Medical treatment chair with backrest and adjustable headrest

Abstract

A medical treatment chair has a backrest (1) and a headrest (2), which has a base support (3) and a head cushion support (4), wherein the base support (3) is coupled to the backrest (1) so as to have an adjustable height and can also be pivoted about a first pivot axis (I). The head cushion support (4) can be pivoted about a second pivot axis (II), and the treatment chair has motors (201, 202, 30, 40) for individually driving the height adjustment and the two pivot adjustments, all of the motors (201, 202, 30, 40) being mounted in the region of the backrest (1).

Description

[0001] Medical treatment chair with backrest and adjustable headrest

[0002] The present invention relates to a medical treatment chair comprising a backrest and an adjustable headrest. In particular, the present invention relates to a dental treatment chair used in dental practices.

[0003] Performing dental examinations and treatments requires proper patient positioning that allows the practitioner to carry out the work ergonomically. At the same time, the patient should be able to lie comfortably in the chair, regardless of their size. The treatment chair should be equally usable for adults and children of different sizes.

[0004] Dental treatment chairs are therefore generally designed with an adjustable backrest that can be moved from a near-vertical to a horizontal position. The patient's head rests on a headrest attached to the backrest, which is height-adjustable. This height adjustment allows the distance between the headrest and the backrest to be changed, thus enabling the treatment chair to be adapted to the patient's height.

[0005] Furthermore, the headrest can be pivoted around a swivel axis perpendicular to the direction of height adjustment. This adjusts the angle of inclination between a plane of the backrest and a plane of the headrest, allowing the patient's head to be positioned according to the examination or treatment being performed. For example, examining a patient's upper jaw requires a slightly different head tilt compared to examining the lower jaw. Often, not only can the tilt of the headrest be adjusted, but the actual head cushion on which the patient's head rests can also be pivoted relative to the base of the headrest around another axis. This additional adjustment option is referred to as neck support.

[0006] To ensure that the patient remains comfortable on the treatment chair when the headrest's inclination is changed, an additional adjustment of the headrest's height position relative to the backrest is necessary.

[0007] In this context, it is known from the prior art that both the adjustment of the headrest's tilt and the associated length compensation, i.e., the adjustment of the distance between the backrest and the headrest, are performed manually. Alternatively, EP 0 517 933 B1 describes a patient chair in which the headrest's tilt can be adjusted by means of an electric drive, and the length compensation is simultaneously performed by means of another electric drive.

[0008] Furthermore, EP 1 372 562 Bl describes a dental treatment chair in which the movement of the headrest tilt is controlled by a corresponding motor. A rotational movement about a second headrest axis, which serves to adjust the tilt of the head cushion, is mechanically predetermined.

[0009] Finally, EP 1 868 555 Bl describes a headrest for a dental treatment chair in which the headrest and head cushion are controlled around their respective axes by means of dedicated motors. Each motor moves a rotary axis, with the motors located at head level within the headrest. This results, firstly, in a considerable volume of the headrest, which must accommodate the motors, and secondly, in motor noise being generated in close proximity to the patient's head, which is perceived as disturbing.

[0010] The present invention is therefore based on the objective of providing a medical treatment chair in which the various adjustment options can be individually made by motor. This is intended to prevent the generation of disturbing noises in the area of ​​the headrest and to enable a compact design of the headrest. This objective is achieved by a medical treatment chair having the features of claim 1. Advantageous further developments of the invention are the subject of the dependent claims.

[0011] As stated above, the medical treatment chair according to the invention provides various options for adjusting the position and inclination of the headrest. Firstly, the headrest is arranged on the backrest of the treatment chair and is height-adjustable. Furthermore, a base support of the headrest is pivotable about a first pivot axis perpendicular to one direction of height adjustment, and a head cushion support is pivotable about a second pivot axis, which is aligned parallel to the first pivot axis, relative to the base support. The treatment chair has motors for individually driving all three adjustments, and according to the present invention, all motors are arranged in the area of ​​the backrest, in particular on the underside of the backrest opposite a support surface for the patient.

[0012] According to the present invention, a medical, in particular a dental, treatment chair with a backrest and a headrest, which has a base support and a head cushion support, is proposed.

