EP3801136B1 - Physiological seat device - Google Patents

Description

The present invention relates to the field of the prevention of morphological and functional disorders of the body induced by the common sitting position. It relates more particularly to a physiological sitting device allowing such prevention. US 2007/222265 A1 , DE 29711329 U1 and EP2172135 A1 are considered as documents reflecting the state of the art and as useful for understanding the invention.

• le mode physiologique de la verticalité associé au mouvement, à l'action et à la posture verticalisée, où la motricité respiratoire est assurée par l'activité tonico-phasique du diaphragme et de la sangle abdominale ; et
• le mode physiologique de l'horizontalité associé à l'immobilité, à la relaxation, au repos et à la posture horizontalisée, où la motricité respiratoire est assurée par l'activité tonico-phasique isolée du diaphragme alors que la sangle abdominale est passive.

The original man had two great dominant functional modes:

• the physiological mode of verticality associated with movement, action and upright posture, where respiratory motor skills are ensured by the tonic-phasic activity of the diaphragm and the abdominal strap; and
• the physiological mode of horizontality associated with immobility, relaxation, rest and the horizontalized posture, where respiratory motility is ensured by the isolated tonic-phasic activity of the diaphragm while the abdominal strap is passive.

Nowadays, with the sedentary lifestyle and the seated position, a third dysfunctional mode predominates which associates the verticalized posture and the respiratory motricity of relaxation. This is the mode of posturo-respiratory degeneration.

• du relâchement et de la distension de la paroi abdominale ;
• de la compression et du tassement de la colonne vertébrale ;
• de l'étirement et de l'allongement du pharynx ; et
• de l'affaissement du plancher buccal, de la cage thoracique et du diaphragme.

Its consequences are morphological with the progressive increase:

• relaxation and distension of the abdominal wall;
• compression and collapse of the spine;
• stretching and lengthening of the pharynx; and
• collapse of the floor of the mouth, rib cage and diaphragm.

• l'efficacité ventilatoire des muscles respiratoires diminue avec l'affaissement du diaphragme ;
• la rigidité de la cage thoracique augmente par insuffisance de mobilisation et par "verrouillage" avec l'accentuation de la cyphose thoracique ;
• la puissance respiratoire moyenne augmente avec la ventilation/minute pour compenser la baisse du volume courant et l'augmentation du volume mort ;
• la compliance des parois pharyngées augmente avec l'allongement du pharynx ;
• les troubles ventilatoires obstructifs du sommeil (TVOS) augmentent avec la puissance respiratoire et la compliance des parois pharyngées ;
• la qualité du sommeil diminue avec les TVOS ;
• les performances métaboliques et cognitives diminuent avec la dégradation du sommeil et de la respiration ;
• la productivité individuelle par rapport au potentiel diminue avec les performances physiques et mentales ;
• la qualité de vie diminue ;
• les affections chroniques augmentent ; et
• le coût social de l'individu augmente, etc.

Its consequences are functional:

• the ventilatory efficiency of the respiratory muscles decreases with the collapse of the diaphragm;
• the rigidity of the thoracic cage increases by insufficient mobilization and by "locking" with the accentuation of the thoracic kyphosis;
• mean respiratory power increases with ventilation/minute to compensate for the decrease in tidal volume and the increase in dead volume;
• the compliance of the pharyngeal walls increases with the lengthening of the pharynx;
• sleep obstructive ventilatory disorders (TVOS) increase with respiratory power and compliance of the pharyngeal walls;
• sleep quality decreases with TVOS;
• metabolic and cognitive performance decreases with the deterioration of sleep and breathing;
• individual productivity relative to potential decreases with physical and mental performance;
• the quality of life decreases;
• chronic conditions are increasing; and
• the social cost of the individual increases, etc.

• l'efficacité ventilatoire des muscles respiratoires ;
• la souplesse, la mobilité et la capacité de la cage thoracique ;
• la diminution de la puissance respiratoire moyenne et des pressions transpariétales inspiratoires ; et
• la diminution des contraintes mécaniques supportées par le squelette axial, etc.

For this reason, the present inventor has proposed a belt for the prevention of posturo-respiratory degeneration and for posturo-respiratory rehabilitation, which has been the subject of the French patent FR2985902 and which comprises a belt part bearing a ventral piece capable of being applied and held on the lower abdomen of the wearer in a zone comprised between the pubis and the umbilicus, and tightening means enabling the ventral piece to provide compression of the lower abdomen of the wearer to supplement the function of stretching and counter-thrust on the diaphragm when the abdominal strap is inactive in a vertical situation, and thus promote:

• the ventilatory efficiency of the respiratory muscles;
• the flexibility, mobility and capacity of the rib cage;
• decrease in mean respiratory power and inspiratory transparietal pressures; and
• reduction of the mechanical stresses supported by the axial skeleton, etc.

However, this belt shows its limits in a seated position when the pelvis is poorly positioned. Nor does it deal with the anti-physiological character of the sitting position. The present inventor now proposes an alternative device to the classic chair. A device that provides physiological conditions for seating and orientation of the pelvis. A device which obliges, without effort or discomfort, on the contrary, the maintenance of an organization and a mobility of the vertebral column in conformity with the physiology of the man in verticalized posture.

The optimal physiological posture is characterized, in verticality, by an alignment of the occipito-altoid and coxo-femoral pivots on a vertical line, tangent to the anterior edge of the third lumbar, projecting to the ground in the middle of the feet. This optimal posture is illustrated on the Figure 1A , on which the vertebral column C and the pelvis B of the person have been shown and the occipito-altoid pivot has been designated by P1, by P2 that of the coxo-femoral pivots which appears on the Figure 1A , by Lb the 3 ^rd lumbar and by V the vertical.

We have illustrated on the Figure 1B a person with retroverted pelvis, shown as a counter-clockwise circle, and thoracic hyperkyphosis, shown as a clockwise circle.

It is emphasized here that, in the description, the claims and the drawings, the right profile of the user has been taken as a convention to define the clockwise and anti-clockwise directions. Of course, these directions are opposite if we consider the left profile of the user.

As can be seen on the Figures 2A and 2B , on which two classic postures of a person in a seated position on a classic chair have been illustrated, of which only the seat and the back have been shown, the sitting position induces retroversion of the pelvis and thoracic hyperkyphosis, also illustrated by counterclockwise and clockwise oriented circles, respectively. The seated position thus promotes posturo-respiratory degradation and its expressions: fatigue, stress, degradation of the state of health, etc.

Sitting is a major public health problem.

The present invention therefore aims to propose a solution making it possible to correct the sitting posture of a person so that it is optimal and conforms to the physiology of man in verticality, by making it possible to prevent retroversion of the pelvis, lumbar delordosis , thoracic hyperkyphosis, muscular hypotonia of the trunk and their orthopedic, morphological and metabolic consequences.

• une pièce lombaire solidaire en rotation de l'assise et positionnée de façon à, en utilisation, venir s'appliquer contre le dos de l'utilisateur, au niveau de ses vertèbres lombaires, et
• une selle de support du haut des cuisses de l'utilisateur, la selle étant reliée à la région avant de l'assise.

The solution according to the present invention is a seat device comprising a base and a seat comprising a rear region and a front region, characterized in that the seat is connected to the base by a connection allowing the seat to pivot by relative to the base about a pivot axis, called seat axis, which is horizontal and orthogonal to the depth direction of the seat, said connection being positioned with respect to the seat in such a way that the seat pivots forwards when a user sits on the seat, being provided means for elastically biasing the seat in rotation backwards, and in that the seat device further comprises:

• a lumbar part integral in rotation with the seat and positioned so as to, in use, come to rest against the back of the user, at the level of his lumbar vertebrae, and
• a support saddle for the upper thighs of the user, the saddle being connected to the front region of the seat.

When the user sits on the seat device according to the present invention, he places the top of his thighs on the saddle and his weight will be applied to the saddle at the level of the point of intersection between the saddle and the plumb with the user's center of gravity, in other words in front of the seat axis. The weight of the user will therefore exert on the seat, due to the lever arm between the seat axis and said point of intersection, a torque of rotation in the clockwise direction, therefore in the direction opposite to the stress exerted on the seat by the respective elastic biasing means, the latter also being configured so that the bias they exert is less than the stress exerted by the user. This clockwise rotation torque causes the seat and the lumbar part to pivot in a single piece in the clockwise direction until the lumbar part comes to rest against the back of the user, at the level of the lumbar vertebrae. , to correctly orient the spine and pelvis. It is emphasized here that the saddle contributes to the freedom of correct orientation of the pelvis in a seated position.

