GB2492188A

GB2492188A - Seat with a contoured pan

Info

Publication number: GB2492188A
Application number: GB1200514.6A
Authority: GB
Inventors: Simon Andrew Freedman
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-06-24
Filing date: 2012-01-13
Publication date: 2012-12-26
Also published as: AU2012273720A2; CA2840357A1; KR20140046443A; US20140132051A1; EP2723215B1; IN2014DN00166A; WO2012175963A1; AP2014007353A0; MX2013015433A; EP2723215A1; AU2012273720A1; BR112013033308A2; JP2014516748A; PL2723215T3; RU2013157389A; GB201200514D0; ES2530177T3; GB201110748D0; CN103747707A

Abstract

A seat with a contoured pan is adapted to support each ischial tuberosity of the pelvis of the user. The contoured pan further comprises two concavely shaped pads 14 adapted to support the thighs of a user at an optimal selected angle of 27 degrees to the horizontal plane, or at least within the range of 22-32 degrees to the horizontal. The seat further includes a leaf spring 22 linkage between the rear sides of the pads 14 that allows for roll movement as a user sits on the seat. A back portion 19 is pivotally mounted to the distal end of the seat. When the user sits down a force F is applied to the seat and the back moves in a direction L toward the vertical engaging with the user. The combined features enable a user to be directed into a comfortable seating position that emulates the shape of the spine when standing.

Description

A Seat

Field of the Invention

The present invention relates to a seat; particularly a seat for use in an office chair, task chair, aircraft seat, bicycle, vehicle, wheelchair, pushchair, child's seat/car seat or bench. Specifically, the invention is a seat that actively directs the sitter into a correct sitting position as hypothesised by the inventor, i.e. a position that emulates the position that the sitter's spine and pelvis would achieve if they were standing.

Background

Traditional chairs with near horizontal seat pans (both forward to back and side to side) force people to sit in a posture that is detrimental to proper functioning of their spines and associated tissues, which can lead to strain, injury and, in some cases, spinal degeneration.

Specifically, horizontal seat pans force a sitting position with a curved back and reduced thoraco-abdominal space, so causing compression of the abdominal viscera, diaphragm and lungs which can result in hindered digestion and breathing. They also put strain on the sitter's side-to-side spinal curves (scoliosis) Since the 1970s, following the work of A.C. Flandal and others, designers have developed sitting devices that allow the thighs to be lower at the knee than buttock.

However, these devices all have their drawbacks. For

example:

"Kneeling Chairs": e.g. US3863978 (Gillings 1975), US3669493 (Vowles 1972), EP0017450 (Mengshoell98O), SF8600691 (Opsvick 1986) and N0320859 (Mengshoel 2006), were the first attempt to increase sitting thigh angle.

In many oases this involved a thigh-to-horizontal angle of up to 45 degrees. The user was prevented from slipping forward in the seat by looking' the leg into shin supports just below the knees. There have been several papers reporting knee strain (anterior cruciate ligaments) due to the unnatural pressure on the knee joint caused by such strain. They can also restrict the free movement of the legs and feet which is uncomfortable for the user.

"Ergonomic Chairs": chief amongst these (developmentally) being the Aeron (Herman Miller 1994), Leap (Steelcase 1999) and Freedom Chair (Humanscale 1999) . These and their imitators can have seat pans tilted but this leads to the user sliding slowly forward. To counter this movement the user tightens leg and trunk muscles so sitting soon becomes painful. The designers of these chairs advocate movement, rather than advising on a beneficial position. The chairs have numerous adjustments for the user; however, research shows uneguivocally that the majority of users rarely bother to adjust their chairs. If adjustments are made they are usually limited only to height.

"Saddle Stools/Chairs": e.g. W00154545 (2001), N020003763 (Mengshoel 2002), U52002167206 (2002), and N0320859 (Mengshoel 2006), use a saddle-like form and achieve the desired thigh angle by allowing the legs to drop either side. These seats work in the same way as a bicycle saddle wherein the weight of the body is taken by the hammock' of muscles that form the perineum. This diamond shaped sheet of muscles (containing the reproductive and excretory organs) hangs over the saddle seat, transferring the weight of the body through the muscle insertions at the ischial tuberosities, pubis and coccyx. Such seats have similar drawbacks to bicycle saddles, i.e. discomfort experienced after prolonged use.

"Sittings Balls": are currently popular and, depending on the size of the ball, may allow the user to gain an advantageous thigh angle as well as providing cushioning and some intended instability, which can all be beneficial. However, such devices do not fit well into a conventional office environment.

