The present invention relates to an adjustable chair. In particular, the present invention relates to an adjustable chair with a variable seat depth and optionally and adjustable footrest height.

BACKGROUND OF THE INVENTION

Conventional chairs are designed to fit and support a user’s body. Some are adjustable with respect to arm rest height or the incline of the back support. Some include adjustable lumbar supports for optimal support of the user’s spine.

However, these adjustability options are not sufficient for a chair for use by users of multiple heights and body shapes. For example, a school chair may be used by a schoolchild over many months, during which time the schoolchild will be growing in height and weight.

Gradually, they will outgrow the chair which leads to discomfort, poor posture and potentially back pain. Alternatively, a school chair may be used by more than one child of differing heights and body shapes on a regular basis. However, without sufficient adjustability the chair will not be suitable for all.

As children grow, their leg length increases. Thus, an increase in their lower leg length will require a chair of increasing height to ensure that the child’s foot can be flat on the floor whilst the underside of their leg makes contact across the seat base. This means that some of the load is supported through the feet whilst the underside of the leg has even pressure against the seat base. This seated position tends to result in an approximate 90 ° bend at the knee when the child is properly seated and supported by the chair. Further, an increase in their upper leg length will require a chair with a deeper seat base to ensure that their upper leg is sufficiently supported in a direction towards the knee. To keep measuring children throughout their time at school and provide a new chair of suitable dimensions to accommodate their growth on a regular basis is time-consuming and expensive.

There is therefore a need for a chair that is suitably adjustable to accommodate the changing leg length of the child over time.

SUMMARY OF THE INVENTION

The present invention seeks to address the problems of the prior art. Aspects of the present invention are set out in the attached claims. According to a first aspect of the present invention, there is provided an adjustable chair comprising: a seat base defining a seating surface portion for receiving a user thereon in use, the seat base comprising an integral seat back engagement portion for engaging with a portion of a seat back, a seat front portion opposing the seat back engagement portion, a first seat side portion and a second seat side portion opposing the first seat side portion, each of the first and second seat side portions located between the seat back engagement portion and the seat front portion and extending substantially transverse to the seat surface portion; and a seat back having a seat base engagement portion dimensioned to slidably engage with the seat back engagement portion to form a seat back adjustment mechanism, wherein the seat back adjustment mechanism is located adjacent at least one of the first and second seat side portions and wherein the seat back adjustment mechanism is movable between a first locked configuration in which the seat back and seat base are fixed relative to one another and the seating surface portion has a fixed surface area, and a second released configuration in which the seat back is slidable relative to the seat base to vary the surface area of the seating surface portion.

Thus, the depth of the seat base can be varied by moving the seat back relative to the seat base to adjust the seating area available for a user to sit on, in use. Thus, for a user of lesser height, the seating surface portion and thus seat depth can be adjusted to bring the seat back closer to the front of the seat base to allow the user to sit comfortably with their back against the seat back.

Having the seat back engagement portion integral with the seat base provides the advantage of simplification of design, with associated cost savings, and increased ease of assembly. Further, the integral nature of the seat back engagement portion and seat base provide the chair with greater structural integrity and strength.

The location of the seat back adjustment mechanism is important. The seat back

adjustment mechanism is provided on the outside edge of the seat base i.e. adjacent at least one of the first and second seat side portions, rather than underneath the seat base. This increases the visibility of the seat back adjustment mechanism.

Further, the seat back adjustment mechanism is provided on the outside edge of the seat base, rather than on the upper surface of the edge of the seat base, to avoid the adjustment mechanism collecting dust and potentially having objects inserted in it e.g. chewing gum and the like, which could potentially damage the mechanism. Further, if provided on the upper surface of the edge of the seat base, a user sitting on the chair could inadvertently apply downward force on the mechanism, thereby releasing the latch from the recess and accidentally allowing the seat back to slide relative to the seat base.

In one embodiment, the seat back adjustment mechanism comprises: a first engagement portion for engagement with a latch; and a latch pivotable about a pivot point, the latch comprising a second engagement portion for engagement with the first engagement portion, wherein the latch is pivotable between the first locked configuration in which the first and second engagement portions are in rigid engagement with one another and the seat back and seat base are fixed relative to one another, and the second released configuration in which the first and second engagement portions are in slidable engagement with one another and the seat back is slidable relative to the seat base.