Thus, the seating device according to the present invention allows the simultaneous correction of the orientation of the pelvis and the organization of the spine, without the user having to perform any action other than simply sitting on the seating device.

Preferably, the saddle is connected to the front region of the seat by a connection allowing the saddle to pivot relative to the seat around a pivot axis, called the saddle axis, which is parallel to the axis seat and in front of the seat axis in the depth direction of the seat, being provided means for elastic biasing of the saddle forwards.

Thus, when the user places the top of his thighs on the saddle, his weight will, in addition to the seat, cause the saddle to pivot counter-clockwise, against the stress exerted on the saddle by the respective elastic biasing means, the latter being configured so that the bias they exert is less than the stress exerted by the user. However, the stress exerted by the saddle on the user further improves, due to the positioning of the saddle on the upper thighs of the user and therefore the absence of support on the pelvis or the sacrum, the prevention of retroversion of the pelvis.

Preferably, the seat device comprises stoppers positioned to limit the pivoting travel of the seat and/or, where appropriate, of the saddle, in both directions of rotation.

Preferably, the connection between the seat and the base is a first pivot connection and, where applicable, the connection between the saddle and the seat is a second pivot connection, the first and second pivot connections each comprising a pivot constituting the seat axis and saddle axis, respectively.

Preferably, the elastic biasing means of the seat and/or, where appropriate, of the saddle are springs, in particular torsion springs, preferably with adjustable tension.

Preferably, the seat is mounted adjustable in position, in the depth direction of the seat, relative to the base, so as to allow adjustment of the distance between the seat axis and the saddle axis, in the depth direction of the seat.

The lumbar part can be fixed to or formed by a part of the backrest, preferably a part of the backrest, in particular the free end region of the backrest, which is in return towards the front region of the seat.

Preferably, the lumbar part is adjustable in position, relative to the seat axis, in the vertical direction and in the depth direction of the seat, so as to allow adjustment of the position of the lumbar part in depending on the build of the user.

Preferably, the saddle is formed of two parts symmetrical with respect to a vertical plane to which the depth direction of the seat belongs, each part of the saddle being intended to support the top of a respective thigh of the user, the the spacing between the two parts of the saddle being preferably adjustable.

Preferably, the saddle comprises a front region, intended to support the upper thighs of the user, plumb with the axes of the coxo-femoral joints of the user, and a rear region which is hollowed out in a medial zone where the seat bones of the user will be located and which goes up in its two lateral zones, so as to slightly envelop the infero-lateral parts of the buttocks.

Preferably, the base is of the rocker type at least in the sagittal plane, possibly also in the transverse plane.

Such a rocker type base makes the seating device unstable to a certain extent. This instability of the base makes it possible to solicit the muscular chains of the user's trunk when he is seated on the seat device, in a manner analogous to their solicitation when the user is standing and the pelvis is unstable and oscillates on the pivots of the lower limb. The sitting device then makes it possible to prevent muscular hypotonia of the trunk.

The base may have a rounded base, optionally having height adjustment wedge interlocking means following the same curve as the base.

The seat device may further comprise means for defining the maximum amplitude of tilting of the base, preferably comprising feet mounted in translation with respect to the base so as to be movable between a position in which they protrude with respect to the base so as to be able to come into contact with the ground to oppose the tilting of the base, and a position in which they do not protrude with respect to the base.

It is possible to provide elastic biasing means, such as for example springs, to bias the feet towards the position in which they protrude with respect to the base.

To better illustrate the object of the present invention, there will be described below, by way of indication and not limitation, a particular embodiment with reference to the appended drawing.

• [Fig. 1A] est une vue schématique de côté d'une personne dans la posture optimale.
• [Fig.1B] est une vue schématique de côté d'une personne dans une posture avec rétroversion du bassin et cyphose thoracique.
• [Fig.2A] est une vue schématique de côté d'une personne assise sur une chaise classique, dans une première posture.
• [Fig.2B] es une vue schématique de côté d'une personne assise sur une chaise classique, dans une posture différente de celle de la Figure 2A.
• [Fig.3] est une vue schématique de côté d'un dispositif d'assise selon un mode de réalisation particulier de la présente invention.
• [Fig.4A] est une vue schématique de côté du dispositif d'assise de la Figure 3, à un premier instant lorsqu'une personne s'assied sur le dispositif d'assise.
• [Fig.4B] est une vue schématique de côté du dispositif d'assise de la Figure 3, à un deuxième instant lorsqu'une personne s'assied sur le dispositif d'assise.
• [Fig.4C] est une vue schématique de côté du dispositif d'assise de la Figure 3, à un troisième instant lorsqu'une personne s'assied sur le dispositif d'assise.
• [Fig.4D] est une vue schématique de côté du dispositif d'assise de la Figure 3, à un quatrième instant lorsqu'une personne s'assied sur le dispositif d'assise.
• [Fig.5A] est une vue schématique de côté du dispositif d'assise de la Figure 3, une personne étant assise sur le dispositif d'assise en position verticale.
• [Fig.5B] est une vue schématique de côté du dispositif d'assise de la Figure 3, lorsqu'une personne est assise et avance.
• [Fig.5C] est une vue schématique de côté du dispositif d'assise de la Figure 3, lorsqu'une personne est assise et recule.
• [Fig.5D] est une vue schématique de côté du dispositif d'assise de la Figure 3, lorsqu'une personne est assise et s'incline vers l'arrière.
• [Fig.5E] est une vue schématique de côté du dispositif d'assise de la Figure 3, lorsqu'une personne est assise et s'incline vers l'avant.
• [Fig.6] est une vue schématique de côté du piétement du dispositif d'assise.
• [Fig.7A] est une vue de côté d'une selle en deux parties et de ses moyens pour le réglage de leur écartement et de leur orientation.
• [Fig.7B] est une vue de face de la selle de la Figure 7A.
• [Fig.7C] est une vue de côté en éclaté de la selle de la Figure 7A.
• [Fig.7D] est une vue de face en éclaté de la selle de la Figure 7A.
• [Fig.7E] est une vue de dessous de la selle de la Figure 7A.
• [Fig.8A] est une vue de dessous des hémi-selles, en éclaté.
• [Fig.8B] est une vue de dessous des hémi-selles, en position rapprochement maximal/non orientées.
• [Fig.8C] est une vue de dessous des hémi-selles, en position écartement intermédiaire/non orientées.
• [Fig.8D] est une vue de dessous des hémi-selles, en position rapprochement maximal/orientées vers le centre.
• [Fig.8E] est une vue de dessous des hémi-selles, en position rapprochement maximal/orientées vers l'extérieur.
• [Fig.9A] est une vue de côté d'un corps d'assise.
• [Fig.9B] est une vue de côté du corps d'assise de la Figure 9A, avec paroi latérale omise.
• [Fig.9C] est une vue de dos du corps d'assise de la Figure 9A.
• [Fig.9D] est une vue de face du corps d'assise de la Figure 9A.
• [Fig.9E] est une vue de dessus du corps d'assise de la Figure 9A.
• [Fig.9F] est une vue de dessous du corps d'assise de la Figure 9A.
• [Fig.10A] est une vue de côté montrant la selle et le corps d'assise.
• [Fig.10B] es une vue analogue à la Figure 10A, avec course maximale de pivotement de la selle.
• [Fig.10C] est une vue analogue à la Figure 10A, avec course intermédiaire et course minimale.
• [Fig.10D] est une vue de face correspondant à la Figure 10C.
• [Fig.11A] est une vue analogue à la Figure 10A, une paroi latérale du corps d'assise ayant été omise.
• [Fig.11B] est une vue analogue à la Figure 10B, une paroi latérale du corps d'assise ayant été omise.
• [Fig.11C] est une vue analogue à la Figure 10C, une paroi latérale du corps d'assise ayant été omise.
• [Fig.11D] est une vue analogue à la Figure 10D, une paroi latérale du corps d'assise ayant été omise.
• [Fig.12A] est une vue montrant le dossier et la pièce de liaison au corps d'assise, en éclaté de côté.
• [Fig.12B] est une vue de face du dossier et de la pièce de liaison au corps d'assise.
• [Fig.12C] est une vue de dos du dossier et de la pièce de liaison au corps d'assise.
• [Fig.12D] est une vue de dessous de la pièce de liaison.
• [Fig.13A] est une vue de côté du dossier relié au corps d'assise par la pièce de liaison.
• [Fig.13B] est une vue de face du dossier relié au corps d'assise par la pièce de liaison.
• [Fig.14A] est une vue de côté du dossier relié au corps d'assise, une paroi latérale du corps d'assise ayant été omise, aux profondeur et hauteur minimales du dossier.
• [Fig.14B] est une vue analogue à la Figure 14A, à des profondeur et hauteur intermédiaires du dossier.
• [Fig.15A] est une vue de l'ensemble selle, dossier et assise, de dos.
• [Fig.15B] est une vue de l'ensemble selle, dossier et assise, de face.
• [Fig.15C] est une vue de l'ensemble selle, dossier et assise, de côté.
• [Fig.15D] est une vue de l'ensemble selle, dossier et assise, de côté avec une paroi latérale du corps d'assise omise.
• [Fig.16A] est une vue de côté du piétement.
• [Fig.16B] est une vue de face du piétement.
• [Fig.17A] es une vue de côté montrant la liaison au piétement du corps d'assise, dans un réglage empêchant tout pivotement du corps d'assise.
• [Fig.17B] est une vue de côté analogue à la Figure 17A, montrant un premier réglage des butées de pivotement vers l'avant et vers l'arrière.
• [Fig.17C] est une vue de côté analogue à la Figure 17A, montrant un second réglage des butées de pivotement vers l'avant et vers l'arrière.
• [Fig.18A] est une vue de côté d'une pièce ressort.
• [Fig.18B] est une vue de face de la pièce ressort.
• [Fig.18C] est une vue de côté montrant la pièce ressort montée sur le support du piétement.
• [Fig.18D] est une vue de face montrant la pièce ressort montée sur le support du piétement.
• [Fig.19A] est une vue de côté montrant le corps d'assise monté sur le support lui-même muni de la pièce ressort.
• [Fig.19B] est une vue de face de la Figure 19A.
• [Fig.20A] est une vue de côté d'un dispositif d'assise conforme aux Figures 7A à 19B, le piétement étant dans une configuration à bascule dans le plan sagittal.
• [Fig.20B] est une vue de face du dispositif d'assise de la Figure 20A.
• [Fig.20C] est une vue de côté d'un dispositif d'assise conforme aux Figures 7A à 19B, le piétement étant dans une configuration à bascule dans le plan transversal.
• [Fig.20D] est une vue de face du dispositif d'assise de la Figure 20C.
• [Fig.21] est une vue de côté d'une variante de réalisation du dispositif d'assise de la Figure 20A.
• [Fig.22] est une vue de face du dispositif d'assise de la Figure 21.
• [Fig.23] est une vue de côté montrant schématiquement les moyens de réglage de la distance entre la pièce lombaire et la selle.
• [Fig.24] est une vue en perspective de la selle seule.
• [Fig.25] est une vue en perspective d'un support de partie de selle.
• [Fig.26] est une vue en perspective de l'autre support de partie de selle.
• [Fig.27] est une vue en coupe transversale de la selle, le capot supérieur n'ayant pas été représenté.
• [Fig.28] est une vue en coupe longitudinale de la selle, le capot supérieur n'ayant pas été représenté.
• [Fig.29] est une vue en coupe transversale de l'assise, montrant les moyens de réglage de la grandeur de la sollicitation élastique exercée par les moyens de sollicitation élastique de l'assise vers l'arrière.
• [Fig.30] est une vue de côté montrant en détail le piétement du dispositif d'assise de la Figure 21.
• [Fig.31] est une vue en perspective montrant le piétement de la Figure 30, dans une position retournée vers le haut.

