EP0382663A1 - System for the mobility, stability and reaction of a human body in a seated position - Google Patents

Abstract

The invention relates to a system which can be fitted to a chair, in which deformable, especially inflatable, elements (4, 5, 6, 8, 9, 10), whose passage from a retraction state to an expansion state and vice versa involves well-defined sequences of movements of the human body, are in communication with a circuit (30, 23, 32, 33) and a source of power, especially of pressurised fluid (22), comprising control means (40, 41) placed under the dependence of a programmer (42) automatically ensuring alternate phases of expansion and of retraction which give rise to stress displacements in human joints and tissues in general, a stabilisation of the human body, in itself and relative to the chair, and a stimulation of a reflex activity of tonic muscles. This programmed-dynamism system aims to periodically assist the user in getting up more easily from the chair in order more easily to subsequently readapt thereto in order to obtain greater comfort and to maintain his alert state. <IMAGE>

Description

The subject of the invention is a system which complements a seat, provided with deformable elements, used to mobilize, stabilize and make the whole of a human body react in the sitting or lying-down station.

The invention will be described more particularly for the sitting station and by choosing the simplest solution of inflatable deformable elements.

We know that prolonged standing is very uncomfortable and that we quickly try to come, if possible, to sitting, which significantly increases the surface area of the body and, consequently, the safety of balance, hence an economy of the muscles responsible for it.

However, prolonged sitting is also difficult to bear because of the immobility and therefore of constancy of the stresses on the human body. But this immobility is relative. Indeed, in a seat with backrest tilted backwards, the line of gravity of the trunk being posterior to the ischium, there is micro-displacements of the pelvis forward and, gradually, deformation of the trunk. When it is a driving position of the vehicle, the tremors, the centrifugal forces and the action on the steering wheel and the pedals increase the stresses by compaction and the destabilization of the body. On the one hand, under the effect of these stresses, the trunk moves, by micro-movements, by in relation to its supports, on the other hand, its own structure undergoes variations in shape which go in the direction of less stability of the segments of this structure with respect to each other.

We therefore tried to limit these micro-movements by multiplying the body's support points, but we very often noticed that the seats with high seats, without backrest, positions releasing the movement of the pelvis around the hips and a line of gravity of the trunk close to the vertical (chair rather than armchair, position in "knees-seated") brought more comfort.

We offer different types of seats tending to respect certain ergonomic rules. This is, of course, the case for seats for cars. Some are now equipped with inflatable pockets or motorized systems adjustable at will by the driver so as to adapt the seat to its morphology.

But, as we have seen, this is not constant and these seats currently offered, either do not offer mobility, or when they do offer it, it takes place only through voluntary action by the user ( U.S. Patent No. 4,634,179) while most of the time the full attention potential thereof is brought other than to the distress signals sent by the forgotten body: brain activity, attentive listening, driving a machine; or finally, when mobility is programmed (French patent application published under number 2239220), stabilization of the body, in itself and in relation to the headquarters, is not satisfactory.

Comfort seems to be achievable only by respecting two apparently contradictory imperatives: mobility and stability of the human body. Thus, we can observe that the discomfort disappears if the body is constantly in motion while maintaining the stability of the body. spine: the walker does not suffer from standing and the rider supports well his sitting position which is dynamic and maintains a good stiffening of the "spinal mast".

An objective of the invention is to artificially cause and without the person concerned having to worry about it a certain alternating movement of the human body, so as to modify the stresses, especially in the load-bearing joints (spine, hips), stabilize the body and trigger a postural adjustment by reflex activity of toned muscles. At the same time, this movement causes a change in the body's support points, which relieves human tissue in pressure against the support and avoids the anesthesia caused by the long press.

This objective is achieved according to the invention by providing a system to be fitted to a seat, comprising a seat with an upper face intended to receive the human body and a backrest with an anterior face intended to receive the human body, deformable elements being arranged in this file and connected by means of connection to an energy source, while automatic control means establish a sequence of passage of these elements from a state of retraction to a state of expansion, characterized in that elements similar deformables are also installed in the seat and in that the arrangement of all of these deformable elements and said sequence are such that the backrest periodically exhibits a posterior and anterior plumb and that, in the seat, forms periodically obliquely from top to bottom and from back to front.

Preferably, the deformable elements are inflatable elements and the energy source is a source of pressurized fluid.

