GB2475115A

GB2475115A - Chair with adjustable backrest

Info

Publication number: GB2475115A
Application number: GB201011082A
Authority: GB
Inventors: Lydia Marie Addison
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-07-28
Filing date: 2010-07-01
Publication date: 2011-05-11
Anticipated expiration: 2030-07-01
Also published as: GB2475115B; GB201011082D0; GB0913186D0

Abstract

An adjustable chair comprises a backrest 3 or lumbar support which is adjustable relative to a seat portion 2 to vary the height and simultaneously to adjust the position of the backrest along the seat portion, thereby varying the depth of the seat portion. The backrest is adjusted by moving it along an angle or incline. The seat portion may also be height adjustable. The seat portion may be mounted on a framework 4 including two similar, opposed tubular members 4a, 4b of low friction material, mounted at a slope relative to the seat. An adjusting mechanism for the backrest is described which may be in the form of a ratchet or rack and pinion. A method for using the chair is also described.

Description

IMPROVEMENTS IN OR RELATING TO FURNITURE

This invention relates to improvements in or relating to furniture and is more particularly but not exclusively concerned with adjustable seating for school children of varying ages.

It tends to be a problem in schools (more particularly in secondary schools) that the same chairs are used by a variety of pupils of varying ages and such chairs are generally not adjustable to cater for the posture requirements and desired lumbar support parameters for the age range and size/height of different pupils. Such chairs may not be ergonomic and may cause some level of discomfort more particularly when used to support a pupil for relatively long periods of time. In an attempt to alleviate this problem, chairs with adjustable backrests have been previously proposed (see e.g. International Patent Specification No. W020070595585). However, such chairs tend to be disadvantageous because the backrest, acting as a lumbar support, is selectively adjustable only in a vertical plane (to adjust the height of the backrest relative to a seat portion) and thus would appear restrictive in the range of support that may be provided.

Once again, where an adjustable backrest is provided it may not be as easily and readily adjustable by e.g. a pupil, particularly whilst the pupil remains seated on the chair, as might otherwise be the case.

It is recognised that sitting for too long in one position or in poor posture can lead to back pain and there is growing concern to the high incidence of chronic and recurrent back pain amongst adolescents which may be due at least in part to the seating utilised in schools to cater for an unrealistic age/size range of pupil. Moreover, it is believed that, in particular, secondary school is a crucial stage of a pupil's development and that bad or ineffective seating could lead to posture problems and even permanent injury or deformity. Owing to body development in secondary school, some children undergo growth spurts' at different ages and thus in any one age group there are likely to be children of widely differing size that tend not to be catered for effectively by current seating. Moreover, sitting in discomfort naturally tends to affect attention span leading to under achievement in academic performance. At present possibly only 50th percentile of pupils' lumbar and posture requirements are being met by current school seating. In an effort to address these problems British Standards have been introduced recently regarding the safety and functionality of such seating (see BS EN 1729-1: 2006). Moreover, it is believed by the Applicant that chair design could be improved to provide correct support for a range of age and size and meet required British Standards, within a single chair.

In infant, nursery and junior schools, a range of chairs of different sizes may be provided in different classrooms correlated to different age ranges. In general, children of one age remain in the same classroom for all academic lessons (rather than continually changing rooms for different lessons as in secondary schools) and the classroom environment may be quite informal Qarticularly in nursery) so that children may not have to remain formally seated for large periods of time. Thus, the problems that tend to exist in providing one chair able to seat children of varying size and age in a comfortable manner for relatively long periods of time would seem much more acute in secondary schools. Even so, it is believed that nursery, infant, and junior schools could still benefit from a chair design able to comfortably seat children of varying age/size ranges and this should also alleviate mismatch chair problems that can occur when purchasing different furniture across a plurality of year groups e.g. three year groups in nursery schools.

Accordingly, it is an object of the present invention to provide a seating apparatus or chair which at least alleviates one or more of the aforementioned problems, or other problem, associated with adjustable seating apparatus/chairs or to provide a seating apparatus/chair which is improved in at least some respect.

