EP0373245B1 - Dental chair - Google Patents

Description

The invention relates to a dental patient chair with means for adjusting the seat height, the inclination of the seat and backrest and the position of the seat and backrest in the longitudinal direction of the chair.

In order to make the patient ergonomic and appropriate for treatment, i.e. To be able to position the patient in an optimally coordinated manner, both in relation to the practitioner and in relation to the treatment to be carried out, it is necessary for the parts, the seat and backrest forming the upper part of a patient chair, both in height and in the longitudinal direction of the chair, and beyond in their inclined position to be able to be adjusted relative to a vertical or horizontal reference plane. Various constructions are known for this.

Dental patient chairs are known from DE-29 38 330 and US Pat. No. 3,302,971, in which parallelogram support arms are provided for height adjustment of the seat. In the patient chair according to US Pat. No. 3,302,971, the parallelogram support arm formed from two link arms is articulated on the one hand on the chair base and on the other hand on a box connected to the seat. The box contains an adjustment drive in the form of a hydraulic piston / cylinder arrangement, one end of which is articulated on the lower link arm of the parallelogram support arm and the other end of which is articulated on the box. The seat in this patient chair is also articulated to the upper link arms via small connecting rods so that an upward movement (height adjustment of the seat) simultaneously causes a progressive inclination movement of the seat to the rear.

A relatively large stroke can indeed be achieved with the known parallelogram support arm constructions; it is disadvantageous, however, that additional means must be provided in order to achieve the above-mentioned longitudinal adjustability of the upper part of the chair. Such additional means for longitudinal adjustability can, as disclosed for example in DE-22 26 572, be a straight guide with a roll-out curve for simultaneously lifting the end of the upper part of the chair.

From DE-2 746 630 an electrical control circuit for adjusting the position of a dental treatment chair is known, in which the actuators, which are provided, for example, for height adjustment of the seat or an inclination adjustment of the backrest, are coupled to an actual value transmitter and in which a setpoint is specified corresponding setpoint generators are available. A digital control circuit with a digital memory as setpoint generator and a digital comparator is presented.

Also known are scissor arm constructions with scissor arms arranged in pairs in the opposite direction, one of which is guided in longitudinal guide elements for the longitudinal adjustment of the upper part of the chair (DE-32 28 834).

Although the last-mentioned scissor arm construction has proven itself very well and has the advantage of being more space-saving than previous known designs, this construction is also in relation to the requirement for less mechanical effort while improving the range of motion, in particular the height adjustment and longitudinal adjustability of the seat regarding, relatively narrow limits.

The invention specified in claim 1 is therefore based on the object of specifying a dental patient chair, the upper part of which can be created with less mechanical effort and also with less space requirement than before, it having to be taken into account that the ergonomic and treatment-related aspects mentioned at the outset correspond to the the versatile adjustment options of the chair required today.

A major advantage of the construction according to the invention is that for the adjustment of the upper part of the chair, according to the intended degrees of freedom, a construction which is relatively simple from a mechanical point of view is provided and does not require any longitudinal displacement elements. The mechanism provided according to the invention practically consists only of a fixed base part, two articulated arms, three drive motors, control electronics and a patient bed forming the upper part of the chair. This can be made in one or more parts. Both electromotive and hydraulic drives can be used as adjusting drives.

Further advantageous refinements and developments of the invention can be found in the subclaims and in the exemplary embodiments described below.

• Figur 1 eine erste Ausführungsform eines zahnärztlichen Patientenstuhles nach der Erfindung in Seitenansicht,
• Figur 2 die Steuerung der Verstellantriebe in einer Prinzipdarstellung,
• Figur 3 den Aufbau der Verstellmechanik für das Stuhloberteil in perspektivischer Darstellung,
• Figur 4 eine Variante zu der in Figur 1 dargestellten Ausführung,
• Figur 5 eine weitere Variante,
• Figur 6 die in Figur 5 gezeigte Ausführung in einer um 90° gedrehten Darstellung,
• Figur 7 eine weitere Variante einer Verstellmechanik für das Stuhloberteil,
• Figur 8 den mit der erfindungsgemäßen Verstellmechanik erzielbaren Verstellbereich in einer Prinzipdarstellung.
• Figur 9 den Geschwindigkeitsverlauf einerseits eines Gelenkpunktes des Stuhloberteils und andererseits der einzelnen Verstellmotoren.
• Figur 10 ein Blockschaltbild zur Darstellung des Steuerungsablaufes.

