EP0491085B1 - Dentist's chair - Google Patents

Description

The invention relates to a dental patient chair, according to the preamble of claim 1.

In dental patient chairs, it is known to change the support parts, such as seat, backrest, headrest, in accordance with the required treatment positions with the aid of suitable adjusting means, which can be mechanical, electromechanical or hydraulic. Such an adjustment can change both their position relative to one another and relative to fixed reference planes such as wall, floor, chair base.

From DE-A-2 941 185 a dental treatment chair is known in which the aim is to automatically convert the pivoting movement of the backrest into a horizontal adjustment of the seat in such a way that a predetermined point of the headrest part remains at least approximately in the initial vertical plane after the pivoting movement . The seat, which is designed here as a parallelogram carrier and carries out a pivoting movement in the event of a height adjustment, is provided with a horizontal position control device for this purpose, which, if the backrest is pivoted upward through an angle, for example horizontally, then the seat is shifted longitudinally so far that the reference point in the vertical remains. This compensation is also achieved when the height is adjusted by means of the parallelogram carrier. The same applies if the backrest and seat are adjusted, whereby the reference point is only kept constant in the vertical.

It is also known to define common treatment positions using control programs, which control programs can be designed to be both fixed and individually changeable. A modern patient chair is usually equipped with three control programs that can be called up at the push of a button if required.

Although it is a relief for the practitioner (doctor and / or helper) to be able to call up and set the different treatment positions relatively easily at the push of a button, it is cumbersome for him, for example, when the backrest and / or the headrest are inclined during a treatment must be changed, the chair must be readjusted to the position previously set for optimal working posture. With such a change in the treatment position, the "mouth point" of the patient inevitably changes, that is to say a reference point which can be defined in the area of the preparation site of the patient's mouth, in relation to a horizontal and vertical reference plane, which has the consequence that the position of the practitioner and its equipment (instrument holders, trays, etc.) in the sense of an adaptation to the changed treatment position is necessary.

The same also applies to a change of patient, because the treatment position once set for optimal working conditions for a patient is no longer optimally suitable for another patient, who generally has a different body size, and must therefore be corrected.

The aim of the invention specified in claims 1 and 2 is to achieve an improvement and to create a dental patient chair in which the cumbersome correction and readjustment of a set chair position, especially when changing the treatment position and also when changing the patient or of the practitioner, is unnecessary.

According to the invention, it is possible to adjust the patient chair to an optimal "mouth point" aligned with the patient to be treated before starting the treatment. This optimally set "mouth point" is then retained even in the course of the treatment of changes in the inclination of the backrest and / or the headrest, which ultimately means that the practitioner does not need to change his working posture and also his facilities and equipment.

This can significantly simplify and improve work ergonomics.

Maintaining the optimally set "mouth point" is advantageously done by storing the position for the headrest part for the set "mouth point" as a setpoint and all changing the "mouth points" to the previously set by changing the angular position of the headrest part or the backrest "Mouth point" to be corrected. This correction advantageously takes place automatically during a change in the back or head support part, so that the patient's head is practically only rotated around the "mouth point".

As already mentioned, the "mouth point" is a reference point assigned to the head support part, which can lie, for example, on the bisector and half the length of the open mouth of a patient's head of average size, a so-called "normal patient's head". The reference point can be determined by adding from the plane defined by the coordinates of the headrest part an empirically determined value corresponding to the dimensions of a "standard patient head", which corresponds to the vertical distance of this point from the aforementioned plane.

The following considerations are used:
The position of a support part in space can be defined by planes of an x, y, z coordinate system. If one considers this coordinate system two-dimensionally (the third dimension is relatively insignificant for the patient positioning), then the position of a support part, simplified by a straight line with the help of two points or a point and an angular relationship, can be determined in the coordinate system. For example, the position of the backrest can be determined in relation to an arbitrarily selectable zero point of an x / y coordinate system are determined by the angle that the backrest makes with respect to a horizontal reference plane or by the x- / y-coordinates of two points lying on a straight line that run in the longitudinal plane of the backrest, the one (x-) coordinate being the distance to a vertical reference plane (wall, cabinet, appliance base) and the other (y-) coordinate indicates the distance to a horizontal reference plane (floor).

