parallel to the floor or surface on which the chair 14 is standing. Furthermore, the distance between an upper surface of the seat platform 4 and the floor is such that a user is able to sit comfortably on the chair 14. In a second position, shown in Figures 3, 4 and 8, the chair 14 is in a rise position. In this position a distance between the seat platform 4 and the floor is increased relative to the neutral position. Furthermore, an angle between the seat platform 4 and the floor is between about 30° and 45°, such that a front edge 20 of the seat platform 4 is closer to the floor that a rear edge 22 of the seat platform 4.

In the rise position a user of the chair 14 is moved into a more standing position. In a third position, shown in Figures 5, 6 and 9, the chair 14 is in a tilted or reclined position. In this position an angle between the seat platform and the floor is between about 30° and 45°, such that the rear edge 22 of the seat platform 4 is closer to the floor that the front edge 20 of the seat platform 4. Furthermore, in this embodiment, in the tilted position, a distance between the front edge 20 of the seat platform 4 and the floor is greater than when the chair 14 is in the neutral position and a distance between the rear edge 22 of the seat platform 4 and the floor is less than when the chair 14 is in the neutral position. A user seated on the chair 14 is therefore tipped backwards in the tilted position.

The base frame assembly 10 comprises a base frame 24 and means 26 to facilitate movement of the chair 14 across the floor. In this embodiment the means 26 to facilitate movement of the chair 14 across the floor comprises castors 28 connected to the base frame 24 as described further below. The castors 28 are connected to the base frame 24 such that when the base frame assembly 10 is in a floor contacting position, the castors 28 are in contact with the floor. In this embodiment the base frame 24 is substantially rectangular and comprises two side frame members 30, a front frame member 32 and a rear frame member 34. The base -8 -frame assembly 10 comprises four castors 28, each castor 28 being connected to the base frame 24 proximate a corner of the base frame 24.

In other embodiments the means 26 to facilitate movement of the chair 14 across the floor may comprise wheels, skids or rollers for example.

In this embodiment the support frame 12 comprises two side frame members 36 and a cross member 38 extending between and joining the two side frame members 36. The cross member 38 is preferably disposed nearer first, rear ends 40 of the side frame members 36 than second, front ends 42 of the side frame members 36. When the support frame 12 is in a floor contacting position at least the two side frame members 36 are in contact with the floor. Preferably the cross member 38 is also in contact with the floor. In this embodiment a distance between outer surfaces of the side frame members 30 of the base frame 24 is smaller than a distance between inner surfaces of the side frame members 36 of the support frame 12.

The seat platform 4 is, in this embodiment, substantially rectangular and comprises two side frame members 44, a front frame member 46 and a rear frame member 48. The front frame member 46 and the rear frame member 48 extend between and connect the two side frame members 44. A part of each of the two side frame members 44, the front frame member 46 and the rear frame member 48 lie in a common plane, which defines a plane of the seat platform 4.

With the chair 14 in the neutral position the base frame assembly 10 is in the floor contacting position and the support frame 12 is raised off the floor such that there is a gap between the support frame 12 and the floor. Accordingly, in this embodiment, in the neutral position the castors 28 are in contact with the floor and the chair 14 is able to be moved across the floor on the castors 28.

With the chair 14 in the tilted position the base frame assembly 10 is in the floor contacting position and the support frame 12 is raised off the floor such that there is a gap between the support frame 12 and the floor. Accordingly, in this embodiment, in the tilted position the castors 28 are in contact with the floor and the chair 14 is -9 -able to be moved across the floor on the castors 28. In this way, a person seated on the chair 14 may be reclined so that there is a lessened risk of them falling off the chair 14 when the chair 14 is moved.

When the chair 14 in the rise position the support frame 12 is in its floor contacting position and the base frame assembly 10 is raised off the floor. As such, in this embodiment, the castors 28 are not in contact with the floor. With the support frame 12 in contact with the floor, the chair 14 cannot easily be moved across the floor (due in part to the weight of the chair 14) and, accordingly, the support frame 12 provides a stable and stationary support for the chair 14 in the rise position.