On this drawing :

• [ Fig. 1A ] is a schematic side view of a person in the optimal posture.
• [ Fig.1B ] is a schematic side view of a person in a posture with retroversion of the pelvis and thoracic kyphosis.
• [ Fig.2A ] is a schematic side view of a person seated on a conventional chair, in a first posture.
• [ Fig.2B ] is a schematic side view of a person sitting on a chair classic, in a posture different from that of the Figure 2A .
• [ Fig.3 ] is a schematic side view of a seating device according to a particular embodiment of the present invention.
• [ Fig.4A ] is a schematic side view of the seating device of the Figure 3 , at a first instant when a person sits down on the seating device.
• [ Fig.4B ] is a schematic side view of the seating device of the Figure 3 , at a second time when a person sits on the seating device.
• [ Fig.4C ] is a schematic side view of the seating device of the Figure 3 , at a third instant when a person sits down on the seating device.
• [ Fig.4D ] is a schematic side view of the seating device of the Figure 3 , at a fourth instant when a person sits down on the seating device.
• [ Fig.5A ] is a schematic side view of the seating device of the Figure 3 , a person being seated on the seating device in an upright position.
• [ Fig.5B ] is a schematic side view of the seating device of the Figure 3 , when a person is seated and moves forward.
• [ Fig.5C ] is a schematic side view of the seating device of the Figure 3 , when a person is sitting and moving backwards.
• [ Fig.5D ] is a schematic side view of the seating device of the Figure 3 , when a person is seated and leans back.
• [ Fig.5E ] is a schematic side view of the seating device of the Figure 3 , when a person is seated and leans forward.
• [ Fig.6 ] is a schematic side view of the base of the seat device.
• [ Fig.7A ] is a side view of a saddle in two parts and its means for adjusting their spacing and their orientation.
• [ Fig.7B ] is a front view of the saddle of the Figure 7A .
• [ Fig.7C ] is an exploded side view of the saddle of the Figure 7A .
• [ Fig.7D ] is an exploded front view of the saddle of the Figure 7A .
• [ Fig.7E ] is a bottom view of the seat of the Figure 7A .
• [ Fig.8A ] is an exploded view of the underside of the semi-saddles.
• [ Fig.8B ] is a view from below of the semi-saddles, in the maximum approach/non-oriented position.
• [ Fig.8C ] is a bottom view of the semi-saddles, in the intermediate/non-oriented spread position.
• [ Fig.8D ] is a bottom view of the semi-saddles, in the maximum approach position / oriented towards the center.
• [ Fig.8E ] is a bottom view of the semi-saddles, in the maximum approach/outward facing position.
• [ Fig.9A ] is a side view of a seat body.
• [ Fig.9B ] is a side view of the seat body of the Figure 9A , with side wall omitted.
• [ Fig.9C ] is a rear view of the seat body of the Figure 9A .
• [ Fig.9D ] is a front view of the seat body of the Figure 9A .
• [ Fig.9E ] is a top view of the seat body of the Figure 9A .
• [ Fig.9F ] is a bottom view of the seat body of the Figure 9A .
• [ Fig.10A ] is a side view showing the saddle and the seat body.
• [ Fig.10B ] is a view analogous to the Figure 10A , with maximum saddle swivel travel.
• [ Fig.10C ] is a view analogous to the Figure 10A , with intermediate stroke and minimum stroke.
• [ Fig.10D ] is a front view corresponding to the Figure 10C .
• [ Fig.11A ] is a view analogous to the Figure 10A , a side wall of the seat body having been omitted.
• [ Fig.11B ] is a view analogous to the Figure 10B , a side wall of the seat body having been omitted.
• [ Fig.11C ] is a view analogous to the Figure 10C , a side wall of the seat body having been omitted.
• [ Fig.11D ] is a view analogous to the Figure 10D , a side wall of the seat body having been omitted.
• [ Fig.12A ] is a view showing the backrest and the connecting piece to the seat body, exploded from the side.
• [ Fig.12B ] is a front view of the backrest and the connecting piece to the seat body.
• [ Fig.12C ] is a rear view of the backrest and the connecting piece to the seat body.
• [ Fig.12D ] is a bottom view of the connecting piece.
• [ Fig.13A ] is a side view of the back connected to the seat body by the connecting piece.
• [ Fig.13B ] is a front view of the back connected to the seat body by the connecting piece.
• [ Fig.14A ] is a side view of the back connected to the seat body, with a side wall of the seat body omitted, at the minimum depth and height of the back.
• [ Fig.14B ] is a view analogous to the Figure 14A , at intermediate depths and heights of the backrest.
• [ Fig.15A ] is a rear view of the saddle, backrest and seat assembly.
• [ Fig.15B ] is a view of the saddle, backrest and seat assembly, from the front.
• [ Fig.15C ] is a view of the saddle, backrest and seat assembly, from the side.
• [ Fig.15D ] is a view of the saddle, backrest and seat assembly, from the side with a side wall of the seat body omitted.
• [ Fig.16A ] is a side view of the base.
• [ Fig.16B ] is a front view of the base.
• [ Fig.17A ] are a side view showing the connection to the base of the seat body, in an adjustment preventing any pivoting of the seat body.
• [ Fig.17B ] is a side view analogous to the Figure 17A , showing a first adjustment of the pivot stops forward and backward.
• [ Fig.17C ] is a side view analogous to the Figure 17A , showing a second adjustment of the forward and rearward swivel stops.
• [ Fig.18A ] is a side view of a spring piece.
• [ Fig.18B ] is a front view of the spring part.
• [ Fig.18C ] is a side view showing the spring piece mounted on the base support.
• [ Fig.18D ] is a front view showing the spring piece mounted on the base support.
• [ Fig.19A ] is a side view showing the seat body mounted on the support itself provided with the spring part.
• [ Fig.19B ] is a front view of the Figure 19A .
• [ Fig.20A ] is a side view of a seating device conforming to Figures 7A to 19B , the base being in a tilting configuration in the sagittal plane.
• [ Fig.20B ] is a front view of the seating device of the Figure 20A .
• [ Fig.20C ] is a side view of a seating device conforming to Figures 7A to 19B , the base being in a tilting configuration in the transverse plane.
• [ Fig.20D ] is a front view of the seating device of the Figure 20C .
• [ Fig.21 ] is a side view of an alternative embodiment of the seating device of the Figure 20A .
• [ Fig.22 ] is a front view of the seating device of the Picture 21 .
• [ Fig.23 ] is a side view schematically showing the means for adjusting the distance between the lumbar part and the saddle.
• [ Fig.24 ] is a perspective view of the saddle alone.
• [ Fig.25 ] is a perspective view of a saddle part support.
• [ Fig.26 ] is a perspective view of the other saddle part support.
• [ Fig.27 ] is a cross-sectional view of the saddle, the top cover not having been shown.
• [ Fig.28 ] is a longitudinal sectional view of the saddle, the top cover not having been shown.
• [ Fig.29 ] is a cross-sectional view of the seat, showing the means for adjusting the magnitude of the elastic stress exerted by the means for elastic biasing the seat to the rear.
• [ Fig.30 ] is a side view showing in detail the base of the seat device of the Picture 21 .
• [ Fig.31 ] is a perspective view showing the base of the Picture 30 , in an upturned position.