According to the present invention there is provided a seating apparatus or chair comprising a backrest which is adjustable relative to a seat portion, said backrest being adjustable (along an incline) relative to the seat portion to vary the height of the backrest (or height of the foremost position of the backrest) relative to the seat portion and simultaneously adjust the position of the backrest along the seat portion.

Further according to the present invention there is provided a backrest adjustment meanslmechanism for a seating apparatus/chair in accordance with the immediately preceding paragraph.

Advantageously, the seating apparatus / chair may be adjusted to simultaneously vary the height of backrest (in particular the height of the foremost point of the backrest) relative to the seat position and the depth of available seat position for sitting upon, by movement of the backrest along the seat portion. In this manner, the backrest is moved, along the seat position, to the correct position for supporting the back of a person / pupil whilst seated in a correct posture with the foremost point of the backrest being at the correct height and forward location for comfortable seating.

Advantageously, embodiments of the present invention may provide a seating apparatus/chair which is suitable for a wide age/size range of persons (pupils) and/or which may allow easy and ready adjustment by a person (particularly a pupil) whilst remaining seated on the chair.

Preferably, the backrest is lockable in at least two, but preferably three or more adjusted back support positions relative to the seat portion by any convenient means.

Preferably, the angle of adjustment incline is about 14 +1-1 or 2 or 3 degrees to the horizontal in order to cater in a particularly satisfactory manner to the comfort of different persons/pupils of varying age/size and achieve three set sizemarks (or more) specified within British Standards recommendations for secondary school seating..

The seat portion (or part thereof) may be at a slight forward upward angle to the horizontal e.g. 2 or 3 degrees.

Preferably, the seating apparatus/chair has a seat which is height adjustable, preferably by gas spring means, preferably, operable by means of a lever or other activator conveniently located underneath the seat portion or at the side of the seating apparatus/chair.

In one embodiment, the seat portion is provided with at least one backrest adjustment means/mechanism which is conveniently located on one side on the seat portion and preferably operable by a handle means (preferably whilst a person or pupil is seated on the seat portion). The adjustment means/mechanism is preferably a slide adjustment. In one embodiment two such adjustment means/mechanisms are provided on opposed sides of the seat portion which may be operable in unison e.g. by associated handles on each side of the seat portion that can be depressed or operated together by each hand of a person / pupil seated on the seating apparatus / chair.

In one embodiment, the seat portion is mounted on a framework, said framework having a part or seat support member arranged at an incline to the seat portion, said backrest being slidably attached to the part / seat support member.

The adjustment means/mechanism may comprise a sleeve (preferably of low friction material) fixed to the backrest to move therewith and mounted on a, or the, seat support member such as a tubular frame member (preferably of low friction material).

Handle means (preferably spring loaded and / or pivotably mounted) may be provided, preferably on the sleeve, which handle means can be activated to disengage locking of the sleeve to the support member to allow the relative position of the sleeve and support member to be selectively adjusted along said incline to at least one other locking position more suited to a person/pupil of different age/size.

In one embodiment, the handle means operates a rod / pin to lift a collar clear of a locking hole whilst the handle is depressed, allowing the sleeve to be sudden to a new position for locking, on release of the handle. The locking positions may be variably

presettable.

Still further according to the present invention there is provided a seating apparatus/chair provided with any feature derivable from this description and drawings and/or provided with one or more of the following features:-a) a backrest adjustable along an angle of incline of about 14 degrees +1-1 or 2 or 3 degrees relative to the horizontal or to a seat portion b) two backrest adjustment means/mechanisms located on opposed sides of a seat portion operable by handle means c) A backrest adjustable in height and along a seat, preferably simultaneously, and preferably having a height adjustable seat portion preferably operated by a gas spring preferably with a lever or actuator preferably underneath said seat d) A backrest and seat portion adjustable to cater for 11-18 year olds and which meets BS Standards BS EN 1729-1: 2006 Further according to the present invention there is provided a method of seating a range of size of persons/pupils on a seating apparatus/chair said method comprising simultaneously adjusting (preferably in a single movement) a backrest relative to a seat portion to vary the height of backrest relative to the seat portion and along the seat portion varying the depth of seat available for sitting.