The chair frame 2 further comprises an actuator 50 configured to move the chair 14 between the tilted position, the neutral position and the rise position. In preferred embodiments the actuator 50 is a linear actuator. The linear actuator 50 is preferably configured such that at a first extent of movement of the linear actuator 50, when the linear actuator 50 has a first length, the chair 14 is in the tilted position and at a second extent of movement of the linear actuator 50, when the linear actuator 50 has a second length, the chair 14 is in the rise position. When the chair 14 is in the neutral position the linear actuator 50 preferably has a third length, between the first and second lengths. Accordingly, on movement of the chair 14 from the tilted position to the rise position the chair 14 will pass though the neutral position. Furthermore, the linear actuator 50 moves in a first direction to move the chair 14 from the neutral position to the tilted position and the linear actuator 50 moves in a second, opposite direction to move the chair 14 from the neutral position to the rise position. In the illustrated embodiment the first length of the linear actuator 50 is less than the third length of the linear actuator 50, and the third length of the linear actuator 50 is less than the second length of the linear actuator 50.

In this embodiment the actuator 50 forms part of a rise and recline mechanism 52 of the chair 14. Further details of the rise and recline mechanism 52 will now be described with particular reference to Figures 10 to 12.

The chair frame 2 further comprises a pair of couplers 54 connected between the seat platform 4 and the base frame 24. Each coupler 54 is connected at a first end 56 to one of the side frame members 44 of the seat platform 4 and at a second end 58 to a respective one of the side frame members 30 of the base frame 24. Each coupler 54 is preferably connected at the first end 56 approximately midway along a length of the side frame member 44 of the seat platform 4 and is preferably connected at the second end 58 approximately midway along a length of the side frame member 30 of the base frame 24. In this embodiment the connection between the first end 56 of the coupler 54 and the seat platform 4 is a fixed connection such that the coupler 54 extends from the side frame member 44 at a fixed angle.

Preferably the fixed angle is approximately 90°. In this embodiment the connection between the second end 58 of the coupler 54 and the base frame 24 is a pivotal connection. This enables an angle between an axis of the coupler 54 and the side frame member 30 of the base frame 24 to be varied. This in turn enables an angle between the plane of the seat platform 4 and a plane of the base frame 24 to be varied. In other embodiments the connection between the first end 56 of the coupler 54 and the seat platform 4 may be a pivotal connection and the connection between the second end 58 of the coupler 54 and the base frame 24 may be a fixed connection. The couplers 54 may extend between the seat platform 4 and the base frame 24 at any distance along the length of the side frame members 44 of the seat platform 4 and the base frame 24.

The base frame assembly 10 further comprises a pair of pivot plates 60 proximate the front frame member 32 of the base frame 24, a first pivot plate 60a being disposed proximate a first end 62 of the front frame member 32 and a second pivot plate 60b being disposed proximate a second end 64 of the front frame member 32. In this embodiment each pivot plate 60 connects a first end 66 of one of the side frame members 30 of the base frame 24 to a respective end 62, 64 of the front frame member 32.

A pair of first, lower connecting arms 68 extend between and connect the base frame assembly 10 and the support frame 12. Preferably a first end 70 of each of the lower connecting arms 68 is attached to the base frame assembly 10 and a second end 72 of each of the lower connecting arms 68 is attached to the support frame 12. In this embodiment the first end 70 of a first one of the lower connecting arms 68a is connected to the first pivot plate 60a and the first end 70 of a second one of the lower connecting arms 68b is connected to the second pivot plate 60b. The first end 70 of each of the lower connecting arms 68 is pivotally connected to the base frame assembly 10. The second end 72 of each of the lower connecting arms 68 is pivotally connected to the support frame 12. The second end 72 of each of the lower connecting arms 68 may be pivotally attached to a mounting element 74 of the support frame 12. In particular, the second end 72 of the first lower connecting arm 68a may be pivotally attached to a first mounting element 74a disposed proximate a first one of the side frame members 36 of the support frame 12. The second end 72 of the second lower connecting arm 68b may be pivotally attached to a second mounting element 74b disposed proximate a second one of the side frame members 36 of the support frame 12.

