WO2023118659A1

WO2023118659A1 - Convertible care chair

Info

Publication number: WO2023118659A1
Application number: PCT/FI2022/050854
Authority: WO
Inventors: Heikki Koivurova; Marko KOSONEN
Original assignee: Romuritari Oy
Current assignee: Romuritari Oy
Priority date: 2021-12-23
Filing date: 2022-12-20
Publication date: 2023-06-29
Anticipated expiration: 2024-06-23
Also published as: EP4452169A4; EP4452169A1; FI20216334A1; FI130692B1

Abstract

The invention relates to a convertible chair comprising a seat part with a front edge and a rear part, the sitting direction of the chair being from the rear part of the seat part towards the front edge; a backrest and a chair frame, to which the seat part and the backrest are supported or which forms the seat part and/or the backrest partly or completely; fixed standing supports (1, 13) for supporting the chair in a first operating mode, which is a static standing position for a person with reduced mobility to sit; at least one rear wheel (2) and at least one front wheel (3) for supporting the chair in a second operating mode; and equipment for moving a load from the standing supports (1, 13) to the front wheel (3) and the rear wheel (2); that is, from the first operating mode to the second operating mode and back to the standing supports (1, 13) to the first operating mode. Equipment for shifting the chair between the first and the second operating modes comprises operating means arranged to be operated by a caring person on the backrest side of the chair, and the equipment comprises tilting means for tilting the chair frame (14) about a fixed point formed by the rear wheel (2) between the first and the second operating modes to a tilting angle (K) of 1.5 to 25 degrees, most preferably 2 to 10 degrees.

Description

CONVERTIBLE CARE CHAIR

This invention relates to a convertible chair, which includes a seat part with a front edge and a rear part, the sitting direction of the chair being from the rear part of the seat part towards the front edge; a backrest and a chair frame, to which the seat part and the backrest are supported or which forms the seat part and/or the backrest partly or completely; fixed standing supports for supporting the chair in a first operating mode, which is a static standing position for a person with reduced mobility to sit; at least one rear wheel and at least one front wheel for supporting the chair in a second operating mode; and equipment for moving a load from the standing supports to the front wheel and the rear wheel; that is, from the first operating mode to the second operating mode and back to the standing supports to the first operating mode.

The primary applications of a chair according to the invention are medical care institutions for persons with reduced mobility and elderly people; however, a chair according to the invention is also suited to other applications, where there is a need to facilitate the transfer of a person sitting on a chair to different places.

In medical care institutions and residential communities for persons with reduced mobility and elderly people, as well as in home care, there is a need to move a person aided by a caring person to different places and between places, such as from a rest room to a dining room to be seated at a table, to a social room and a washroom. Efforts are naturally made to maintain and advance independent moving and muscle use of elderly people and persons with health issues, but in certain situations and when the health condition of the person being cared for impairs, assisting actions of a caring person become necessary. One problem, in particular, is related to accompanying a person to the dining table and, correspondingly, moving a person from the table to a social room, for example. A conventional solution in medical care institutions is a chair equipped with fixed legs, which is dragged on the floor surface while the person is sitting on the chair. This operation requires the caring person to use great force in an ergonomically unfavourable position while, at the same time, forces causing damage to the chair and abrasion harming the floor surfaces are exerted on the chair legs and structure. A frequent problem is also the transfer of a person being cared for from their own rest room to common rooms, when the functional capacity of the person is not sufficient for using a rollator.

Problems described above have been solved, for example, with the use of a wheel chair, which, however, involves several disadvantageous characteristics, such as wheel chair dimensions and shortcomings related to the sitting comfort, as well as a high purchase price. One known solution is a chair structure, in which the rear legs of the chair are equipped with wheels, onto which the chair can be leaned during the transfer. However, this solution involves a high risk of accidents, because the caring person must take care of maintaining the balance of the chair during the transfer. Due to the lack of balance, the above-described chair is not suited to longer transfers, such as moving a person from a rest room to a dining room, for example.

In addition, a chair solution is known where the rear legs of the chair are equipped with fixed directionally locked wheels and, articulated at the lower end of the front legs, there is a construction with which the directionally locked front wheels included in the construction can be set in a load-bearing position with a foot lever operated by the caring person. This solution is only suitable for transferring the chair in the direction of the directionally locked wheels and requires that the foot lever is pressed continuously during the transfer; therefore, the chair is only suitable for short transfers and is additionally difficult to use as regards maintenance of balance by the caring person.

Publication US2021361517 proposes a convertible chair, in the static standing position of which the seat part is in a raised position and the front wheels are locked. In the transfer position of the chair, the seat part is slightly lower at the rear while the front wheels rotate and turn enabling a transfer of a person in the sitting direction. In addition, the seat part and the backrest of the chair are articulated to the chair frame in such a way that they can be folded for converting the chair to a rollator position, in which the travel direction of the chair is opposite to the transfer direction. The construction of the chair is complicated and its use is difficult, in addition to which the standing position based on the wheel locking is not very steady and stable.

