EP3108867A1

EP3108867A1 - Dental patient chair

Info

Publication number: EP3108867A1
Application number: EP16175492.4A
Authority: EP
Inventors: Giulio Mattiuzzo
Original assignee: Cefla SCARL
Current assignee: Cefla SCARL
Priority date: 2015-06-23
Filing date: 2016-06-21
Publication date: 2016-12-28
Anticipated expiration: 2036-06-21
Also published as: CN106264962A; EP3108867B1; CN106264962B

Abstract

Mechanism for moving reclining chairs (1), preferably dental patient chairs, comprising a backrest (2) and a seat (3) moving relative to each other, and wherein said backrest is supported by an oscillating mechanism, further comprising:
- at least a cam (14) having a pre-set curvilinear contour; said cam supports said seat and is at least oscillating around an axis substantially corresponding to an oscillating axis of the seat;
- at least a carriage, a slide or similar elements (12);
- at least a leading hole (11) for said carriage (12);
characterized in that
said leading hole (11) extends substantially in the direction of the contour of said cam, and said carriage (12) has cooperating means with the contour of said cam (14), while said carriage (12) is slidingly actuated by the oscillating mechanism of the backrest, so that when said carriage (12) slides inside said leading hole (11) thanks to an actuating system, said carriage (12), interfering with cam's (14) contour, commands at least an oscillatory movement controlled by the contour of the cam (14) itself.

Description

The present invention refers to the technical field of dental patient chairs. More particularly, the invention refers to an apparatus and a method allowing the movement of said chair, through a mechanism making use of a cam and a rounded hole inside which a carriage slides, with a carriage actuating said cam, according to the preamble of claim 1.
In the history of dentistry, at least until 1960, dentists used to work standing, while today dentists use to work sitting. Dental unit manufacturers strive to provide dental treatment units allowing dentists to work ergonomically, i.e. comfortably and without damaging their musculoskeletal system while providing dental therapy.
At the same time, dental patient chairs must be comfortable for patients: a patient feeling comfortable is more relaxed, and for dentists working is easier.
Moreover, generally dental patient chairs should allow to support the patient in the so-called Trendelemburg position. The Trendelemburg position, or anti-shock position, is the position in which the patient must lie in case of shock, or during the performance of special exams. The patient is supine, lying so that her/his head is lower than her/his knees and her/his pelvis.
Dental patient chairs have been industrially manufactured for more than 100 years; patent regarding dental patient chairs are e.g. EP0477762 of Pelton & Crane , EP0253943 of Castellini , US4173372 of Reynolds .
The above-quoted patents, with many others, describe the internal structure of the chair allowing the movement of the chair itself. As a matter of fact, typically dental patient chairs allow a position wherein the backrest forms an angle of about 90° with respect to floor (upright position), and a position wherein the backrest is parallel to floor (reclined position), and all the positions intermediate between these two extreme positions. These chair positions are obtained through a wide variety of relatively complex mechanisms and actuators. Moreover, in order to modify the laws of relative motion between backrest and seat, the interventions for replacing or modifying parts of said mechanism are complex and time-consuming, as they require the access and disassembly of a considerable number of parts of the kinematic chain of articulation between backrest and seat.
DE202011109649U discloses a chair according to the preamble of claim 1. A treatment chair (1) is disclosed comprising a seat surface (2), a backrest (3), a base (4) and an adjusting system (7). The adjustment system comprises a first guide rail (8) in the form of a first leading hole or slot and at least one second guide track (9) also in the form of a leading hole or slot. A guide pin (10) engages both first and second slots. The first slot (8) and the second slot (9) are arranged to one another such that upon adjustment of the adjusting system (7) between a first end position (16) and a second end position (17) of the guide bolt (10) the seat surface (2) is adjusted relative to the backrest (3). The seat surface cannot be freely raised from the adjustment mechanism and access to the said mechanism is not allowed by simply oscillating upward the seat surface. On the contrary in order to take away the seat surface for allowing access to the mechanism the seat has to be disassembled from the mechanism or the mechanism has to be accessed from another side.
Aim of the present invention is providing a mechanism allowing to position the back rest from the upright position to the reclined position and vice versa, which is efficient and inexpensive to produce. Moreover, the mechanism produces a coordinated movement with the seat, swinging until a position ergonomically correct for the patient is reached; in case of need, the chair can swing up to Trendelemburg position.
A further aim is the possibility of varying in a simple and effective way the geometric law operating this movement: changing the geometry of the cam, the movement itself can be accelerated or decelerated, or anyway modified as desired.
A further aim is allowing to reach special positions of the patient, with pre-set angles between patient's trunk and legs.
These objects are achieved by an apparatus and a method having the features of the independent claims. Advantageous embodiment and refinements are specified in the claims dependent thereon.
The advantages of the present invention are that the present invention consists in a mechanism having a particularly simple construction, making use of a single actuator, which does not require special tools for its production, in that moulds are not necessary, but the simple shaping of parts obtained from elements made of metal sheet is sufficient.
In a preferred embodiment, the simplified mechanism of the present invention makes use of a minimal number of components, which are reduced to six. Said components are two by two the same component, mounted in a symmetric position, therefore the components to be produced are only three. As a comparison, today known patient chairs comprise at least ten symmetrical components, which therefore have to be produced in left and right version, therefore the components to be produced are at least twenty.
By providing a cam which oscillates around an horizontal axis which is transversal to the longitudinal axis of the chair, and which cam is not linked or locked to the rest of the adjusting mechanism and specifically to the cooperating carriage, the seat can easily be raised up with an oscillating mechanism allowing access to the said mechanism in a very simple and rapid manner similarly to a car hood.
Accessing the adjusting mechanism and the cam being linked to the said mechanism only though the axis of oscillation allows to change very easily the cam in order to change the geometry of the adjusting system and the relation between the position of the back rest relatively to the corresponding position of the seat when displacing the back rest from an upright to an inclined position or vice versa.
According to an embodiment the cam cooperates with the carriage by being urged with its surface against the cooperating means of the carriage by gravity.
Further advantages and properties of the present invention are disclosed in the following description, in which exemplary embodiments of the present invention are explained in detail based on the drawings:

Figure 1: Axonometric view of a patient dental chair in a reclined position;
Figure 2: Axonometric view of a patient dental chair in an upright position, wherein the upholstery was removed;
Figure 3: Axonometric view of a dental patient chair in a totally reclined position (Trendelemburg), wherein the upholstery was removed;
Figure 4A: Side view of a dental patient chair in an upright position;
Figure 4B: Side view according to figure 4A in which the cam is highlighted;
Figure 5A: Side view of a section of the chair in a reclined position;
Figure 5B: Side view according to figure 5A in which the cam is highlighted;
Figure 6A: Schematic view of a patient in isoweight position;
Figure 6B: Schematic view of a patient in a tilted position.

Figure 1 shows a typical dental chair comprising a back rest 2, a seat 3, a base 4 and a pantograph arm 5. The pantograph arm 5 allows the rise and descent of the seat 3, indicatively from a height of 360 mm to 840 mm. The top end of the pantograph arm is a sort of turret supporting the mechanism for the reclining of backrest and the mechanism for the coordinated movement of the seat. The chair 1 is shown with reclined backrest, nearly parallel to the floor.
Figure 2 shows the same chair 1 in an upright position, with the backrest 2 at about 70° with respect to the floor, and the seat 3 at about 12° with respect to the floor. The upholstery was removed from the seat 3, so as to show the internal mechanism allowing the movements of the chair.
Figure 3 shows the same chair completely reclined in Trendelemburg position, with the backrest 2 nearly parallel to the floor, and the seat 3 positioned to slightly rise patient's legs with respect to patient's head. From the seat 3 the upholstery was removed, so as to show the internal mechanism allowing the movements of the chair.
In Figures 2 and 3 the support 6 of the upholstery and the motoreducer 7 are apparent.
Figures 4A and 4B show in section the dental chair 1 in the same position of Figure 2, so as to clarify the operation of the movement mechanism. Figures 4A and 4B shows the starting point of the movement leading to the reclining of backrest 2.
Actuating the motoreducer 7, the rotation movement of an arch 8 is started along the hole or slot 11 through a carriage 12. Alternatively, the carriage can be made of other sliding elements lead along the slot 11, like e.g. slides or similar elements. Integral with said arch 8 through a transversal shaft, a wheel 9 engages a cam 14 present in the rising plate 10, which, having its fulcrum in the axis 13, starts to rise vertically moving the seat support 6. It is worth noting that the two cams 14 are mounted on the external sides of the frame element supporting the backrest reclining mechanism, and that each of them is simply inserted with a supporting hole on a supporting shaft, which is stationary and integral to said frame element, which is indeed the axis of fulcrum 13. This construction ensures a very simple and direct access to the cam 14, and the possibility of its fast replacement.
Other alternatives can be realizing cam 14 in two parts, a supporting frame which has its steady fulcrum in the axis 13, and to which a part supporting the edge contoured according to the law of motion is releasably fixed. In this way, the law of motion can be modified simply by replacing the contoured part, e.g. disassembling the seat and manually uplifting the cam 14 in order to work on the fixing of the moveable contour part to the steady part.
In this way, not only adjustments, but also possible maintenance and reconditioning are easy.
Figures 5A and 5B show a section of dental chair 1 in the same position of Figure 3. Figures 5A and 5B show the movement of wheel 9 which is now in its end-of-stroke position, so leading to the rise of support 6 supporting the upholstery.
It is apparent that the extension of the rising angle and the dynamic law through which the rising occurs depend on the geometric shape of a cam 14 present on the lower side of the rising plate 10. Varying the cam radius and its centre (in case of a circular cam), the width of the rising angle of the seat and the speed with which the rising occurs can be varied. Designing cams with different geometric shapes (ellipses, parabolas, hyperboles) the acceleration and the rising mode of the backrest are varied.
In the embodiment shown here, the movement of the backrest 2 and of the seat 3 occur in a coordinated way, so that when the backrest descends, the angle between patient's trunk and legs progressively increases approximately from 95° to 180°.
In a (not shown) alternative embodiment, the design of the cam has a geometric shape such as to link specific positions of the backrest to specific inclinations of the seat, leading to the possibility of reaching patient's positions wherein:

Approximately, patient's trunk is at 25° with respect to floor, while patient's thighs are perpendicular to floor, and her/his calves are parallel to floor; the angle between patient's trunk and thighs is 130°. In this position, patient's weight is homogenously distributed (isoweight, maximal comfort position); the position of the patient is schematically shown in Figure 6A.
Patient's trunk is in an optimal position for the dentist, while the seat keeps the relative angle steady with respect to the backrest. The angle between patient's trunk and thighs is approximately 105-120° (tilting position); the patient's position is schematically shown in Figure 6B.

In other words, the angle between patient's trunk and thighs can be kept in the range of 95-130°, but the patient is reclined, with her/his head at a height suitable for dentist's work. This position is very comfortable for the patient, who can homogenously distribute her/his weight, and at the same time ergonomic for the dentist.
In a further (not shown embodiment) the cam can be designed so that the final point of the completely reclined position brings the patient to a position perfectly horizontal to the floor (patient table).
From all the above, one can appreciate that in the chair according to the present invention the relationship between movement of the backrest and movement of the seat affects in a nearly intuitive and direct way the shape of the cam contour, and therefore the design of the coordinated movements of backrest and seat is a relatively direct operation.

1.: Dental patient chair
2.: Backrest
3.: Seat
4.: Chair base
5.: Pantograph arm
6.: Upholstery support
7.: Motoreducer
8.: Arch
9.: Wheel
10.: Rising plate
11.: Hole or slot
12.: Carriage
13.: Axis
14.: Cam

Claims

Mechanism for moving reclining chairs (1), preferably dental patient chairs, comprising a backrest (2) and a seat (3) moving relative to each other, and wherein said backrest is supported by an oscillating mechanism, further comprising:
- at least a cam (14) having a pre-set curvilinear contour; said cam supports said seat and is at least oscillating around an axis substantially corresponding to an oscillating axis of the seat;

- at least a carriage or a slide (12);

- at least a leading hole or slot (11) for said carriage (12);
characterized in that
said leading hole or slot (11) extends substantially in the direction of the contour of said cam,
said carriage (12) has cooperating means with the contour of said cam (14);
while said carriage (12) is slidingly actuated by the oscillating mechanism of the backrest, so that when said carriage (12) slides inside said leading hole or said slot (11) thanks to an actuating system, said carriage (12), interfering with cam's (14) contour, commands at least an oscillatory movement controlled by the contour of the cam (14) itself and
said cam being freely displaceable by oscillation form a position in which it cooperatively interferes with the said cooperating means of the carriage (12) in a position in which the cam (14) is at a distance from the said cooperating means.
Mechanism for moving reclining chairs (1) according to claim 1, wherein said cam (14), carriage (12) and said hole or slot (11) can be produced by sheet stamping in a single version and mounted preferably two by two, or in a higher number according to need.
Mechanism for moving reclining chairs (1) according to claim 1, wherein said cam (14), carriage (12), and said hole or slot (11) can be produced in a single version and mounted, keeping the specific contour realized in right and left version.
Mechanism for moving reclining chairs (1) according to claim 1 to 3, wherein said cam (14) has an arc of a circle, or elliptic, or parabolic, or hyperbolic, or linear contour, or a combination of the preceding.
Mechanism for moving reclining chairs (1) according to one of the preceding claims, wherein said cam (14) has a discontinuous or undulated contour with convexities and concavities, so that the patient is brought in a position in which the patient is substantially parallel to the floor (Trendelemburg), and successively in a position wherein the patient has her/his head at the height desired by her/his dentist, but patient's trunk forms an angle comprised between 105° and 130° with respect to her/his thighs (maximal comfort position, tilting position).
Mechanism for moving reclining chairs (1) according to claim 1 to 3, wherein the shape of cam (14) allows to bring the patient in a position perfectly parallel to the floor, like on a patient's table.
Mechanism for moving reclining chairs (1) according to one of the preceding claims, wherein the actuating system is chosen from the group consisting of: at least one motoreducer (7), a hydraulic and/or pneumatic and/or manual system.
Mechanism according to one or more of the preceding claims, characterized in that the cam or the two cams is/are mounted outside of a supporting central turret, each on an oscillating axis on the corresponding side of said turret, said axes being coaxial to each other.
Mechanism according to one or more of the preceding claims, characterized in that said cam or cams are made of substantially flat plates, shaped correspondingly to cam contour, and are replaceable from the outside of the chair supporting mechanism through other cams having different contours, in order to modify the laws of motion between backrest and seat.
Method for moving the backrest (2) and the seat (3) of reclining chairs (1) one relative to each other, preferably of dental patient chairs, making use of a mechanism according to claims 1 to 9, wherein the possibility of movement of backrest and seat depend on the geometric shape of cam (14).