Show it:

• 1 shows a first embodiment of a dental patient chair according to the invention in side view,
• FIG. 2 shows the control of the adjustment drives in a basic illustration,
• FIG. 3 shows the structure of the adjustment mechanism for the upper part of the chair in a perspective view,
• FIG. 4 shows a variant of the embodiment shown in FIG. 1,
• FIG. 5 shows a further variant,
• FIG. 6 shows the embodiment shown in FIG. 5 in a representation rotated by 90 °,
• FIG. 7 another variant of an adjustment mechanism for the upper part of the chair,
• Figure 8 shows the adjustment range achievable with the adjustment mechanism according to the invention in a schematic diagram.
• FIG. 9 shows the speed profile on the one hand of a hinge point of the upper part of the chair and on the other hand of the individual adjustment motors.
• Figure 10 is a block diagram showing the control process.

FIG. 1 shows a basic illustration of a dental patient chair in a side view. The chair upper part 1 shown here as a one-piece patient couch, which consists of the seat 2 and backrest 3 in a known manner, is carried by an adjustment mechanism, generally designated 4, which is supported on a standing level (floor), designated 5. The adjustment mechanism 4 is such that the upper chair part 1 can perform a height adjustment according to the arrows 6, an inclination of the backrest according to the arrows 7 and a longitudinal displacement of the entire upper chair part according to the arrows 8.

The adjustment mechanism 4 consists of two articulated arms 9, 10 which are articulated to one another at the articulation point 11 and whose free ends on the one hand via an articulation point 12 with a rigid attachment part 13 of the chair upper part 1 and on the other hand at the articulation point 14 with a fixed one on the standing level 5 Base part 15 is articulated.

The two articulated arms 9, 10 can be adjusted with the aid of three adjustment drives 16, 17, 18 so that the upper part of the chair can be moved in the direction of arrows 6, 7 and 8. The adjusting drives 16, 17 and 18 are advantageously spindle drives, the motors M1, M2 and M3 of which, as shown in simplified form in FIG. 2, are controlled by a control device 20 which will be explained in more detail later. The control can take place in a known manner either via program selection keys 19 or with the aid of individual keys 21, 22, 23, which are combined, for example, in a keypad 24 arranged on the chair back 3.

In the exemplary embodiment shown, the spindle drive 16 is connected to the electric motor M1 on the one hand via a joint 25 to the articulated arm 9 and on the other hand by means of a joint 26 to an attachment part 27 fastened to the seat 2. The adjustment drive 17 with the adjustment motor M2 is connected analogously to the adjustment drive 16 on the one hand by means of joint 28 to the articulated arm 10 and on the other hand by means of joint 29 to an extension 30 of the articulated arm 9. Finally, the adjustment drive 18 is by means of a joint 31 with an elevated base 34 of the base part 15 and connected to an extension 33 of the articulated arm 10 by means of joint 32. Although this arrangement of the adjustment drives has proven to be advantageous, other arrangements are also conceivable within the scope of the invention, for example an arrangement in which the adjustment drive 17 does not act between the articulated arms 9 and 10, but between the base 34 and articulated arm 9, or at which the adjustment drive 16 does not engage between the seat and the articulated arm 9, but between the seat and the base 34 or between the seat and the articulated arm 10.

It is understandable that in the construction shown, the three adjustment motors M1, M2 and M3 must be precisely controlled in order to achieve a harmonious movement of the patient chair in the direction of the three arrows 6, 7 and 8. If, for example, the upper part of the chair is only adjusted in height, ie only in the direction of the arrows 6, it is not sufficient to activate only one adjustment drive; rather, all three adjustment motors have to be controlled here. The control is carried out with the aid of the control device 20 shown in FIGS. 2 and 10, which contains a microprocessor which receives information about the respective actual position of the relevant chair parts via position transmitters G1, G2 and G3 and which accordingly adjusts the adjusting motors M1, M2 and M3 the desired adjustment. The transmitters G1 to G3, which indicate the respective position of the relevant articulated arm or chair part to the control device 20, can be of an electrical, optical or optoelectronic type and can be arranged either on the drives themselves or at the articulation points of the articulated arms.

If hydraulic lifting cylinders are used, as indicated in the embodiment according to FIG. 7, the lifting cylinders would be controlled by the control unit 20 via electromagnetic valves.

FIG. 3 shows the patient chair according to FIG. 1 in a perspective view obliquely from the front in a raised position.