"Moving/Movement-control/exercise chairs": e.g. U55588704 (Harza, 1996); U57090303 (Kropa, 2006); US2009/0079243 (Kunzler et al, 2009) ; U52009/0135133 (Kunzler et al, 2009), can involve movement for either exercise or health and the possibility to control other apparatus. Movement is often beneficial to humans and its complete absence for extended periods is detrimental, however, the addition of poorly controlled or poorly guided movement in a work seat will often lead to distraction and discomfort. It is erroneous to think that by providing ample free movement in a sitting device that the body will find the best position for comfort and health.

"Dual-pad/tilting/Shaped Chairs": e.g. U54387925 (Barker et al, 1983); U54552404 (Congleton, 1985); GB2226756 (National Research Development Corporation, 1988); U55580128 (Johnson et al, 1996) ; Wa 2006/073019 (Train Corp et al, 2006); WED 01/76420 (Hansen, 2001); (US7387339 (Bykov et al, 2008); US7063386 (Dowty et al, 2006); US6357827 (Brightbill et al, 2002); US5024485 (Berg et al, 1991); U55713632 (Su, 1998); W02009040861 (Manzini Roberto, 2009); Wa 94/08491 (Bustanate Serrano, 1994) are primarily concerned with the comfort of the sitter.

Shaped pads often resemble early, shaped "tractor-type" seats. These seats, which keep a central anterior to posterior ridge, create the same problems of discomfort after a little while as the previously mentioned saddle seats. Dual pads are an improvement but providing these without any contouring will not allow adeguate forward tilting of the seat pads without the movement of the sitter, the same is true for flat, tilting seats. To be truly comfortable, the inventor has noted, the pads should allow for a small degree of roll, pitch and yaw.

By observing patients the present inventor concluded that humans have not evolved to sit and, therefore, any work chair must be designed to emulate the position that the pelvis and spine achieve in the standing posture of the individual. A detailed anatomical knowledge and expertise in spine, pelvic and musculo-skeletal structure and function led to a hypothesis in how best to achieve this improved seated position.

In studying spines for many years the inventor realised that when an individual moves from the standing to sitting position there is dramatic change in spinal and pelvic posture. Firstly, as most seats have horizontal or slightly downward sloping seat pans this does not allow the lumbar spine to achieve a stable position and so reguires the overuse of insufficient spinal and paraspinal muscles to maintain an upright position -these muscles are not meant to maintain an upright position for a sustained period. Secondly, the human body is full of asymmetries, no place more so than in the legs, as they are the longest parts of the body. Most people have a leg length difference and hence a difference in pelvic height. This uneven pelvic height causes side to side curves (scoliosis) in the spine.

When sitting on a normal, fixed, non-adaptive chair the pelvis is usually forced into a horizontal position, hence creating changes, stresses and discomfort on the spinal scoliosis.

Through an extended process of prototyping and empirical testing resulting in the present invention, it has been possible to reproduce the pelvic and spinal positions achieved when standing.

The invention produced is counterintuitive, as it looks uncomfortable but, nevertheless, is extremely comfortable.

It looks simple but has a high level of complexity and is a practical innovation.

Summary of the Invention

The present invention seeks to provide a seat that actively directs the sitter into a sitting position wherein the sitter's spine and pelvis have a similar structural and postural position as when the sitter is standing. In order to achieve this the seat must allow a considerable downward slope of the thighs (from hip to knee), without the sitter sliding forward, and each side of the pelvis must be helped to achieve the same relative height to the other as they have when standing.

In a broad aspect of the invention there is provided a seat with a contoured pan adapted to support each ischial tuberosity of a user and enabling the thighs of a user to be supported at a position between 15 and 45 degrees to the horizontal plane.

The contoured seat pan provides a cup-like support such that, even when at an angle, a user will sit comfortably and not slide forward. The function of preventing a user from sliding forward may be achieved through other means that are equivalent to a contoured seat pan, such as ridges, a non-slip rubber surface or even adhesive/straps.

These functional equivalents may be incorporated instead of a strictly "contoured" seat pan.

Preferably the seat pan supports a thigh angle of 22 to 32 degrees (but optimally the pan is selected to support the thighs at 27 degrees) to the horizontal plane, which causes the lumbar spine to replicate the anterior facing curve (lordosis) it achieves when a person is standing.

