FR3036615A1 - MEDICAL ARMCHAIR EQUIPPED WITH A SYSTEM TO HELP PATIENTS TO SIT AND COME TOGETHER - Google Patents

Abstract

Armchair (1) medicalized comprising: - a frame (2) provided with a base (5), - a seat (14) movable relative to the base (5) and including a half-seat (14A) and a front half-seat (14B) rear mutually articulated about an axis A, and - a mechanism (33) of articulation of the seat (14) can adopt a folded configuration placing the seat (14) in a low position close of the base (5), and a deployed configuration placing the seat (14) in a high position spaced from the base (5), this mechanism (33) two superimposed deformable quadrilaterals, including a lower quadrilateral which, in the folded configuration, is convex and, in the deployed configuration, is concave.

Description

The invention relates to the field of medical chairs, and more particularly to chairs equipped with mobile seats to help people with mobility problems. and / or reduced muscular strength (hereinafter referred to as "patients") to sit and stand up. Sitting and standing up are complex movements involving the joints of the ankle, knee and hip, calf muscles (anterior tibia), thighs (quadriceps), glutes and back (lumbar) muscles. ), and further assume a proper functioning of the inner ear, organ of the balance of the human body. For the patients with the so-called psychomotor-mismatch or MPRT syndrome (especially the elderly or with bone or muscle lesions or even balance disorders), sitting down and standing up poses significant risks of fall and therefore trauma. About this syndrome, cf. in particular the article by P.Manckoundia et al. "Psychomotor Disadvantage Syndrome", in Geriatrics and Neuropsychiatric Psychology of Aging, Vol.12, March 2014, and N. Meesmaecker's "State of the Art Report". Psychomotor Disability in a Specialized Center for Geriatrics ", Institute for Masso-Physiotherapy Training in Rennes, 25 2011. In most patients with MPRT, post-retropulsion symptoms are observed (tendency to project backwards). during the transition from sitting posture to standing posture) and oppositional hypertonia (reflex muscular tension opposing the proposed movement). These symptoms are often accompanied by that of stasobasophobia (phobia of standing, verticality and walking), which leads the patient to fear the action of getting up from the sitting posture. To sit up and get up, patients can use the arms 35 resting on the armrests that usually equip the medical chairs, but it requires some strength. Patients may also be assisted by caregivers, but these are then exposed to various musculoskeletal disorders (particularly low back pain) due to the combination of the following factors: posture discomfort, repetition of handling operations ; patient weight.

Various chairs and chairs with telescopic seats have been proposed to help patients sit up and get up. There are thus chairs powered by an electric motor driven by a remote control operable by the patient. This technology, illustrated by US Pat. No. 7,090,297 (La-Z-Boy), is not without its disadvantages: first, to be supplied with electricity, the chair must be connected to the mains and can not therefore be driven; secondly, because of the power supply, this chair is relatively heavy, which makes it tedious its possible movement (eg from one room to another).

There are also chairs equipped with mechanical spring (spring) or pneumatic (cylinder), which are lighter and do not require any external energy input. This technology is particularly illustrated by British Patent GB 1 406 420 (Warwick), which describes a medical chair with a movable seat controlled by a spring mechanism. However, it can be shown that this chair lacks ergonomics, because the movement followed by the seat during its articulation is quite different from the movement of the legs of the patient, who therefore risks, by sitting or standing up, losing the balance.

A first objective is therefore to provide a medical chair more secure for patients. A second goal is to provide a medical chair for patients who have lost the habit of sitting and getting up without help (and especially patients with MPRH) to find this habit. A third objective is to provide a reliable and relatively lightweight medical chair, allowing easy movement. For this purpose, there is provided a medical chair comprising: a frame provided with a base, - a movable seat relative to the base and including a front half-seat and a rear half-seat mutually articulated about an axis A, and 3036615 3 a hinge mechanism of the seat can adopt a folded configuration placing the seat in a low position close to the base, and an expanded configuration placing the seat in a high position away from the base , this mechanism 5 comprising: a lower frame rotatably mounted relative to the base around an axis B and with respect to the half-seat before a C axis located near a front edge of that -this ; o an upper frame rotatably mounted relative to the lower frame 10 about an axis D located between the axes B and C, and relative to the half-seat back around an axis E located in the vicinity of a rear edge of it; a coupling arm rotatably mounted relative to the base around an axis F and with respect to the front half-seat around an axis G spaced from the axis C; an elastic return member which urges the articulation mechanism towards its deployed configuration; the axes A, B, C, D, E, F and G being parallel and defining, in a plane perpendicular to them: - the axes B, C, G, F, a deformable lower quadrilateral; the axes A, C, D, E, a deformable upper quadrilateral; the axes A, B, C, D, E, F and G being positioned such that the lower quadrilateral is convex in the folded configuration, and concave by the axis G in the deployed configuration.

