EP0543151B1 - Postural balancing seat - Google Patents

Description

The invention relates to seating furniture according to the preamble of claim 1. The seating furniture is suitable for use in a professional and in a private activity.

Such seating, which is based on the rotatable mounting of a seat part over an axis of rotation, is known, for example, from WO-A-85/04084, special measures having to be taken by connecting the seat part by means of a holding belt to a backrest which can be rotated about an axis, in order to prevent the seat part from tipping over when moving forward and to ensure secure storage of the body or parts thereof on the rotatably mounted surfaces, the seat part and the back of the seating furniture.
This creates in the seating according to the prior art, especially by the connection of the backrest and seat part by means of the belt, the disadvantage that movement of the seat part to the front is hindered or prevented by taking the sitting position that the lower edge of the backrest by the geometry and guidance of the tether in this position a three times greater forward than the seat part, so that any movement of the seat part forward is prevented by the pressure of the lower edge of the back against the body of the user.
On the basis of this prior art, the invention is based on the object of creating seating which enables movement of the vertebrae in the endangered lumbar region during prolonged sitting.

According to the invention, this object is achieved in a piece of seating furniture according to the preamble of claim 1 by the features specified in its characterizing part. Further features of the invention are the subject of dependent claims 2 to 18.

Another seating furniture, which is based on a bearing of the seat part above a rotatable axis below the seat surface, is in US-A-50 048 893 described. The seat part can slide forward on the segment of a circular curve by installing a roller bearing in a setting for a work posture. In addition, a second axis of rotation is installed in the seat part, so that the seat can rotate forward by up to 15 ° and backward by approx. 5 °, depending on the pressure of the thigh.
This second axis of rotation in the seat part has the disadvantage that no force 14 can be generated from the weight of the upper body for a restoring moment about the first axis of rotation in the region of the floor, and that the seat part does not support the higher starting position above the shaft simple way that can be moved back.

One of the widespread diseases that can also arise as a result of incorrect stress when sitting quietly is back pain. Spiegel No. 23/45, pp. 214 - 235, dated June 3, 1991, reports about back pain as a common disease.
The cause of this is generally described as lack of movement and quiet long sitting during work. As a medical measure to reduce back damage, the so-called back schools were set up by the German Society for Orthopedics and Traumatology. One of the goals of these back schools is to help the individual find the individual pain-free middle position of the spine.

The general questions relating to back pain are described in P. Oldenkott in "intervertebral disc damage", TRIAS-Thieme Verlag, Stuttgart / 1988.

The present invention relates to a piece of seating furniture which makes it easier to find the pain-free middle position when sitting and avoids the disadvantages of the harmful, static sitting position through conscious or unconscious movement in the sitting position.

One way to find a middle position while sitting is by kneeling. The body weight rests on an inclined support for the angled knees and another support for the pelvis. The middle position of the upper body, which is favorable for the spine, is found by balancing the upper body towards the front and back. This type of balancing has the disadvantage with respect to the back that any active movement of the upper body is triggered by tightening the ligamentous apparatus in the back and thereby the pressure forces within the spine are even increased.

• jede ausgleichende Bewegung im Lendenwirbelbereich sich als Pendelbewegung des verlängerten Rückgrates, im Bereich des Kopfes als starke Schwankung bemerkbar macht;
• die ruhende Mittelstellung auf Dauer auch die Ursache für einen Schmerz im Bereich der Lendenwirbel sein kann;
• bei jeder eigentlich entspannenden Bewegung im Bereich der Mittellage, das Moment und damit die Druck-Kräfte auf die entsprechenden Wirbel verstärkt werden;
• ein Knie oder die gebeugten Unterschenkel auf die Dauer nicht in der Lage sind, äußere Kräfte zu übertragen.

In the case of alternative seating furniture with a knee support, several disadvantages can be seen, namely that

• every compensatory movement in the lumbar region is felt as a pendulum movement of the elongated spine, in the area of the head as a strong fluctuation;
• the resting middle position can also cause pain in the lumbar region in the long term;
• with every actually relaxing movement in the middle position, the moment and thus the pressure forces on the corresponding vertebrae are increased;
• a knee or the bent lower legs are not able to transmit external forces in the long run.

With this sitting method, a pain is generated after a long sitting, despite the middle position, which can lead to further cramping in the back.

• die Sitzposition auf einer beweglichen Sitzfläche eingenommen wird;
• die Sitzfläche und damit der Körper auf der Sitzfläche durch ein leichtes Beugen oder Strecken der Beine aus der gewählten Sitzposition horizontal aus der Ruhestellung verschoben werden kann;
• und die Sitzfläche sich dabei auf einer Linie bewegt, die den jeweiligen Krümmungsmittelpunkt unterhalb der Sitzfläche hat.