In other words, the present invention causes the body to replicate the position of the pelvis and spine as occurs when standing. When the standing lordosis is achieved it is the natural positioning of the vertebral structures that hold the body upright, not the muscles of the back.

When the natural standing lordotic posture is lost, as with a horizontal seat pan, the muscles of the back attempt to support the person in an upright position.

These muscles soon tire and allow the lumbar spine to curve (slump) forward which has a detrimental effect to the rest of the spine, shoulders, neck, arms and forearms.

Preferably the seat pan is comprised of two separate, at least partially concave, shaped seat pads for each side of a user, wherein each pad supports the tissues and shapes around each ischial tuberosity. This structure enhances the body's natural cushioning features and so reduces the need for wasteful/excessive cushioning.

The seat pan could be formed in a single integrated piece that performs the function of the two seat pads otherwise described herein.

By focusing on the support of ischial tuberositites and understanding that for the most part, the variation of their distance apart in the adult human population is only approximately 12% it becomes possible to produce seats that support a far wider range of users than standard seats.

In a preferred form of the invention each seat pad is attached to a base/pedestal structure by a lug with an internal silicon bush at the front and are also connected by a pivoting leaf-spring and another silicon bush at the back. This allows each seat pad to vary its height, towards the back, in a linked way, relative to the other pad. This addresses the fact that it is essential for comfortable sitting that one side of the pelvis might be higher than the other as in most standing people.

The leaf spring also allows the springing movement of a back post, a movement that helps in the treatment of hypertonicity in the back muscles provided by a series of "back balls" located on a seat back portion. The pads also have a silicon mounting bush within the lug at the front and between the mountings at the back, which allow for a controlled amount of roll in the seat pad.

Preferably the back porticn is self adjusting in response to a user sitting on the contoured pan. The self adjusting back component of the invention can be used to treat hypertonicity (elevated tone) in the postural back muscles. Furthermore, the seat is preferably manually adjustable in height only; with the result that many superfluous and wasteful manual adjustment mechanisms (as

found in the prior art) can be discarded.

The seat can be used in an adapted form for use in bicycle and motorcycle seats. Research has shown that use of standard bicycle saddles can lead to low fertility and erectile dysfunction in males. The standard saddle is also irritating to haemorrhoids. Many people do not ride bicycles as they find them uncomfortable and this is because much of the body weight is transferred through the perineum rather than the ischialtuberosities as outlined by the present invention.

A seat according to the invention, specifically for bicycle use, may be modified by cutting off approximately half of the pad to reduce its size. In other words, some uses of the seat of the invention may necessitate utilising only part of each pad.

The invention is also anticipated for use in wheelchairs and integrated into other seat structures, such as a bench. Indeed the invention could also be in the form of a portable or retrofit insert for any seat/chair.

Brief Description of the Drawings

Figure 1 shows a side view of a seat according to the invention in a raised position; Figure 2 shows a side elevation view of the seat in a lowered position; Figure 3 shows a rear elevation view of the seat in the lowered position; Figure 4 shows a general perspective view of the seat of the invention; Figure 5 shows a closer view of the seat when the seat back has been loaded; Figure 6 shows a closer view of the seat when in a resting position; Figure 7 shows a detailed rear view of the seat; Figure 8 shows a detailed underneath view of the seat; Figure 9 illustrates a side view where the seat pads have been tilted by a load; Figure 10 illustrates a front view where the seat pads have been loaded as in Figure 9; Figure 11 illustrates a rear perspective view of the seat; and Figure 12 illustrates a detailed rear view, comparable to Figure 7, where the seat pans are tilting.

Detailed Description

Figure 4 best illustrates a general view of a seat according to the present invention incorporated into an office chair which has a conventional base with five feet/wheels 11 converging into a central pedestal 12. A height adjustment means 13 is incorporated into the pedestal 12, which may be in the form of a screw thread (as shown) or pneumatic/spring cylinder. Figures 1 and 2 illustrate relatively raised and lowered positions of the seat by virtue of the height adjustment means 13. Height of the seat from the ground is adjusted for oomfort dependent on the length of a user's legs, e.g. so feet will be flat on the floor.

The seat itself includes a seat pan preferably formed from two pads 14 which have an at least partially concave construction and are a mirror-image of each other. These pads 14 are preferably independently mounted onto a frame structure 15 at the upper end of the pedestal 12 that supports each pad and a back portion 16, pivotally attached at an axis 17 (best seen in Figure 6) Seat back 16 also features a series of padded supports 18 or "back balls" that, in use, contact a user's back.