[0013] - wherein the base support is height-adjustable and coupled to the backrest, and is furthermore pivotable about a first pivot axis which is oriented perpendicular to a direction of height adjustment,

[0014] - wherein the headrest support can be pivoted relative to the base support about a second pivot axis which is aligned parallel to the first pivot axis,

[0015] - the treatment chair has motors for individually driving the height adjustment as well as the two swivel adjustments and

[0016] - wherein all motors are arranged in the area of ​​the backrest, preferably on an underside opposite a support surface of the backrest.

[0017] The treatment chair according to the invention thus offers maximum flexibility with regard to the adjustment options for the position and tilt of the headrest, with all adjustments being motor-driven. However, by positioning the motors in the backrest area according to the invention, it is avoided that they are located directly in the headrest area and thus the headrest's volume is not unnecessarily increased. Furthermore, the motor noise is now generated at a position further away from the patient's head, so that it is either not perceived at all or, at most, only minimally disturbing. The advantageous embodiments described in the dependent claims relate in particular to the question of how the corresponding movements of the motors are then transmitted or relayed in order to translate the motor movements into the desired height adjustment or the adjustment of the tilt(s) of the headrest.

[0018] Preferably, the treatment chair is designed with a guide element that is linearly movable along the backrest and coupled at one end to the headrest base via the first pivot axis. In one variant, the motors responsible for driving the two swivel adjustments, as well as the other mechanisms for transmitting the movements, are located on the guide element and thus move together with the guide element when the headrest base is adjusted in height. In this case, the motors responsible for the various tilt settings move synchronously with the headrest relative to the backrest.This has the advantage that the elements for transmitting movement for the tilt adjustment can be kept simpler in terms of their construction, since the distance between the motors and the corresponding pivot axes of the headrest remains essentially unchanged.

[0019] In a second, preferred variant, the motors responsible for driving the two swivel adjustments are arranged in a fixed position on the underside of the backrest, and only the additional mechanism for transmitting the movements, and thus for swiveling the headrest, moves together with the guide element. In this case, the drive shafts responsible for transmitting the rotary movements of the motors are designed in such a way that their length is variable, thus compensating for the changing distance when the headrest height is adjusted. In particular, it can be provided that the two drive shafts are each telescopically designed.In this case, the design of the components required for motion transmission is slightly more complex; however, all motors can now be arranged in an area of ​​the backrest where sufficient space is available, and therefore the motors do not necessarily have to be designed to be as compact as possible.

[0020] Both versions therefore allow for convenient, motorized adjustment of the headrest tilt, regardless of the headrest's height position. As will be explained in more detail below, a certain degree of length and angle adjustment is still necessary. However, this is manageable thanks to the advantageous positioning of the motors and the favorable coupling via the length-adjustable drive shafts.

[0021] Regarding the height adjustment, a first embodiment provides that motor-driven toothed belts run parallel to the direction of the height adjustment on both sides of the guide element, and the guide element is coupled to these belts. Preferably, two guide rods also run parallel to the toothed belts, along which the guide element is guided. This ensures that the guide element, and thus the headrest itself, is reliably moved along the backrest during the height adjustment. Each toothed belt is preferably driven by its own motor, with both motors then being controlled synchronously.

[0022] In a second embodiment, only one motor is used for height adjustment. This motor drives a spindle rod which runs parallel to the direction of height adjustment on one side of the guide element and which is coupled to the guide element in such a way that a rotation of the rod is converted into a linear adjustment of the guide element.

[0023] For adjusting the inclination of the headrest base relative to the backrest, it is preferably provided that the corresponding motor is coupled to a first drive shaft, wherein the first drive shaft, which may be telescopic, extends along the guide element towards the base and interacts with at least one first push lever. This first push lever is connected to the base at an end opposite the first drive shaft via a third pivot axis, which is eccentric to the first pivot axis. The first drive shaft is preferably coupled to the at least one first push lever via a spindle nut. Depending on the direction of rotation of the first drive shaft, the spindle nut moves along it, thereby either pushing the first push lever towards or pulling it away from the base.The at least one first thrust lever is preferably angled and rotatably connected to the spindle nut, and in particular two first thrust levers may be provided, which run laterally parallel to an axis defined by the first drive shaft. A rotary movement of the motor is efficiently converted by these measures into a corresponding rotation of the headrest base about the first pivot axis.