The object of the invention is to provide a convertible chair, with which it is possible to remove the problems described and which suits better than prior art to the above-mentioned care needs.

The characteristics of the invention are described in more detail in the characterising part of the independent claim. Structural solutions related to the implementation of the invention and details complementing the features of the independent claim are described in the dependent claims.

The problems described can be removed with a chair according to the invention proposed now and its technical solutions. A chair according to the invention is suited to all typical indoor transfer needs of a person as well as to passages with fixed surfaces in outdoor areas. In addition, a chair according to the invention offers a good sitting comfort for a person sitting in the chair during prolonged sitting as well. Furthermore, a chair according to the invention relieves the load of a caring person during longer transfers and particularly regarding transfers that are needed during a dining situation, wherein, when using known and typical solutions, a chair resting on fixed legs is dragged on the floor surface to and from the table while a person is sitting on the chair.

A characteristic feature of the invention is that the suitability of the chair to different needs can be changed by a caring person while a person is sitting in the chair. For the stable standing position, the chair is equipped with separate fixed standing supports and, for the transfer position of the chair, with load-bearing wheel constructions that maintain the stability of the chair. While resting on fixed standing supports, the chair is kept in place in a stable manner supported to the floor surface. The chair also comprises equipment for transferring a load from the standing supports to the front wheel and the rear wheel; that is, from a first operating mode to a second operating mode and back to the standing supports to the first operating mode. Equipment for shifting the chair between the first and second operating modes comprises operating means arranged to be operated by a caring person on the backrest side enabling for the caring person to easily shift the chair between the operating modes while another person is sitting on the chair. The equipment also comprises tilting means for tilting the chair frame about a fixed point formed by the rear wheel between the first and the second operating modes to a tilting angle of 1.5 to 25 degrees, most preferably 2 to 10 degrees, thus achieving a safer transfer position for the person sitting on the chair. A tilted transfer position is also safe, if the person sitting in the chair has a sudden attack of illness.

Advantageously, in the transfer phase of the chair and the person sitting in it, the chair is set to the transfer position by tilting the chair to rest on the rear wheels of the chair, and the front wheel(s) of the chair are moved with a mechanical arrangement in the height direction relative to the chair frame to a position, in which the front wheel(s) of the chair and the rear wheels of the chair function as a load-bearing component. The shift of the height position of the front wheels can be performed in the different embodiments of the chair in a motorised way, with spring forces, or by using muscular strength of the caring person, and the height position of the front wheels is mechanically locked in the height position required by the transfer position of the chair. Henceforth in this description text, the term 'front wheels' is used regardless of whether the chair is equipped with one or more front wheels. In the transfer position of the chair, the rear wheels and the front wheels function together as load-bearing components. The front wheels are castor type wheels enabling for the caring person to steer the chair in the desired direction and to a desired position. The rear wheels of the chair are fixedly fastened to the chair frame in a directionally locked manner and the rear wheels may also be wheels according to prior art equipped with a brake mechanism. The positions of the loadbearing wheels in the construction of the chair are located so that the centre of gravity of the chair and the person sitting in it is essentially between the rear wheels and the front wheels of the chair for ensuring the stability of the transfer. When shifting from the transfer position of the chair to the standing position to rest on the fixed standing supports of the chair, the height position lock of the front wheels is disengaged and the front wheels are set with a mechanical arrangement to a position in which they do not bear any load and the chair is supported to the floor surface on the fixed standing supports. The rear wheels of the chair can also function as fixed standing supports in the rear part of the chair, when the rear wheel brakes are engaged.

The mechanical arrangement for shifting the height position of the front wheels of the chair can be implemented in the different embodiments of the chair with several different technical solutions, which are described in more detail in the technical structural description and the description of figures. Basic solutions include use of an electrical, pneumatic or hydraulic actuator for the mechanism, use of the mechanism based on muscular strength of the caring person, use relying on spring force, and use of gravity. A characteristic feature of the solutions of these embodiments is the locking of the height position of front wheels in the transfer position of the chair.

In some embodiments of the invention, the shift between the operating modes can be implemented, instead of changing the height position of the front wheels, by changing the height position of the rear wheels by either lifting or lowering the rear wheels relative to the chair frame. The technical effect characteristic of the invention can also be achieved by changing the height position of both the front wheels and the rear wheels relative to the chair frame when shifting between the operating modes. The front wheels and the rear wheels can also be connected to each other by joints in such a way that, when changing the operating mode, the height position of the front wheels changes proportionally more than the height position of the rear wheels so that a tilt characteristic of the invention is achieved with a height position change of the wheels. Alternatively, the shift between the operating modes can also be implemented by changing the height position of the standing supports relative to the chair frame, in which case the wheels of the chair can be fixedly mounted relative to the chair frame.

Advantageously, separate fixed standing supports located in the front part of the chair are height-adjustable and fastened to the chair frame.