If we refer to the Figure 3 , it can be seen that there is shown schematically a seating device 1 according to one embodiment of the present invention. The seat device 1 comprises a base 2, a seat 3, a backrest 4 and a saddle 5.

The base 2 is defined so as to rest, by its lower part, on the ground and to support, by its upper part, the seat 3, the backrest 4 and the saddle 5.

As will emerge from the following description, the underframe 2 according to the present invention is remarkable for the arrangement of its lower part, or base, and of its upper part. Thus, in the Figures, the base 2 has been represented schematically by a circular sector delimited by two rectilinear lines 21 meeting at a vertex materializing the upper part 22 of the base 2 and by an arc of a circle connecting the ends of the lines 21 and materializing the lower part 23 of the base 2.

The present invention is not limited to any structure of the base 2 between the upper part 22 and the lower part 23, and one could use, for the upper parts 22 and lower 23, structures already employed in conventional chairs. , such as metal rods.

In this embodiment, the base 2 is of the rocker type, which means that its lower part 23 actually has at least one contact surface with the ground which follows an arc of a circle whose center, according to the present invention, belongs to the horizontal line passing through the upper part 22 of the base 2. Such a contact surface may be implemented in any appropriate form, also well known per se, such as for example by the use of two curved parts, in particular of wood , connecting four legs of the base. One could also provide, for example, a single contact surface defined by a plate which follows an arc of a cylinder whose axis is horizontal and passes through the upper part 22 of the base 2.

Such a rocker-type base 2 offers the user a functional and dynamic posture by allowing him to rock forwards and backwards in the sagittal plane, as will emerge from the Figures 5A to 5E .

In addition, the base 2 is not stable, and the muscle chains of the user's trunk will therefore be stressed when the user naturally seeks balance. This prevents muscular hypotonia of the trunk.

It is emphasized here that it could also be provided that the lower part 23 allows a tilting of the seat device 1 to the left and to the right, in other words transversely to the sagittal plane, to further amplify the functional and dynamic character of the seat device 1. It could thus be provided that the lower part 23 is formed by a plate which follows a spherical cap of a sphere whose center is located on the horizontal line passing through the upper part 22 of the base 2.

The upper part 22 of the base 2 is connected to the seat 3 by a pivot connection 6, represented by a circle on the Figure 3 , allowing relative pivoting between the base 2 and the seat 3 around a pivot axis, called seat axis, designated by the reference A1 and represented by a smaller circle on the Figure 3 . Here, the seat axis A1 is globally located in the middle part of the seat 3, in the depth direction of the seat 3.

According to the present invention, the seat device 1 also comprises means for elastically biasing the seat 3 in rotation in the anti-clockwise direction, as illustrated by a circle bearing the arrow F1 on the Figure 3 . Here again, these elastic biasing means can be implemented in any appropriate form without departing from the scope of the present invention.

Adjustable stops for stopping the pivoting of the seat 3 (not shown on the Figure 3 ) can be carried or formed by the base 2 to define the end positions of the seat 3 in the anti-clockwise direction and in the clockwise direction.

In the embodiment represented schematically in the Figures, the seat 3 and the backrest 4 are made in one piece, in a single piece, a first region of which, extending globally horizontally, forms the seat 3 and of which a second region, extending overall vertically, forms the backrest 4. Here, a shell shape has been given to this part, for a pleasant and modern aesthetic appearance. It is therefore easy to understand that the backrest 4 will pivot together with the seat 3 around the axis A1.

The backrest 4 extends from a rear region 31 of the seat 3 and has a free end region 41, namely the region of the upper horizontal edge of the backrest 4, which returns horizontally at least slightly towards the region front 32 of the seat 3. A buffer 42, forming the lumbar part according to the present invention, is fixed here to the free end region 41, so as to form the part of the backrest 4 which will come into contact with the back of the user. The lumbar part 42 may be made of foam and fabric, rubber, etc. Of course, the lumbar part 42 could be formed directly by the free end region 41 of the backrest 4, and not by a part attached thereto.

As will be described below, the backrest 4 is sized so that the lumbar part 42 is located at the height of the lumbar vertebrae of the user seated on the seat device 1. Advantageously, the lumbar part 42 offers a convex surface, to prevent contact of the lumbar part 42 against the back of the user does not lead to pain or discomfort in the user.

The saddle 5 is configured to support the upper thighs of the seated user, plumb with the axis of the coxo-femoral joints. The saddle 5 is connected to the seat 3, at the level of the front region 32 of the latter, by a pivot connection 7, represented by a point on the Figure 3 , allowing relative pivoting between the seat 3 and the saddle 5 about a pivot axis, called the saddle axis, designated by the reference A2 and represented by the same point on the Figure 3 . The saddle axis A2 is therefore located in front of the seat axis A1, in the depth direction of the seat 3.

According to the present invention, the seat device 1 also comprises means for elastically biasing the saddle 5 in clockwise rotation, as illustrated by a circle bearing the arrow F2 on the Figure 3 . Here again, these elastic biasing means can be implemented in any appropriate form without departing from the scope of the present invention.

Stops for stopping the pivoting of the saddle 5 (not shown on the Figure 3 ) are carried or formed by the seat 3 to define the limit switches of the saddle 5 counterclockwise and clockwise.

For example, the various stops can be positioned so that in the absence of a person seated in the seat device 1, the seat 3, the backrest 4 and the saddle 5 are in the configuration illustrated on the Figure 3 : the seat 3 and the backrest 4 are at least slightly inclined towards the rear and the saddle 5 is at least slightly inclined towards the front. This particular configuration allows the user to sit naturally on the seat device 1, as can be seen in the Figures 4A to 4D .