Many advantageous features of the seating apparatus / chair and / or backrest adjustment means / mechanism present invention will be apparent from the following

description and drawings.

An embodiment of a seating apparatus or chair in accordance with the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which FIGURE A shows a simplified schematic illustration of how the same size chair of a general form known per se is unable to cater for all children of secondary level age range; FIGURE 1 shows a simplified side view of the seating apparatus/chair in accordance with the present invention with a backrest in a first position of relative adjustment; FIGURE 2 shows a simplified side view of the seating apparatus/chair similar to FIGURE 1 with the backrest in a second position of relative adjustment; FIGURE 3 shows a simplified side view of the seating apparatus/chair similar to FIGURE 1 with the backrest in a third position of relative adjustment; FIGURES 4 to 6 show perspective side views of a seating apparatus/chair prototype in accordance with the present invention corresponding to opposite side views shown in FIGURES ito 3; FIGURE 7 shows a perspective view of the seating apparatus/chair prototype looking at the underside of a seat portion of the seating apparatus/chair; FIGURE 8 shows a plan perspective view of the seating apparatus/chair prototype; FIGURES 9a, 9b, 9c show views corresponding to FIGURES 1 to 3 illustrating how the different positions of the backrest can be utilised effectively to support pupils of different ages and sizes; FIGURE 10 shows a simplified schematic sectional view of the backrest adjustment means/mechanism; FIGURE 11 shows detail views of a handle utilised in the backrest adjustment mechanism FIGURE 12 shows a simplified schematic view showing an adjustment angle of incline of 14 degrees to the horizontal for the backrest adjustment.

FIGURE A illustrates the problem of attempting to provide a ingle chair to cater for a wide age and size range of children e.g. as encountered in secondary school.

The view on the far left of FIGURE A is statistically of a 16-18 year old pupil seated in a size mark 5 chair C. The view to the right of the FIGURE is statistically of an 11 year old pupil seated in the same chair C. Here the 11 year old pupil is seating improperly so that the feet cannot touch the floor: the lower, middle view of FIGURE A shows how the pupil would have to sit to rest their feet on the floor (a position in which there is no lumbar support).

FIGURES 1 to 3 show a seating apparatus or chair I designed to overcome the problems illustrated in FIGURE A. FIGURES 1 to 3 show the seating apparatus/chair I having an ergonomically shaped seat portion or pan 2 and adjustable backrest 3.

Advantageously, the position of the backrest 3 relative to the seat portion 2 can be readily and easily adjusted by hand and by a pupil whilst being seated on the chair 1; said backrest being simultaneously adjustable both in height and along the seat portion (i.e. to vary the depth of the seat portion accessible for sitting on by the pupil), in a manner to be explained. In this manner, the foremost point of the backrest can be adjusted in height and forward/rearward location to be comfortable for the seated person/pupil. The seat portion 2 is mounted on a pedestal base B of a known format generally used for office chairs comprising five equi-angularly spaced limbs Ba (see FIGURE 8) terminating in vertical feet Bb. The base B has a central vertical cylindrical tubular portion Bc receiving extendable rod or piston Bd connected to the underside of the seat portion 2 and utilised to vary the height of the seat portion 2 above the base in the same general manner as an adjustable height seat on an office chair. Thus, the tubular portion Bc and rod or piston Bd comprises a gas spring compression means which in this instance is activatable by the pupil via gas spring lever L (not shown in FIGURES 1 to 3) in generally known manner.

The seat portion 2 is mounted on a framework 4 including two similar, opposed tubular members 4a, 4b of low friction material, such as low friction steel tubing, generally of non-circular (e.g. square, rectangular or polygonal cross section) and mounted at a similar inclined angle relative to the seat with the aid of the central, raised generally C-shaped, flat plate, bridge member 4c.