[0024] To adjust the tilt of the headrest support relative to the base support, the corresponding motor is preferably coupled to a second drive shaft, which may in turn be telescopic and also extends towards the base support. This second drive shaft interacts with at least one second push lever, which is connected to the headrest support via a fourth pivot axis that runs eccentrically to the second pivot axis. Here, transmitting the motor's movement to adjust the tilt of the headrest support requires more effort, as the movement transmission must be possible regardless of the tilt of the base support relative to the backrest.

[0025] Preferably, the second drive shaft is coupled to a threaded spindle via a universal joint, the universal joint being positioned essentially in the region of the first pivot axis. The threaded spindle itself then preferably interacts with a sliding nut that is coupled to the second push lever, the sliding nut moving along the threaded spindle depending on its direction of rotation to push or pull the second push lever towards or away from the headrest support.

[0026] The aforementioned compensation, necessitated by a change in the inclination of the base support, is achieved according to a preferred embodiment by providing a drive rod between the second drive shaft and the universal joint, which is coupled to the second drive shaft via a compensating joint. This compensating joint can, in particular, comprise a hollow cylindrical guide element and a guide body slidably mounted within the guide element, with one of the two compensating joint parts being arranged on the second drive shaft and the other compensating joint part on the drive rod. Particularly preferably, the hollow cylindrical guide element has two elongated slots or recesses, and the guide body is further provided with two lateral projections that engage accordingly in the slots or recesses.This creates the possibility of a certain degree of length compensation, and also allows for a certain degree of angle compensation.

[0027] Ultimately, the described measures ensure that, despite the inventive positioning of the adjustment motors in the backrest area, the corresponding movements are efficiently transmitted to allow individual adjustment of the height and tilt of the headrest base, as well as the tilt of the head cushion support relative to the base. The space required for this in the headrest area is extremely small, allowing for a compact design and preventing disturbing noises for the patient.

[0028] The invention will now be explained in more detail with reference to the accompanying drawing. The drawing shows:

[0029] Figure 1 shows a view of the underside of a medical treatment chair according to a first embodiment of the present invention with backrest and headrest;

[0030] Figure 2 shows a view of the headrest arranged on the guide element to illustrate the adjustment options regarding the inclination of the headrest and the head cushion;

[0031] Figure 3 shows a view of the upper end area of ​​the backrest with the coupling elements for transmitting the motor movement to the various pivot axes of the headrest;

[0032] Figures 4 and 5 are analogous views to Figure 3 showing different inclinations of the headrest base support;

[0033] Figure 6 shows a side sectional view of the components responsible for pivoting the headrest support; Figures 7-9 show views of the top of the headrest corresponding to Figures 3 to 5 in the three different tilt settings of the headrest;

[0034] Figure 10 shows a view of the compensating joint for the motion transmission to adjust the inclination of the headrest support;

[0035] Figures 11a and 11b illustrate the function of the compensating joint;

[0036] Figure 12 shows another view illustrating the components responsible for adjusting the tilt of the headrest support;

[0037] Figures 13 and 14 show the underside of a second embodiment of a medical treatment chair; and

[0038] Figure 15 shows a sectional view of a telescopic drive shaft in the embodiment shown in Figures 13 and 14.

[0039] Before the various components for adjusting the headrest in relation to the backrest of the treatment chair according to the invention are explained in detail below, the adjustment options available for the treatment chair according to the invention will first be explained in general terms, particularly with reference to Figures 1 and 2. Figure 1 shows the underside or back of the treatment chair, without showing the covers for the backrest 1 and the guide element 10 that are provided during actual use, so that the various components for generating and transmitting movement are more clearly visible.

[0040] The figures show a backrest 1 and a headrest 2. The distance between the headrest 2 and the backrest 1 can be adjusted to the patient's size, ensuring comfortable resting on the treatment chair. As shown in Figure 1, the headrest 2 can be moved along an indicated axis H, allowing the distance between the headrest and backrest 1 to be variably adjusted to the patient's size. Depending on the type of examination or treatment being performed, the patient's head must be positioned accordingly, particularly its tilt. For this purpose, the headrest 2, consisting of a base support 3 and a head cushion support 4, is pivotally mounted about a first axis I.This first axis I is essentially perpendicular to the direction of the height adjustment H and allows the overall inclination of the headrest 2 to be changed, with three different inclination settings being shown in Figures 3 to 5.