In one embodiment, the first engagement portion comprises a plurality of recesses, each recess being dimensioned to receive at least a portion of the second engagement portion therein.

Preferably, the latch is biased towards the first engagement portion.

The latch may be biased towards the first engagement portion under force from a coil spring engaged with the latch and arranged between the latch pivot point and the second engagement portion.

Preferably, the latch is pivotable between the first locked configuration and the second released configuration on application of force to a portion of the latch located distal to the second engagement portion.

In one embodiment, the seat base engagement portion comprises the first engagement portion and the seat back engagement portion comprises the latch.

Preferably, the seat back is provided as a single-piece moulding. This provides strength to the chair and stability for the slidable movement of the back rest relative to the seat base.

More preferably, the seat back is provided with a plurality of apertures which act as air-holes to provide ventilation to the back of a user when sitting in the chair. The apertures further allow controlled flexing of the seat back by a user when sitting in the chair, thus increasing the comfort of a user, during use.

In one embodiment, the adjustable chair comprises a second seat back adjustment mechanism such that a seat back adjustment mechanism is located adjacent each of the first and second seat side portions, both seat back adjustment mechanisms must be moved from the first locked configuration to the second released configuration to allow the seat back to be slidable relative to the seat base.

In a further embodiment, the adjustable chair further comprises a footrest extending away from the seat base, the footrest comprising: a first footrest portion extending away from the seat base, the first footrest portion comprising a footrest engagement portion for

engagement with a second footrest portion; and a second footrest portion comprising a footplate for receiving the feet of a user in use, , the second footrest portion having a first footrest engagement portion dimensioned to slidably engage with the footrest engagement portion to form a footrest adjustment mechanism, and the footplate being arranged distal to the first footrest engagement portion, wherein the footrest adjustment mechanism is moveable between a footrest locked configuration in which the first and second footrest portions are in fixed engagement with one another and the footplate is at a fixed distance from the seat base, and a footrest released configuration in which the first and second footrest portions are slidable relative to one another to adjust the distance between the footplate and the seat base.

In one embodiment, the footrest adjustment mechanism comprises: a first engagement portion for engagement with a latch; and a latch pivotable above a fixed pivot point, the latch comprising a second engagement portion for engagement with the first engagement portion, wherein the latch is pivotable between the footrest locked configuration and the footrest released configuration.

In one embodiment, the footrest adjustment mechanism first engagement portion comprises a plurality of recesses, each recess being dimensioned to receive at least a portion of the footrest adjustment mechanism second engagement portion.

Preferably, the footrest adjustment mechanism latch is biased towards the plurality of recesses of the footrest adjustment mechanism.

The footrest adjustment mechanism latch may be biased towards the plurality of recesses of the footrest adjustment mechanism under force from a second coil spring engaged with said latch and arranged between the pivot point of said latch and the footrest adjustment mechanism latch recess engagement portion. Preferably, the footrest adjustment mechanism latch is pivotable between the footrest locked configuration and the footrest released configuration on application of force to a portion of the said latch located distal to the latch recess engagement portion.

In one embodiment, the first footrest portion comprises the first engagement portion and the second footrest portion comprise the footrest adjustment mechanism latch.

In one embodiment, the first footrest portion is pivotally engaged with the seat base.

Preferably, the footrest is pivotable from the vertical position to a position beneath the seat base. This allows the user to move the footrest backwards slightly when standing in position to lower themselves into the chair. As the user’s feet move slightly beneath the seat base in the normal manner, the footrest will be swung away from the vertical in a direction towards the seat base by the lower legs of the user as their feet are moved under the chair. This movement of the footrest is particularly beneficial when a user slides the chair forwards, for example, when sliding the chair under a desk. The user’s feet will inevitably end up beneath the chair as they are sliding it, and the benefit of the footrest swinging away from the vertical is extremely beneficial in such a situation.

In one embodiment, the footrest is pivotable from the vertical position in a direction away from the seat base.