In contrast, seating according to the main claim contains the properties that

• the seating position is taken on a movable seat;
• the seat and thus the body on the seat can be moved horizontally from the rest position by slightly bending or stretching the legs from the selected sitting position;
• and the seat surface moves on a line that has the respective center of curvature below the seat surface.

The rocking chair enables a known way of sitting on a moving seat. With every movement of the chair, a horizontal movement of the seat part is included. The characteristic of the rocking movement is a rolling movement on a curve that has the center of curvature above the seat. This means that the axis of rotation is above the seat part.

In contrast, the movement according to the invention is a horizontal or a tilting movement backwards or forwards.

• ein Drehen der Auflagefläche und
• ein anschließendes Beugen des Oberkörpers.

According to the knowledge of the back schools, lateral movements of the upper body should be avoided and, for example, certain forward / lateral movements should be divided into two phases:

• a turning of the support surface and
• then bending the upper body.

Accordingly, in the case of a piece of seating furniture according to the invention, the seat part is stably supported on the side and can only move forward and backward. This means that the seat part can tip forward or backward about an axis below the seat part.
The rotation of the seat part is described in connection with FIG. 3.

Due to the possibility of being able to move forward or backward, the seat part is not in a stable position without an even weight load, ie without a seated person according to the rules of strength. For the theoretical case that an evenly distributed vertical force acts and the resultant of this force runs through the center of the axis of rotation of the seat, this state is stable according to the laws of mechanics. This condition is stable because every time the seat is twisted, part of the loaded surface also moves upwards. The external force counteracts this upward movement.

When the seat is loaded by a seated person in the middle position, the vertical force is generated by the weight of the body. The legs stand neutral on the floor and allow horizontal force transfer to the seat part to hold the seat part in the correct position under the upper body and above the pivot point. The resulting force of the body also runs through the center of the axis of rotation in this case.

According to the type of sitting according to the invention, it is therefore possible to shift the position of the seat part under the body with a small horizontal force. The forces to perform the movement are generated by the large and insensitive muscles of the feet and legs and transmitted through the large lever of the legs. The horizontal movement also allows the affected lumbar vertebrae to move well, while the head and shoulder girdle remain in the middle.

On the other hand, changing the sitting position on a rigid seat part has the disadvantage that the various forces have to be generated via other sensitive muscles and ligaments and are transmitted via the small lever of the loaded vertebrae. The lumbar vertebrae change their position only slightly.

1, the seating and the associated function of sitting are described below.

1 shows a side view of the seating situation and the forces acting on it. Here, the seat part 6 is supported on 2 stiffeners 7 and rotatably supported in the pivot point 8. The seated person is through the feet 1, the lower legs 2, the thighs 3 and the backbone 4 and Head 5 formed. The feet 1 stand on the floor 10 and allow the transmission of horizontal forces to the seat part 6. The connection between the backbone 4 and the thigh 3 is shown as a joint 9. The transmission of force to the seat surface takes place over part of the thigh 3 and the pelvis, which is shown as a horizontal extension 11 of the thigh 3.

The backbone is shown in connection with a lateral guide 12. Only one horizontal assistant, a moment around point 8, can be picked up in this guide. In reality, the weight rests on feet 1 and axis of rotation 8. Legs 2 and 3 act as transmission levers. In the middle position, the horizontal forces at 12 are "0". The joint 9 is actually formed by the 5 lumbar vertebrae, which allow a deflection and movement of the seat part under the upper body in the horizontal direction.

This horizontal deflection enables the center position to be sought and the lumbar vertebrae under constant pressure to move.

The influence of the deflection and the external forces occurring in the process are now described below.

When moving forward in the direction of the feet, the rear part of the seat part moves parallel (congruent) to the circular arc 13 upwards.
In the area of the pelvis 11 that rolls on the seat surface, greater pressure is generated on the seat surface. This means that more body weight is transferred to the seat. The resulting force 14 no longer runs through the center of rotation 8 in the middle, but to the right of the center. This force forms a stabilizing moment about the pivot point 8 to return the seat part 6 to the starting position.

The movement described forward affects the 5 lumbar vertebrae as an extension. In normal sitting, however, the spine is flexed and the vertebrae and intervertebral discs are subjected to extreme pressure on their front.

A partial extension of the vertebrae from this seated position relieves the spine. It is felt to be pleasant.
In this phase of moving forward and stretching the lumbar vertebrae, the backbone is increasingly supported by the strong and insensitive abdominal muscles - which is also perceived as pleasant.