[0041] Since changing the inclination of the headrest 2 can often lead to an uncomfortable positioning of the patient's head, additional compensation is provided by a so-called neck support. For this purpose, the headrest support 4, which carries the actual headrest on which the patient's head rests, is pivoted about a second pivot axis II relative to the base support 3 of the headrest 2. Both axes I and II run parallel to each other, as can be seen in Figure 2, and, as already explained, are perpendicular to the direction of the height adjustment H.Because, according to the present invention, it is possible to individually adjust all three parameters - height adjustment, inclination of the base support and inclination of the headrest support - there is maximum flexibility with regard to the arrangement and alignment of the various components of the headrest 2, so that a suitable and comfortable positioning of the patient's head for treatment is always ensured.

[0042] All three adjustment options are to be motorized, with corresponding drives, described in more detail below, being responsible for this. These drives can be controlled by a user via operating elements not shown. A key aspect of the present invention is that the motors used here are all arranged in the area of ​​the backrest 1. In particular, they are located on the underside of the backrest 1, which is then covered during subsequent use of the treatment chair. Apart from the fact that this covering already further dampens the noise of the motors, the positioning away from the headrest 2 means that the motor noise is barely or not at all perceptible to the patient.Furthermore, the relocation of the motors responsible for the two tilt adjustments to the area of ​​the backrest 1 allows the dimensions of the headrest 2 to be kept compact. The following section will first explain how to adjust the headrest 2 along direction H to change its height. For this purpose, the headrest 2 is coupled to a guide element 10, which is adjustable on the backrest 1 and is moved linearly along direction H by means of motors 20i and 2Ü2. The guide element 10 is approximately T-shaped, with an elongated section extending towards the headrest 2, and coupled to the headrest 2 at its front end in the manner described in more detail below.At the end furthest from the headrest 1, the guide element 10 is slightly widened, forming two lateral wings which interact appropriately with two guide rods 231 and 232 attached to the backrest 1. For example, the guide element 10 may have corresponding openings or longitudinal grooves in these areas into which the guide rods 231 and 232 engage, so that the guide element 10 is guided along the direction of height adjustment H.

[0043] To adjust the height position, two motors 20i and 202 are provided, arranged on either side of the guide rods 231 and 232, and interacting with toothed belts 221 and 222, which in turn run parallel to the guide rods 231 and 232. The motors 20i and 202 are controlled synchronously and, if necessary via appropriate gearboxes, drive their respective toothed belts 22i and 222, respectively, which then interact with a corresponding coupling element 12 of the guide element 10, so that the guide element is moved along the direction H, depending on the direction of rotation of the toothed belts 22i and 222. With the help of the control element, which is not shown in detail in the figures, it is therefore possible, for example, for a dentist or another treating person to control the drive for the height adjustment in such a way that the distance h (see figure 1) of the headrest 2 from the backrest 1 is adapted to the size of the person sitting or lying on the treatment chair.

[0044] Alternatively to the embodiment shown, the use of a single motor would also be possible, a possible solution for which will be explained later with reference to Figures 13 and 14.

[0045] The aforementioned widened design of the guide element 10 at the end furthest from the headrest 2 further results in an enlarged support surface 15, which serves to accommodate two additional motors 30 and 40, responsible for the various tilt adjustments. Both motors 30 and 40, as well as motors 20i and 2Ü2, can be individually controlled, allowing the pivoting about axes I and II to be performed separately. The following section will first explain the overall tilt adjustment of the headrest 2, i.e., the pivoting of the base support 3 about axis I.