An adjustable chair as claimed in claim 15, wherein the seat base defines a first plane and the footrest pivots in a second plane, wherein the first and second planes are transverse to one another.

The footrest pivot position is carefully selected so that it is at approximately the same height as the natural pivot point of the user’s knee joint. Thus, when swinging, the footplate remains at approximately the same distance from the knee of the user. This also allows an increased level of upward swing movement of the footrest.

A further advantage of a swinging footrest is the ability of a user e.g. a child, to move the footrest (in a fidgeting fashion) while resting their feet on it during use of the chair. Studies have demonstrated that this leg movement in children can assist with concentration during learning events and assists with the dissipation of excess energy, whilst remaining in the seated position.

A further advantage of the footrest feature is safety related. Whilst using a chair with a footrest that is adjustable to accommodate the leg-length of the user, the user is less likely to attempt to put their feet on the floor during use of the chair and try to push backwards such that the chair tips on the rear legs. Excess tipping can destabilise the chair, resulting in the child being injured as they fall backwards with the chair.

A further advantage of the chair of the present invention is that the height of the chair is fixed, and it is the backrest and/or footrest that are adjustable in dependence upon the dimensions of the user. Thus, in a classroom setting, every child will be sitting at the same height on the base. Thus, no matter the height of an individual child, they will be at the same level as their peers of various different heights to themselves. Further, this means that each child will be seated at an appropriate height to use fixed height desks and tables.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a view from one side of an embodiment of a chair in accordance with the present invention;

Figure 2 is a front view of the chair of figure 1 ;

Figure 3 is a view from the other side of the chair of figure 1 ;

Figure 4 is a rear view of the chair of figure 11 ;

Figure 5 is a perspective view from behind of the chair of figure 1 ;

Figure 6 is a perspective view from the front of the chair of figure 1 ;

Figure 7 is a view from above of the chair of figure 1 ;

Figure 8 is a view from below of the chair of figure 1 ;

Figure 9 is a front view of the chair back of the chair of figure 1 ;

Figure 10 is a perspective view of the chair back of figure 9;

Figure 11 is a front view of the footrest of the chair of figure 1 in an extended configuration;

Figure 12 is a perspective view of the footrest of figure 11 ;

Figure 13 is a front view of the footrest of the chair of figure 1 in a retracted configuration;

Figure 14 is a perspective view of the footrest of figure 13;

Figure 15 is a perspective view of the chair of figure 1 , showing the foot rest in an extended configuration and the back rest in an extended configuration;

Figure 16 is a perspective view of the chair of figure 1 , showing the footrest in a retracted configuration and the chair back in a retracted configuration;

Figure 17 is a side view of the chair of figure 15;

Figure 18 is a side view of the chair of figure 16:

Figure 19 is a front view of the chair of figure 15; Figure 20 is a front view of the chair of figure 16;

Figure 21 is a side view of the chair of figure 1 , showing the footrest in an extended configuration and pivoted outwards from the chair base;

Figure 22 is a side of the chair of figure 1 , showing the footrest in an extended configuration and pivoted inwards under the chair base;

Figure 23 is a perspective view of the chair of figure 22;

Figure 24 is a perspective view of the chair of figure 23;

Figure 25 is a block illustration of the front view of the chair of figure 1 ;

Figure 26 is a section B-B through the chair of figure 25;

Figure 27 is a section A-A through the chair of figure 25;

Figure 28 is an enlarged view of the detail D of figure 26;

Figure 29 is an enlarged view of the detail C of figure 27;

Figure 30 is a side view of a user sitting in an embodiment of a chair in accordance with the present invention with the footrest swung forward (the adjustable backrest is not shown); and

Figure 31 is a side view of the user and chair of figure 30 with the footrest swung under the seat base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the figures, the same figures references have been used to refer to the same features of the invention.

The figures show an adjustable chair 10 comprising a seat base 12 adapted to receive a user thereon in use and defining an exposed seating surface area 14 for receiving a user thereon in use. Seat base 12 is substantially planar. Although shown as a one-piece moulding, it will be appreciated that the seating surface area 14 may padded for the comfort of the user. In the embodiment shown, the front edge 40 of seat base 12 is shown as curved, in a contour known in the industry as a‘waterfall’ front edge. This assists with the comfort of a user and the back of a user’s knees are supported by a smooth curved surface.