When the seat part moves backwards, the front part of the seat surface moves upwards.
In the area of the thighs 3, greater pressure is generated on the seat. This means that more body weight is transferred to the seat. The resulting force 15 no longer runs through the center of rotation 8 in the middle, but to the left of the center. This force forms a stabilizing moment to the left about the pivot point for returning the seat part 6 to the starting position.
The proposed way of sitting is stable even with this backward movement according to the laws of mechanics.

The described movement backwards affects the 5 lumbar vertebrae like a bend - which is perceived as less pleasant. Due to the possibility of easily recognizing the differences, the optimal sitting position can be sought again, namely as a middle position between the pleasant direction of movement and the unpleasant, unhealthy movement.

• Im Sitzen werden die Lendenwirbel zur Entspannung bewegt, der Oberkörper und der Kopf können dabei ruhig gehalten werden und die einleitende Kraft für die Bewegung wird über die große und unempfindliche Muskulatur der Beine erzeugt und übertragen.
• Im Bereich der Bandscheiben der Lendenwirbel ist es möglich, die einzelnen Wirbel zunächst zu mobilisieren. Es ist möglich die Wirbelsäule nach beiden Richtungen, nach vorne und nach hinten, abwechselnd durchzubiegen. Hierdurch wird die Belastung zwischen den Wirbeln und Bandscheiben von der Vorder- auf die Rückseite und umgekehrt verlagert.
• Auf die Wirbelsäule wirkt eine schwellende Belastung. (zu/abnehmend)
• Die praktische Erfahrung zeigt weiter, daß das beim Sitzen oft übliche Vorbeugen, das in der Wirbelsäule zwar erhebliche Belastungen erzeugt, aber oft nicht unmittelbar wahrgenommen wird, auf dem neuen Sitzmöbel in den Beinen als zusätzliches starkes Moment und starker Druck spürbar wird und damit leicht ausgeglichen werden kann.
• Die Funktion des Sitzmöbel und die Körperfunktionen bilden eine Funktionseinheit, welche ein aktives Sitzen ermöglicht.

The seating furniture and the associated technique of sitting, as described in FIG. 1, therefore have the following advantageous features:

• While sitting, the lumbar vertebrae are moved to relax, the upper body and the head can be kept still and the initiating force for the movement is generated and transmitted via the large and insensitive muscles of the legs.
• In the area of the intervertebral discs of the lumbar vertebrae, it is possible to first mobilize the individual vertebrae. It is possible to move the spine in both directions, forwards and backwards bend alternately at the back. This shifts the load between the vertebrae and intervertebral discs from the front to the back and vice versa.
• A swelling load acts on the spine. (increasing / decreasing)
• Practical experience also shows that the often common prevention when sitting, which creates considerable stress in the spine, but is often not perceived immediately, can be felt on the new seating furniture in the legs as an additional strong moment and pressure and thus easily balanced can be.
• The function of the seating furniture and the bodily functions form a functional unit that enables active sitting.

1 shows a simple version of the seating furniture. Various devices for exercising sitting will now be explained.

Fig. 2 shows the side view of a chair or stool (without backrest 26), which has 2 tubular frames 21 on the left and right of the seat part 20 as a support structure. The seat surface, not shown, is rectangular.

The support structure stands on the axis of rotation 23, which rests, for example, on a base, the floor 24. This axis of rotation 23 can be designed as a rod with a round, semicircular or angular cross section. It has been shown that a rod with a diameter of 10-20 mm enables a comfortable movement of the seat.
The rod can be firmly connected to the seating furniture or can lie loosely on the floor or even under a cover (eg carpet or rubber mat). The rod or the axis of rotation can also be part of a foundation construction or a joint, not shown.

With the known office chairs it is possible to adjust the angle of the seat to personal needs. In the In the middle position, the seat is adjusted forward with a slight slope. This possibility is shown in FIG. 2 with the specification of the pivot point 25.

Sitting in the middle position can be perceived as pleasant. A fit that fits the body and is padded with a thin cushion has proven itself.
In general, relaxation takes longer when sitting by leaning back against an existing backrest. With the new type of sitting, the relaxing "curvature of the spine to the rear" in the area of the lumbar vertebrae is achieved by moving the seat part forward. The movement mechanism is therefore contrary to the movement used to date. This can also result in contact with the backrest 26, specifically with the upper edge of the backrest. The pleasantly relaxing "curvature of the spine" is enhanced.

When practicing sitting on a stool according to FIG. 2, there has never been a risk of tipping over for several months, since one gets used to the simple movement quickly and easily.