[0046] It is essential that, in the area of ​​the first pivot axis I, the front end of the guide element 10 is pivotably coupled to the base support 3 of the headrest 2. Pivoting about this axis I is then achieved by the fact that the base support 3 has a second axis III (see Figure 3 or 6) extending eccentrically to this first axis I, to which a push lever 35 pivotally engages in order to pull the axis III towards the backrest 1 or push it away from it.Figures 3-5 (Figures 7-9 show corresponding views of the upper surface of the headrest 2) illustrate three different positions of the double-armed push lever 35. It can be seen that the upper surface O2 of the base support 3, and thus of the headrest 2 as a whole, pivots towards the upper surface Oi of the backrest 1. This reduces the angle α, shown in Figure 12 and enclosed by the backrest 1 and headrest 2, as the push lever 35 moves further away from the backrest 1. The corresponding mounting of the base support 3 and the coupling between the push lever 35 and the third axis III therefore result in a linear movement of the angled push lever 35 being converted into a pivoting of the headrest 2 and thus an adjustment of the headrest 2's inclination.

[0047] The linear movement of the push lever 35 required to change the headrest inclination is now accomplished with the aid of the aforementioned motor 30, which is coupled, for example, via a suitable gear 31 to a first drive shaft 32. This drive shaft extends along the guide element 10 from the motor 30 towards the front end of the guide element 10. Optionally, this first drive shaft 32 can be guided at approximately half the height of the guide element 10 by means of a corresponding guide element 17, thus ensuring consistently correct alignment of the drive shaft 32. At its front end, this drive shaft 32 then interacts with a spindle nut 34, which is pivotally connected to the push lever 35.Depending on the direction of rotation of the motor 30 and thus the direction of rotation of the drive shaft 32, this spindle nut 34 moves along the front end area of ​​the drive shaft 32 away from the backrest 1 or towards it and thus, as already mentioned, pulls the axis III of the base support 3, which runs parallel to the axis I, in a corresponding direction via the push lever 35, so that the base support 3 is pivoted as explained above.

[0048] Ultimately, this causes the base carrier 3 to pivot around axis I, thereby realizing the tilt adjustment of the headrest 2.

[0049] For the additional neck adjustment, i.e., the tilting of the headrest support 4 relative to the base support 3 about axis II, a further motor 40 is responsible. This motor 40 is positioned on the enlarged area 15 of the guide element 10 in the same way as the motor 30 for the tilt adjustment, and thus moves together with the guide element 10 when the height of the headrest 2 is changed. This motor 40 is also initially coupled via a suitable transmission, e.g., a gear transmission 41, to a further drive shaft 42. This drive shaft extends parallel to the first drive shaft 32 along the guide element 10 towards the front end and may, if necessary, be guided at approximately half the height of the guide element 10.

[0050] In a manner similar to adjusting the inclination, the headrest support 4 is pivoted relative to the base support 2 of the headrest 2 by being pivotably coupled to the base support 3 on the aforementioned second axis II. Simultaneously, a push lever 45 engages a fourth axis IV, which is aligned parallel to the second axis II. In this area, the push lever 4 moves the headrest support 4 away from or towards the backrest 1, thereby changing the angle β (see Figure 2) between the base support 3 and the headrest support 4. The second push lever 45 is particularly visible in Figures 2 and 6, with Figure 6 also showing the arrangement of the slightly eccentric fourth axis IV.

[0051] It is further evident that, due to the possibility of adjusting the inclination of the base support 3 relative to the backrest 1, a difficulty arises in that a linear transmission of the rotational movement of the second drive shaft 42 to the thrust lever 45 is not possible at every inclination of the headrest 2, since the thrust lever 45, and thus axis II, does not coincide with the axis of rotation I for the headrest 2, and the axis of rotation I for the base support 3 is also not in the same plane as the drive train for the neck support. Several measures are provided to address this.

[0052] A first measure consists of providing a universal joint 43 approximately in the area of ​​the first pivot axis I, which enables the change in angle when transmitting the rotary motion. The universal joint 43 is coupled at its end facing the second pivot axis III or the push lever 45 to a threaded spindle 44, which interacts with a sliding spindle nut 46. This nut, in turn, is pivotably connected to the push lever 45, analogous to the spindle nut 34. Depending on the direction of rotation of the threaded spindle 44, the sliding spindle nut 46 moves along the spindle to ultimately pull the push lever 45 towards the upper end of the headrest 2 or towards the backrest 1.