An object of the invention is that the front face of the backrest is provided with inflatable elements with articular action in the form of several parallel tubes arranged transversely to the length of the backrest considered according to the length of the human body to be supported, spaced apart. others along the anterior side of the backrest and presenting, in the inflated state, sections such that the section of the tube furthest from the seat is the largest.

Another object of the invention consists in that the upper face of the seat is provided with inflatable elements with articular action in the form of several parallel tubes arranged transversely to the length of the seat considered according to the length of the human body to support, spaced from each other along the upper face of the seat and having, in the inflated state, a different increasing section from the strand furthest from the backrest to the strand closest to it.

The rolls of the file on the one hand and of the seat on the other hand are preferably three in number.

The back tubes are advantageously arranged between an internal cover surrounding the back and an external cover covering the whole of this internal cover and back rolls, but left free at the bottom of said front face of the back.

The seat tubes are advantageously arranged between an internal cover surrounding the seat and an external cover surrounding all of this internal cover and the seat tubes.

According to another object of the invention, said fluid connection means comprise a distributor connected by a supply line to said source of pressurized fluid and connection lines arranged between the distributor and, on the one hand, the flanges of the backrest , on the other hand, the seat tubes, the distributor and these connecting pipes being provided so that, during inflation phases of the inflatable elements with articular action, the tubes of the backrest are the first to be supplied with pressurized fluid and the tubes of the seat are only then followed, when the pressure of the fluid under pressure admitted into the distributor reaches a predetermined value, while a non-return valve duct disposed between the tubes of the seat and the tubes of the backrest allows, during the phases of deflating inflatable elements with articular action, the total deflation of the tubes of the seat by passage, in at least one of the tubes of the file, of the pressurized fluid leaving the seat tubes.

An object of the invention also consists in that said distributor comprises: a cylinder at a longitudinal end from which open said supply pipe and a connection pipe between this distributor and the strands of the backrest as well as a discharge pipe provided an electromagnetic valve; a movable bell sliding in this cylinder, urged by a compression spring in the direction of said end towards a rest position; and the mouth in the cylinder of a connecting pipe between this distributor and the socks of the seat, in a location such that this mouth is closed by said bell as long as the latter is in the rest position and it is in communication with said supply line when a sufficient pressure of the pressurized fluid arriving via this supply line displaces the bell against the compression spring, while members for controlling the source of pressurized fluid and control members of the electromagnetic valve are placed under the control of a programmer.

• les fig. 1, 2 et 3 schématisent le profil d'un corps humain dans trois positions assises;
• les fig. 4 et 5 schématisent le profil du rachis respectivement en position relâchée et en position de redressement actif et mon­trent chacune un aplomb antérieur et un aplomb postérieur avec l'état correspondant d'une articulation vertébrale.
• les fig. 6 et 7 représentent un siège selon l'invention respective­ment en coupe longitudinale et en vue de face (cette dernière vue étant donnée avant la finition du siège);
• la fig. 8 représente en perspective un des boudins gonflables de ce siège et la fig. 9 représente un tel boudin muni d'une en­veloppe;
• la fig. 10 est le schéma d'un circuit à air comprimé permettant le gonflage et le dégonflage alternés des boudins gonflables;
• la fig. 11 et la fig. 12 sont deux coupes dans des plans orthogo­naux d'un distributeur prévu dans le schéma de la fig. 10;
• les fig. 13 à 16 montrent la position du corps humain pendant qua­ tre phases successives de fonctionnement d'un siège de véhicule;
• la fig 17 montre la position du corps humain dans l'une des phases de fonctionnement d'un fauteuil dans le cas d'une station assise;
• et la fig. 18 montre la position du corps humain dans l'une des phases de fonctionnement d'un fauteuil, dans le cas d'une sta­tion couchée.

We will explain in more detail the invention and give an exemplary embodiment thereof without limitation, with reference to the attached drawing in which:

• fig. 1, 2 and 3 show schematically the profile of a human body in three seated positions;
• fig. 4 and 5 show diagrammatically the profile of the spine respectively in the relaxed position and in the active straightening position and each show an anterior and a posterior plumb with the corresponding state of a vertebral joint.
• fig. 6 and 7 show a seat according to the invention respectively in longitudinal section and in front view (the latter view being given before the seat is finished);
• fig. 8 shows in perspective one of the inflatable tubes of this seat and FIG. 9 shows such a tube fitted with an envelope;
• fig. 10 is the diagram of a compressed air circuit allowing the alternating inflation and deflation of the inflatable tubes;
• fig. 11 and fig. 12 are two sections in orthogonal planes of a distributor provided in the diagram of FIG. 10;
• fig. 13 to 16 show the position of the human body during qua three successive phases of operation of a vehicle seat;
• Fig 17 shows the position of the human body in one of the operating phases of a chair in the case of a sitting station;
• and fig. 18 shows the position of the human body in one of the operating phases of a chair, in the case of a reclining station.