The backrest 3 includes an ergonomically shaped lumbar support region 3a and spaced, curved tubular members 3b, 3c that together straddle the seat portion 2 and are fixed to the outside of a respective sleeve member 5 of an associated backrest adjustment means/mechanism M to be described, said sleeve member being slidably adjustable with the backrest 3 along the tubular members 4a, 4b on appropriate operation of handles H of the means/mechanism M positioned on the underside of members 3b, 3c.

FIGURE 1 shows diagranmiatically optimum setting for the chair 1 to cater for the maximum age/size range. The seat portion 2 is in an elevated position on the gas spring compression means (this can be varied to suit) and the backrest 3 has been moved along the seat portion 2 to the rearmost position (420 mm from seat portion front 2a as shown) offering maximum depth of seat for sitting on by an older pupil.

The height of the centre of the backrest 3 (or foremost point of the backrest) above the seat is 210 mm.

FIGURE 2 shows a mid setting position (with seat portion 2 at a lower position) showing the backrest 3 having been moved forward (along the seat portion) and downward from the position as shown in FIGURE 1. The backrest is now 380 mm from the seat portion front 2a reducing the depth of seat for sitting on by a younger / smaller pupil. The height of the centre of the backrest 3 (or foremost point of the backrest) above the seat portion 2 is now reduced to 200 mm.

FIGURE 3 shows the lowest setting position to cater for the lowest age/size range of pupil with the backrest 3 moved downwardly again and to the most forward position along the seat portion reducing the available depth of seat for sitting on to a minimum requirement. The backrest 3 is now 340 mm from the seat portion front 2a and the height of the centre of the backrest 3 (or foremost point of the backrest) above the seat portion 2 is now 190 mm.

FIGURES 1 to 3 show desirable relative dimensions of the seat portion 2/backrest 3 in these three positions to meet required British Standards.

FIGURES 4 to 6 show positions similar to FIGURES 1 to 3 from an opposite side view and of a prototype of the chair which also shows the lever L (not shown in FIGURES 1 to 3 or FIGURES 9a, 9b, 9c) for height adjustment of the chair.

FIGURES 9a, 9b, 9c, 9d show how the relative size of pupil is catered for and posture supported correctly in each of the three afore-described positions.

FIGURE 10 shows a longitudinal, vertical sectional view through one of the two backrest adjustment means/mechanisms M utilised on the chair 1.

The adjustment means M comprises the sleeve 5 (also of low friction materials at least in the area of contact with tubular member 4a, 4b) selectively slideably adjustably mounted on associated tubular member 4a, 4b (comprising a support member) of the framework 4 of the chair 1. Tubular member 4a, 4b is provided with three longitudinally spaced adjustment holes (key holes) 4c, 4d, 4e and FIGURE 10 shows adjustment pin or rod 6 extending vertically through hole 4d and through lower longitudinal slot 4f in member 4a, 4d. The lower end of rod 6 is received in recess hi in handle H. The Handle H is pivotally mounted in the bottom wall 4f of tubular member 4a, 4b via hinge pin p passed through matching receiving hole h2 at one end of the handle H. Handle H is provided with a stop or flange h3 (not shown in FIGURE ii) at an opposite end of the handle engageable with a stepped part 4g of the bottom wall 4f in order to retain the handle to the tubular member 4a, 4b in a ready for adjustment position.

Rod 6 extends upwardly through collar 7 into cup-shaped housing 4h extending upwardly from the top wall 4j of tubular member 4a, 4b. Collar 7 is seated in a locking position in hole 4d preventing relative movement of the sleeve 5 and tubular member 4a, 4b, thereby locking the position of the backrest relative to the seat portion.

The cup-shaped housing 4h has an internal diameter wide enough to receive collar 7, on the application of an upward force in the direction of arrow X in FIGURE' 10 against spring loading provided by helical coil compression spring 8 surrounding the upper end of collar 7, above the collar and within housing 4h.