The two articulated arms 9, 10 each consist of two spaced-apart side cheeks 9a, 9b; 10a, 10b, which practically form a U-shaped part through cross-connecting struts 9c, 10c. It can be seen from the illustration that the side cheeks 10a, 10b do not run parallel to one another, but are at a smaller distance from the joint point 11 than from the joint point 14. The distance A of the joints 11 is thus smaller than the distance B of the joints 14. The same also applies to the articulated arm 9, the side cheeks 9a, 9b of which lie within that of the articulated arm 10. This reduction in the distances in the area of the connecting joint 11 results in a constriction which creates additional space in this area for accommodating other components. E.g. the free space thus obtained can be used to accommodate a sliding track or to hold a device (doctor's or assistant's device).

It has proven to be particularly advantageous if the base part 15, as shown, has a stand base 34 which is arranged such that the joints 14, on which the one ends of the articulated arm 10 are articulated, are arranged adjacent to the foot end of the chair, namely at a height C (FIG. 1), which corresponds approximately to the length D of the articulated arm 10 articulated there. This height is expediently about 300 mm above the level 5. The two articulated arms 9, 10 are expediently of the same length; however, this is not absolutely necessary.

In the embodiment shown so far, spindle drives are used in which the spindle is moved in and out of the spindle drive part. In the shown in Figure 4 Variant, which corresponds to the construction of the base and the articulated arms of the embodiment shown in Figures 1 and 3, the drive parts on the motors flanged spur gears that drive the spindles. Worm or toothed belt gears can also be used instead of the helical geared motors. With regard to the arrangement of the adjustment drives, what has already been said about the embodiment according to FIG. 1 applies, ie for structural or other reasons the articulation points of the adjustment drives can also be selected differently than shown. It is also conceivable to reverse the linkage of the gear and spindle, as shown.

The exemplary embodiment according to FIGS. 5 and 6 differs from the previously described embodiments in that instead of the spindle drives, electric or hydraulic motors with very high reduction gears, for example planetary gears, are provided and these drives are arranged coaxially at the articulation points of the articulated arms and thus drive them directly . In this exemplary embodiment, too, two independently movable articulated arms 36, 37 are present on a stand base 35, which corresponds to that designated by 34 in FIG. 1, one end of which is interconnected by means of an articulation 38 and the other end of which is articulated by means of joints 39 to the base 35 and on the other hand, are articulated by means of joints 40 to an extension 41 of the upper part of the chair. At all three articulation points 38, 39, 40, adjustment drives with adjustment motors 42, 43 and 44 are provided. Low-voltage direct current motors are preferably used as adjusting motors, which, as shown in simplified form in FIG. 2, are controlled independently of one another. The engine speeds are reduced to the "effective speed" of the parts to be adjusted (articulated arms and seat frame or articulated arm and base) with the help of suitable ones Gear components, which are designated in Figures 5 and 6 with 45, 46 and 47. Such gears can be, for example, planetary gears. The torque transmission takes place in the illustrated embodiment in that the gear components are rotatably connected to the chair base 35, the articulated arm 36 and shoulder 41 and the drive shaft of the gear is rotatably connected to the articulated axes 38, 39 and 40 of the articulated arms 36, 37.

The arrangement of the drive units (motor and transmission), as shown in dashed lines in FIG. 6, can be provided both inside and outside the articulated arms. An arrangement of the drive unit within the articulated arms has the advantage that the output can take place on both sides, whereby a better torsional rigidity of the articulated arms is achieved.

The height adjustment of the seat in the embodiment presented is largely carried out by pivoting the articulated arm 36 around the axle bearing 39; the longitudinal adjustment is primarily carried out by pivoting the second pivot arm 37 around the axle bearing 38. However, with exact height adjustment or longitudinal displacement, a combination of both movements will result, which is determined by control unit 20 (FIG. 2) in accordance with the position of the position transmitter.

In Figure 6, which shows the chair in a rear view corresponding to the arrow in Figure 5, the different joint distances A, B, which the side cheeks of the articulated arms have, can be seen very clearly, as a result of which the aforementioned constriction at the joint joint (11 in 3 and 38 in Fig. 5) results.