The chair 10 further comprises a seat back 16. Seat back 16 has an elongate U-shaped seat base engagement portion 18 and seat base 12 has a corresponding seat back engagement portion 20 which is an elongate tubular structure and is dimensioned to fit within the U-shaped seat base engagement portion and is in slidable engagement with seat back engagement portion 20 to form an adjustment mechanism 24. Seat back adjustment mechanism 24 is composed of the seat base engagement portion 18 and the seat back engagement portion 20.

Seat back engagement portion 20 is provided with a plurality of recesses 26 and seat base engagement portion 18 is provided with a latch mechanism.

The latch mechanism comprises a latch 28 which is pivotably about fixed pivot point 30 and a coil spring 32. Latch 28 comprises a coil spring engagement portion 34 which is engaged with coil spring 32. Latch 28 further comprises a recess engagement portion 36 located on the same side of the pivot point 30 as the coil spring 32. Recess engagement portion 36 is located adjacent recesses 26 and is dimensioned to be received within one of the plurality of recesses. Coil spring 32 biases the latch 28 towards the recesses 26 and holds the latch recess engagement portion 36 within a selected recess 26, in use.

The button portion 38 of latch 28 distal to the recess engagement portion 36 comprises a convex surface to allow easy engagement by a user during adjustment of the seat back adjustment mechanism.

Latch 28 is provided such that the button portion 38 is presented on the outward edge of the seat base 12. This allows ease of access for a user, whilst avoiding the disadvantages of conventional chairs where adjustment mechanisms are provided on the upper surface of the edge of the seat base i.e. foiling of the adjustment mechanism by dust and other debris. Further, the potential danger of accidental release of the adjustment mechanism by inadvertently leaning on it, is avoided.

Thus, in use, the recess engagement portion 36 of latch 28 is biased by coil spring 32 into a recess 26, thus preventing the seat base engagement portion 18 and seat back engagement portion 20 from being slidable relative to one another. It is to be appreciated that, when the backrest is pushed backwards, once engaged, any pressure applied to the latch mechanism (apart from pressure applied to button portion 38) will not encourage the latch 28 to be released from the recess 26. Instead, the recess engagement portion 36 will be more firmly pushed into engagement with the recess 26.

On application of force by a user to the button portion 38 of latch 28, latch 28 is pivoted about the fixed pivot point 30 to compress coil spring 32 and move coil spring engagement portion 36 of latch 28 out of engagement with recess 26. Once the coil spring engagement portion 36 and recess 26 are disengaged, seat base engagement portion 18 and seat back engagement portion 20 can be slidably moved relative to one another thus moving the seat back relative to the seat base and altering the exposed seating surface are 14.

Seat base 12 has a front edge 40 and a rear edge 42. Movement of the seat back 16 in a direction from the rear edge 42 of seat base 12 towards the front edge 40 of seat base 12 will reduce the exposed seat surface area 14. Subsequent return movement of the seat back 16 toward the rear edge 42 of seat base 12 will increase the exposed seating surface area 14 available for a user to sit on.

After slidable movement of seat back 16 relative to seat base 12, release of force on button portion 38 of latch 28 will allow the latch 28 to pivot back about fixed pivot point 30 under the biasing influence of coil spring 32 as it decompresses, thus bringing recess engagement portion 36 of latch 28 back into contact with the seat back engagement portion so that the recess engagement portion 36 of latch 28 may once again engage with one of the recesses 26. The amount of adjustment made to the seating surface area 14 depends on the amount of movement of seat base engagement portion 18 relative to seat back engagement portion. The plurality of recesses is provided at staggered intervals to permit a plurality of points of adjustment and therefore a corresponding number of different sizes of seating surface area 14 that may be achieved using the same adjustable chair. Typically, the range of adjustment will be sufficient to accommodate the anticipated range of heights of potential users of the chair. Ideally, the plurality of recesses will be evenly spaced and sufficient in number to cover the full range of adjustment and allow incremental adjustments to be made to suit the requirements of a user.