Once collar 7 has been lifted from its locking position in hole 4d into housing 4h, the upper end of rod 6 is received in co-axial cup-shaped reduced diameter housing extension 4i and sleeve 5 can be sudden either to the right or left along tubular member 4a, 4b whilst upward force is maintained on handle H. Low friction materials are used for the contact surfaces between the sleeve 5 and tubular member 4a, 4b in order to ensure an easy action. In this way, collar 7 can be moved above hole 4c or 4e as desired, and the handle H released allowing the collar 7 to lockingly engage the selected hole 4c, 4e by the action of the compression spring 8 pushing the collar 7 out of housing 4h in a manner which should be readily envisaged.

At the same time, handle H is returned to its original position relative to the sleeve 5.

In this way, the backrest 3 can be locked in any one of three selected positions corresponding to those shown in FIGURES Ito 3, or 4 to 6.

F1GURES 9a, 9b, 9c show a pupil positioned on the chair 1 ready to operate the handle H simply by the application of an upward force with the fingers. It is not even necessary for the pupil to see the handle H while operating the handle.

Advantageously, each handle H is located on the side of the seat portion 2 where the pupil's hand naturally rests and the handles H are operated in unison to depress the handles simultaneously. The sleeves 5 can be gripped together with the depressed handles on each side of the chair and moved along the incline of the tubular members 4a, 4b to adjust the height and fore and aft position thereof relative to the seat portion in an easy single action by the pupil.

Whilst only three locking positions have been illustrated it is possible that more locking positions could be provided if required.

In an alternative embodiment (not shown) the sleeve may be lockable to the tubular member in any location along the tubular member and the locking means could be any suitable arrangement such as a ratchet mechanism.

If preferred, only one handle need be provided to operate the two adjustment means/mechanisms or only one adjustment means/mechanism may be provided (e.g. on one side of the chair only).

The Applicant has realised that the ease of simultaneous adjustment of the backrest in two dimensions (i.e. height and along the seat) for the required standard of comfort (based on specified dimensions for depth of seat support etc for age/size range) of different pupils is critical (in particular to meet BS Standards) and FIGURE 12 shows that the angle of incline of the movement of the sleeve 5 (corresponding to the angle of movement of the backrest 3' as shown in FIGURE 12) relative to the (horizontal) seat portion 2 is critical at 14 degrees (the angle is exaggerated in FIGURE 12 for ease of illustration). A deviation of a few degrees (or less) may render the seat less comfortable than otherwise would be the case. Backrest 3' is shown positioned in three different positions relative to seat portion 2' (shown at an exaggerated upward angle) corresponding with the three positions shown in FIGURES 1 to 3 of the drawings. The foremost point of the backrest is shown at 3a' in each case and this point moves at the 14 degrees angle.

Whilst the backrest 3' is shown moving along a straight or linear path incline it is possible in an alternative embodiment that movement is along a non-linear path (for

example curved).

The use of low friction materials for the adjustment means/mechanism M is important for ease of use and in another embodiment (not shown) a suitable low friction material, fluid or bearing may be provided in between the sleeve 5 and tubular member 4a, 4b.

Additionally, it is possible that the seat portion and/or backrest may be cushioned or upholstered.

Whilst the backrest adjustment means/mechanism M as described comprises a slidable sleeve mounted on a tubular member, other embodiments of adjustment means/mechanisms are possible e.g the slidable sleeve could be inside the tubular member or a projection/bar (possibly engageable with a toothed rack) on the backrest could be received in a slot in the tubular member (or other frame member). An adjustment means/mechanism could be provided on one side of the seating apparatus/chair with handle means and means to lock the backrest in any one of a number of selectable positions with a (similar) adjustment means or relatively slidable components being provided on the opposed side of the chair but without lockable means; the opposed side may or may not be provided with handle or grip means that can be gripped with the other handle means to assist in movement of the backrest in one easy balanced movement on each side of the seating apparatus/chair.