Figure 6 illustrates a side view of a seat according to the invention in its initial unloaded or "resting" state, i.e. without the weight of a person applied. The seat pads 14 rest at a relatively high angle and it will be apparent that seat back 16 is reclined at an angle over vertical in this first resting position, before a person sits on the seat.

As illustrated in Figure 5, when a force F is applied to the seat pan 14 (e.g. by a person sitting down), pressure in the vicinity of the pivot 17 causes the seat back 16 to move in a direction L toward vertical.

Figures 5 and 6 generally show a relative linkage arrangement of the seat pads where the frame structure 15 is connected to the pedestal and the spine-shaped seat back 16 is connected at a second pivot 19 (located between the first pivot 17 and the upwardly curving back portion of seat back 16) by a link arm 20 to a front lug 21 extending from the underside of a seat pad. The lugs include an internal silicon bush that provides some flexibility (i.e. "give") to the pad movement.

The distal end of the curved seat back terminates in the first pivot connection point 17 where a leaf spring 22 is mounted and spans between the two seat pads 14 as best seen in Figure 7. A further set of resilient bushes 23 (made of silicon or equivalent) are mounted with and extend from the rear underside of the seat pads 14 to connect with the leaf spring 22 spanning therebetween.

The resilient nature of the bushes 23 provide a limited freedom of yaw movement in the pads.

In totality the mechanism is designed to articulate each pad using a rose joint pivot system, accompanied by a leaf spring/bush arrangement. Each pad, therefore, has a degree of movement in several directions to adapt to a sitting person, but yet direct said person into an optimum position based around the incline angle of the seat pads.

Particularly, by virtue of the seat pads being attached to the base/pedestal structure 15/20 by a lug 21 with an internal silicon bush at the front and also connected by the pivoting leaf-spring 22 and another silicon bush 23 at the back; each seat pad is able to vary its height, towards the rear, in a linked way, relative to the other pad. This addresses the fact that it is essential for comfortable sitting that one side of the pelvis might be slightly higher than the other as in most standing people.

Figures 9 to 12 illustrate the linked articulated movement of the rear of the seat pads 14 where the right-hand seat pad 14A (see Figure 10) is depressed lower than the left-hand pad 14B by the weight/physiology of a person (not illustrated) sitting on the seat.

Figure 12 particularly shows th e tilting (rolling/seesawing) nature of the seat pads by virtue of the leaf spring 22 wherein, as one pad lowers, the other rises.

The linked articulated movement oan be inoorporated into a seat independently of the optimum sitting angle provided by the oontoured pads beoause it addresses variations in pelvic shapes that are not solved by the sitting thigh angle alone.

The leaf spring 22, being resilient, also allows springing movement of the seat baok 16 via its pivotal oonneotion 17, a movement that helps in the treatment of pain in the baok muscles provided by the series of "baok balls" 18 boated on a seat baok portion. As mentioned, the pads have a silicon mounting bush within the lug at the front and between the mountings at the baok, whioh allow for a controlled amount of roll in the seat pad.

A more conventional seat back (as in an office chair) may be incorporated with the seat which is not necessarily pivotally linked to the seat pads.

While a leaf spring is illustrated in the presently preferred embodiment of the invention, such biased movement could be provided by other spring types or pneumatic cylinders.

Preferably the back pcrtion 16 is self adjusting in response to a user sitting on the contoured pan 14. The self adjusting back component of the invention can be used to treat pain in the postural back muscles or for the general accommodation thereof. Furthermore, it should be noted that the seat is preferably manually adjustable in height only; with the result that many superfluous and wasteful manual adjustment mechanisms (as

found in the prior art) can be discarded.

Preferably, when loaded with the weight of a person, seat pads 14 should accommodate and support a user's thighs at an angle selected to be substantially 27° below the horizontal while the curved and contoured nature of the seat pads 14 comfortably prevents a user from sliding forward.

It will be appreciated that the pivot mechanism of the seat back 16 connected via the leaf spring could take several forms or, in the case of a stool-type design, be removed completely. In such a device the two seat pads 14 can be at a fixed angle of approximately 27°.

Guidance for the use of the invention recommends that the users feet are flat on the floor when in the final sitting position, or at least in a position which allows the muscles thighs and legs to be relaxed. There could also be occasions when the occupier might want to use a foot rest on the lower part of the chair so that lower legs could be angled backwards or in the case of the invention being used on a higher seat such as a bar stool a higher foot rest could be incorporated to support the feet..

