GB2543565B

GB2543565B - Stackable chair

Info

Publication number: GB2543565B
Application number: GB1518782.6A
Authority: GB
Inventors: Michell Andrew
Original assignee: RATSTANDS Ltd
Current assignee: RATSTANDS Ltd
Priority date: 2015-10-23
Filing date: 2015-10-23
Publication date: 2019-10-09
Anticipated expiration: 2035-10-23
Also published as: GB2543565A; GB201518782D0

Description

STACKABLE CHAIR

The present invention relates generally to stackable chairs and a method of stacking such chairs.

Storage of chairs when not in use is a common problem, which has been addressed by providing chairs that are stackable upon one another. Usually, this requires the chair to be composed of sloping legs and a sloping backrest, such that the seat of a lower chair can fit between the legs of an upper chair, and the backrest of the upper chair can rest on the backrest of the lower chair.

In particular, such chairs are composed of components having certain thicknesses. For instance, the legs of a chair may comprise tubes (e.g. having circular or substantially rectangular cross-section), and the width of those tubes may be taken to be the distance across their cross-section in a particular direction. For two chairs to be stacked one atop another, and spaced apart by a desired vertical displacement, the legs must have a slope given by the ratio of the width to the vertical displacement; that is, the arccosine of the thickness divided by the vertical displacement. This approach can be applied mutatis mutandis to the slope of a chair's backrest.

It is desirable to be able to stack chairs with as small a vertical displacement as possible, usually limited by the depth of the seat, which is typically substantially horizontal. For instance, the base of an upper seat may sit (when stacked) on the upper portion of a lower seat.

It is also desirable to provide backrests having at least a portion that is substantially vertical. In particular, a human back (and specifically the spine) is not flat (i.e. planar or linear). The spine of a healthy human adult forms an 'S' shape in the Sagittal plane; that is, the back is substantially convex proximal to the neck (the thoracic curve) and substantially concave proximal to the pelvis (the lumbar curve). Chairs with sloping backs generally support the lower portion of the thoracic curve (i.e. the lower thoracic vertebrae) and/or the upper portion of the lumbar curve (i.e. the upper lumbar vertebrae). To support the lower lumbar vertebrae, a lumbar support is required, which must possess a steeper slope than the portion of the backrest supporting the thoracic curve.

Chairs provided with a backrest with a slope that is too shallow are uncomfortable and/or can cause back disorders. This sets a theoretical limit on the amount of slope that a backrest may possess, and therefore on the thickness of the backrest, which can adversely impact on the comfort of stackable chairs.

It can therefore be seen that stackable chair design is based predominantly on finding a balance between three competing aims: small vertical displacement when stacked; steep slope of (a portion of) the backrest and a minimum thickness of the backrest, in order to provide comfort, structural rigidity and/or padding.

One way of overcoming the above-mentioned constraints is to avoid using a lumbar support at all, for instance by having a void below the backrest. This approach may produce a chair with a small vertical displacement when stacked, and may have a comfortably padded backrest, at the cost of not supporting the user's back with a substantially vertical portion of backrest.

One way of avoiding the above-mentioned constraints is to configure the chairs to stack in a direction away from vertical. Each chair in the stack will therefore have a finite horizontal displacement (usually forward, away from the backrest). This approach may produce a chair with a small vertical displacement when stacked, may have a steeply sloping portion of backrest, and may have a comfortably padded backrest; however, the number of chairs that may be stacked together is significantly limited, as with each chair added to the stack, the centre of mass of the stack moves forward, eventually outside the footprint of the lowermost chair in the stack.

It is therefore desirable to provide a chair that has a small vertical displacement when stacked, has a steeply sloping portion of backrest to support a seated user's lower lumbar spine, has a comfortably padded backrest, and in addition has a relatively small horizontal displacement (e.g. substantially no horizontal displacement) when stacked.

The present invention is concerned with the configuration of a chair's backrest, and therefore discussion of configurations of seat and legs is minimised as this is considered to be well within the application of common general knowledge of the skilled person.