Even so, safety is important whatever adjustment means/mechanism is provided, so that the means/mechanism should be safely accessible without risk of fingers becoming trapped or injured by said means/mechanism.

The Applicant has made further design changes/improvements to the seating apparatus/chair in accordance with the present invention.

Accordingly, a further embodiment of a seating apparatus/chair in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings in which;-FIGURE 13 show a front view of the further embodiment; FIGURE 14 show a sectional side view taken on line B-B of FIGURE 13; FIGURE 15 shows a front, sectional view of the seating apparatus/chair taken on line C-C of FIGURE 14; FIGURE 16 shows a sectional view of a seat portion and part of a backrest of the seating apparatus/chair drawn to an enlarged scale taken on line D-D of FIGURE 13, through a backrest adjustment means/mechanism, of said seating apparatus/chair; FIGURE 17 is a side view of the seat portion and part of the backrest looking in the direction of arrow X in FIGURE 14, and FIGURE 18 is a partial underside view of the seat portion shown in FIGURE 17 FIGURES 13 to 18 show an embodiment of a seating apparatus/chair 100 having a hollow seat portion or pan 102 and adjustable backrest 103.

The backrest 103 can be adjusted relative to the seat portion 102 along a similar angle (i.e. 14 degrees) by operating handle H'. However, the adjustment means M in the previously described embodiment has been replaced by a ratchet type mechanism/means R, including cam type component 104 and rack 105, in this embodiment, said component and rack being housed (the rack being fixed or moulded) within the seat portion. Lifting of the handle H' disengages the cam type component 104 from the rack 105 having, in this instance, a set of three steps 1 04a, 104b, 104c providing 3 adjustment positions of the backrest 103 relative to the seat portion 102, in a maimer which should be self-explanatory from FIGURES 13 to 18 of the drawings. The seat portion 102 has an elongate open slot 105' mouldedlfixed therein above the rack steps 104a,104b,104c of rack 105. The slot 105' is covered by upping, to prevent finger entrapment in use, said upping being in the form of a handle slideway 107 (see FIGURE 18) projecting from the outside of the seat portion 102; said upping is also moulded/fixed into the seat portion.

Thus, it is believed that the arrangement shown in FIGURES 13 to 18 has an improved, safer, backrest adjustment means by, advantageously, providing said means R within the seat portion out of the way of any fingers that might be injured by the mechanism during adjustment.

The adjustment means may be any suitable means, preferably provided within the seat portion, and could be any form of ratchet mechanism or rack and pinion mechanism with any desired number of adjustment positions (steps).

Thus, the backrest 103 can be adjusted relative to seat portion 102, by sliding backrest support bars 106 (see FIGURE 17), using side levers L, operated by handles H', up and down the 14 degree slope of the seat portion handle slideway 107. The backrest 103 may be locked in place in each of the three selectable adjustment positions by a torsional spring loaded actuator ( cam type component 104), operated by a handle H', locating in ratchet channels (steps 1 04a, I 04b. I 04c) when the handle is released, in a manner which should be self-explanatory from FIGURES 13 to 18 of the drawings.

The cam type component 104 is lifted out of the associated step or slot 1 04a, 1 04b, I 04c on lifting of the associated handle H', against the action of spring means (not shown) e.g. a leaf spring means.

Advantageously, the cam type component 104 is held securely in each of the rack steps 104a, 104b, lOc by upper detent means dl, d2, d3, which may be in the form of ridges or steps.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced or supplemented by an equivalent or generic term. For example, the term backrest' may be replaced by back or lumbar support'; seat portion' may be replaced by seat pan'; along the seat portion' may be replaced by fore and aft of the seat portion'. Further it is to be understood that individual features, method or functions relating to the seating apparatus/chair or backrest adjustment means! mechanism might be individually patentably inventive. Any term as used herein may be accompanied by the term means'. The singular may include the plural and vice versa. Additionally, any range mentioned herein for any parameter or variable shall be taken to include a disclosure of any derivable sub-range within that range or of any particular value of the variable or parameter arranged within, or at an end of, the range or sub-range.