Various additional features may be provided, alone or in combination: the sum of the centers FG and CG is less than or equal to the center distance BC; the angle between the planes respectively defined by the axes A and C on the one hand and C and G on the other hand is between 70 ° and 120 °; the angle between the planes respectively defined by the axes A and C on the one hand and C and G on the other hand is about 90 °; the center distance DE is greater than or equal to the center distance AC; the center distance is less than or equal to the center distance BD; The center distance AE is greater than or equal to the center distance CD; the return member is a gas spring; The gas spring is of the lockable type; the gas spring comprises a body fixed on the lower frame, and a rod fixed on the upper frame. Other objects and advantages of the invention will become apparent from the description of an embodiment, given hereinafter with reference to the accompanying drawings in which: FIG. 1 is a perspective view of a medical chair , shown alone, whose seat is in a low position; Figure 2 is a view of the chair of Figure 1, in which a patient sits; Figure 3 is a perspective view of the chair of Figure 1, the seat is in the upper position; Figure 4 is a view of the chair of Figure 3, with a patient standing up from the chair or sitting in it; FIG. 5 is a side view of the seat in the low position and of its hinge mechanism in folded configuration; Figure 6 is a kinematic diagram illustrating the hinge mechanism in its folded configuration; Figure 7 is a side view of the seat in the up position and its hinge mechanism in deployed configuration; Figure 8 is a perspective view, from the rear, of the seat in the raised position and its articulation mechanism in deployed configuration; Fig. 9 is a kinematic diagram illustrating the hinge mechanism in its deployed configuration; Figure 10 is a longitudinal sectional view showing the seat in the upper position and illustrating the return member with, inset, a larger scale detail centered on an adjustable stop; FIG. 11 is a diagram illustrating the various positions of the seat between its low position and its high position; Figure 12 is a comparative diagram illustrating the different positions of the seat of the patent chair GB 1 406 420, between its low position and its high position.

In Figure 1 is shown a medical chair 1 for people of advanced age or suffering from bone lesions or muscle, or balance disorders (hereinafter simply called "patients"). This chair 1 is intended not only to enable them to adopt a sitting position, but also to facilitate their movement for caregivers.

The chair 1 comprises a frame 2 formed of metal tubular elements (in particular steel or aluminum alloy). This frame 2 includes a carriage 3 provided with wheels 4 enabling the chair 1 to be moved, a base 5 mounted on the carriage 3, a mast 6 that is adjustably fixed (in particular at an angle) on the base 5, and, as illustrated , tubes 7 which extend laterally from the base 5 to allow the adjustable mounting of armrests 8. The carriage 3 comprises for example a main beam 9 and a pair of longitudinal members 10 at the ends of which are fixed the wheels 4 The chair 1 comprises a backrest 11 mounted on the mast 6, and, optionally, a headrest 12 mounted at an upper end of the mast 6, surmounting the backrest 11. Furthermore, as in the illustrated example, the chair 1 is preferably equipped with a handlebar 13 formed by a transverse bar fixed to the upper end of the mast 6, to facilitate the movement and operation of the chair 1 by a caregiver. In what follows, the term "back" defines a location on the side of the file 11; the term "before" defines, conversely, an opposite location. The term "bottom" defines a location on the side of the wheels 4; the term "high" defines, conversely, an opposite location. Generally speaking, the terms "back", "front", "down" and "up" are used in the context of normal positioning and use of the chair 1, as is commonly the case with the chair. habit in everyday life. The same is true of the terms "vertical" and "horizontal", assuming that the chair 1 rests on a horizontal floor.

The chair 1 comprises a seat 14 movable relative to the base 5 between a low position (FIGS. 1, 2, 5, 6) in which the seat 14 extends in the vicinity of the base 5 to allow a seat patient 15 to be comfortably seated in the chair 1, as shown in Figure 2, and a high position (Figures 3, 4, 7, 8, 9, 10) 35 in which the seat 14 is spaced from the base 5 to help the patient 15 to get up by pushing him behind his thighs or, on the contrary, to sit by cushioning and accompanying his movement.