We will first examine the conditions of comfort of a seated human body by considering its mobility and then referring to Figs. 1 to 5 then considering the stability of this human body.

We know that for reasons of ligament and muscle tension, the mobility of the pelvis around the hip joints is all the greater as the thigh-pelvis angle is more open. Fig. 1 shows in this respect the drawback of a seat that is too low while FIG. 2 highlights the advantage of the Japanese position and FIG. 3 that of the rider's position in the saddle - and the interest, in this case, of an obliquity from top to bottom and from back to front. It is therefore necessary for a vehicle seat to be adjustable in height to be adaptable to people of different sizes, but, in addition, it would be very interesting if the seat height varies over the time of use to allow a variation of the thigh-pelvis angles (coxo-femoral mobilization) and thigh-leg (knee mobilization). In the system according to the invention, there will therefore be created, when the flanges of the seat are inflated, preferably an obliquity from top to bottom and from back to front.

The plumbs can be studied using figs. 4 and 5 which correspond respectively to a relaxed body and to a body making an effort of stretching. Without muscular activity (fig. 4), the vertebral discs undergo significant stresses as well in anterior balance (left of the figure) as in posterior balance (right of the figure). On the contrary, if there is active straightening of the spine (fig. 5), in anterior balance (left of the figure) the discs are relieved while the posterior articular elements are in support and, in posterior balance (right of the figure ), the opposite occurs. The anterior balance is really the antidote to collapse in a seated station if the spine is not flexed; it is the stable position of the trunk unlike the posterior plumb. An alternation of the two plumbs therefore appears primordial; an inclination of five to fifteen degrees on either side of the vertical seems sufficient. This alternation will preferably be created in the system according to the invention, during the inflation of the flanges of the backrest, by the formation of an inflated zone whose thickness is greater towards the top of the backrest than towards the bottom of that -this.

In addition, support in the dorso-lumbar area and support in the cervico-dorsal area are important to maintain alignment of the spine and reshape natural curvatures. It is desirable, moreover, that these supports act from the bottom up to respect the order of construction of the spinal parts on the pelvis and obtain an articular modeling.

Stability is to be considered in the anteroposterior and horizontal plane and in the frontal plane. In the antero-posterior and horizontal plane, it is important to contain the sliding of the ischium forward, sliding which is particularly pronounced in motor vehicles because of the constant search for the pedals. In the frontal plane, in cars, there are lateral micro-displacements which are also to be limited.

• 1 - un dossier ayant une mobilité propre permettant au tronc d'os­ciller entre un aplomb antérieur et un aplomb postérieur afin d'é­viter les constances d'écrasement et de tension dans les articula­tions porteuses et, lors de l'aplomb antérieur, obtenir une stabilité.
• 2 - une assise modulable, réglable en hauteur et présentant tantôt une obliquité de bas en haut et d'arrière en avant, tantôt une obliquité de haut en bas et d'arrière en avant, pour mobiliser les genoux et les hanches et permettre la mobilité vers l'aplomb antérieur.
• 3 - des appuis actifs permettant d'éviter l'effondrement des zones cervico-dorsale et dorso-lombaire ou mieux encore d'obtenir un vé­ritable modelage articulaire en agissant de bas en haut;
• 4 - des possibilités de stabiliser l'ischion dans le plan antéro-­postérieur,dans le plan horizontal et dans le plan frontal;
• 5- un changement des points d'appui pour soulager les tissus hu­mains en pression,particulièrement au niveau ischiatique.
• 6 - une stimulation des structures musculaires de soutien (réflexes toniques posturaux) pour se rapprocher d'une position assise dyna­miquel ce qui a de l'intérêt aussi pour la circulation et l'éveil de la proprioceptivité,donc le maintien de la vigilance.
• 7 - respect de la notion fondamentale de stabilité des appuis.