[0053] It must also be taken into account that when the inclination of the base support 3 is changed from an upper position to a lower position, an additional length compensation must be carried out. This is made possible by the fact that the drive shaft 42 does not extend in one piece to the universal joint 43, but rather the universal joint 43 is coupled to a drive rod 47 on its side facing the motor 40, with a compensating joint 48 being provided between the drive shaft 42 and the drive rod 47. As shown in more detail in Figures 10, 11a, and 11b, the compensating joint 48 is formed by a hollow cylindrical guide element 49, which is provided at the rear end of the drive rod 47, i.e., the end facing the motor 40. The wall area of ​​this hollow cylindrical guide element 49 has elongated slots or recesses 50 on two opposite sides.

[0054] The end of the drive shaft 42 facing the compensating joint 48 is provided with a spherical guide body 51, the diameter of which corresponds to the inner diameter of the guide element 49. This guide body is inserted into the interior of the hollow cylindrical guide element 49 and engages in the recesses 50 with two lateral projections or arms 52. This spherical design of the guide body 51 allows, firstly, a slight angular offset between the drive shaft 42 and the drive rod 47. In particular, however, as shown in Figures 11a and 11b, it also allows for length compensation. This is necessary to compensate for the length difference in the drive train required to adjust the headrest support 4 when the inclination of the base support 3 is changed.Ultimately, regardless of the inclination of the base support 3 relative to the guide element 10, the fourth motor 40 can be used to push the thrust lever 45 towards or away from the backrest 1, thereby allowing the headrest support 4 to be pivoted relative to the base support 3 from an orientation parallel to it.

[0055] Overall, the measures described result in i. the base support 3 and thus the headrest 2 being linearly adjusted relative to the backrest 1 along axis H; ii. the base support 3 being pivoted about axis I relative to the guide element 10 and thus the backrest 1; and iii. the inclination of the head cushion 4 relative to the base support 3 being additionally changed.

[0056] A second embodiment of a treatment chair according to the invention will be explained below with reference to Figures 13-15. It should first be noted that the main changes here are in the arrangement of the motors 20, 30, and 40 provided for the various adjustment options, as well as in the coupling of these motors 20, 30, and 40 to the respective drive trains. However, there are no differences with regard to the conversion of the rotary movements provided in particular by the motors 30 and 40 into a pivoting of the headrest 2 and a tilting of the head cushion 4 relative to the base support 3. Here, the corresponding components are identical to those of the first embodiment and are accordingly provided with the same reference numerals in Figures 13 and 14. The explanations regarding...The descriptions of these components in connection with the first embodiment also apply identically to this second embodiment.

[0057] A first difference in the second embodiment shown in Figures 13 and 14 is that only a single motor 20 is used for adjusting the height of the headrest 2, in contrast to the two motors 20i and 2Ü2 coupled to the belt drives in the first embodiment. This single motor 20 is located on the right side of the entire drive train in the illustrated embodiment and is coupled to a spindle rod 25 that extends parallel to the direction of height adjustment on the side of the guide element 10. This guide element 10 is mounted in the same way as in the first embodiment, guided in the direction of height adjustment by means of two guide rods 231 and 232, and is coupled to the motor-driven spindle rod 25 via a lateral spindle nut 26.

[0058] Depending on the direction of rotation of the motor 20 and thus of the spindle rod 25, the spindle nut 26 with the associated guide element 10 moves along the axis H, allowing the height position of the headrest 2 to be changed. Since only a single motor 20 is required in this case to perform the height adjustment, the overall material cost is reduced compared to the first embodiment, and the synchronous operation of two motors is eliminated. Despite this, a robust drive coupling is achieved, enabling simple yet reliable height adjustment of the headrest 2.

[0059] The other key difference compared to the first embodiment is that the motors 30 and 40 responsible for performing the pivoting movements described above no longer move together with the guide element 10, but are instead fixed in place on the underside U of the backrest 1. Preferably, these motors 30 and 40 are positioned near the motor 20 responsible for height adjustment, as shown, so that all three motors can be easily enclosed in a single housing. Apart from the fact that this ultimately leads to a more compact arrangement of the drive components, this approach also allows for improved sound insulation.

[0060] Analogous to the first embodiment, here the motors 30 and 40 drive respective drive shafts 32 and 42, which then interact with the corresponding transmission components in the area of ​​the headrest 2 as described above, in order to pivot the base support 3 about the first pivot axis and the head cushion 3 about the second pivot axis. However, since the motors 30 and 40 are now stationary, as mentioned, it must be ensured by other means that the drive transmission can take place independently of the height position of the headrest 2.