It should be noted that, because the two seat pads 14 are contoured to the buttocks of the user, explicit cushioning on said pads 14 can be relatively thin.

General principles of the seat according to the invention can be adapted for use in a wheelchair or other seat designs such as a bicycle or motorcycle seat. Operation is otherwise the same as described above In all cases the seat pads (or integrated single seat pan) include a concave portion to cup and support each ischialtuberosisty of a user in a way which does not put undue pressure on the perineum and also avoids muscle tightening which would otherwise result from a user attempting to prevent slipping forward.

The seat of the invention, in all forms, can be moulded in relatively few parts, e.g. all major elements of the office chair of Figures 1 to 4 can be moulded from aluminium such that it can be particularly lightweight.

Claims

What I Claim Is: 1. A seat with a contoured pan adapted to direct the thighs of a user to be supported at a position between 22 and 32 degrees to the horizontal plane.
2. The seat of claim 1 wherein the position is substantially 27 degrees to the horizontal plane.
3. The seat of claim 1 or 2 with a contoured pan adapted to support each ischial tuberosity of a user and enabling the thighs of a user to be supported.
4. The seat according to any preceding claim wherein the seat pan is comprised of two at least partially concavely shaped seat pads adapted to support each ischial tuberosity of a user.
5. The seat according to claim 4 wherein each seat pad is independently mounted on a seat support.
6. The seat according to claim 4 wherein a rear side of each seat pad is linked to the other for (roll) movement, such that lowering a rear side of one pad will cause a corresponding raising of the rear of the other pad.
7. The seat according to claim 6 wherein the link is provided by a resilient element spanning between the rear side of the pads.
8. The seat according to claim 7 wherein the seat pads are attached to the resilient element by a resilient connection.
9. The seat according to claim 8 wherein the resilient element is a leaf spring and the resilient connection is a rubber bush.
10. The seat according to any of claims 6 to 9 wherein a front side of each pad is mounted for pivotal (pitch) movement to a seat support structure.
11. The seat according to any of the preceding claims, further including a back portion, pivotally mounted in relation to the seat pan.
12. The seat according to claim 11 wherein the back portion is pivotally mounted at a distal end thereof to a resilient element spanning between a rear side of two seat pads, there being a second pivotal connection from the back portion toward a seat support structure, wherein each seat pad is mounted at a front side thereof for pivotal (pitch) movement to the seat support structure.
l3.The seat according to claim 11 or 12 wherein, in use, the back portion is arranged to pivot toward the back of a seated user in response to a force applied to the contoured pan.
14. The seat according to any preceding claim wherein the seat pan is cushioned by a relatively thin layer of padding.
15. The seat according to any of the preceding claims wherein th e contoured pan i s functionally substituted or complimented by a ridge, non-slip rubber surface, adhesive or strap means.
16. The seat of any preceding claim, further including a height adjustment mechanism.
17. A seat including two seat pads mounted on a support structure wherein a rear side, relative to a user's sitting direction, of each seat pad is linked to the other for roll movement, such that lowering a rear side of one pad will cause a corresponding raising of the rear of the other pad.
18. The seat of claim 17 wherein the link is provided by a resilient element spanning between the rear side of the pads.
19. The seat according to claim 18 wherein the seat pads are attached to the resilient element by a resilient connection.
20. The seat according to claim 19 wherein the resilient element is a leaf spring and the resilient connection is a rubber bush.
21. The seat according to any of claims 17 to 20 wherein a front side of each pad is mounted for pivotal, pitch, movement to a seat support structure.
22. The seat according to any of preceding claims 17 to 21, further including a back portion, pivotally mounted in relation to the seat pan.
23. The seat according to claim 22 wherein the back portion is pivotally mounted at a distal end thereof to a resilient element spanning between a rear side of the two seat pads, there being a second pivotal connection from the back portion toward the support structure, wherein each seat pad is mounted at a front side thereof for pivotal (pitch) movement to the seat support structure.
24. The seat according to any of claims 17 to 23 wherein the two seat pads provide a surface for supporting each buttock of a user and the seat pads are integrated into a single pan forming the support surface.
25. A wheelchair incorporating a seat according to any preceding claim.
26. The wheelchair according to claim 25 wherein the seat is height adjustable relative to a footrest.
27. A bicycle or motorcycle incorporating a seat according to any of claims 1 to 24.
28. A seat substantially as herein described with reference to the accompanying drawings.