To obtain good comfort when seated, in the most difficult situations which are those encountered in driving a machine, the following seven conditions can be drawn from previous considerations:

• 1 - a backrest with its own mobility allowing the trunk to oscillate between an anterior plumb and a posterior plumb in order to avoid constants of crushing and tension in the load-bearing joints and, during the anterior plumb, obtain stability .
• 2 - a modular seat, adjustable in height and sometimes having an obliquity from bottom to top and from back to front, sometimes an obliquity from top to bottom and from back to front, to mobilize the knees and the hips and allow mobility towards the anterior balance.
• 3 - active supports making it possible to avoid the collapse of the cervico-dorsal and dorso-lumbar zones or better still to obtain a true articular modeling by acting from bottom to top;
• 4 - possibilities of stabilizing the ischium in the anteroposterior plane, in the horizontal plane and in the frontal plane;
• 5- a change of the support points to relieve the human tissues under pressure, particularly at the ischial level.
• 6 - stimulation of the supporting muscular structures (postural tonic reflexes) to get closer to a dynamic sitting position, which is also of interest for circulation and the awakening of proprioceptivity, thus maintaining vigilance.
• 7 - respect for the fundamental notion of support stability.

We will now describe an example of a seat specially designed for the automobile, then we will show that this seat meets the seven conditions set out above and we will then recall the various types of seats known to show that they cannot not comply with most of these conditions.

The section in fig. 6 shows the backrest 1 and the seat 2 of a seat. On the front face 3 of the backrest 1 were fixed transversely three strands 4,5,6. Similarly, on the upper face 7 of the seat 2 were fixed transversely three flanges 8,9,10. One of these tubes is shown in fig. 8; it is provided with at least one connecting tube 11. Each of the tubes is introduced into an envelope such as the envelope 12 visible in FIG. 9; this envelope is provided with openings 13 for the connections to the pipes 11 and with a self-gripping strip 14 for fixing on an internal fabric cover such as the cover 15 which surrounds the backrest 1 or the cover 16 which surrounds the seat 2. These covers are themselves provided with several longitudinal self-gripping strips 17 and 18 respectively visible in FIG. 7 which cooperate with the strips 14 for fixing the flanges 4,5,6 and 8,9,10. In these internal covers 15 and 16 are provided longitudinal pockets for the passage of the compressed air supply pipes of the tubes; the entire compressed air circuit will be described later using fig. 10 to 12. As seen in fig. 6, an external cover 19 surrounds the assembly of the internal cover 15 and the rolls 4,5,6 of the backrest and an external cover 20 surrounds the assembly of the internal cover 16 and the rolls 8,9,10 of the seated. These external covers have the appearance of the covers usually used for automobile seats and allow the extension of the tubes, but provision has been made for the external cover 19 to be left free at 21 at the bottom of the front face 3 of the backrest, to a reason which will be given later.

The three sections 4,5,6 of the backrest have determined diameters. The largest 6 is placed at the base of the occiput, a means 5 at the cervico-dorsal hinge (between the shoulders) and another means 4 towards the dorso-lumbar area. The three tubes 8, 9, 10 of the seat have different diameters which grow from the front tube 8 to the rear tube 10.

Fig. 10 gives the diagram of the hydraulic circuit. This comprises: a source of compressed air 22 which may in particular be a compressor, a membrane pump or a connection with pneumatic circuits existing elsewhere; a distributor 23 provided with a compressed air inlet nozzle 24, an air outlet nozzle 25 provided with an electromagnetic valve 26, a nozzle 27 for connection with the flanges of the backrest, a nozzle 28 for connection with the flanges of the seat and a safety nozzle 29.

A supply line 30 connects the source of compressed air 22 to the inlet nozzle 24. An evacuation line 31 is connected to the valve 26. A line 32 for connection with the flanges of the backrest connects the nozzle 27 to the tube 4 and a pipe 33 for connection with the tubes of the seat connects the nozzle 28 to the tube 10. The tube 4 is connected to the tube 5 by a line 34 and the tube 5 is connected to the tube 6 by a line 35. The sausage 10 is connected to sausage 9 by a pipe 36 and the sausage 9 is connected to sausage 8 by a pipe 37. In addition, a pipe 38 provided with a non-return valve allows the passage of compressed air exclusively from the sausage 10 to the tube 4.

This assembly is controlled by sending an electric current either to a member (40) for commissioning the source 22, for example starting a compressor, a membrane pump or opening an air inlet valve. compressed, or on a coil 41 of the electromagnetic valve. These commands are normally placed under the dependence of a programmer 42, as indicated by the electrical connections 43 and 44. This programmer 42 is put into service by a switch 45 and an electrical connection 46 connected to a pad 47 of this switch. Provision has also been made for manual control to be carried out by switching the switch 45 on the stud 48 connected to electrical connections 49.50 provided with switches 51.52. This manual control is used in particular during the initial adjustments of the position of the flanges, plumbs, obliquities, etc. and it allows it to be temporarily maintained in use. normal in a position deemed particularly comfortable.