According to a first aspect of the present invention there is provided a stackable chair comprising: a seat; a plurality of legs; and a backrest comprising: a first substantially planar portion for supporting a lower portion of the thoracic curve of a user's spine and an upper portion of the lumbar curve of the user's spine; and a second substantially planar portion for supporting a lower portion of the lumbar curve of the user's spine, wherein the second substantially planar portion is pivotable between a stacking position in which it is substantially coplanar with the first substantially planar portion and a support position in which it is substantially non-coplanar with the first substantially planar portion; and a stop for restricting movement of the second substantially planar portion beyond the stacking and support positions respectively.

In this way, when in use, the backrest may comprise a portion that may be substantially vertical in order to support the lower lumbar spine, and when stacked the lumbar support may be moved into a sloped configuration to allow vertical stacking of the chairs upon one another.

In the context of this specification, substantially coplanar may be understood to mean differing in slope by up to 10 degrees, in particular up to 5 degrees, more particularly up to 2 degrees. Substantially non-coplanar may be defined in a corresponding manner.

In the support position, the backrest may comprise a lumbar support, and/or the backrest may be substantially convex.

The first substantially planar portion may have a first slope, and the second substantially planar portion may have a second slope in the stacking position that is substantially coplanar with the first slope, and the second substantially planar portion may have a third slope in the support position that is substantially greater than the first slope.

The first slope may be between 45 degrees and 85 degrees from horizontal, in particular between 55 degrees and 80 degrees, more particularly between 65 degrees and 75 degrees, for instance approximately 71 degrees.

The second slope may be within approximately 2, 5 or 10 degrees of the first slope.

The third slope may be approximately 90 degrees from horizontal, in particular at least 75 degrees from horizontal, more particularly at least 80 degrees from horizontal, in either rotational sense.

The backrest may further comprise a first curved portion adjacent to the first substantially planar portion, and/or a second curved portion adjacent to the second substantially planar portion, that may be arranged such that when the second substantially planar portion is in the support position, the first substantially planar portion, the second substantially planar portion and the first and/or second curved portions form a substantially continuous curve having a shape substantially the same as a lumbar curve of a user.

In this way, the back/spine of a user may be supported substantially continuously throughout the lumbar curve.

The second substantially planar portion may be pivotally connected to the first substantially planar portion, either directly or indirectly, for instance via a backrest support frame.

The second substantially planar portion may be connected to the first substantially planar portion so as to form a continuous surface. For instance, a single surface, cover and/or layer of upholstery may extend over the first and second portions. Alternatively, the portions may be connected such that there is a discontinuity between their respective surfaces. For instance, each portion may be upholstered separately. Alternatively or additionally, the two portions may be spaced from one another. This may result in a gap between the two portions; this gap may be present in both pivotal positions of the second substantially planar portion, or may be present only in one pivotal position of the second portion, and/or all intermediary positions. Alternatively, even though the two portions may be spaced from one another, a continuous surface may extend between the two portions, for instance by virtue of a single surface, cover and/or layer of upholstery between the first and second portions.

The second substantially planar portion may be pivotable substantially only between the support and stacking positions. The second substantially planar portion may be biased toward at least one of the support and stacking positions.

In this way, the second substantially planar portion may provide additional support to the lumbar spine, and/or may automatically move into the support position when in use.

The chair may be a padded chair. The seat may be substantially horizontal.

According to a second aspect of the present invention, there is provided a method of stacking a plurality of chairs, comprising: providing a plurality of chairs according to any preceding claim; placing the second substantially planar portion of at least one of the plurality of chairs in the stacking position; and placing said at least one of the plurality of chairs on top of another one of the plurality of chairs.

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

Figure 1 shows a stackable chair according to the present invention.

Figure 2 shows two stackable chair of the kind shown in figure 1 stacked upon one another.

Figure 3 shows an alternative arrangement in which the lumbar support of the chair is non-moveable, which does not form part of the invention.