The "mouth point" can thus be precisely defined by the coordinates of an x / y coordinate system with respect to a vertical and horizontal reference plane. These coordinates can be saved as a setpoint in a computer and continuously compared with actual values. If the values deviate, the upper part of the chair is adjusted by height adjustment and / or longitudinal displacement in order to maintain the "mouth point" in accordance with the entered target value.

The set "mouth point" can advantageously be entered as a variable. If the "mouth point" is changed in the x direction, it is advantageously possible to adapt it to the equipment (cabinets) adjacent to the patient chair; if, on the other hand, the "mouth point" is only changed in the y direction, it is advantageously possible to adapt it to the size of the practitioner.

At this point it should be pointed out that the proposed change of the "mouth point" in the sense of an adaptation to the equipment and the body sizes of the practitioner and patient does not necessarily with the aforementioned retention of the "mouth point" when changing the inclination of the backrest and / or Head rest part needs to be coupled during a change of treatment, that this change in the "mouth point" is rather an advantage in itself.

In patient chairs with a relatively long backrest, in which the patient's head rests on the backrest itself, the headrest part can be designed as a longitudinally adjustable head cushion, corresponding position sensors being provided in the area of the headrest; It is also conceivable to provide position sensors on the backrest itself in the area of the headrest, e.g. in the form of pressure sensors responsive to the contact pressure of the patient's head, with the aid of which the position of the patient's head in relation to the backrest can be detected.

It is particularly advantageous to provide the headrest as a separate headrest, which is at least adjustable in the longitudinal direction relative to the backrest, and to provide corresponding position sensors between the headrest holder and the stationary backrest. The values detected by the position transmitters can correspond to the coordinate values in the already mentioned x / y coordinate system, which defines the position of the support part with respect to a horizontal and vertical reference plane.

Special advantages can be achieved if one or more storage systematics, which are defined by programs, are provided. With such a positioning system, such as that developed by the Institute of Industrial Sciences Darmstadt (see W.Rohmert / I.Mainzer / P.Zipp "The dentist in the field of ergonomics"), the individual chair positions can be set to a freely selectable reference height (y Coordinate), according to the selected working height or working size of the practitioner. If these values, which correspond to an optimally set "mouth point", are stored, then all programs of the proposed storage system are oriented towards this set, optimal "mouth point". When you call up any programmed treatment position, both the working height, ie the height of the reference point representing the "mouth point", as well as the distance in the horizontal to a vertical reference plane for all working positions. For another patient with a different body size, this optimal "mouth point" is maintained by adjusting the upper part of the chair to adjust the headrest to the other body size in the x and y directions.

• Figuren 1/2 eine erste Ausführungsform des erfindungsgemäßen Patientenstuhles in stark vereinfachter Darstellung in einer Seitenansicht,
• Figur 3 eine zweite Ausführungsform des erfindungsgemäßen Patientenstuhles, ebenfalls in stark vereinfachter Darstellung in einer Seitenansicht,
• Figur 4 die in Figur 3 gezeigte Ausführungsform in zwei verschiedenen Stellungen,
• Figur 5 ein Blockschaltbild einer Steuer- und Recheneinheit.

Further advantages result from the following description of exemplary embodiments of the invention. Show it:

• FIGS. 1/2 a first embodiment of the patient chair according to the invention in a greatly simplified representation in a side view,
• FIG. 3 shows a second embodiment of the patient chair according to the invention, likewise in a greatly simplified representation in a side view,
• FIG. 4 shows the embodiment shown in FIG. 3 in two different positions,
• Figure 5 is a block diagram of a control and computing unit.

1 shows, in a greatly simplified form, a dental treatment chair in a side view. The treatment chair contains a stationary base part 1, on which a chair upper part, generally designated 2, is held in a height-adjustable manner. The base part contains a base 1 a and a height-adjustable base part 1 b. The upper part 2 of the chair contains a support 3 which can be adjusted along the upper part 1b, on which the seat 4 and backrest 5 of the chair are held. There is also a headrest part on the backrest 5 6 arranged longitudinally (arrow 10). Corresponding controllable drives A1, A2 are provided in order to adjust the height of the chair part 2 and also in the longitudinal direction of the chair (arrows 7 and 8). The same applies to the backrest 5, the inclination of which can be changed in the direction of arrow 9 by a controllable drive A3. After the arrangement of the adjustment drives is known per se, it will not be shown in more detail. It should only be pointed out that both hydraulic and pneumatic, but preferably electrical, drives can be considered.