Figs. 11 and 12 allow a better view of the embodiment of the distributor 23. This comprises, in addition to the members already mentioned, a bell 53 which can slide in a cylinder 54 carrying the nozzles 24, 25, 27, 28 and 29. This bell 53 is biased, by a spring 55, adjustable by an adjustment screw 56, towards the bottom of the figures to come to bear against a flange 57 formed in the cylinder 54. In this position of the bell 53, the inlet nozzle 24 is in fluid connection with the nozzle 27 for connection with the tubes of the backrest, but not with the nozzle 28 for connection with the tubes for the seat. If the pressure of compressed air under the bell 53 becomes high enough, the bell rises and releases the nozzle 28 for connection with the flanges of the seat; this nozzle 28 is then also in fluid connection with the nozzle 24.

In addition to the joint action tubes described above, it is also possible to provide in the seat and in the file other manually actuated tubes, for example by means of a pear. These complementary flanges can in particular allow alternation of the bearing zones on the seat or reinforce the lateral wedging.

After assembly and adjustment carried out with the manual control, one can pass to the programmed control which will be that normally put into service, at least during the prolonged uses of the seat. The operation of the system is then broken down into four phases.

In a first phase, the programmer closes the electromagnetic valve 26 and activates the source of compressed air 22. The compressed air is distributed in the tubes 4, 5, 6 of the backrest which gradually swell from the dorso-lumbar tube 4 to cervico-dorsal sausage 6. This results, as can be seen in fig. 13: a passage of the trunk from the posterior plumb to the anterior plumb; an ascending modeling of the dorso-lumbar curvature and the cervico-occipital curvature; mobilization of the hip joint towards flexion, from the shoulder to the retropulsion and from the elbow to the flexion; and a slight tilt from head to back, the subject tending to maintain its horizon line at first.

In a second phase, the bell 53 rises under pressure increased air and frees the nozzle 28 which distributes the compressed air in the tubes 10, 9, 8 of the seat. As can be seen in FIG. 14, there is an oblique upward movement during which the external cover 19 of the backrest can slide on the flanges 4, 5 and 6 because its lower end 21 is free, which avoids rubbing clothes; at the same time, the modeling effect of the tubes 4, 5 and 6 of the backrest continues and even increases, these tubes receiving additional pressure; this effect also changes location and is exerted in the lumbar and cervico-dorsal regions. The coxo-femoral joint is first modified towards extension, again opening the lumbo-femoral angle and the knee is mobilized in extension. The horizon line changes and the head is mobilized towards flexion.

A very important thing then occurs: a whole reflex activity of the postural tonic muscles is triggered by this movement of the head, by the extension of the knee, by the increase in the support of the hands on the steering wheel and of the heels on the floor and by the anterior balance accompanied by a spinal stretch. The subject is indeed placed in conditions close to those which precede the rising from the sitting station. This activity which comes from the subject himself but without participation of his will increases or modifies certain parameters: active spinal stretch, slight flexion of the coxo-femoral region, slight tilting of the trunk forward (the subject tends to leave the supports of the backrest ), slight abduction of the shoulder, taking greater support from the hands which automatically go up on a steering wheel or slide forward from an armrest of an armchair, active wedging of the heels, recoil of the pelvis which is further facilitated by the position of the rod 10 in front of the ischium and taken up by the pelvis from its normal place from where it always slides more or less during the posterior support phase.

In a third phase, the programmer 42 stops the supply of compressed air by the source 22 and at the same time opens the electromagnetic valve 26. The pressure in the distributor 23 will decrease and the close will decrease. The tubes 8, 9, 10 of the seat will deflate first because they are the most compressed by the weight of the trunk, the air which they contain can still be evacuated when the nozzle 28 is no longer in communication with the bottom of cylinder 54, via line 38, flange 4 and line 32. The seated person will, during this phase, arrive at the position shown in FIG. 15.

During this descent of the seat, there is: an ascending shaping of the spine (the free part 21 of the external cover 19 taking its place); an increase in the cervical stretching and as a result of the postural tonic activity, the fact that the individual seeks, automatically, to maintain his horizon line; mobilization of the shoulder in antepulsion and slight adduction; mobilization of the coxo-femoral region and knee in flexion; a sliding of the hands towards the middle of a steering wheel or an armrest. It will be noted that, the descent of the seat being done with an anterior balance, we avoid the sliding of the pelvis forward.