The base 5 may be immovably fixed to the carriage 3, or, as in the example illustrated, adjustable at least in height and, optionally, in rotation, by means of a jack 16 provided with a locking mechanism actuable by means of a lever 17 projecting from the patient's reach 15. The base 5 is, in the illustrated example, in the form of a metal part comprising a horizontal plate 18 and side flanges 19 folded square to the plate 18 horizontal. It is preferable that the base 5 (and thus the seat 14 and the armrests) be locked in rotation while the patient sits or stands up, so as to secure the patient. . For this purpose, and as illustrated in particular in Figure 1, at least one of the tubes 7 is provided with a stand 20 which abuts against the cross member 9. According to an embodiment illustrated in Figures 1 to 4, the Chair 1 is equipped with a footrest 21 movable in height between a low position (illustrated in the figures) in which the footrest 21 extends in the vicinity of the ground to allow the patient 15 to take support when it sits and stands up, and a high position in which the footrest 21 is spread away from the ground to keep the feet of the patient away from the ground, which prevents them from rubbing against it during chair movements 1. As seen in particular in Figures 1 to 4, the chair 1 is provided with a mechanism 22 for actuating the footrest 21, including a foot control lever 23 and a linkage linkage 24 from the lever 23 to the footrest 21, 25 the tilting of the control lever 23 placing the re footrest 21 in its upper position or, conversely, in its low position. Advantageously, the actuating mechanism 22 simultaneously controls the locking of at least two of the wheels 4 (eg the rear wheels) in the lower position of the footrest 21, so as to prevent the chair 1 from escaping when patient 15 stands up or sits. The seat 14 is in two parts: it comprises a half-seat 14A front for supporting the thighs of the patient 15, and a half-seat 14B back to support its pelvis. The half-seats 14A, 14B are mutually articulated around a common axis A, located in the vicinity of a rear edge of the front half-seat 14A and a front edge of the rear half-seat 14B.

As illustrated in the figures, and in particular in FIGS. 5 and 7, the front half-seat 14A comprises a metal front plate 25 provided with flanges 26; likewise, the rear half-seat 14B comprises a metal rear plate 27 provided with flanges 28.

The axis A is, in the illustrated example, formed by a pair of bolts 29 through which the plates 25, 27 are rotatably mounted relative to each other. The seat 14 comprises a flexible cushion 30 having a front portion 30A mounted on the front plate 25 through a front plate 31A slidably mounted thereon, and a rear portion 30B mounted to the rear plate 27 by via a rear plate 31B slidably mounted thereon and hinged relative to the front plate 31A around a hinge 32. The pad 30 is preferably made of a foam, e.g. Viscoelastic foam (commonly referred to as shape memory foam). The trays 31A, 31B may be made of plastic, wood or, advantageously, a material derived from wood (typically agglomerated, medium, laminate). The chair 1 further comprises a mechanism 33 for articulating the seat 14, designed to be able to adopt a folded configuration placing the seat 14 in its low position (FIGS. 5, 6), and an unfolded configuration placing the seat 14 in its high position (Figures 7, 8, 9). This mechanism 33 comprises, firstly, a lower frame 25 rotatably mounted relative to the base 5 about an axis B and with respect to the half-seat 14A before a C axis located in the vicinity of 'a front edge of it. In the illustrated example, the axis B is formed by a pair of bolts 35 by which the lower frame 34 is rotatably mounted on the flanges 19 of the base 5.

The lower frame 34 could be formed of a pair of parallel rods interconnected by a brace. In the example illustrated in the figures, and in particular in FIG. 8, the lower frame 34 is nevertheless in the form of a one-piece metal part comprising a rectangular plate 36 provided with a notch 37 whose function will appear below. ), and lateral edges 38 folded at right angles to the plate 36.