Finally, FIG. 7 shows an embodiment which does not require any electronic control of the adjustment drives compared to those described so far, but which does not require such an exact movement sequence guaranteed like the previously described embodiments. In this embodiment, the articulated arms consist of parallelogram linkage arms 48, 49, one articulated axis of which is articulated to a common connecting part 50 and the other ends of which are articulated to a base 51 via articulations 57 and to a support part 52 via articulations 58, to which the articulation 53 is used Chair top 1 is articulated. The one parallelogram linkage 49 is used in this version mainly for height adjustment of the upper part of the chair, while the parallelogram linkage 48 is used for adjusting the chair in the longitudinal direction of the chair. The adjustment drives used are electromotive or, as shown in the figure, hydraulic adjustment drives 54 to 56.

In contrast to the above-described embodiments, electronic regulation can be dispensed with here; however, the linear motion sequence is then not as optimal as in the previously described embodiments.

After the mechanical structure of the chair has been described in various variants, the following figures explain the sequence of movements of the upper part of the chair and the control of the adjustment drives.

FIG. 8 first shows the possibility of movement offered by the chair base mechanism according to the invention.

The curve labeled 60 shows the envelope curve within which movement of the upper part of the chair is possible on the basis of the double articulated arm construction explained. For the sake of simplicity, this envelope curve 60 is shown for the articulation point 12. The strongly bordered curve 60a within the envelope curve 60 represents the adjustment range that can be used in practice. In the following consideration it is assumed that the articulation point 12 (representative of a any other point of the upper part of the chair) from the starting position P₀ (with the coordinates x₀, y₀) to the position P₁ (with the coordinates x₁, y₁) is to be brought. The position P 1 is represented, for example, by the program P 1, which can be called up with one of the program selection buttons 19. In order to bring the upper part of the chair from the reference point P₀ to the point P₁, this would have to be carried out both upwards and forwards (towards the foot end).

Before the control process is explained, the control unit 20 is first described in more detail with reference to FIG. 10. The control unit contains a central processor 61 (CPU) to which the switches 21 to 23 for manual adjustment of the upper part of the chair and on the other hand the program selection buttons 19 for automatic adjustment of the upper part of the chair are connected to one of the three freely selectable chair positions P 1 to P 3 to the serial interfaces 63 are. At the CPU, the transducers G₁ to G₃ with the interposition of A / D converters 64 and the adjustment motors M1 to M3 with the interposition of A / D converters 65 and servo units 66, which include a power output stage for the motor with control circuit, are also connected. With 67 the work program for the CPU is designated, with 68 the memory for the programs P₁ to P₃.

At the starting or reference point P₀ the electronics of the control unit 20 asks which actual values the sensors G₁ to G₃ have. From this information, the processor 61 then calculates the coordinates (x₀, y₀) of P₀. Then the processor calculates the shortest distance (S₁ in Fig. 8) between the starting point and the selected point P₁ with the coordinates x₁ and y1.

The movement of the upper part of the chair, when it is adjusted from the starting point P₀ to the selected position point P₁, should not take place uniformly, but instead according to a certain curve with a linear increase at the beginning of the movement and with linear drop towards the end of the movement. Advantageously, the movement transitions are smooth, which results in a so-called ramp curve, as shown in FIG. 9 above. According to such a ramp curve, there is a gentle increase over a certain first time period a, a uniform rise over a certain second time period b, and a gentle decay of the movement over a third time period c (until the selected position is reached). With such a sequence curve, it is necessary that the individual adjusting motors M1 to M3 show different speed behavior over the relevant running time (t). Such a speed behavior for the three motors M1 to M3 is shown in the V / t diagrams in FIG. 9 below the flow curve shown. In order to get a relatively smooth start in the adjustment movement of the upper part of the chair at the beginning of the movement (corresponding to section a) of the flow curve in FIG. 9), it may be necessary, for example, to keep the speed of the adjustment motor M1 very low during this time period during the Actuator M2 is immediately driven at a relatively high speed. It can also be advantageous in the phase-out phase (section c)) that the adjusting motor M3 runs at a negative speed, ie in the opposite direction of rotation.

The computer of the central processor 61 calculates the individual V / t diagrams for the individual motors M1 to M3 on the basis of the specified flow curve. The voltages required to achieve the speed values in accordance with the predefined curve are supplied to the adjusting motors M1 to M3 via the power output stages 66. In order to achieve the most accurate adherence to the trajectory, control loops are preferably provided which control and, if necessary, correct the curve values by constantly querying the values of the transmitters G1 to G3 and comparing them with the target values.