[0061] For this purpose, the two drive shafts 32 and 42 are designed to be telescopic, such that their length can be adjusted and, in particular, they automatically adapt to the selected height setting for the headrest 2. More precisely, each of the two drive shafts 32 and 42 now consists of a first, stationary drive shaft 32a or 32b, which is directly coupled to the respective motor 30 and 40, and a second, hollow drive shaft 32b or 42b, which is connected to the other transmission components and into which the front end sections of the stationary shafts 32a and 42a engage.

[0062] Figure 15 shows a cross-sectional view of the drive shaft 32 associated with the first motor 30, wherein the end region of the stationary drive shaft 32a facing away from the motor 30 then engages slidably with the hollow shaft 32b. This sliding engagement allows the overall length of the drive shaft 32 to be changed; however, it must also be ensured that a rotation of the stationary drive shaft 32a also results in a rotation of the further hollow drive shaft 32b.

[0063] As shown in Figure 15, the inner wall of the hollow drive shaft 32b has longitudinally extending recesses or grooves 33b positioned opposite each other, into which corresponding projections or pins 33a on the stationary drive shaft 32a engage with minimal play. This design allows for relative axial displacement between the two shafts. Simultaneously, the essentially positive engagement between the pin-like projections 33a and the grooves 33b enables the transmission of rotation and torque.

[0064] The recesses or grooves 33b preferably extend over the entire area of ​​the hollow shaft 32b. The pin-like projections 33a, on the other hand, could only be provided at a front end region of the stationary shaft 32a. For example, these projections 33a could be formed on an end cap, which is then placed on the corresponding voice-side end of the stationary shaft 32a and rotates with it.

[0065] Of course, the positive-locking, telescopic interlocking of the partial drive shafts 32a and 32b can also be implemented in other ways. The crucial point is that, overall, a drive shaft 32 is created which reliably transmits the rotation provided by the motor 30 and whose resulting overall length is simultaneously variable. The additional drive shaft 42 associated with the motor 40 is designed in the same way. It also consists of a stationary partial drive shaft 42a and a hollow partial drive shaft 42b, into which the front end of the stationary shaft 42a slides in a positive-locking manner, again enabling rotational transmission and simultaneously achieving length adjustment.

[0066] Of course, it would be conceivable to transfer only partial ideas from the second embodiment to the first embodiment. In particular, for example, the design of the drive for the height adjustment from the second embodiment could be used in the first embodiment, and the positioning of the additional motors 30 and 40 on the guide element 10 could still be such that they move together with it. Furthermore, the drive concept for the height adjustment provided in the first embodiment can, of course, be retained and used in combination with the additional motors 30 and 40, which are stationary in the second embodiment.

[0067] Ultimately, this allows for highly flexible, individual adjustment of the headrest's position and orientation, with all settings conveniently controlled by motors. In both embodiments, all motors responsible for the various adjustments are located away from the headrest, significantly reducing noise and enabling a sleek and compact design.

Claims

Claims 1. Medical, in particular dental, treatment chair with a backrest (1) and a headrest (2) which has a base support (3) and a head cushion support (4), wherein the base support (3) is height-adjustable coupled to the backrest (1) and is furthermore pivotable about a first pivot axis (I) which is oriented perpendicular to a direction (H) of the height adjustment, wherein the head cushion support (4) is pivotable about a second pivot axis (II) which is oriented parallel to the first pivot axis (I) relative to the base support (3), wherein the treatment chair has motors (20, 20i, 2Ü2, 30, 40) for individually driving the height adjustment and the two pivot adjustments and wherein all motors (20, 20i, 2O2, 30, 40) are arranged in the area of ​​the backrest (1), preferably on an underside (U) which is opposite a support surface of the backrest (1).

2. Medical treatment chair according to claim 1, characterized in that it has a guide element (10) which is arranged to be linearly movable on the backrest (1) and is coupled at an end area to the base support (3) of the headrest (2) via the first pivot axis (I), wherein preferably two guide rods (231, 232) run parallel to the direction (H) of the height adjustment, along which the guide element (10) is guided.