According to one embodiment illustrated in the figures, and in particular in FIGS. 5, 7 and 8, the axis C is formed by a tube 39 integrated in the lower card (for example by being welded to the plate at the level of FIG. a front edge thereof) and rotatably mounted between two bearings 40 fixed (eg by screwing) to the half-seat 14A before, on either side laterally thereof. The articulation mechanism 33 comprises, in the second place, an upper frame 41 rotatably mounted on the one hand with respect to the lower frame 34 about an axis D situated between the axes B and C, and on the other hand relative to the half-seat 14B rear about an axis E located in the vicinity of a rear edge thereof. The upper frame 41 could be formed of a pair of parallel rods interconnected by a spacer. In the example illustrated in the figures, and in particular in FIG. 8, the upper frame 41 is nevertheless in the form of a one-piece metal part comprising a rectangular plate 42 provided with a central slot 43 (the function of which will appear hereinafter). -after), and lateral edges 44 folded square relative to the plate 42. In the example shown, the axis D is formed by a pair of coaxial bolts 45 by which the upper frame 41 is mounted in position. rotation on the lateral edges of the lower frame 34. According to a preferred embodiment, the axis D extends in the plane formed by the axes B and C (in other words, the axes B, C and D are coplanar). The axis E is formed by a pair of coaxial bolts 46 by which the upper frame 41 is rotatably mounted relative to the rear half-seat 14B, and more specifically on tabs 47 formed protruding from the back plate 27. The articulation mechanism 33 comprises, thirdly, a coupling arm 48 rotatably mounted on the one hand with respect to the base 5 about an axis F, and on the other hand with respect to the half front seat 14A about an axis G spaced from the axis C and located on the side thereof opposite the front plate 25. The coupling arm 48 could be in the form of a single central rod (that is to say extending in a longitudinal plane 35 of symmetry of the chair 1). However, in the example illustrated, the coupling arm 48 comprises a pair of connecting rods 49 arranged laterally on either side of the base 5, secured to one another by means of a spacer. 50 (here in the form of a crossbar). As can be seen in the figures, the axis F of rotation of the coupling arm 48 is offset relative to the axis B of rotation of the lower frame 34, both forwards and downwards, the arm 48 being itself shifted forward relative to the entire lower frame 34. The axis F is for example formed by a pair of bolts 51 through which each rod 49 is rotatably mounted relative to a flange 19 of the base 5.

As is further seen in FIGS. 5, 7 and 8, the arm 48 is rotatably coupled to the front half-seat 14A via a lug 52 projecting from the front plate, of which it is solidary (eg by welding). According to an embodiment illustrated in these figures, the tab 52 is horn-shaped and the axis G of rotation of the arm 48 with respect to the half-seat 14A is attached to one end of the tab opposite to that this. In the illustrated example, the axis G is formed by a pair of coaxial bolts 53. The axes A, B, C, D, E, F and G are mutually parallel and extend transversely, that is to say perpendicular to a general plane of symmetry of the chair 1. In this way, the axes A, B, C, D, E, F and G define, in any plane perpendicular to them (and in particular in the general plane of symmetry of the chair 1): the axes B, C, G, F, a lower BCGF quadrilateral deformable; The axes A, C, D, E, a deformable upper ACDE quadrilateral. Since the tab 52, which carries the axis G, is integral with the front plate 25, the AC side of the upper quadrilateral ACDE and the CG side of the lower BCGF quadrilateral are rigidly secured. Since, furthermore, the axes B and F are fixed and the axis D is integral with the lower frame 34 (ie on the BC side of the lower BCGF quadrilateral), the deformations of the BCGF and ACDE quadrilaterals are related. at each configuration of the lower quadrilateral BCGF corresponding a single configuration of the upper quadrilateral ACDE, and vice versa. The articulation mechanism 33 is however not free, otherwise gravity would keep it in its folded configuration. The chair 1 comprises a resilient return member 54 which urges the articulation mechanism 33 towards its deployed configuration, so that in the absence of any resisting force hindering the deformation of the restoring member 54, Deployed configuration is the one occupied by default articulation mechanism 33. According to an advantageous embodiment, the return member 54 is interposed between the lower frame 34 and the upper frame 41 which it tends to move away from one another. The return member 54 is for example a gas spring, and in this case comprises a cylinder body 55 which, in the illustrated example, is fixed to the lower frame 34 (and more specifically to a yoke 56 secured to it). ci) being hinged thereto, and a rod 57 slidably mounted relative to the body 55 and fixed to the upper frame 41 through the notch 37 and the slot 43, being articulated relative to the upper frame 41. As illustrated in FIG. 8, notch 37 and slot 43 provide angular clearance for rod 57 to allow pivoting thereof, which accompanies the tilting of upper frame 41 relative to lower frame 34 during deployment. (or, conversely, folding) of the articulation mechanism 33. As illustrated in FIG. 10, and more particularly in the detail locket thereof, the hinge mechanism 33 may be provided with an adjustable stop 58 for adjusting the deployed configuration of the mechanism 33 (and thus the high position of the seat 14). As in the example shown, this stop 58 may be in the form of a knob screwed into the bar 50 bracing the connecting rods 49 of the coupling arm 48. The stop 58 has a mushroom-shaped handle 59 and a rod 60 at the end of which a hemispherical shoe 61 is mounted. In deployed configuration, the plate 36 of the lower frame 34 abuts against the shoe 61, which blocks in position the articulation mechanism 33. By screwing (or unscrewing) the rod 60 in the bar 50 by means of the handle 59, the position of the pad 61 is adjusted, which makes it possible to adjust the deployed configuration of the articulation mechanism 33 (and thus the position 14) to the morphology (and in particular to the size) of the patient 15. The movable seat 14 (with its articulation mechanism 33) can thus accompany and assist the patient's movements of 35 seconds. sit from the upright posture, and conversely get up from the sitting posture.