The chair frame 2 further comprises a pair of second, upper connecting arms 76. Each of the upper connecting arms 76 extends between and connects the base frame assembly 10 and the support frame 12. Preferably a first end 78 of each of the upper connecting arms 76 is attached to the base frame assembly 10 and a second end 80 of each of the upper connecting arms 76 is attached to the support frame 12. In this embodiment the first end 78 of a first one of the upper connecting arms 76a is connected to the first pivot plate 60a and the first end 78 of a second one of the upper connecting arms 76b is connected to the second pivot plate 60b. The first end 78 of each of the upper connecting arms 76 is pivotally connected to the base frame assembly 10. The second end 80 of each of the upper connecting arms 76 is pivotally connected to the support frame 12. The second end 80 of each of the upper connecting arms 76 may be pivotally attached to one of the mounting elements 74 of the support frame 12. In particular, the second end 80 of the first upper connecting arm 76a may be pivotally attached to the first mounting element 74a and the second end 80 of the second upper connecting arm 76b may be pivotally attached to the second mounting element 74b.

The chair frame 2 comprises a catch mechanism 82 comprising a catch member 84 and a peg 86. In this embodiment the chair frame 2 includes a pair of catch members 84 and a respective pair of pegs 86. Each catch member 84 is rotatably connected to one of the pivot plates 60 by a suitable pin (not shown) that defines a rotational axis 88 of the catch member 84. Each catch member 84 comprises a lever 90 and a hook portion 92. The lever 90 is disposed on one side of the rotational axis 88 and the hook portion 92 is disposed on an opposite side of the rotational axis 88. Each peg 86 extends or projects from one of the lower connecting arms 68. Each peg 86 projects from the lower connecting arm 68 proximate but at a distance from the first end 70 of the lower connecting arm 68, such that at certain rotational positions of the catch member 84 the hook portion 92 engages with and extends at least partially around the respective peg 86.

A link 94 extends between and connects the seat platform 4 and each of the catch members 84. In particular a first link 94a is connected at a first end 96 to the first side frame member 44a of the seat platform 4 and at a second end 98 to a first one 15 of the catch members 84a. A second link 94b is connected at a first end 96 to the second side frame member 44b of the seat platform 4 and at a second end 98 to a second one of the catch members 84b. Preferably the second end 98 of the each of the links 94 is pivotally or rotationally connected to a distal end 100 of the lever 90 (furthest from the rotational axis 88) of the respective one of the catch members 84. 20 In preferred embodiments each link 94 comprises a first section 102 and a second section 104. The second section 104 extends from the first section 102 such that an axis of the first section 102 is at an angle of between about 100° and 150° to an axis of the second section 104.

A pivot bar 106 extends between and is connected to the first and second catch members 84. In this embodiment a first end 108 of the pivot bar 106 is connected to the lever 90 of the first catch member 84a and a second end 110 of the pivot bar 106 is connected to the lever 90 of the second catch member 84b. The pivot bar 106 extends across the chair frame 2 in a direction substantially parallel to the front frame member 32 of the base frame 24.

In this embodiment a stop plate 107 is attached to the front frame member 32 of the base frame 24. The stop plate 107 provides a stop surface 109 formed by an edge of the stop plate 107. When the chair 14 is in its tilted position the pivot bar 106 is not in contact with the stop surface 109. When the chair 14 reaches its neutral position, the pivot bar 106 contacts the stop surface 109, which prevents further 5 rotation of the catch members 84. During movement of the chair 14 between the neutral position and the rise position the pivot bar 106 remains in contact with the stop plate 107 such that the catch members 84 remain in a fixed position relative to the base frame 24. In this embodiment the base frame assembly 10 comprises a first stop plate 107a proximate the first end 62 of the front frame member 32 and a 10 second stop plate 107b proximate the second end 64 of the front frame member 32.