On the Figure 4A , the user stands upright, in the optimum posture, in front of the seat device 1, as for a conventional chair.

On the Figure 4B , the user has lowered himself by bending his knees until the top of his thighs is in contact with the saddle 5. It can be seen that the vertical V1 passing through the occipito-altoid pivot P1 no longer coincides with the vertical V2 passing through the coxo-femoral pivot P2. The sacrum S is tilted backwards by the pelvis in retroversion, and the spine C is bent backwards (thoracic kyphosis).

On the Figure 4C , the user continued to lower himself, initially by pivoting the saddle 5 around the saddle axis A2 in the counter-clockwise direction until coming into contact with the corresponding stopper, then secondly by pivoting the seat 3/backrest 4/saddle 5 assembly around the seat axis A1 clockwise, causing the lumbar part 42 to bear against the user's back, at the level of the lumbar vertebrae. It can also be noted that the natural movement of the user has also led to a slight pivoting of the entire seat device 1, since the base 2 is here of the rocker type.

The user is then already in the optimal posture, in which the occipito-altoid P1 and coxo-femoral P2 pivots are aligned on a vertical line V tangent to the anterior edge of the third lumbar Lb, and maintains this posture when the device d seat 1 returns to the vertical position as shown in the Figure 4D .

This optimal posture is obtained thanks to the combined action of the lumbar part 42, which bears against the back of the user at the level of the lumbar vertebrae, and of the saddle 5, which supports the upper thighs and allows good orientation of the user's pelvis B.

The user will maintain this optimal posture as long as they remain seated, even if they tilt forwards or backwards, as can be seen on the Figures 5A to 5E .

On the Figure 5A , the base 2 is vertical.

On the Figure 5B , the user sought to move forward slightly, which led to the inclination of the base 2 forwards while the seat 3/backrest 4/saddle 5 assembly remains in the same position as on the Figure 5A , by relative rotation around the seat axis A1, so that the user remains in the optimum posture, in particular with his back vertical.

In the same way, if the user tries to move back slightly, the base 2 will tilt backwards while the seat 3/backrest 4/saddle 5 assembly still remains in the same position as on the Figure 5 , by relative rotation around the seating axis A1, as shown in the Figure 5C .

If the user leans backwards, he will, through his back, pivot the backrest 4 backwards, and therefore also the seat 3 and the saddle 5, around the seat axis A1, until the seat 3 comes into contact with the corresponding stopper, contact from which the inclination of the user backwards will be transmitted to the base 2 and will tilt the entire seat device 1 backwards, as shown in the Figure 5D .

Similarly, if the user leans forwards, he will cause the seat 3/backrest 4/saddle 5 assembly to pivot forwards around the seat axis A1 until it comes into contact with the stop corresponding stop, contact from which the inclination of the user forwards will be transmitted to the base 2 and will tilt the entire seating device forwards, as shown in the Figure 5E .

In this backward or forward movement, the relative positions of the seat 3, of the lumbar part 42 and of the saddle 5 remain unchanged, so that the back of the user is maintained in the same position. than previously, with the difference that the occipito-altoid and coxo-femoral pivots are aligned on a line L1 inclined backwards or a line L2 inclined forwards, and no longer on a vertical line.

Consequently, the seat device 1 indeed makes it possible to correct the seated posture of the user so that it is optimal, so as to prevent retroversion of the pelvis, lumbar delordosis, thoracic hyperkyphosis and muscular hypotonia of the trunk, while offering freedom of movement to the user to provide him with a functional and dynamic seat.

We represented on the Figure 6 a schematic view of a base 2 provided with an example of end-of-travel means 24 to limit the tilting of the base 2 in the sagittal plane. These end-of-travel means 24 comprise two pairs of feet 25 each mounted to slide in a housing 26 fixed by any appropriate means, such as for example by fixing lugs, to the base 2, with a pair on the front side of the base 2 and a pair on the rear side, and each foot 25 of the same pair being in the vicinity of a respective side end of the base 2.

Each housing 26 is open at its lower end 26a and has a vertical opening 26b which extends parallel to the longitudinal axis of the foot 25 and ends, at its upper end, in a lateral notch perpendicular to said longitudinal axis.

Each foot 25 has a slightly widened lower end 25a for better contact with the ground, and its upper end is provided with a stud 25b which extends through the slot 26b and which the user can grasp to move the foot 25 upwards against the action of a compression spring 27 resting on the closed upper end of the housing 26 and on the upper end of the foot 25.

In the normal position, the foot 25 extends out of the housing 26 under the action of the biasing of the spring 27, the stud 25b stopping the translation of the foot 25 downwards by contact against the lower end of the slot 26b. The lower end 25a of the foot 25 is then likely to come into contact with the ground and prevent greater pivoting of the base 2.

In the embodiment illustrated in the Figure 6 , the foot 25 and the light 26 are sized so that the foot 25 comes immediately into contact with the ground while the base 2 is vertical. In other words, the means 24 here prevent any tilting of the base 2. The means 24 thus make it possible to convert the tilting seat device into a non-tilting device.

When the user wishes to be able to tilt the base 2 again, it suffices for him to raise the feet 25 using the studs 25b, then to rotate the feet 25 to place the studs 25b in the corresponding notches, preventing the feet 25 to come back down.

It is emphasized here that it would be possible to provide the lower end 25a of each leg 25 with a castor, so that the seat device 1 could be converted from a device with a tilting base into a device with a tilting base. castors, allowing the user to move it more easily on the ground.

It is also emphasized that it would be possible to size the foot 25 and the light 26 so that the foot 25 does not come into immediate contact with the ground, so as to allow at least a slight tilting of the base 2.

As a variant, the feet 25 could be height-adjustable with respect to the housings 26, for example by a system of the clamping screw type similar to that which can be encountered for height-adjustable parasol feet. In this way, the user can adjust the distance over which the feet 25 protrude out of the housings 26, and therefore the maximum angle at which the base 2 can be tilted forwards or backwards.

The principles underlying the present invention have been schematically illustrated on the Figures 3 to 6 . A more precise embodiment will now be described below as regards the structure of the various parts, with reference to the Figure 7A at 21D.

We will first describe the way in which the saddle 5 can be made, with reference to the Figures 7A to 8E .

In general, the saddle 5 according to the present invention comprises a front region, intended to support the upper thighs, plumb with the axes of the coxo-femoral joints, and a rear region which is hollowed out in a medial zone where the sit bones will be located, so as to avoid pressing on them, and which rises in its two lateral zones, so as to slightly envelop the infero-lateral parts of the user's buttocks. Such a configuration of the saddle 5 makes it possible to wedge the pelvis B without direct support, thus preserving the freedom of orientation and the motility of the sacrum S and of the pelvis B. The legs are not supported.

The saddle 5 is here in two separate parts 50 which are symmetrical with respect to a vertical plane to which the depth direction of the seat 3 belongs. Each part 50 comprises a first region 51 and a second region 52. The first two regions 51 of the two parts 50 together form the front region of the saddle 5 mentioned above. Each region 52 extends rearwardly from the posterior and lateral side of the first region 51, each second region 52 forming one of said lateral regions of the rear region of the saddle 5 mentioned above. It can also be emphasized here that the edge zone 51a, on the plane of symmetry side, of each first region 51 rises, while the rear 52a and lateral 52b edges of each second region 52 also rise.

The two parts 50 of the saddle 5 could each be fixed directly to the seat 3. However, as illustrated in the Figures, the parts 50 are mounted in such a way as to allow adjustment of their spacing and possibly of their orientation in order to adapt as finely as possible to the morphology of the user.

In particular, each part 50 is here formed by a saddle padding 500 and a plate 501 on which it is fixed. The 500 saddle padding is shaped to match to the description above and is made of a soft, resilient and comfortable material. The plate 501 is made of a rigid material and two threaded holes open out on the underside of the plate 501, in each of which is received a screw allowing the attachment of a connection member 502.

As can best be seen on the Figure 7E , each connection member 502 is in the form of a flat, elongated bar, of rigid material, in which a first longitudinal slot 502a is formed starting from one end of the bar and ending before the other end, a second slot 502b in the vicinity of said other end and following an arc of a circle whose center is materialized by a through hole 502c, which is therefore located between the first and second slots 502a, 502b. One screw passes through through hole 502c and is screwed into a corresponding hole in plate 501, while another screw passes through second lumen 502b and is screwed into the other hole in plate 501.