Nevertheless, it can make sense to design a chair with a backrest 26, as shown in FIG. 2, and to refer the user to a possible tilting back of the chair. It may make sense to provide a safety device 22 with a stop against tipping.

In connection with the description of FIGS. 1 and 2, a device has been described in which the possibility of movement of the seat surface is based on the bearing in a joint or the bearing of the unloaded chair in an indifferent state of equilibrium.

This storage is not always possible with swivel chairs or in confined spaces, such as those found in cars or airplanes. According to a further concept of the invention, the seat surface can therefore also be movably supported on a curve or straight line as a support which enables a comparable movement of the seat part.

This type of storage is shown in Fig. 3 and will now be described. As in Fig. 1, the selected representation is a side view.
The movable seat part 37 rests on a chair base 30 with the rollers 31. The height is adjusted via the vertical support 32. The frame 33 is height-adjustable and optionally rotatably mounted on this vertical strut 32. The circular slide curve 34 is fastened on the frame 33, on which the seat part is guided when the seat part moves. The seat part 37 rests on the struts 35 and 36 as parts of the support structure. The bevel of the seat part indicates that the angle of the seat part, as shown in Fig. 2, can be adjusted.

According to the invention, the seat part and the person sitting on it can slide forward and backward along the curve 34 when the seat part moves. In the normal sitting position in the middle position, the amplitude of this movement is approx. 5 cm. The entire circular curve 34 is therefore not required as a support for the seat part, but only corresponding supports 40 under the supports 35 and 36. These shorter curves 38 and 39 are drawn here as the tangents to the circular curve 34. The slope of curves 38 and 39 and the type of curve e.g. Circular arc, ellipse, parabola ... can be varied depending on which movement characteristics are desired. When running as a horizontal glide curve, it makes sense to reset the seat movement, e.g. to be provided in the form of a spring.

The image also contains a backrest 41 and the corresponding armrests 42. The backrest 41 and the armrests 42 are firmly connected to the frame 33 here. Since the effort required to move the seat part with the legs is generally less than the pushing forces required to adjust the roller / swivel chair, the chair can be moved via body contact with the fixed backrests.

When installing a movable seat in a car, good contact between the back and the backrest is important. Good contact with the backrest 41 is ensured by a Sitting position generated behind the normal central position, ie the resulting support (body) force 43 runs between the axis of rotation of the seat part and the backrest. When there is a corresponding load, the seat tries to move backwards and presses the back against the upholstery, which can be shaped to be health-friendly.

This type of sitting is particularly advantageous for professional activities that require power transmission with the arms (such as assembly line assembly or mechanical processing of workpieces).

• für körperlich schwere Arbeit,
• für leichte und Schreibtischtätigkeiten,
• für Arbeiten am Bildschirm und Hausarbeit.

The use of the seating furniture therefore makes sense for each of the sedentary activities:

• for physically difficult work,
• for light and desk work,
• for work on the screen and housework.

The seating furniture, in coordination with the bodily functions of the seated person, enables a seating technique that enables active sitting (no passive rest).

• vor und während des Hinsetzens -
  Das statisch nicht fixierte Sitzteil wird durch eine äußere Kraft oder von Hand durch die sich setzende Person gehalten.
• ab Beginn des Sitzens -
  Das Sitzteil wird durch den Kontakt über das Becken und die Bewegung der Beine (Beugen/Strecken) in die statisch bestimmte Mittellage gebracht und das Körpergewicht wird auf der Drehachse oder der oder den Führungsschiene(n) und auf den Füßen der sitzenden Person abgefangen.
• beim Aufstehen -
  Das statisch nicht mehr abgesicherte Sitzteil wird durch eine äußere Kraft z.B. mit der Hand oder einer Abstützung gehalten.

Since the seating and the body functions form a functional unit, a functional sequence for a seating process can be described as follows:

• before and while sitting down -
  The seat part, which is not statically fixed, is held by an external force or by hand by the person sitting down.
• from the start of sitting -
  The seat part is brought into the statically determined middle position by contact via the pelvis and the movement of the legs (bending / stretching) and the body weight is absorbed on the axis of rotation or the guide rail (s) and on the feet of the seated person.
• while getting up -
  The seat part, which is no longer statically secured, is held by an external force, for example with the hand or a support.

Example of seating furniture according to FIG. 2 lateral length of the frame 21 47 cm Diameter of the axis of rotation 23 1.6 cm Seat height 46 cm amplitude 5 cm

Type of seat part:
flat metal shell (like on a combine or agricultural tractor) padded with pillows.