The linear actuator 50 of the illustrated embodiment is pivotally or rotationally connected at a first end 112 to the support frame 12 and is pivotally or rotationally connected at a second end 114 to the pivot bar 106. Preferably the linear actuator 50 is centrally located across a width of the chair frame 2. The first end 112 of the linear actuator 50 is mounted to the cross member 38 of the support frame 12. The second end 114 of the linear actuator 50 is connected to the pivot bar 106 approximately midway between the first and second ends 108, 110 of the pivot bar 106.

The operation of the rise and recline mechanism 52 to move the chair 14 between the rise position, neutral position and tilted position will now be described with additional reference to Figures 13 to 18.

In the neutral position of the chair frame 2 (Figures 1, 2, 7, 10, 13 and 14) the seat platform 4, the base frame 24 and the support frame 12 are all substantially parallel to each other. As described above, the castors 28 of the base frame assembly 10 are in contact with the floor on which the chair 14 is standing, and the support frame 12 is raised off the floor. The chair 14 can therefore be moved as required on the castors 28. Furthermore, in the neutral position an end of the hook portion 92 of each of the catch members 84 is engaged with the respective peg 86. Because the catch members 84 are connected to the base frame assembly 10 and the pegs 86 are attached to the support frame 12, this engagement of the hooks 92 with the pegs 86 retains the support frame 12 in its raised position.

Starting from the neutral position, a user may then actuate the linear actuator 50 to move the chair frame 2 into its tilted or reclined position (Figures 5, 6, 9, 11, 17 and 18). The linear actuator 50 moves in a first direction such that, in this embodiment, a length of the linear actuator 50 decreases (from its third length to its first length). This causes the pivot bar 106 to apply a force to each of the levers 90 to rotate the catch members 84 in a first direction. This causes the hooks 92 to extend further around the pegs 86, so that each of the pegs 86 locates further in a bite or throat 116 of the respective hook 92. Because the hooks 92 remain engaged with the pegs 86 during movement of the chair 14 from the neutral position to the tilted position, the support frame 12 is unable to move with respect to the base frame assembly 10 and the support frame 12 remains in its raised position. Accordingly the base frame assembly 10 remains in its floor contacting position, such that the chair 14 can be moved as required on the castors 28.

Rotation of the catch members 84 in the first direction causes an angle between an axis of each lever 90 and the respective side frame member 30 of the base frame 24 to increase. In this embodiment each lever 90 extends substantially perpendicularly to the base frame 24 when the chair 14 is in the tilted position. The links 94 connected to the levers 90 in turn apply a force to the seat platform 4 to cause rotation of the couplers 54 about their pivotal connections. An angle of the plane of the seat platform 4 relative to the plane of the base frame 24 therefore increases, such that the seat of the chair 14 tilts or reclines rearwardly.

A user may then actuate the linear actuator 50 to move the chair frame 2 back to its neutral position and then into its rise position (Figures 3, 4, 8, 12, 15 and 16). The linear actuator 50 moves in a second direction such that, in this embodiment, a length of the linear actuator 50 increases (from its first length to its second length).

As the chair frame 2 moves back towards the neutral position rotation of the catch members 84 caused by movement of the pivot bar 106 means that each of the pegs 86 moves towards an end of the respective hook portion 92. It will be appreciated that movement of the peg 86 towards the end of the hook portion 92 is due to relative movement of the hooks 92 and the pegs 86. In this embodiment the pegs 86 remain stationary and the catch members 84 (and therefore the hook portions 92) move during movement of the chair frame 2 between the tilted and neutral positions.