As can best be seen on the Figure 8A , a rack 502d is provided on one of the two longitudinal walls of the first slot 502a, so that when the connection members 502 are placed one above the other, their first slots 502a are opposite and define an opening in which a gear 502f is mounted, the two racks 502d being on different sides so that the gear 502f engages the two racks 502d.

The two connecting members 502 are supported by a connecting member 503 comprising a first receiving region 503a having a groove in which the connecting members 502 are received so as to be able to slide along their longitudinal direction, first receiving region 503a from which extend two branches 503b parallel to each other and each provided at its free end with a through hole 503c, offset in height with respect to the first reception region 503a, for mounting a pivot 504 which constitutes the saddle axle.

A through hole is provided in the first receiving region 503a, for the passage of a rod of a wheel 505, rod which will be secured to the gear 502f, so that a manual rotation of the wheel 505 by the user will spin gear 502f.

Finally, a spring 506 is mounted on the pivot 504.

On the Figure 8B , the two parts 50 of the saddle 5 are in the position of maximum approach / not oriented. By rotating the wheel 505 in a first direction, the user can separate the connection members 502 from each other and thus separate the two parts 50 without modifying their orientation, as can be seen on the Figure 8C showing parts 50 in an intermediate (non-maximum)/non-oriented spread position.

Independent of the spacing between the two parts 50, the user can also loosen the screws extending into the second lumens 502b, then rotate each part 50 around the pivot axis constituted by the screw passing through the through hole 502c, the pivoting being guided by the movement of the other screw in the second light 502b. The parts 50 can thus be oriented more towards the center, as illustrated in the Figure 8D , or face more outward, as shown in the Figure 8E .

The user can thus adjust the spacing and the orientation of the parts 50 of the saddle 5 to conform optimally to his morphology.

We will now describe how such a saddle 5 can be pivotally connected to the seat 3, in other words an example of structure for the pivot connection 7, with reference to the Figures 9A to 11D .

The seat 3 is here formed by a seat body 30 in the form of a tubular piece of rectangular cross section, open at its two longitudinal ends, and in which an opening 30a is provided in the upper face, in starting from the end of the front side of the seat 3.

In each of the two vertical side walls 30b of the seat body 3 are provided, starting from the rear side of the seat 3 (on the left if we look at the Figures 9A to 9F ), a first through hole 30c, a series of second through holes 30d in the vicinity of each other and stopping before the beginning of the opening 30a, a third through hole 30e, at the front end, and a series of fourth through holes 30f arranged in the vicinity of each other, above the third hole 30e and following an arc of a circle whose center is the third hole 30e.

Each of the two ends of the pivot 504 is rotatably mounted in a corresponding third hole 30e, the means for connecting the two parts 50 to one another being received in the seat body 30 through the opening 30a. The saddle 5 can thus pivot relative to the seat body 30. In addition, a branch of the spring 506 is then resting on the bottom, so that the spring 506, which constitutes elastic biasing means, can exert a bias clockwise elastic.

A rod 33 can be introduced into a fourth hole 30f of one wall 30b until it passes through the corresponding fourth hole 30f in the other wall 30b, the rod 33 then extending across the inside of the seat body 30 so as to form a stop for the pivoting of the saddle 5. It is thus possible to define the inclination at which the saddle 5 will stop when no one is sitting on it.

On the Figure 10A and 11A , the pivoting is maximum, the rod 33 being placed in the fourth holes 30f furthest forward, on the Figure 10B and 11B pivoting is intermediate, and on the Fig. 10C and 11C the pivoting is minimal, here zero the saddle 5 being held pressed against the seat body 30.

We will now describe how file 4, and in particular the exhibit lumbar 42, can be adjusted in height and depth with respect to the seat body 30, with reference to the Figures 12A to 14B .

The backrest 4 includes a thin vertical rod 40 which widens at its upper end region 41 to carry the lumbar piece 42.

The backrest 4 is connected to the seat body 30 by a connecting piece 43 which has a first curved part 43a, the upper end 43b of which is open, a slot 43c being provided in the outer face of the first part 43a and opposite the upper end 43b, so that the vertical rod 40 can be introduced into the upper end 43b and come out of it on the other side through the slot 43c.

The height of the lumbar part 42 can thus be adjusted by causing the rod 40 to slide vertically in the connecting part 43, the backrest 4 being held in the desired position by tightening a wheel 44 which passes through a through hole 43d, provided at this effect in said outer face of the connecting piece 43, and which presses on the vertical rod 40 and clamps it against the connecting piece 43.

The user can thus position the lumbar part 42 so that it can bear against his back at the level of the lumbar vertebrae.

The connecting piece 43 has, in the extension of the first part 43a, a second part 43e formed of an upper region 43f and a lower region 43g, both of plate type, parallel and facing one of the 'other. A rack 43h is provided on the face of the upper region 43f facing the lower region 43g. The upper and lower regions 43f, 43g are spaced from each other so as to be able to extend inside the seat body 30, passing through the rear end of the latter, and to allow a toothed wheel axis 45 to extend between them and to engage the rack 43h. Thus, once the second part 43e has been introduced into the seat body 30, the pin 45 is introduced into the first holes 30c, as can be seen in the Figures 13A and 13B .

The axis 45 is here provided with a button at each of its two ends, projecting relative to the seat body 30, so that a rotation of the axis 45 causes, by meshing of the rack 43h, a sliding of the second part 43e in the seat body 30. The user can thus adjust the backrest 4 to a minimum depth, as on the Figure 14A , or at an intermediate depth, as on the Figure 14B , figures in which a side wall 30b of the seat body 30 has been omitted.

We represented on the Figures 15A to 15D the seat 3 / backrest 4 / saddle 5 set.

We will now describe how this assembly can be pivotally connected to the base 2, in other words an example of structure for the pivot connection 6, with reference to the Figures 16A to 19B .

We can first of all emphasize that the base 2 is here a base of the type with rocker likely to be fitted with interlocking wedges to allow height adjustment of the seat 3 / backrest 4 / saddle 5 assembly, in order to obtain the ideal radius of curvature according to the size of the user. Thus, the base 2 has means enabling a wedge 9 to be fitted therein which follows the same curve as the lower part 23, this wedge 9 also having means enabling another wedge 9 to be fitted therein which follows the same curve. The height adjustment is thus obtained by interlocking one or more wedges 9. Of course, each wedge 9 will follow a curve whose radius of curvature is different from that of the other wedges 9. The means for fitting a wedge may be for example clips, fitting of male lugs into female housings, screws, etc.

The base 2 comprises a U-shaped support 28 whose two wings 28a are triangular and taper upwards, and a foot 28b ( Figures 17A to 17C ) extends downwards from the bottom 28c of the support 28 to be received in a sliding manner, so as to be adjustable in height, in a cylindrical housing 20a carried at the upper end of a base 20 forming the leg part proper. The rotation of the foot 28b relative to the housing 20a, and therefore of the support 28 relative to the base 20, can be free or locked by any appropriate means. Advantageously, the height adjustment stroke of the foot 28b is equal to the height of a wedge 9, so as to offer the user the possibility of adjusting the seat 3 to any height in the entire height range that provide the wedges 9 and the foot 28b.

Each wing 28a has a through hole 28d ( Figure 18C ) opposite that of the other wing 28a, for mounting a pivot 28e which will itself extend through a second through hole 30d of the seat body 30, so that the seat body 30 can pivot relative to support 28.

Each wing 28a further has, along each of its two inclined edges, an elongated slot 28f serving to receive a stop bolt 28g. Thus, two stop bolts 28g extend across the support 28 so as to constitute, for one, a stop for stopping the pivoting of the seat body 30 towards the rear, and, for the other , a stopper for forward pivoting.

The user can thus define the positions of the pivoting limit switches of the seat 3 / backrest 4 / saddle 5 assembly, simply by loosening the nut of a stop bolt 28g, by sliding the screw of the bolt d stop 28g along the lights 28f, then tightening the nut to immobilize the stop bolt 28g.