The adjustable chair parts are assigned position sensors G1 to G4, with which the respective actual position of the chair parts can be detected in relation to a horizontal and vertical reference plane. The sensors G1, G2 and G4 are linear displacement sensors, while the sensor G3 is designed as an angle sensor.

With the help of the position sensor, the position of the chair parts 2 to 6 can be related to an x- / y-coordinate system, its x-axis in a horizontal reference plane, preferably in the floor plane, and its y-axis in a vertical reference plane, preferably in Level of a room wall, to which the base part 1 has a defined distance (a), is clearly defined. For example, the position of the backrest 5 can be determined by the coordinates of two points P1, P2 which go through a straight line running along the backrest and / or by the angle of inclination α with respect to a reference plane.

M denotes the "mouth point" of a schematically represented "norm patient head" (H), whose position in the coordinate system is determined by the coordinates x _M , y _M. The "mouth point", which is to represent a reference point corresponding to the preparation site, can preferably be defined so that it is on the bisector between Upper jaw and lower jaw of an open patient's mouth and about half "mouth depth". From this "mouth point" there is a vertical distance (b) to the aforementioned plane of the backrest 5, which runs through the two points P1 and P2. The "mouth point" M can therefore be based on the dimensions of an empirically determined average patient head (standard patient head). can be clearly determined in an x / y coordinate system.

If the inclination of the backrest 5 is changed, e.g. brought into the position 5 'shown in dashed lines, the position of the "mouth point" M would inevitably change with respect to the coordinate system by the dimension Δx, Δy. As can be clearly seen from the comparison of the two positions M, M ', a change in the "mouth point" also means a change in the working posture of the practitioner. Using the exemplary embodiment, the practitioner would have to correct his working position and also the position of his devices and devices set to this working position by the dimension Δx and Δy.

According to a first proposal of the invention, this correction is avoided by, when the inclination of the backrest changes, the adjustment drives A1 and A2, which bring about the height adjustment and longitudinal displacement of the upper part of the chair, are adjusted synchronously in order to maintain or keep the "mouth point" constant. Further explanations are given in the description of the block diagram according to FIG. 5. The result of this synchronous adjustment is shown in Figure 2. From the starting position drawn with solid lines, which corresponds to the position shown in FIG. 1, the position shown in dash-dotted lines results in the case of a changed inclination of the backrest. So while the inclination of the backrest is changed, the upper part of the chair is synchronously lowered on the one hand by the dimension Δy and on the other hand by the dimension Δx to the reference plane y, So drove to the dentist without changing the "mouth point".

According to a further proposal of the invention, as further shown in FIG. 2, the “mouth point” M can be changed individually in the y direction, for example brought into the position indicated by y _M1 . Such a change advantageously allows adaptation to the height of the practitioner. If the "mouth point" is changed in the y direction, for example because the practitioner wants to change from a seated to a standing treatment position, the new new "mouth point" (y _M ), as previously described, are retained.

FIG. 3 shows a further advantageous variant of a patient chair. This differs from the previously described embodiment in that the headrest part 6 is designed as a separate headrest, which is adjustable in the direction of arrows 11 and 12 relative to the (shorter) backrest 5 and that the seat 4 and backrest 5 are still together in the direction the arrow 13 can be tilted relative to the carrier 3. Appropriate adjustment means A4, A5 and A6 as well as corresponding sensors G4, G5 and G6 are available accordingly. With the help of the sensors G4, G5, the position of the headrest relative to the backrest can be detected. The adjustment means A4 and A5 can be manually operated adjustment means; it is also conceivable and advantageous to provide electrical adjustment drives here as well. To adjust the headrest 6 in the direction of arrow 11, for example, an adjustment motor can be arranged in the interior of the backrest 5, which adjusts the headrest support (sword) designated by 14 via a toothed rack or the like.

The headrest 6, which can be adjusted along the backrest in accordance with the direction of the arrow 11, makes it possible to adapt the "mouth point" (M) to different patient sizes, by changing the headrest position for a patient with a different body size - here for a smaller patient according to the dashed line shown position (H ') - as described above, the chair upper part is corrected by the dimension Δx and Δy so that the "mouth point" M is maintained, whereby the practitioner does not need to change his working posture and also his associated instruments and devices.