The movement of the articulation mechanism 33 is now described, starting firstly with the patient's standing posture and with the deployed configuration (adjustable, as we have just seen) of the articulation mechanism 33 (and therefore from the high position of the seat).

In this configuration, illustrated in FIGS. 3 and 4, the wheels 4 of the chair 1 are assumed to be locked and the footrest 21 lowered. The patient 15 presents himself back to the chair 1 and his feet on the footrest 21 down, slightly bends the legs. It can be used with the arms coming to grip the armrests 8 (whose height is preferably adjustable), as shown in FIG. 4, which solicits, albeit in a moderate manner, the extensor muscles of the elbow (in particular the brachial triceps ). The back of the thighs (hamstring muscles) coming to rest on the half-seat 14A before, and the pelvis (and buttocks) on the back half-seat 14B, the patient 15 can then 15 indulge to sit down releasing his muscles without fear of shock coccyx, the spring 54 damping its movement. The spring 54 is, for this purpose, chosen to slow down (and thus dampen, but not to thwart) the folding movement of the articulation mechanism 33, and this for a panel of patients having varied weights between a minimum value (eg on the order of 35 to 40 kg) and a maximum value (eg of the order of 80 to 90 kg). It is conceivable to choose a gas spring 54 adjustable force to adapt to the weight of the patient 15. Alternatively, it is conceivable to provide several models of chairs 1 each adapted to a narrow range of weight and covering a wide range range of weight, and that one selects according to the weight of the patient. Once the patient sits 15, a carer can unlock the wheels 4 and raise the footrest 21 to freely move the chair 1 (with the patient) by means of the handlebar 13.

Conversely, starting from the sitting posture of the patient 15 and the folded configuration of the articulation mechanism 33 (and assuming the wheels 4 locked and the footrest 21 lowered, FIGS. 1 and 2), the patient 15, for Initiating the movement of standing up, begins by leaning the bust forward, which moves its center of gravity forward and transfers some of its weight to its feet by decreasing the resisting force opposed to the deployment of the mechanism 33 articulation under the spring return effect 54.