2 instead of on the axis of rotation 23 on a plate with a thickness greater than 1.6 cm, the same seating comfort is made possible. For this purpose, the plate extends from the axis of rotation 23 to the right up to the protection 22 against tipping. This construction enables static sitting on a seat part secured against tipping and active sitting in the middle position by moving the seat part forward.

By replacing the frame 21 of the support structure with a gas pressure spring, the height of the seat part can be made adjustable.

Claims (18)

1. An item of seating furniture for sitting in the midway position, with a seat part (6; 20; 37) and a supporting structure (7; 21; 35, 36) for the seat part, whereby the two fixed parts are rotatable about a fulcrum (8; 23) which extends crosswise to the direction of seating and below the seat part in the area of the floor,
   characterised in that

   - the seat part (6; 20; 37) is rotatable out of the position of the possible midway position of a sitting person and around the fulcrum (8; 23) without any limiting means

   - the depth of the seat part (6; 20; 37) in the seating direction is on both sides of the fulcrum (8; 23) so great that on the one hand

   - in the event of a rotation of the seat part (6; 20; 37) out of the midway position and forwards by the body weight of a person (1, 2, 3, 4, 5, 9, 11), by reason of the action of a restoring force (14) behind the fulcrum (8; 23) on the sitting area of the seat part (6; 20; 37), a stabilising moment about the axis of rotation (8) acts to restore the seat part (6; 20; 37) to the starting position, and on the other hand

   - upon rotation of the seat part out of the midway position rearwardly by the body weight of a person due to the action of a restoring force (15) in front of the axis of rotation (8; 23) a stabilising moment about the fulcrum (8) acts on the sitting area of the seat part (6; 20; 37) in order to restore the seat part (6; 20; 37) to the starting position.
2. An item of seating furniture according to claim 1, characterised in that the supporting structure is supported on the fulcrum.
3. An item of seating furniture according to claim 1, characterised in that the fulcrum consists of a continuous rod or of parts thereof.
4. An item of seating furniture according to one or more of the preceding claims, characterised in that the fulcrum is a part of the supporting structure.
5. An item of seating furniture according to one or more of the preceding claims, characterised in that the fulcrum is rotatably mounted in a fixed bearing and that the supporting structure is adapted to rotate about the central point of the axle.
6. An item of seating furniture according to one or more of the preceding claims, characterised in that the fulcrum rests on a support in such a way as to roll and in that the seat part is rotatable by a rolling movement of the axle on the support.
7. An item of seating furniture according to one or more of the preceding claims, characterised in that the supporting structure consists of a plurality of frames parallel with the seating direction.
8. An item of seating furniture according to one or more of the preceding claims, characterised in that the claims are mounted for movement on a rigid axle or parts thereof while the seat part can be rotated forwards or backwards by rolling on the axle profile.
9. An item of seating furniture according to one or more of the preceding claims, characterised in that the axle or parts thereof are fixed on the floor.
10. An item of seating furniture according to one or more of the preceding claims, characterised in that the fulcrum is incorporated into the base of the chair.
11. An item of seating furniture according to one or more of the preceding claims, characterised in that the fulcrum, in the seating direction, is constituted by the front edge of the chair base and in that the seat part is, via the supporting structure, so mounted on the chair base that in the midway position, during sitting, the rest of the chair base is rotated upwardly about the fulcrum.
12. An item of seating furniture according to one or more of the preceding claims, characterised in that the supporting structure is constructed to be vertically adjustable by means of a gas spring.
13. An item of seating furniture according to one or more of the preceding claims, characterised in that the seat part with the supporting structure is mounted for forwards and rearwards displacement on guide rails or segments thereof.
14. An item of seating furniture according to one or more of the preceding claims, characterised in that the guide rails consist of segments of arcs about the fulcrum.
15. An item of seating furniture according to one or more of the preceding claims, characterised in that the guide rails are incorporated into the chair base in such a way as to be adjustable in height.
16. An item of seating furniture according to one or more of the preceding claims, characterised in that the seat part can be locked on the supporting structure, is rotatable about an axis parallel with the fulcrum and can be secured by a locking means so that the angle of inclination of the seat area can be fixed in the midway position and adapted to the person.
17. An item of seating furniture according to one or more of the preceding claims, characterised in that a back part is fixed on the seat part, the back part being so adjustable that upon a movement of the seat part forwards, a part of the back can be inclined rearwardly beyond the outer edge of the back part.
18. An item of seating furniture according to one or more of the preceding claims, characterised in that the seat part can in each case be braced by an abutment against being tilted rearwards and/or forwards.

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