The user can choose, for example, to limit the forward pivoting more strongly than the backward pivoting, as on the Figure 17B , or provide the same maximum angle of inclination forwards and backwards, as on the Figure 17C .

We will now describe how the seat 3 / backrest 4 / saddle 5 assembly is elastically biased in the direction of counter-clockwise rotation by elastic biasing means 29, here a spring part 29, with reference to the Figures 18A to 19B .

The spring part 29 is a torsion spring formed by a metal wire which, in a first end region 29a, is wound into turns, in a central region 29b, is bent so as to form a front U, in a second region end 29c, to be wound again in turns coaxial with those of the first end region 29a. In particular, the central region 29b is formed by a stem portion which is parallel to the axis of the turns but offset from it, the spring part 29 being U-shaped.

A mounting leg 29e extends outward from each end region 29a, 29c, for mounting the spring piece 29 to the support 28, as shown in the figures. Figures 18C and 18D . In particular, a series of through-holes 28h will have been provided in the vicinity of each other and following an arc of a circle centered on the through-hole 28d in which the pivot 28e is mounted, each mounting branch 29e being able to be mounted selectively in one of the holes 28h. Once the spring part 29 is mounted in the support 28, the central region 29b is located on the front side of the seat 3 with respect to the through-hole 28d.

If we now refer to Figures 19A and 19B , it can be seen that when the seat body 30 is pivotally mounted on the support 28 around the pivot 28e, the central region 29b surrounds the lower outer part of the seat body 30, the spring part 29 being dimensioned for this purpose. Thus, the central region 29b presses against the underside of the seat body 30 and will elastically urge the latter so that it pivots around the pivot 28e in the anti-clockwise direction.

The user can adjust the magnitude of this elastic stress by modifying the positioning of the mounting branches 29e in the holes 28h.

We represented on the Figures 20A to 20D the seating device incorporating the structures as described in connection with the Figures 7A to 19B .

Because the support 28 is capable of pivoting relative to the base 20, then locked in position by any appropriate means, the user can orient the base 20 relative to the support 28 so that the base 2 is of the rocker type in the sagittal plane, as shown in the Figures 20A and 20B , or of the rocker type in the transverse plane, as illustrated in the Figures 20C and 20D .

Furthermore, the user is able to adjust the position of the lumbar part 42 so that it comes into contact with the back both with the appropriate effort and in the appropriate position.

The modification of the force applied by the lumbar part 42 on the user's back depends on the clockwise rotation torque applied to the seat 3 by the weight of the user. A first solution, simple, consists in adjusting the magnitude of the elastic stress exerted by the elastic stress means of the seat 3 in anti-clockwise rotation. The greater the magnitude of the elastic stress, the smaller the resultant of the elastic stress and of the torque applied by the user on the seat 3, and therefore the greater the force applied by the lumbar part 42 against the back. of the user will be low. In the case where these elastic biasing means are formed by a spring, it suffices to modify the stiffness of the spring, for example by replacing it with another spring or, more simply, by adjusting the spring as described above.

This adjustment can also be obtained by adjusting the distance between the seat axis A1 and the saddle axis A2, as is possible in the particular embodiment described above.

On the Figure 17A , the pivot 28e has been placed in the fourth of the second through-holes 30d of the seat body 30, starting from the left. The action of the weight on the seat 3 takes place along the vertical line tangent to the 3 ^rd lumbar Lb, as illustrated in the Figure 4D . In this position, the pivot 28e, and therefore the seat axis A1, is relatively close to the pivot 504 (saddle axis A2).

If the pivot 28e is removed and placed in the first of the second through holes 30d, starting from the left, the distance between the pivot 28e and the pivot 504 is greater, and the position of the action weight remains unchanged because the user remains on the saddle 5 whose position relative to the seat 3 does not change. Thus, the lever arm between the action of the weight and the pivot 28e is greater, and therefore the torque exerted by the user on the seat 3 is greater.

On the Figures 3 to 20D , described above, there is shown in detail and, to an extent sufficient for the understanding and implementation of the invention, schematically, a particular embodiment of the seat device according to the present invention. If we now refer to Figures 21 to 31 , it can be seen that there is shown a variant embodiment incorporating the functional means described above in a design providing an external appearance that could be described as more modern.

If we first refer to the Figure 21 and 22 , it can be seen that the seat device 1′ according to this variant comprises a base 2′, a seat 3′, a backrest 4′, a lumbar part 42′ and a saddle 5′.

As can be seen on the Figures 30 and 31 , the base 2' is of the rocker type and is remarkable, compared to those described above, in that it comprises a U-shaped part 20', the two side arms 21' of which are curved, following an arc of a circle, and in contact with the ground and that on the underside of each lateral arm 21' is provided a rectilinear tab 22', one end of which is fixed, by any appropriate means, such as for example by screws to the underside of the respective side arm 21', in the region close to the base of the U-shape of the piece 20, the rest of the tab 22' not being integral with said lateral arm 21' and extending freely as far as the free end of said lateral arm 21', while being generally horizontal at rest, namely in the absence of stress from the seating device 1' by a user, where the seat 3' is substantially horizontal. We represented on the Picture 26 the base 2' in this position at rest. The end of the tongue 22' is at a distance from the free end of the side arm 21' and the tongue 22' is made of a flexible material having elastic properties, so that in the event that the device seat 1' is in a tilted position towards the rear and the user leaves the seat device 1', the tabs 22', resting on the ground, by their free end regions, bring back, due to their elasticity, base 2' in this rest position.

If we now refer to the Picture 23 , it can be seen that the lumbar part 42' is also adjustable in height, on the same principle of sliding of an upper part bearing the length part 42' in a lower part connected or integral with the seat, with maintenance in position by a wheel 40', here provided on the side.

It is emphasized here that the lumbar part 42' is here advantageously a roller 420' mounted free to rotate about its axis while being carried, at each of its ends, by two vertical arms 421' defining a fork shape across which the roll 420' stretches.

Always with reference to the Picture 23 , it can be seen that the depth of the backrest 4' can also be adjusted, on the same principle of translation, relative to the seat 3', by a system of rack 43' and toothed wheel 44', the rotation of this the latter being controlled by a 45' side wheel ( Picture 21 ), the backrest 4' thus being able to be brought closer to or moved away from the saddle 5' as illustrated by the two pairs of arrows.

If we now refer to the Picture 24 , it can be seen that the saddle 5' is again in two parts 50' symmetrical with respect to a vertical plane to which the depth direction of the seat 3' belongs, and that the spacing between these two parts 50' is also adjustable, the parts associated with this adjustment are received in a casing assembly 51' that is more pleasing to the eye.

In particular, a part 50' of the saddle 5' is carried by a first angled support 52', and the other part 50' is carried by a second support 52'. We represented on the Picture 25 the first support 52' and on the Picture 26 the second support 52'. If we refer to these figures, as well as to the Figures 27 and 28 , it can be seen that each support 52' comprises a first casing part 520', also bent. The first support 52' includes a first horizontal bar 521' extending out of the first housing part 520'. The first bar 521' has, on its upper side, a first rebate 522', pushed from its free end to the vicinity of the entry into the first casing part 520', where it ends in a second rebate 523' narrower. The first rebate 522' is here interrupted by a through opening 524' in which a block carrying a rack will be fixed, on the inside. The second support 52' is of similar shape, with the difference that the first and second rabbets 522' and 523' are located on the lower side of the second bar 521' and along the opposite longitudinal edge thereof. As can best be seen on the Picture 29 , the heights of the first and second bars 521' are such that in the assembled position the second bar 521' extends above the first bar 521' and a central space 525' is delimited laterally by the first two rabbets 522' facing each other, including the two blocks carrying the racks in the openings 524', and vertically by the upper and lower sides respectively of the first and the second bar 521'. A gear 526' is received in the central space 524' and engages the two racks, and a vertical guide pin (not shown) passes through the center of the gear 526' and extends beyond it. below and above, in a longitudinal slot 527' provided for this purpose in the first bar 521' and the second bar 521' respectively. Of course, provision could be made for the first rabbets 522' to be free of the openings serving to receive the blocks carrying the racks, and for the racks to be formed directly on the vertical faces, on the inside, of the first two rabbets 522'.