3036615 12 The patient can use his arms by gripping the armrests 8 and leaning against it, which further lightens the weight carried by the seat 14, to the point where the spring 54 can freely stretch into deploying the articulation mechanism 33, which pushes the patient both upwards (through the back half-seat 14B) and forward (through the front half-seat 14A) and further reduces the weight borne by 14. The patient 15 thus assisted can easily reach the posture illustrated in Figure 4 where, although his legs are still slightly bent, the effort that must consent to the patient 15 to extend completely 10 is modest . The hinge mechanism 33 is not only designed to provide the patient with a pushing effort to get up; it is designed to perform an ergonomic accompanying movement, that is to say closer to the kinematics of the human body moving from the sitting posture to standing posture, and vice versa. For this purpose, the axes A, B, C, D, E, F and G are positioned (that is to say, the lower frame 34, the upper frame 41, the half-seat 14A before, the half rear seat 14B and coupling arm 48 are sized) such that the lower BCGF quadrilateral is convex in the folded configuration of the mechanism 33, and concave by the G-axis in the expanded configuration of the mechanism 33. Recall that a quadrilateral is convex when its diagonals are included in the perimeter defined by the quadrilateral, and concave when one of the diagonals is located outside this perimeter. In other words, that the lower quadrilateral BCGF is concave by the axis G means that the angle between the segments GF and GO, measured on the inner side of the quadrilateral BCGF, is greater than 180 °. It can be seen that: as long as the lower quadrilateral BCGF is convex, the segment AE (and with it the back half-seat 14B) is animated, during deployment or folding of the articulation mechanism 33 during a said translative phase (denoted T in FIG. 11), of a substantially vertical translation movement (arrow F1 in FIG. 6) to an intermediate configuration in which the segments GF and GO are aligned; 3036615 13 since, after the intermediate configuration, the lower quadrilateral BCGF becomes concave, the segment AE (and with it the back half-seat 14B) is animated, during deployment or folding of the articulation mechanism 33 during a so-called rotary phase (denoted R in FIG. 11), with a substantially rotational movement from rear to front (in the case of deployment, arrow F2 in FIG. 9) or vice versa from front to back (in FIG. the case of aliasing). The movement of the articulation mechanism 33 (and thus of the seat 14) is therefore subdivided into two phases. During the translational phase T, the back half-seat 14B accompanies the vertical translational movement of the pelvis (and buttocks) of the patient 15, ie when he initiates the movement of standing up from the sitting posture, or when he ends the movement of sitting down. As for the half-seat 14A before, it is animated by a combined movement of vertical translation and rotation of low angular amplitude which accompanies both the ascent (in the case of the transition to standing posture) or the descent (in the case of transition to the sitting posture) of the knee joint and the rotation of the thighs around it. In the movement of deployment of the articulation mechanism 33, the axis C is animated, during the translative T phase, a large amplitude upward movement of rotation, centered on the axis B (arrow F3 on Figure 6). It will be observed that during the translational phase T, the assembly of the seat 14 is translated towards the rear. This movement reassures (and therefore relaxes muscles) patients with a retropulsion symptom, inclined by reflex to project their body backwards during the transition from sitting posture to standing posture. During the rotating R phase, the complete seat 14 (half-seat 14A 30 front and half-seat 14B rear) accompanies the rotation movement secured to the pelvis and the thighs of the patient 15 around the knee joint, which remains at substantially constant height. In the movement of deployment of the articulation mechanism 33, the axis C is animated, during the rotary phase R, with a low-amplitude rotational movement downwards, centered on the axis B (arrow F4 9), which frees the knee joint and allows the patient 15 to complete without difficulty the extension of his legs to rise. In addition, it will be observed that during the rotational R phase, the entire seat 14 translates forward, which, after the translational T phase which accompanies the patient with a retropulsion symptom backwards. , propels the latter forward towards the end of the movement and allows him to stand permanently. To obtain this complex kinematics, at least one of the following conditions a) to e) must be satisfied: a) The sum of the centers FG and CG is less than or equal to the center distance BC: FG + CG BC b) L angle, denoted a, between the planes respectively defined by the axes A and C on the one hand and C and G on the other hand, is between 70 ° and 120 °: 70 ° to 120 ° (In the example illustrated, the angle α is about 90 °). c) The center distance DE is greater than or equal to the center distance AC: DE AC 20 d) The distance between the centers is less than or equal to the center distance BD: BD BD In other words, the anchorage point of the frame The upper frame on the lower frame is closer to the C axis than the B axis. E) The center distance AE is greater than or equal to the center distance CD: 25 AE CD Two, three or four of the conditions a) to e) may be jointly satisfied. In the illustrated example, all conditions a), b), c), d) and e) are jointly satisfied. As an example, a list of parameters and their corresponding numerical values are given below, for which the articulation mechanism 33 functions correctly, that is to say that it makes it possible to obtain the phase translative and rotational phase, for the benefit of patient safety, and allows for ergonomic seating. In the following table, a succession of two contiguous letters, among the letters A, B, C, D, E, F and G, corresponds to the distance separating the axes defined by their respective letters. Thus, BC 3036615 denotes the center distance (i.e. the shortest distance) defined between the axes B and C. Parameter value FG 192 mm BC 253 mm CD 65 mm CG 34 mm CA 188 mm AE 160 mm DE 281 mm cc 9'18 °, BFx 64 mm BFz 25 mm 5 BFx means the distance between the vertical planes passing through the B and F axes, and BFz the distance between the horizontal planes passing through these same axes. FIG. 12 compares a diagram similar to that of FIG. 11 to illustrate the various positions of the seat of the patent chair GB 1 406 420 between its extreme positions represented in FIGS. and 3 of this patent. In the diagram of Figure 12, whose orientation is reversed with respect to Figures 2 and 3 of this patent, the front of the seat is on the right. It can be seen that the rear part of the seat is moved substantially vertically and forwardly, without any significant component of rotation, while the front end of the seat is moved essentially translation still directed backwards, including at the end of the movement. Such kinematics do not follow the movement of the human body, and in particular do not provide the patient with MPPR the forward pulse which at the end of the movement is necessary for him to recover. Conversely, the articulation mechanism 33 of the chair 1 described above allows, thanks to the decomposition of the movement in two phases, namely an essentially translative phase followed (or preceded, depending on whether the patient sits or stands up) of a substantially rotational phase, which makes it suitable for the kinematics of the human body. This results in improved security for the patient with MPRT, whose symptoms of retropulsion, oppositional hypertonia and stasobasophobia can thus be effectively combated.