In a fourth phase, the tubes 4, 5, 6 of the backrest deflate in turn from top to bottom and the subject returns to posterior balance as shown in fig. 16. This will lead to restoring the vertebral discs and decompressing the posterior articular elements and tilting the pelvis backwards, which tends to remove lordosis from the lumbar area. As a result, the coxo-femoral region is mobilized in extension, the head rocks forward and removes lordosis from the cervical area and the shoulder and elbow are mobilized in extension. The chest that was expanding in the previous three phases relaxes (lowering of the ribs).

Fig. 17 shows the position of the human body during the second phase in the case of an armchair and a seated station while FIG. 18 represents the position of the human body during the second phase in the case of an armchair and a reclining station in which the invention allows a certain articular mobilization.

The programmer 42 makes it possible to modify the duration of the modeling activity phases and their frequency and, thereby, the duration and the frequency of the rest phases. In the case of an autonomous compressed air source such as a compressor or a diaphragm pump, the compression speed can be adjusted to adjust the speed of the modeling action. In addition, the screw 56 of the distributor 23 makes it possible to adjust the pressure in the tubes. We therefore have the possibility of acting on a plurality of factors in order to adapt well sits on the peculiarities of his job.

• 1 - le dossier est prévu pour provoquer le passage de l'aplomb pos­térieur à l'aplomb antérieur;
• 2 - l'assise qui peut, en outre, comporter des moyens de réglage en hauteur est prévue pour créer périodiquement une obliquité de haut en bas et d'arrière en avant;
• 3 - l'effet de modelage créé par les appuis actifs prévus a été expliqué lors de la description des phases de fonctionnement;
• 4 - la stabilisation de l'ischion ou le replacement constant du bassin vers l'arrière ont également été expliqués dans cette description ; le calage latéral peut-être assuré, comme on l'a indiqué,par des boudins complémentaires, mais, de plus, le re­placement du bassin vers l'arrière résout déjà ce problème car c'est le glissement en avant avec un rachis lombaire mis en cy­phose qui dans la plupart des sièges entraine une instabilité latérale;
• 5 - l'alternance des appuis créés par les boudins soulage les tis­sus humains en appui;
• 6 - il y a déclenchement d'une activité réflexe des muscles toni­ques posturaux notamment dans la deuxième phase de fonctionne­ment;
• 7 - les appuis sont stables car,si des structures gonflables pré­sentent en elles-mêmes une certaine instabilité, ces structures n'interviennent qu'au moment où le tronc est placé par elles dans les meilleures conditions de stabilité (aplomb antérieur et étirement rachidien).

It is clear from what has just been said that the seat described meets the seven conditions mentioned above:

• 1 - the backrest is intended to cause the passage from the posterior plumb to the anterior plumb;
• 2 - the seat which may, in addition, include height adjustment means is provided to periodically create an obliquity from top to bottom and from back to front;
• 3 - the modeling effect created by the planned active supports was explained during the description of the operating phases;
• 4 - the stabilization of the ischium or the constant replacement of the pelvis towards the rear have also been explained in this description; lateral wedging can be ensured, as indicated, by additional tubes, but, moreover, the replacement of the pelvis towards the rear already solves this problem because it is the sliding forward with a lumbar spine placed in kyphosis which in most seats causes lateral instability;
• 5 - the alternation of the supports created by the sausages relieves the human tissues in support;
• 6 - there is triggering of a reflex activity of the postural tonic muscles in particular in the second phase of functioning;
• 7 - the supports are stable because, if inflatable structures present in themselves a certain instability, these structures only intervene when the trunk is placed by them in the best conditions of stability (anterior balance and spinal stretching) .

We will now examine to what extent the various types of seats currently known meet some of the seven conditions listed above, it being understood that those of these conditions not mentioned here for a type of seat are not at all fulfilled by this type of seat.

The ergonomic seats with fixed geometry to which the molded seats are attached to the back shapes have very good stability and their geometry has a certain ischion retention effect.

The seats with fixed seat and movable back allow the trunk to oscillate between a posterior plumb and an anterior plumb, but only if the user moves voluntarily.

The seats with fixed backrest and movable seat allow the seat to oscillate between two reverse obliquities, but only if the user moves voluntarily.