Thus, adjustment of the position of the seat back 16 relative to the seat base 12 will vary the seating surface area 14 and, in particular, will vary the distance between the seat back 16 and the front edge 40 of seat base 12. This allows the same adjustable chair to be used by users of different heights. More specifically, the chair can be adjusted to suit users where the distance between the hips and knees of each user varies. This is particularly important where the chair is to be used by an individual child who will grow in height over time or where the chair is to be used by multiple individuals of different heights and/or femur lengths.

Seat back 16 is provided as a single-piece moulding and is provided with apertures 17. The single-piece moulding provided stability to the seat back adjustment mechanism, whilst apertures 17 act as ventilation to allow air to circulate around the back of the user to increase comfort levels during use. Further, apertures 17 allow a controlled level of flex within the seat back 16, thus further assisting with the comfort of the user when sitting in the chair 10. The chair 10 is further provided with a footrest 22 extending from the front edge 40 of seat base 12. The footrest is specifically shown in figures 11 and 12 and comprises a first footrest portion 44 and a second footrest portion 46 engaged with first footrest portion 44. First footrest portion 44 extends away from the seat base 12 and comprises a second footrest engagement portion 48 for engagement with the second footrest portion 46. First footrest portion 44 further comprises a seat base attachment portion 50 which engages with footrest attachment portion 52 of seat base 12.

Second footrest portion 46 comprises a footplate 54 for receiving the foot of a user in use. The footplate 54 is arranged distal to the first footrest portion 44. Second footrest portion 46 further comprises a first footrest engagement portion 56 dimensioned to slidably engage with the second footrest engagement portion 56 on the first footrest portion 44. First and second footrest engagement portions form a footrest adjustment mechanism 58.

Footrest adjustment mechanism 58 is composed of the second footrest engagement portion 50 of the first footrest portion 44 and the first footrest engagement portion 56 of the second footrest portion 46.

First footrest portion 44 is provided with a plurality of recesses 64 and second footrest portion 46 is provided with a latch mechanism.

The latch mechanism comprises a latch 60 which is pivotable about fixed pivot point 62 and a coil spring 70. Latch 60 comprises a coil spring engagement portion 72 which is engaged with coil spring 70. Latch 60 further comprises a recess engagement portion 74 located on the same side of the pivot point 62 as the coil spring 70. Recess engagement portion 74 is located adjacent recesses 64 and is dimensioned to be received within one of the plurality of recesses 64. Coil spring 70 biases the latch 60 towards the recesses 64 and holds the latch recess engagement portion 74 within a selected recess 64, in use.

The button portion 76 of latch 60 distal to the recess engagement portion 74 comprises a convex surface to allow easy engagement by a user during adjustment of the footrest adjustment mechanism 58.

Thus, in use, the recess engagement portion 75 of latch 60 is biased by coil spring 70 into a recess 64, thus preventing the first footrest engagement portion 56 and the second footrest engagement portion 48 from being slidable relative to one another. Once engaged, any pressure applied to the footrest in a downward direction will not encourage the latch 60 to be released from the recess 64. Instead, the recess engagement portion 75 will be more firmly pushed into engagement with the recess 64 on application of downward pressure on the footplate 54 by the feet of a user.

On application of force by a user to the button portion 76 of latch 60, latch 60 is pivoted about the fixed pivot point 62 to compress coil spring 70 and move coils spring engagement portion 72 of latch 60 out of engagement with recess 64. Once the coil spring engagement portion 72 and recess 64 are disengaged, the first footrest engagement portion 56 may be slidably moved relative to the second footrest engagement portion 48, thus moving the second footrest portion 46 relative to the first footrest portion 44 and altering the distance between the footplate 54 and the front edge 40 of seat base 12.

Movement of the second footrest portion 46 in a direction away from the seat base 12 will extend the length of the footrest 22, thus extending the distance between the footplate 54 and the seat base 12. Subsequent return movement of the second footrest portion 46 back towards the seat base 12 will reduce the length of the footrest 22 and thus bring the footplate 54 closer to the seat base 12.