Trials conducted with this chair 1 show that patients who have lost the habit of sitting and getting up without help can find this habit through daily use of the chair. It is conceivable to go beyond merely assisting the movements of standing up and sitting down (eg progressively during a rehabilitation program) by limiting the stroke of the articulation mechanism 33 (and therefore the seat 14) by means of a locking system of the spring 54. This locking system acts for example on a shutter valve of a decompression vent of the spring 54, which blocks the rod 57 in 15 position, regardless of this position. The locking system is for example actuated on the handlebar 13 by means of a handle 62 manually operable and connected to the spring 54 by a cable 63, in the manner of a bicycle brake. The articulation mechanism 33 certainly adds weight to a chair that would be lacking, but this weight can remain contained, to the extent that the parts that constitute it are relatively few and light enough. In total, the chair can remain relatively light. In addition, if the axes A, B, C, D, E, F and G are sufficiently greased, the mechanism 33 provides the chair 1 a high reliability, and therefore a long life.

Claims (10)

REVENDICATIONS1. Armchair (1) medicalized comprising: a frame (2) provided with a base (5), a seat (14) movable relative to the base (5) and including a half-seat (14A) before and half rear seat (14B) mutually articulated about an axis A, and a mechanism (33) for articulating the seat (14) can adopt a folded configuration placing the seat (14) in a low position close to the base (5), and an expanded configuration placing the seat (14) in a high position spaced from the base (5), this mechanism (33) comprising: o a lower frame (34) rotatably mounted relative to the base (5) about an axis B and with respect to the half-seat (14A) front around a C axis located near a front edge thereof; o an upper frame (41) rotatably mounted relative to the lower frame (34) about an axis D located between the axes B and C, and relative to the half-seat (14B) rear about an axis E located near a rear edge thereof; a coupling arm (48) rotatably mounted relative to the base (5) about an axis F and with respect to the front half-seat (14A) about an axis G separated from the axis C ; an elastic return member (54) which urges the articulation mechanism (33) towards its deployed configuration; the axes A, B, C, D, E, F and G being parallel and defining, in a plane perpendicular thereto: the axes B, C, G, F, a deformable lower BCGF quadrilateral; the axes A, C, D, E, an upper deformable quadrilateral ACDE; the axes A, B, C, D, E, F and G being positioned such that the lower BCGF quadrilateral is convex in the folded configuration, and concave by the G axis in the deployed configuration. 2. Armchair (1) according to claim 1, characterized in that the sum of the centers FG and CG is less than or equal to the center distance BC. 3. Armchair (1) according to claim 1 or claim 2, characterized in that the angle between the planes respectively defined by the axes A and C on the one hand and C and G on the other hand is between 70 ° and 120 °. 4. Armchair (1) according to claim 3, characterized in that the angle between the planes respectively defined by the axes A and C on the one hand and C and G on the other hand is about 90 °. 5. Armchair (1) according to one of the preceding claims, characterized in that the center distance DE is greater than or equal to the center distance AC. 6. Armchair (1) according to one of the preceding claims, characterized in that the distance between CD is less than or equal to the center distance BD. 10 7. Armchair (1) according to one of the preceding claims, characterized in that the center distance AE is greater than or equal to the center distance CD. 8. Armchair (1) according to one of the preceding claims, characterized in that the member (54) of return is a gas spring. 9. Armchair (1) according to claim 8, characterized in that the gas spring (54) is of the lock type. 10. Armchair (1) according to claim 8 or claim 9, characterized in that the gas spring (54) comprises a body (55) fixed on the frame (41) below, and a rod (57) fixed on the upper frame (34). 20