FIG. 4 shows the chair according to FIG. 3 in two different chair positions, which can be typical for two different treatments. The first chair position shown in solid lines can be suitable, for example, for a seated practitioner and treatment of the lower jaw, while the second position shown in broken lines can be typical for treatment of a seated practitioner on the upper jaw. Both chair positions, advantageously determined by a control program, have a common "mouth point" M, which is retained during the transition from the first position indicated by solid lines to the second position shown in broken lines, which ultimately means that the patient's head merely changes during this change in the treatment position is rotated around the "mouth point" M.

The mode of operation and further advantages of the chair according to the invention are shown on the basis of the block diagram in FIG. 5, specifically using the example of the embodiments according to FIGS. 1 and 2.

As already explained, the chair in this embodiment has three controllable drives A1, A2 and A3, which are advantageously electromotive drives. The drives are powered by power amplifiers 20 and A / D converters 21 Central unit 22 (CPU) controlled. Corresponding sensors G1 to G4, e.g. in the form of potentiometers, are provided between the chair parts, which are adjustable relative to each other, i.e. between the base and upper part, between the base part and support, and between the seat and backrest and headrest, which, depending on their relative position, provide a signal corresponding to the adjustment path deliver the central unit 22. Corresponding to the three available controllable drives, switches S1 to S3 are available, which can be used to initiate height adjustment and longitudinal displacement of the upper part of the chair, as well as inclination of the backrest. The drives A1 to A3 are also controlled by the central unit 22 via a serial interface 23.

P1 to P _n denote program selection keys with which various chair programs can be called up from a program memory 24 via the serial interface 23 and the central unit 22. These programs can be programs that can be entered individually or also chair programs from storage systematics, in which certain dental treatments are assigned to certain dental positions according to an ergonomic scheme. Such a storage system is described, for example, in the article cited on page 5.

25 designates a memory in which the x / y values of the “mouth point” M can be stored as a setpoint. This stored target value can be corrected by an input unit 26 via the serial interface 23 in the central unit 22, as has been described with reference to FIG. 2 for adapting the height of the practitioner, by increasing the y value from an average value corresponding to an average size is changed below. This corrected value is shown on a display 27 and automatically taken into account when a chair program is called up using the program selection buttons P 1 to P _n .

By means of a selection button 28, the optimal "mouth point" can be called up either for a sitting treatment or for a standing treatment.

Advantageously, the control program, i.e. in the program memory 24, an antropometric table is taken into account, by means of which a "mouth point" corresponding to the size of the practitioner is specified for a standing or sitting treatment. However, this software specification is not fixed; rather, it can be expediently corrected individually by the practitioner, if desired, according to his personal wishes.

The work program of the central unit 22 is designated 29.

It is advantageous if the manufacturer of the patient chair already specifies various "mouth points" for certain treatments and sizes of practitioners and incorporates them into a corresponding program. These values can be changed by the clinician if necessary by overwriting the program.

If the practitioner wants to set the setpoint for a "mouth point" himself, this setting is done as follows:
If the patient has taken a seat in the chair, the practitioner will bring the chair into a position suitable for the treatment, in which the "mouth point", ie the center of the preparation site, lies in a working position that is favorable for him. If this position is reached, after a corresponding triggering process, the x / y value is entered as a target value into the memory 25 via the memory input key 30. The central unit 22 detects the values determined by the corresponding transmitters G1 to G4, angle values being processed accordingly in the arithmetic unit of the central unit.

If there is then a change of treatment location, e.g. initiated from the upper jaw to the lower jaw and vice versa and the backrest is changed in its inclined position, the resulting actual values of the sensors G1 to G3 in the central unit are compared with the target values from the memory 25, with deviations in the sense of a longitudinal displacement and height adjustment is changed so that the "mouth point" M is retained. If the inclination of the backrest changes, the height and longitudinal position of the upper part of the chair change synchronously with respect to the x / y planes.

If the practitioner changes his working position, e.g. from sitting to standing, or it turns out that a practitioner with a different height is working on the patient chair, he can consciously change the y-value of the "mouth point" through an act of will with the help of the input unit 26. With such a change in the "mouth point", all programs stored in the program memory 24 are then automatically corrected for this "mouth point".