3. Medical treatment chair according to claim 2, characterized in that a motor-driven spindle rod (25) is arranged parallel to the direction (H) of the height adjustment, which is coupled to a motor (20) for driving the height adjustment and interacts with a spindle nut (26) arranged on the guide element (10).

4. Medical treatment chair according to claim 2, characterized in that that parallel to the direction (H) of the height adjustment on both sides of the guide element (10) motor-driven toothed belts (22i, 222) run, with which the guide element (10) is coupled.

5. Medical treatment chair according to claim 4, characterized in that each toothed belt (22i, 222) is driven by its own motor (20i, 2O2), wherein both motors (20i, 2O2) are controlled synchronously.

6. Medical treatment chair according to one of claims 2 to 5, characterized in that the motor (30) for adjusting the inclination of the base support (3) relative to the backrest (1) is coupled to a first drive shaft (32), wherein the first drive shaft (32) extends in the direction of the base support (3) and interacts with at least one first push lever (35) which is connected to the base support (3) at an end (36) away from the first drive shaft (32) via a third pivot axis (III) which runs eccentrically to the first pivot axis (I).

7. Medical treatment chair according to claim 6, characterized in that the first drive shaft (32) is coupled to the at least one first push lever (35) via a spindle nut (34), wherein the spindle nut (34) moves along the first drive shaft (32) depending on the direction of rotation of the first drive shaft (32) in order to push the first push lever (35) towards the base support (3) or to pull it away from the base support (3).

8. Medical treatment chair according to claim 7, characterized in that the at least one first push lever (35) is angled and rotatably connected to the spindle nut (34), wherein preferably two first push levers (35) are provided which run laterally parallel to an axis defined by the first drive shaft (32).

9. Medical treatment chair according to one of claims 2 to 8, characterized in that, that the motor (40) for adjusting the inclination of the headrest support (4) relative to the base support (3) is coupled to a second drive shaft (42), wherein the second drive shaft (42) extends in the direction of the base support (3) and interacts with at least one second push lever (45) which is connected to the headrest support (4) via a fourth pivot axis (IV) which is eccentric to the second pivot axis (II).

10. Medical treatment chair according to claim 9, characterized in that the second drive shaft (42) is coupled to a threaded spindle (44) via a cardan joint (43), wherein the cardan joint (43) is positioned substantially in the area of ​​the first pivot axis (I).

11. Medical treatment chair according to claim 10, characterized in that the threaded spindle (44) interacts with a sliding spindle nut (46) which is coupled to the second push lever (45), wherein the sliding spindle nut (46) moves along the threaded spindle (44) depending on the direction of rotation of the threaded spindle (44) in order to push the second push lever (45) towards or away from the headrest support (4).

12. Medical treatment chair according to claim 10 or 11, characterized in that a drive rod (47) is provided between the second drive shaft (42) and the cardan joint (43), which is coupled to the second drive shaft (42) via a compensating joint (48).

13. Medical treatment chair according to claim 12, characterized in that the compensating joint (48) has a hollow cylinder-like guide element (49) and a guide body (51) slidably mounted in the guide element (49), wherein one of the two compensating joint parts (49, 51) is arranged on the second drive shaft (42) and the other compensating joint part (49, 51) is arranged on the drive rod (47).

14. Medical treatment chair according to claim 13, characterized in that the hollow cylindrical guide element (49) has two elongated slots or recesses (50) and the guide body (51) is provided with two lateral projections (52) which engage in the slots or recesses.

15. Medical treatment chair according to one of claims 6 to 14, characterized in that the motors (30, 40) for driving the two swivel adjustments are arranged fixedly on the backrest (1), wherein the first and / or second drive shaft (32, 42) are length-variable, in particular telescopically designed.

16. Medical treatment chair according to claim 15, characterized in that the first and / or second drive shaft (32, 42) are each formed by two partial drive shafts (32a, 32b, 42a, 42b) which each engage in a form-fitting, sliding manner.

17. Medical treatment chair according to one of claims 6 to 14, characterized in that the motors (30, 40) for driving the two swivel adjustments are arranged on the guide element (10) and are moved together with the guide element (10) when the height of the base support (3) is adjusted.

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