As the length of the linear actuator 50 increases, the chair frame 2 moves past the neutral position towards the rise position. As the chair frame 2 moves past the neutral position, the hook portion 92 of each of the catch members 84 disengages from the respective peg 86. The support frame 12 is then able to move relative to the base frame assembly 10. The configuration of the upper and lower connecting arms 76, 68 and the connection of the first end 112 of the actuator 50 to the support frame 12 means that as soon as the hooks 92 disengage from the pegs 86 a continued increase in the length of the linear actuator 50 results in relative movement between the base frame 24 and the support frame 12 to increase a distance between the support frame 12 and the base frame 24. During an initial phase of movement the base frame assembly 10 remains in its floor contacting position and the support frame 12 moves in a direction towards the floor. When the support frame 12 is in contact with the floor, during a second phase of movement the base frame 24 moves relative to the support frame 12 such that the base frame assembly 10 is raised from its floor contacting position. The chair frame 2 is then supported on and by the support frame 12.

During the second phase of movement, once the base frame assembly 10 is raised from its floor contacting position, a continued increase in the length of the actuator 50 causes the base frame 24 and the seat platform 4 to tilt at an angle to the support frame 12. In particular, the base frame 24 and seat platform 4 move such that a distance between the front frame member 32 of the base frame 24 is closer to the support frame 12 that the rear frame member 34 of the base frame 24. Similarly, the front frame member 46 of the seat platform 4 is closer to the support frame 12 that the rear frame member 48 of the seat platform 4.

Contact of the pivot bar 106 with the stop surface(s) 109 when the chair 14 reaches the neutral position means that during movement of the chair 14 from the neutral position to the rise position the seat platform 4 does not move with respect to the base frame 24, and the seat platform 4 remains substantially parallel to the base frame 24.

To move the chair from the rise position back to the neutral position a user actuates the actuator 50 to move in its first direction so that a length of the actuator 50 decreases (from the second length to the third length). Initially, the base frame 24 and seat platform 4 move in a direction towards the support frame 12, and an angle between the plane of the base frame 24 and the plane of the support frame 12 and an angle between the plane of the seat platform 4 and the plane of the support frame 12 both decrease.

At a point in the movement of the actuator 50, the means 26 to facilitate movement of the chair 14 across the floor (in this embodiment the castors 28) makes contact with the floor. A further decrease in the length of the linear actuator 50 then causes the support frame 12 to raise off the floor. As the actuator 50 reaches its third length, and the chair 14 approaches the neutral position, the hook portions 92 of the catch members 84 engage with the pegs 86. This retains the support frame 12 in its raised position and the chair 14 is then fully supported by the base frame assembly 10, and in particular the castors 28.

The chair frame 2 further comprises means to adjust a height or distance between the floor and the seat platform 4 when the chair 14 is in the neutral position. This allows a seat height of the chair 14 to be varied depending on the use of the chair 14 and in particular on the needs of the users of the chair 14.

With particular reference to Figures 19 to 21, in this embodiment the means 26 for facilitating movement of the chair 14 across a floor comprises a height adjustment mechanism 118, which allows a distance between the base frame 24 and the floor to be adjusted when the chair 14 is in the neutral position or the tilted position.

In preferred embodiments each of the castors 28 is connected to the base frame 24 by a respective height adjustment mechanism 118. Each height adjustment mechanism 118 comprises a mounting plate 120 secured to the base frame 24. In particular a mounting plate 120 is secured proximate each of the four corners of the base frame 24. Each mounting plate 120 comprises a rectangular stem portion 122 including a plurality of threaded holes 124. The threaded holes 124 are arranged in a line that extends along an axis of the mounting plate 120. The mounting plate 120 further comprises a plurality of engagement teeth 126 extending from side edges 128 of the stem portion 122. The side edges 128 of the stem portion 122 extend substantially parallel to the axis of the mounting plate 120 and the engagement teeth 126 each extend in a direction substantially perpendicular to the side edges 128. A plurality of teeth 126 extend from each side edge 128 and are spaced apart along a length of the side edge 128, such that gaps 130 are provided between adjacent engagement teeth 126. Additionally, the engagement teeth 126 extend from the stem portion 122 at an angle to a plane of the stem portion 122, such that the engagement teeth 126 project from a first side surface 132 of the stem portion 122. In this embodiment four engagement teeth 126 extend from each side edge 128 of the mounting plate 120, such that there are three gaps 130 associated with each side edge 128 of the mounting plate 120.