Claims

CLAIMS1. A seating apparatus or chair comprising a backrest which is adjustable relative to a seat portion, said backrest being adjustable (along an incline) relative to the seat portion to vary the height of the backrest (or height of the foremost position of the backrest) relative to the seat portion and simultaneously adjust the position of the backrest along the seat portion.
2. Apparatus as claimed in claim 1 in which the backrest is lockable in at least two, but preferably three or more adjusted back support positions relative to the seat portion by any convenient means.
3. Apparatus as claimed in claim 2 in which the angle of adjustment incline is about 14 +1-1 or 2 or 3 degrees to the horizontal.
4. Apparatus as claimed in any one of the preceding claims in which in which the seat portion (or part thereof) is at a slight forward upward angle to the horizontal e.g. 2 or 3 degrees.
5. Apparatus as claimed in any one of the preceding claims having a seat which is height adjustable, preferably by gas spring means, preferably, operable by means of a lever or other activator conveniently located underneath the seat portion.
6. Apparatus as claimed in any one of the preceding claims in which the seat portion is provided with at least one backrest adjustment means/mechanism which is conveniently located on one side on the seat portion and preferably operable by a handle means (preferably whilst a person or pupil is seated on the seat portion) and/or in which the adjustment means/mechanism is preferably a slide adjustment and/or in which two such adjustment means/mechanisms are provided on opposed sides of the seat portion which may be operable in unison e.g. by associated handles on each side of the seat portion that can be depressed or operated together by each hand of a person / pupil seated on the seating apparatus / chair and/or in which the seat portion is mounted on a framework, said framework having a part or seat support member arranged at an incline to the seat portion, said backrest being slidably attached to the part / seat support member and/or in which the adjustment means/mechanism comprises a sleeve (preferably of low friction material) fixed to the backrest to move therewith and mounted on a, or the, seat support member such as a tubular frame member (preferably of low friction material and/or in which handle means (preferably spring loaded and I or pivotably mounted) is provided, preferably on the sleeve, which handle means can be activated to disengage locking of the sleeve to the support member to allow the relative position of the sleeve and support member to be selectively adjusted along said incline to at least one other locking position more suited to a person/pupil of different age/size and/or in which the handle means operates a rod / pin to lift a collar clear of a locking hole whilst the handle is depressed, allowing the sleeve to be sudden to a new position for locking, on release of the handle and/or in which the locking positions may be variably presettable.
7. Apparatus as claimed in any one of the preceding claims having a back rest adjustment means/mechanism in the form of a ratchet type or rack and pinion mechanism.
8. Apparatus as claimed in any one of the preceding claims in which a, or the, back rest adjustment means/mechanism is within the seat portion.
9. A seating apparatus or chair substantially as herein described with reference to any of the FIGURES of the accompanying drawings.
10. A backrest adjustment means/mechanism for a seating apparatus/chair as claimed in any one of claims ito 9.
11. A seating apparatus/chair provided with any feature derivable from this description and drawings and/or provided with one or more of the following features:-a) a backrest adjustable along an angle of incline of about 14 degrees +1-1 or 2 or 3 degrees relative to the horizontal or to a seat portion b) two backrest adjustment means/mechanisms located on opposed sides of a seat portion operable by handle means c) A backrest adjustable in height and along a seat, preferably simultaneously, and preferably having a height adjustable seat portion preferably operated by a gas spring preferably with a lever or actuator preferably underneath said seat d) A backrest and seat portion adjustable to cater for 11-18 year olds and which meets BS Standards BS EN 1729-1: 2006
12. A method of seating a range of size of persons/pupils on a seating apparatus/chair said method comprising simultaneously adjusting (preferably in a single movement) a backrest relative to a seat portion to vary the height of backrest relative to the seat portion and along the seat portion varying the depth of seat available for sitting.