Claims (12)

1. Dental patient's chair with means for adjusting the height of the seat, the position of inclination of the seat and backrest as well as the position of the seat and backrest with respect to the longitudinal direction of the chair, in which two articulated arms (9, 10; 36, 37; 48, 49) connected to one another in an articulated manner are provided, the free ends of which are hinged on one side to the seat (2) or to a support (52) for the seat (2) and on the other side to a stationary base (34, 35, 51) which is raised in relation to a stationary plane, characterized in that to adjust the articulated arms (9, 10; 36, 37; 48, 49) three separately controllable adjusting drives (16, 17, 18; 42, 43, 44; 54, 55, 56) are provided, with the three adjusting drives being arranged in such a way that the first one adjusts the lower articulated arm (10, 36, 49) relative to the stationary base (34, 35, 51), the second one adjusts the upper articulated arm (9, 37, 48) relative to the lower articulated arm (10, 36, 49) and the third one adjusts the seat (2) relative to the upper articulated arm (9, 37, 48), and in that a control device (20) is present, which controls the three adjusting drives in the sense of an alteration of a chair position.
2. Dental patient's chair according to claim 1, characterized in that the first adjusting drive (18, 42, 54) is hinged between the lower articulated arm (10, 36, 49) and the fixed stationary base (34, 35, 51), the second adjusting drive (17, 43, 55) is hinged between the two articulated arms and the third adjusting drive (16, 44, 56) is hinged between the seat (2) and the upper articulated arm (9, 37, 48) hinged to the seat.
3. Dental patient's chair according to claim 1 or 2, characterized in that the two articulated arms (9, 10; 36, 37; 48, 49) are arranged in such a way that the stationary base (34, 35, 51) with the connection joints (14, 39, 57) of the one articulated arm (10, 37, 49) is located nearer to the foot end of the seat than the common moving joint (11, 38, 50) of the two articulated arms.
4. Dental patient's chair according to one of claims 1 to 3, characterized in that the vertical distance (C) of the moving joint (14, 39, 57) of the one articulated arm (10, 36, 49) on the stationary base (34, 35, 51) from the stationary plane (5) corresponds approximately with the length (D) of the articulated arm (10, 36, 49) hinged thereto.
5. Dental patient's chair according to one of claims 1 to 4, characterized in that the articulated arms (9, 10; 36, 37) are constructed in a U-shape and in this way form side walls (9a, 9b; 10a, 10b) in each case spaced apart from one another and connected to one another by transverse connection elements (9c, 10c) and that at least the one articulated arm (10) forms a constriction towards the common moving joint (11), in that the joint distance (A) of the side walls to one another is smaller at the common moving joint (11) than the joint distance (B) of the side walls at the opposite moving joint (14).
6. Dental patient's chair according to one of claims 1 to 5, characterized in that the two articulated arms (48, 49) comprise a parallelogram linkage in each case.
7. Dental patient's chair according to one of claims 1 to 6, characterized in that electromotor drives (16 to 18, 42 to 44) are provided.
8. Dental patient's chair according to claim 7, characterized in that the drives (42 to 44) are arranged directly on the moving joints, to which the two articulated arms are hinged on one side to one another and on the other side to the seat and stationary base.
9. Dental patient's chair according to claim 7, characterized in that spindle drive motors with flange-connected reduction gears are provided.
10. Dental patient's chair according to one of claims 1 to 9, characterized in that the control unit (20) contains a central processor (CPU), to which position sensors (G₁ to G₃) are attached, which supply the CPU (61) with information on the starting position (actual value) of the adjusting drives (M₁ to M₃) or the parts of the chair to be adjusted, in that in the CPU (61) the coordinates (x₀, y₀) associated with the starting position (P₀) are calculated, in that in accordance with a selection of a position (P₁, P₂, P₃), preferably selectable by means of a program selector key (19), the coordinates (x₁, y₁) of the selected position are taken up in the CPU (61), in that the CPU (61) determines with the aid of the coordinate information the distance (S₁) between the starting position (P₀) and the selected position (P₁) and thereafter controls the adjusting drives (M₁ to M₃) attached thereto according to a predetermined sequence curve (Figure 9).
11. Dental patient's chair according to claim 10, characterized in that the sequence curve contains a rising function having a linear acceleration at the beginning of the movement, subsequently a uniform movement and towards the end of the movement a decelerating function with linear retardation.
12. Dental patient's chair according to claim 11, characterized in that the sequence curve is defined like a ramp with softly rising function at the beginning of the adjusting movement and softly falling function at the end of the adjusting movement.

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