The seats with backrest and seat forming a single piece block, pivoting around a fixed axis and seats with seat pivoting around a fixed axis and seats pivoting around an axis carried by the seat allow the trunk to oscillate between a posterior plumb and an anterior plumb, but only if the user moves voluntarily.

The seats with a movable seat linked by a pivot to the back which is held at its upper part by a fixed pivot and the seats with fixed seat and spring back do not meet any of the seven conditions listed.

The seats with backrest and seat swiveling independently of each other and held by springs offer good active support and allow the trunk to oscillate between two plumbs, but only if the user moves voluntarily.

Three other types of seats produced or offered better meet some of the seven conditions listed above.

The so-called "kneeling-sitting" seats have good stability, stimulate postural tonic reflexes, allow the trunk to oscillate if the user moves voluntarily and offer an obliquity from top to bottom and from back to front of the seat. However, these seats have the disadvantage of not respecting the ergonomic rule of freedom of movement and of not allowing normal plantar support. They provide for a dynamic sitting position, with no muscular resting phase in the back.

Variable ischio-lumbar seats in which the backrest is mounted on a fixed pivot and the seat is supported by a structure mounted on a fixed pivot located near the floor while a strap passing over a roller and connecting the seat the backrest rotates the backrest according to the movement of the movable seat, has good stability and provides active lumbar support, measured in poor conditions (posterior plumb) so that this support does not prevent the pelvis from sliding towards the front; they allow oscillation of the trunk between a posterior plumb and an anterior plumb only if the user moves voluntarily.

With regard more particularly to car seats, the seats with inflatable structures or motorized modules enabling them to match the moving morphology of the user have, in themselves, good stability and a relative lateral stabilization action of the ischium, but they do not stabilize it in the antero-posterior plane; they make it possible to adjust the supports but these are not really active once their adjustment has been made and they lose their effectiveness when sliding the ischion forward, which can then become quite unsuitable and therefore requiring new adjustments diverting attention from the pipe. We do not envisage the transition from the backrest to a previous balance. There is no possibility for the seat to have an obliquity from top to bottom and back to front.These seats do not provide for changes in the support of human tissue under pressure on the seat, swings in the backrest or exchange obliqueness of the seat, once the adjustments have been made and there is no stimulation of the supporting muscular structures.

As for the seats comprising structures with programmed dynamism currently proposed, apart from the fact that they offer active supports (note that there is no action from bottom to top), we can oppose them the same In addition, if they bring a change in the points of support, this does not concern the ischial zone, however most concerned. Finally, the fundamental notion of stability of the human body on the supports does not seem to be respected: Indeed, the modeling elements acting on a human body vertically posterior, therefore unstable, can, on the contrary, promote instability.

This examination of the various types of known seats shows that these seats are far from fulfilling all of the seven conditions set out above. In summary, it can be said that, so far, the seats are trying to adapt to the shape of the user but, as it is variable, this is difficult, uneconomical, often inadequate and distracts the attention that must be paid to the pipe eventually.

In an opposite approach, the system described here allows the human body to periodically resume its most stable form.

It fulfills the seven defined conditions and has, in addition, other advantages: one can decide the exact place of the inflatable elements for a better adaptation to the morphology of the user and, possibly a preventive effect on the articular deteriorations or a therapeutic effect prolonging a spinal rehabilitation; the spacing of the inflatable elements eliminates the unpleasant impression of sticking to the seat, in addition to the system itself which, as we recall, periodically encourages the user to leave the backrest support; in in the case of machine operators, stimulation of the postural tonic musculature provides greater comfort and increases alertness, thus improving safety; anxiety is reduced thanks to the maintenance of optimal tone, better placement of the diaphragm (correction of the dorso-lumbar area) and good support stability despite the movements.

The system according to the invention is easy to install and remove on any type of seat. It can be switched from a car seat to a lounge seat. It is possible, by economy or ease of installation, to use only the tubes 4 and 5 for the backrest (possibly combined in a single envelope) and the tube 10 for the seat without fundamentally affecting the efficiency of the system. It is simple and reliable and can strengthen other systems tending to improve the qualities ergonomic seat. It can, of course, also be integrated into the structures of the seat, in the construction thereof. The distributor can, of course, be replaced by electromagnetic valves driven by electrical pulses.

Finally, it should be noted that it gives the user complete freedom of movement (no straps, blockages).

The applications of the invention are manifold: they particularly interest drivers of vehicles (cars, airplanes, etc.) and people who must have attention without fail, spectators looking for great comfort, people with ankyloses or paralysis.