As already mentioned, the position transmitter G4 can, if the head support part 6 rests on the backrest and can be displaced along this, be formed by suitable pressure-sensitive sensors which, depending on the contact pressure that the patient's head exerts on the head support part 6, one of the Transfer the appropriate size to the central unit.

Analogously to the above-described block diagram for the embodiment according to FIGS. 1 and 2, the control device also works for the embodiment shown in FIGS. 3 and 4, in which the headrest part 6 is designed as a separate headrest, which is adjustable along the backrest 5 and also about an axle bearing in the direction the arrow 12 is arranged tiltable, and in which the entire upper part of the chair relative to the Carrier part 3 is arranged tiltable. In this embodiment, the drives A4 to A6 are expediently also motor drives.

Claims (11)

1. Chair for dental patients, comprising
   a base part (1) on which an upper chair part (2) is supported in a height-adjustable and longitudinally displaceable manner, the upper chair part having a seat support part (4), back support part (5) and head support part (6) for the patient,
   adjusting means with controllable drives (A1, A2) at least for the height adjustment and longitudinal displacement of the upper chair part (2) as well as further adjusting means (A3) to adjust the position of inclination of the back support part (5),
   locators (G1 to G3) associated with the seat and back support parts (4, 5), which locators detect the respective actual position of the chair parts at least 2-dimensionally in the x and y planes, corresponding to a height adjustment and longitudinal displacement of the upper chair part, as well as an adjustment of the back support part, and
   a control unit (22) which has the effect that upon a change of the position of the seat and back support part (4, 5) the drives (A1, A2) for the height adjustment and longitudinal displacement of the upper chair part (2) are activated in the sense of maintaining constant the actual value (x) in the vertical plane,
   characterized in that
   there is at least one further set of adjusting means (A4, A5) for the relative adjustment of the head support part (6) in relation to the back support part (5) and there are locators (G4, G5) associated therewith,
   in that there are means (S1 to S3; 30, 25) for the input and storing of a desired value (x_M, y_M) which corresponds to the position of a reference point (M) associated with the head support part (6), and
   in that the control unit is designed as a control and computing unit (22) in such a way that corresponding to the actual position of the head support part (6) an actual value (x, y) for the reference point (M) is determined with reference to both planes (x, y),
   whereby upon a change of the position of the seat and back support part (4, 5) the drives (A1, A2) for the height adjustment and longitudinal displacement of the lower chair part (2) are adjusted in the sense of maintaining constant the reference point (M) corresponding to the entered desired value.
2. Chair for dental patients according to claim 1, characterized in that means (P1 to Pn, 24) are provided for the input and storing of values determining the position of the adjustable chair parts for a plurality of different chair positions and in the control and computing unit (22) the position values (x, y) of the adjustable chair parts are determined for the different chair positions on the aforementioned desired value (x_M, y_M) as common reference point (M), whereby there are means to activate the controllable drives (A1 to A3) in order to start up one of the different chair positions.
3. Chair for dental patients according to claim 1 or 2, in which input means (26) are provided, with which the desired value (x_M, y_M) for the reference point (M) can be altered.
4. Chair for dental patients according to claim 3, in which the input means (26) change the desired value (x_M, y_M) of the reference point (M) in the vertical (y-)direction.
5. Chair for dental patients according to claim 4, in which with the aid of the input means (26) a desired value representing the height of a person carrying out treatment can be determined.
6. Chair for dental patients according to one of claims 3 to 5, in which a display device (27) is associated with the input means (26).
7. Chair for dental patients according to one of claims 1 to 6, in which the reference point (M) is determined by a "mouth point" of the average patient's head determined empirically in its size, the "mouth point" being located at a defined distance (b) from the head support part (6).
8. Chair for dental patients according to one of claims 1 to 7, in which the reference point (M) can be adjusted corresponding to the height of the patient by adjusting the head support part (6) relative to the back support part (5).
9. Chair for dental patients according to one of claims 1 to 8, in which the head support part is formed as a headrest (6) supported in a longitudinally adjustable manner relative to the back support part (5).
10. Chair for dental patients according to claim 9, in which the locator (G4) associated with the head support part is activated upon contact with the patient's head.
11. Chair for dental patients according to claim 10, in which pressure sensors responding to the contact pressure of the patient's head (PH) are provided as locator (G4).

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