The present invention will be described with respect to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. Each drawing may not include all of the features of the invention and therefore should not necessarily be considered to be an embodiment of the invention. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that operation is capable in other orientations than described or illustrated herein.

It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to “an embodiment” or “an aspect” means that a particular feature, structure or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the present invention. Thus, appearances of the phrases “in one embodiment”, “in an embodiment”, or “in an aspect” in various places throughout this specification are not necessarily all referring to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments or aspects.

Similarly, it should be appreciated that in the description various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual drawing or aspect should not necessarily be considered to be an embodiment of the invention. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The use of the term “at least one” may mean only one in certain circumstances.

The principles of the invention will now be described by a detailed description of at least one drawing relating to exemplary features of the invention. It is clear that other arrangements can be configured according to the knowledge of persons skilled in the art without departing from the underlying concept or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Figure 1 shows a stackable chair according to the present invention, comprising a seat 2, legs 4 and a backrest 6. The seat 2, legs 4 and backrest 6 are connected together via a support frame 8, the backrest support portion of which being visible.

The backrest 6 comprises an upper portion 10 that is substantially planar in form and is tilted at a slope of approximately 70 degrees to the horizontal. The backrest 6 also comprises a lower portion 12 that is also substantially planar and is arranged substantially vertically. The region between the upper 10 and lower 12 portions forms a gentle curve for supporting the lumbar curve in the back of a user 14.

Figure 2 shows two stackable chair of the kind shown in figure 1 stacked upon one another. The lower portion 12 of the backrests 6 of each of these chairs has been moved from the support position shown in figure 1 to a stacking position in which the upper 10 and lower 12 portions are substantially coplanar. This allows the chairs to be stacked one upon the other in an efficient manner.

Figure 3 shows an alternative arrangement in which the lower portion 12 of the backrest 6 is non-moveable, which does not form part of the invention. Due to the increased effective thickness of the backrest 6, in order to stack these chairs efficiently, each subsequent chair must be horizontally displaced relative to the preceding chair. This in turn imposes design restrictions, for instance on the slope of the legs 4 of the chair, as is apparent from the figure.

In addition, only a finite number of chairs of the kind shown in figure 3 may be stacked one upon the other before the centre of mass of the stack of chairs moves forward outside the footprint of the legs 4, causing the stack to topple.

Claims

1. A stackable chair comprising: a seat; a plurality of legs; and a backrest comprising: a first substantially planar portion for supporting a lower portion of the thoracic curve of a user's spine and an upper portion of the lumbar curve of the user's spine; and a second substantially planar portion for supporting a lower portion of the lumbar curve of the user's spine, wherein the second substantially planar portion is pivotable between a stacking position in which it is substantially coplanar with the first substantially planar portion and a support position in which it is substantially non-coplanar with the first substantially planar portion; and a stop for restricting movement of the second substantially planar portion beyond the stacking and support positions respectively.

2. The stackable chair of claim 1, wherein the first substantially planar portion has a first slope, and the second substantially planar portion has a second slope in the stacking position that is substantially coplanar with the first slope, and a third slope in the support position that is substantially greater than the first slope.

3. The stackable chair according to claim 1 or claim 2, wherein the backrest further comprises a first curved portion adjacent to the first substantially planar portion, and/or a second curved portion adjacent to the second substantially planar portion, arranged such that when the second substantially planar portion is in the support position, the first substantially planar portion, the second substantially planar portion and the first and/or second curved portions form a substantially continuous curve having a shape substantially the same as a lumbar curve of a user.

4. The stackable chair according to any preceding claim, wherein the second substantially planar portion is pivotally connected to the first substantially planar portion.

5. The stackable chair according to any preceding claim, wherein the second substantially planar portion is biased toward at least one of the support and stacking positions.

6. A method of stacking a plurality of chairs, comprising: providing a plurality of chairs according to any preceding claim; placing the second substantially planar portion of at least one of the plurality of chairs in the stacking position; and placing said at least one of the plurality of chairs on top of another one of the plurality of chairs.