The casing assembly 51' is formed by the first casing parts 52', by an upper cover 53' and a lower cover 54' ( Picture 24 ). The covers 53' and 54' are generally semi-cylindrical, each with an opening 531', 541' in their side wall which extends over part of the circumference, the two openings 531' and 541' communicating with one the other and defining a space in which is located a locking handle 55' which is pivotally mounted about an axis parallel to the pivot axis A2 of the saddle 5', by means of pivots (not shown) mounted each partly in a side hole 550' ( Picture 27 ) of the handle 55' and partly in a corresponding hole provided in the upper cover 53' (not visible). The handle 55' notably comprises a projection 551' which extends through an opening provided in a first cylindrical intermediate part 56' surrounded by the covers 53' and 54', and through an opening provided in a second intermediate part 57' partially surrounded by the first intermediate piece 56' and themselves surrounding the first and second bars 521'.

The various parts described above are dimensioned so that, in a first position, called blocking, represented on the Figures 27 and 28 , the projection 551' presses on the second bar 521' of the second support 2' in such a way that a clamping of the bars 521' against each other is obtained, preventing any relative movement between the first and second 52' brackets. In the locking position, the rest of the handle 55' is advantageously flush with the outer surface of the cover higher than 53' ( Picture 24 ). In a second position, called the release position, the handle 55' has been pivoted upwards, which has the effect of releasing the support exerted by the projection 551' on the second bar 521', to an extent such that a relative translation between the first and second supports 52' is permitted, in the direction parallel to the pivot axis A2 of the saddle 5'. This translation is carried out directly by the user, pulling or pushing the supports 52', which will slide inside the upper 53' and lower 54' covers. The presence of the gear 526' and the two racks makes it possible to maintain a mirror movement of the two parts 50', namely a movement of the latter which is symmetrical with respect to a median vertical plane to which the direction of depth of the 'seat 3'.

The means described above therefore constitute means for adjusting the spacing of the two saddle parts 50'.

If we refer again to Figures 27 and 28 , it can be seen that the means for biasing the saddle 5' in forward rotation comprise two torsion springs 58', one on each side of the handle 55', which surround the first intermediate piece 56' while being received in grooves 580' provided for this purpose in the upper covers 53' and 54' (grooves visible only for the lower cover 54'). A first branch of each spring 58' is fixed to the upper cover 53', which is itself fixed in position, because it is fixed by any appropriate means to the seat 3', and a second branch of each spring 58' is secured angled supports 52', in particular via the first and second intermediate pieces 56' and 57' to which the second branch is fixed, for example by being received in radial holes provided for this purpose. The springs 58' are configured to bias the saddle 5' in forward rotation.

If we finally refer to the Picture 29 , it can be seen that there are shown means for elastic biasing of the seat 3' towards the rear which cooperate with means for adjusting the magnitude of their elastic bias. These elastic biasing means are two traction springs 30' arranged vertically, the lower ends of which are fixed to a bar 31' integral with the base 2' and the upper ends of which are fixed to a slider 32' arranged inside a U-shaped part 33' forming part of the seat 3', so as to be able to slide perpendicularly to the bottom of the U-shaped part 33'. The slider 32' is provided, at its center, with a threaded hole 34' in which is received a threaded rod 35' extending to the outside of the U-shaped part 33', where it is fixed to a wheel 36' allowing the user to rotate the threaded rod 35'. It will easily be understood that a rotation of the extruded rod 35' in one direction will cause a translation of the slider 32' in a first direction, for example corresponding to an elongation of the springs 30', and therefore to an increase in the magnitude of the stress. that they exert on the seat 3', and that a rotation in the opposite direction will cause a translation of the slider 32' in the opposite direction, reducing the elongation of the springs 30', up to for example the position illustrated on the Picture 29 wherein this elongation is zero, and therefore a reduction in the magnitude of said stress. The slider 32', the threaded rod 35' and the knob 36' therefore constitute said adjustment means. It is emphasized that the above configuration of said adjustment means and of the elastic biasing means does indeed allow the seat 3' to pivot relative to the base 2, the pivoting leading to a bending of the springs 30'.

It is understood that the particular embodiment which has just been described has been given as an indication and not limiting and that modifications can be made without thereby departing from the scope of the present invention.

Claims (12)

1. - A seat device (1) comprising an underframe (2) and a seat (3) comprising a rear region (31) and a front region (32), characterised in that the seat (3) is connected to the underframe (2) by a link (6) allowing the seat (3) to pivot relative to the underframe (2) about a pivot axis, called seat axis (A1), which is horizontal and orthogonal to the depth direction of the seat (3), said link (6) being positioned relative to the seat (3) such that the seat (3) pivots toward the front when a user sits on the seat (3), there being provided means for elastically biasing the seat (3) in rotation toward the rear, and by the fact that the seat device (1) further comprises:

   - a lumbar part (42) which is rotationally secured to the seat (3) and positioned so as, during use, to press against the back of the user, at the lumbar vertebrae of the latter, and

   - a saddle (5) for supporting the top of the thighs of the user, the saddle (5) being connected to the front region (32) of the seat (3).
2. - The seat device (1) according to claim 1, characterised in that the saddle (5) is connected to the front region (32) of the seat (3) by a link (7) allowing the pivoting of the saddle (5) relative to the seat (3) about a pivot axis, called saddle axis (A2), which is parallel to the seat axis (A1) and in front of the seat axis (A1) in the depth direction of the seat (3), means being provided for elastically biasing the saddle (5) in rotation toward the front.
3. - The seat device (1) according to any one of claims 1 and 2, characterised in that it comprises stops (28f, 28g; 30f, 33) positioned in order to limit the pivoting travel of the seat (3) and/or, if applicable, of the saddle (5), in both directions of rotation.
4. - The seat device (1) according to any one of claims 1 to 3, characterised in that the link between the seat (3) and the underframe (2) is a first pivot link (6) and, if applicable, the link (7) between the saddle (5) and the seat (3) is a second pivot link (7), the first and second pivot links (6, 7) each comprising a pivot (28e, 504) making up the seat axis (A1) and the saddle axis (A2), respectively.
5. - The seat device (1) according to any one of claims 1 to 4, characterised in that the means (29, 506) for elastically biasing the seat (3) and/or, if applicable, the saddle (5) are springs, in particular torsion springs, preferably with adjustable tension.
6. - The seat device (1) according to claim 2 or any one of claims 3 to 5 when taken in dependency of claim 2, characterised in that the seat (3) is mounted with adjustable position, in the depth direction of the seat (3), relative to the underframe (2), so as to allow the adjustment of the distance between the seat axis (A1) and the saddle axis (A2), in the depth direction of the seat (3) .
7. - The seat device (1) according to any one of claims 1 to 6, characterised in that the lumbar part (42) is position-adjustable, relative to the seat axis (A1), in the vertical direction and in the depth direction of the seat (3), so as to allow the position of the lumbar part (42) to be adjusted as a function of the build of the user.
8. - The seat device (1) according to claim 2 or any of claims 3 to 7 when taken in dependency of claim 2, characterised in that the saddle (5) is formed by two parts (50) which are symmetrical relative to a vertical plane to which the depth direction of the seat (3) belongs, each part (50) of the saddle (5) being intended to bear the top of a respective thigh of the user, the separation between the two parts (50) of the saddle (5) preferably being adjustable.
9. - The seat device (1) according to claim 2 or any one of claims 3 to 8 when taken in dependency of claim 2, characterised in that the saddle (5) comprises a front region, which is intended to support the top of the thighs of the user, directly above the axes of the coxofemoral joints of the user, and a rear region which is hollowed out in a medial zone where the ischiums of the user will be located and which rises up in its two lateral zones, so as to slightly surround the inferolateral portions of the buttock.
10. - The seat device (1) according to any one of claims 1 to 9, characterised in that the underframe (2) is of the tilting type at least in the sagittal plane, optionally also in the transverse plane.
11. - The seat device (1) according to claim 10, characterised in that the underframe (2) has a rounded base (23) having means for nesting height adjusting wedge (9), following the same curve as the base (23).
12. - The seat device (1) according to any one of claims 10 and 11, characterised in that it comprises means (24) for defining the maximum tilting amplitude of the underframe (2), preferably comprising feet (25) mounted in translation relative to the underframe (2) so as to be movable between a position in which they protrude relative to the underframe (2) so as to be able to come into contact with the floor to oppose the tilting of the underframe (2), and a position in which they do not protrude relative to the underframe (2).

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