Each height adjustment mechanism 118 further comprises a support plate 134 that engages with and is securable to the mounting plate 120. In particular, the support plate 134 includes a threaded hole 136, and a tooth 138 that extends from each side edge 140 of the support plate 134. Each tooth 138 extends from the support plate 134 at an angle to a plane of the support plate 134, such that each tooth 138 projects from a first side surface 142 of the support plate 134. Furthermore, each tooth 138 projects from the support plate 134 proximate a first end 144 of the support plate 134.

An arm 146 extends from a second side surface 148 of the support plate 134. In particular, a first end 150 of the arm 146 is attached to the support plate 134. The arm 146 is attached to the support plate 134 at a second end 152 of the support plate 134. One of the castors 28 is connected to a second end 154 of the arm 146. A spindle 156 of the castor 28 extends through a hole 158 in the arm 146 such that an axis of rotation of the spindle 156 is perpendicular to an axis of the arm 146.

Each tooth 138 of the support plate 134 is sized to be received in one of the gaps 130 between the engagement teeth 126 of the mounting plate 120. In a first orientation of the support plate 134 a first tooth 138a extending from a first side edge 140a of the support plate 134 locates in a gap 130 between adjacent engagement teeth 126 extending from a first side edge 128a of the mounting plate 120 and a second tooth 138b extending from a second side edge 140b of the support plate 134 locates in a gap 130 between adjacent engagement teeth 126 extending from a second side edge 128b of the mounting plate 120. With each tooth 138 of the support plate 134 engaged with the engagement teeth 126 of the mounting plate 120, the threaded hole 136 in the support plate 134 is aligned with one of the threaded holes 124 in the mounting plate 120. A securing bolt (not shown) can then be inserted through the aligned holes 124, 136 to secure the support plate 134 to the mounting plate 120, and therefore secure the arm 146 and castor 28 to the base frame 24.

In the first orientation of the support plate 134, the support plate 134 is secured to the mounting plate 120 such that the first end 144 of the support plate 134 is above the second end 152 of the support plate 134. In this first orientation the arm 146 is in a first position relative to the base frame 24 such that there is a first distance between the castor 28 (and therefore the floor) and the base frame 24.

In a second orientation of the support plate 134, the first tooth 138a extending from the first side edge 140a of the support plate 134 locates in a gap 130 between adjacent engagement teeth 126 extending from the second side edge 128b of the 25 mounting plate 120 and the second tooth 138b extending from the second side edge 140b of the support plate 134 locates in a gap 130 between adjacent engagement teeth 126 extending from the first side edge 128a of the mounting plate 120. In this second orientation the threaded hole 136 in the support plate 134 aligns with another one of the threaded holes 124 in the mounting plate 120 so that the support plate 134 may still be secured to the mounting plate 120 using a suitable bolt.

In the second orientation of the support plate 134, the support plate 134 is secured to the mounting plate 120 such that the second end 152 of the support plate 134 is above the first end 144 of the support plate 134. In this second orientation the arm 146 is in a second position relative to the base frame 24 such that there is a second distance between the castor 28 (and therefore the floor) and the base frame 24, the second distance being different to the first distance.

So that the castors 28 remain in contact with the floor, it will be appreciated that when the support plate 134 is to be secured to the mounting plate 120 in the second orientation, the spindle 156 of the castor 28 is inserted through the hole 158 in the second end 154 of the arm 146 in the opposite direction to when the support plate 134 is secured to the mounting plate 120 in the first orientation. The ability to insert the spindle 156 of the castor 28 through the hole 158 in the arm 146 in two different directions may be achieved by a simple push fit of the spindle 156 into the hole 158.