Claims (10)

1-System to equip a seat, comprising a seat (2) with an upper face intended to receive the human body and a backrest (1) with an anterior face intended to receive the human body, deformable elements (4,5,6 ) being arranged in this file and connected by connecting means (32,33,23,30) to an energy source (22) while automatic control means (40,41,42,43,44) establish a sequence of passage of these elements from a state of retraction to a state of expansion, characterized in that similar deformable elements (8,9,10) are also installed in the seat (2) and in that the arrangement of all of these deformable elements (4,5,6,8 9,10) and said sequence are such that the backrest (1) periodically has a posterior balance (Fig. 16) and an anterior balance (Fig. 13 , 14,15) and that, in the seat (2), an obliquity is formed periodically from top to bottom and from back to front (Fig. 14). 2-System according to claim 1, characterized in that the deformable elements (4,5,6,8,9,10) are inflatable elements and the energy source (22) is a source of pressurized fluid. 3-System according to claim 2, characterized in that the backrest (1) is provided on its front face (3) with inflatable elements in the form of several parallel tubes (4,5,6) arranged transversely to the length of the backrest considered according to the length of the human body to be supported, spaced from each other along the anterior face (3) of the backrest and having, in the inflated state, sections such as the section of the rod most distant from the seat is the most important. 4- System according to claim 2 or 3, characterized in that the seat (2) is provided on its upper face (7) with inflatable elements in the form of several parallel tubes (8, 9, 10) arranged transversely to the length of the seat considered according to the length of the human body to be supported, spaced from each other along the upper face (7) of the seat and having, in the inflated state, a different increasing section of the flange (8 ) the furthest from the file (1) to the flange (10) closest to the latter. 5 - System according to claim3, characterized in that the flanges (4,5,6) which is provided with the backrest (1) are three in number. 6 - System according to claim 4, characterized in that the flanges (8,9,10) which is provided with the seat (2) are three in number. 7 - System according to claim3 or5, characterized in that the flanges (4,5,6) which is provided with the backrest (1) are arranged between an internal cover (15) surrounding the backrest (1) and an external cover (19 ) covering the whole of this internal cover (15) and these tubes (4,5,6), but left free (21) at the bottom of said anterior face (3) of the backrest. 8 -System according to claim4 or6, characterized in that the tubes (8,9,10) which is provided with the seat (2) are disposed between an internal cover (16) surrounding the seat (2) and an external cover (20) surrounding all of this internal cover (16) and these tubes (8, 9, 10). 9 - System according to claim4 dependent on claim 3, characterized in that said fluid connection means comprise a distributor (23) connected by a supply line (30) to said source of pressurized fluid (22) and pipes of connection (32,33) arranged between the distributor (23) and on the one hand the tubes (4,5,6) with which the backrest (1) is provided and on the other hand the tubes (7,8,9) which is provided with the seat (2), the distributor (23) and these connecting pipes (32,33) being provided so that, in the inflation phases of the inflatable elements with articular action, the tubes (4,5,6 ) with which the backrest (1) is provided are the first to be supplied with pressurized fluid and the flanges (8, 9, 10) with which the seat (2) is provided only afterwards, when the pressure of the pressurized fluid admitted into the distributor (23) reaches a predetermined value, while a conduit (38) with non-return valve (39) disposed between the tubes which is mu denies the seat and the tubes with which the backrest is provided allows, in the deflation phases of the inflatable elements with articular action, the total deflation of the tubes which the seat is provided with by passage, in at least one (4) of the tubes with the backrest, pressurized fluid leaving the tubes (8,9,10) with which the seat is provided. 10 -System according to claim 9, characterized in that said distributor (23) comprises: a cylinder (54) at a longitudinal end from which open (24,27) said supply line (30) and a line (32) of connection between this distributor and the tubes (4,5,6) with which the backrest (1) is provided, as well as a discharge pipe (31) provided with an electromagnetic valve (26); a movable bell (53) sliding in this cylinder (54), urged by a compression spring (55) in the direction of said end towards a rest position; and the mouth (28) in the cylinder (54) of a pipe (33) connecting this distributor (23) and the tubes (8, 9, 10) with which the seat (2) is provided at a location such that this mouth (28) is closed by said bell (53) as long as the latter is in the rest position and that it is in communication with said supply line (30) when sufficient pressure of the fluid under pressure arriving via this supply line (30) displaces the bell (53) against the compression spring (55), while control members (40) of the source of pressurized fluid (22) and members control (41) of the electromagnetic valve (26) are placed under the control of a programmer (42).

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