After slidable movement of the second footrest portion 46 relative to the first footrest portion 44, release of force on button portion 74 of latch 60 will allow the latch 60 to pivot back about fixed pivot point 62 under the biasing influence of coil spring 70 as it decompresses, thus bringing recess engagement portion 74 of latch 60 back into contact with the second footrest engagement portion 48 so that the recess engagement portion 74 of latch 60 may once again engage with one of the recesses 64. The amount of adjustment made to the length of the footrest 22 depends on the amount of movement of the first footrest engagement portion 56 relative to the second footrest engagement portion 48. The plurality of recesses 64 are provided at staggered intervals to permit a plurality of point of adjustment and therefore a corresponding number of different footrest 22 lengths that may be achieved using the same adjustable chair.

Thus, adjustment of the position of the second footrest portion 46 relative to the first footrest portion 44 will vary the overall length of the footrest 22 and, in particular, will vary the distance between the footplate 54 and the front edge 40 of seat base 12. This allows the same adjustable chair to be used by users of different heights. More specifically, the footrest can be adjusted to suit users where the distance between the feet and knees of each user varies. This is particularly important where the chair is to be used by an individual child who will grow in height over time or where the chair is to be used by multiple individuals of different heights and/or tibia lengths. Thus, without the need to alter the height of the chair, a user who is not sufficiently tall to place their feet on the ground when sitting in the chair can still use the chair with comfort by adjusting the footrest 22 length so that the footplate 54 is located an appropriate distance from the front edge 40 of seat base 12 to allow them to comfortably rest their feet on footplate 54 when seated on seat base 12.

The seat base attachment portion 56 of the first footrest portion 44 is pivotably attached to the footrest attachment portion 52 of seat base 12. Thus, footrest 22 can be pivoted about front edge 40 of seat base 12 to allow a user to pivot the footrest 22 out of the way when sitting down or getting up from the chair.

In the‘rest’ position, the footrest 22 will hang approximately vertically under the influence of gravity. When sitting down, a user will typically position their legs slightly under the seat base 12. As they move their legs into this position, the back of their lower legs will apply force to the footrest 22 to pivot it away from the vertical and slightly under the seat base 12. As the user relaxes in the chair, and moves their lower leg forwards, the footrest 22 will return under gravity to the vertical‘rest’ position and the user may then place their feet on the footplate 54. This movement of the footrest 22 away from the vertical and under the seat base 12 is particularly useful when a user has their feet on the ground and is attempting to slide the chair, for example, under a desk or table. The footrest 22 will then swing away from the vertical under the influence of the user’s legs, thereby not interfering with the user’s intention whilst sliding the chair in a forward direction.

Alternatively, the pivot design could be modified to bias the footrest in the‘rest’ position such that the footrest 22 will naturally sit vertically. However, due to the pivot geometry, if the chair is pushed backwards or forwards, the footrest 22 will swing under the influence of contact with the user’s lower legs. However, if a downward force is applied to the footplate 54 by a user sitting in the chair, movement of the footrest 22 away from the vertical will be move difficult i.e. the greater the weight applied to the footplate 54, the harder it will be to swing the footrest 22 backwards and forwards. This ensures that, when sitting in the chair, the footrest 22 is less likely to swing away from the vertical when a user is resting their weight on the footplate 54 through application of force through their feet.

It is to be appreciated that the latch design for both the backrest and footrest adjustment mechanisms is such that when load is applied it is not the pivots that are loaded. Instead, it is the outside of the catch that are loaded such that the latch is pushed in against the recess in which it is received. This avoids the situation where the pivots could shear under the weight of a user. A seat back adjustment mechanism is located on each side of the chair in the described embodiment. However, a single footrest adjustment mechanism is provided, thereby providing the advantage of single-handed adjustment of the distance of the footplate 54 from the seat base 12. A centrally located pivot point for the footrest relative to the seat base is provided in the described embodiment, rather than a pivot point being provided at each side of the front edge of the seat base. The centrally located pivot point is out of reach of a user sitting on the chair. Whereas, if the pivot point was located at each side of the front edge of the seat base, there is a potential risk of the user’s fingers being trapped when swinging the footrest if their hands were resting towards the front edge of the seat base 12.