In the present embodiment, therefore, in which four engagement teeth 126 extend from each side edge 128 of the mounting plate 120, such that there are three gaps 130 associated with each side edge 128 of the mounting plate 120, the support plate 134 may be engaged with the mounting plate 120 such that there are six different positions of the arm 146 relative to the base frame 24. The seat platform 4, and therefore the seat of the chair 14, may therefore be secured at one of six different heights.

The present invention therefore provides a chair that has a more stable support structure when the chair is raised but which enables the chair to be easily moved across the floor when the chair is not raised.

Claims

-20 -CLAIMS1. A chair frame comprising: a seat platform; a support frame; a base frame assembly including a base frame and means to facilitate movement of the chair across a floor; and an actuator configured to move the seat platform relative to the support frame and the base frame, wherein the chair has a first state in which the base frame assembly is in a floor contacting position and the position of the seat platform relative to the base frame is variable and a second state in which the support frame is in a floor contacting position and the position of the seat platform relative to the support frame is variable.
2. A chair frame as claimed in Claim 1, wherein the actuator is configured to move the seat platform between a recline position when the chair is in the first state and a rise position when the chair is in the second state.
3. A chair frame as claimed in Claim 1 or Claim 2, wherein the actuator is a linear actuator.
4. A chair frame as claimed in Claim 3, wherein the linear actuator travels through a first range of movement when the chair is in the first state and through a 25 second range of movement when the chair is in the second state.
5. A chair frame as claimed in any preceding claim, wherein the means to facilitate movement of the chair across a floor comprises castors.
6. A chair frame as claimed in any preceding claim, further comprising a catch mechanism configured to cause the chair to transition between the first and second states. -21 -
7. A chair frame as claimed in Claim 6, wherein the catch mechanism is engaged with the support frame when the chair is in the first state and disengaged from the support frame when the chair is in the second state.
8. A chair frame as claimed in Claim 6 or Claim 7, wherein the catch mechanism comprises a hook connected to one of the base frame assembly and the support frame and a peg connected to the other one of the base frame assembly and the support frame, the hook being engaged with the peg when the chair is in the first state.
9. A chair frame as claimed in Claim 8, wherein the catch mechanism comprises a hook connected to the base frame assembly and a peg connected to the support frame, and a lever extends from the hook and is connected to the seat platform.
10. A chair frame as claimed in Claim 8 or Claim 9, wherein the peg extends from a connecting arm extending between the base frame and the support frame.
11. A chair frame as claimed in any preceding claim, wherein in the first state an angle between a plane of the seat platform and a plane of the base frame is variable.
12. A chair frame as claimed in any preceding claim, wherein in the second state an angle between a plane of the seat platform and a plane of the support frame is variable.
13. A chair frame as claimed in any preceding claim, wherein in the first state the support frame is not in a floor contacting position and in the second state the base frame assembly is not in a floor contacting position.
14. A chair frame as claimed in any preceding claim, further comprising a stop surface configured to retain the hook in a fixed position relative to the base frame when the chair is in the second state.
15. A chair frame as claimed in any preceding claim, further comprising a height -22 -adjustment mechanism permitting a distance between a plane of the base frame and a floor contacting plane of the means to facilitate movement of the chair across a floor to be adjusted.
16. A chair frame as claimed in Claim 15, wherein the height adjustment mechanism comprises a mounting plate including a plurality of gaps and a support plate having a tooth, the tooth being engageable in each of the gaps, and the mounting plate being attached to the base frame and the support plate being attached to the means to facilitate movement of the chair across a floor.
17. A chair frame as claimed in Claim 16, wherein the means to facilitate movement of the chair across a floor comprises castors, and wherein an arm extends from the support plate and a castor is attached to the arm by a spindle, and the spindle is engageable with the arm to secure the castor to the arm in two different and opposite directions.