In an embodiment, in addition to the fixed standing supports located in the front part of the chair, the rear wheels of the chair equipped with brakes can also function as fixed standing supports of the chair. Thus, when shifting from the fixed standing position of the chair to the transfer position, the brake mechanism of the rear wheels is released.

The frame construction of the chair can be implemented with alternative materials and manufacturing techniques. As regards the design and sitting comfort, an advantageous solution is a monolithic die-cast plastic construction, which is resistant in a washroom use as well and protects the mechanisms of the chair from splashes during a washing situation. One advantage is also easy cleanability. In a monolithic structure, the seat part and the backrest of the chair are in a fixed position relative to each other. Thus, technical means with which the chair is shifted between the operating modes are located inside the monolithic plastic construction.

In an embodiment, the seat part and the backrest of the chair can be separate structural parts articulated with each other, enabling adjustment of the backrest tilt relative to the seat part to lockable positions with prior art solutions for optimising the sitting comfort.

The backrest of the chair can also be equipped with armrests that are connected by joints to the lateral surfaces of the backrest and foldable from the normal position of the armrest to a position that is parallel to the backrest thus facilitating the transfer of a person from bed to chair or from chair to bed, etc., in the lateral direction of the chair. The chair can also be equipped with footrests for allowing the person sitting in the chair to rest their feet.

The chair can also be equipped with a gripping element located in the upper part of the backrest to facilitate the transfer and handling of the chair performed by the caring person.

Preferably, the axles of the front wheel and/or the rear wheel of the chair are under the chair and, most preferably, the axles of all of the wheels of the chair are under the chair in all operating positions. Thus, the chair requires very little space and the chair is therefore easy to handle in confined spaces as well. For example, the chair can be moved very near the bed by the caring person so that it is easy for the person sitting on the chair to move from the chair to bed. Preferably, the outer edge of the rear wheel can extend by 1 to 3 cm over the contour of the backrest so that the chair can be completely tilted to the ground in such a way that the backrest is against the floor. Thus, for example, when a person sitting in the chair gets a sudden attack of illness, the caring person can set the chair to a position that is safe for the sitting person. If the chair comprises armrests and a gripping element, the armrests may be arranged in such a way that the armrests touch the ground instead of the backrest when tilting the chair completely against the floor, whereupon the gripping element arranged in the backrest remains slightly elevated from the floor thus enabling for the caring person who operates the chair to tilt the chair safely against the floor without the fingers of the caring person getting caught between the chair and the floor.

The width of the seat part of the chair may range between 45 cm and 55 cm and the total width of a chair equipped with armrests between 55 cm and 65 cm. Thus, when the chair has a width of a normal sitting chair, it is possible, for example, to place multiple chairs side by side at a normal dining table or in other existing rooms.

The distance between the front wheels of a chair equipped with two front wheels may range between 20 cm and 40 cm, preferably 22 cm and 30 cm. The distance between the rear wheels of a chair equipped with two rear wheels may range between 20 and 40 cm, preferably 25 and 35 cm. The distance between the axles of the front wheel and the rear wheel may range between 30 cm and 60 cm, preferably 32 cm and 50 cm. The diameter of the front wheels and the rear wheels may range between 7 cm and 15 cm, preferably 8 cm and 12 cm, the wheels thus being easy to locate under the chair frame. Thanks to small wheels located near each other, the chair can be easily shifted between the operating modes and the turning radius of the chair is very small making it easy to handle the chair in the transfer position in confined spaces as well.

The different operating modes and technical solutions of the chair are described below with figures, in which Figure 1 is a phased sequence of images illustrating the different operating modes of the chair and shifting between them,

Figure 2 illustrates the positioning of the wheel constructions and fixed standing supports,

Figure 3 is a basic drawing illustrating the different operating positions of the chair,

Figure 4 shows a basic embodiment of the height position adjustment mechanism of the front wheels of the chair,

Figure 5 shows a second basic embodiment of the height position adjustment mechanism of the front wheels of the chair,

Figure 6 illustrates a third basic embodiment of the height position adjustment mechanism of the front wheels of the chair.

Figure 1 illustrates the principle of use of one embodiment of the chair and the positions of its different components in the different phases. In Phase A, when a person is sitting in the chair, the chair rests on fixed front standing supports 1 and the rear wheels 2 of the chair. The fixed front standing supports 1 equipped with a one-time height position adjustment are located in front of the front wheels 3 while the rear wheels 2 of the chair function as standing supports at the back of the chair. The front wheels 3 of the chair do not bear a load in Phase A and may either touch slightly the floor surface 5 or be 1 to 2 mm above the floor surface 5. Phase B illustrates the shift to the transfer position where the caring person tilts the chair backwards by pulling from the backrest 4 of the chair, whereupon the chair is supported to the rear wheels 2. In Phase C, the carer activates the mechanism for changing the height position of the front wheels 3 of the chair, whereupon the front wheels 3 of the chair move down to the bottom position and lock in a desired height position. The paths of the components of the mechanism for changing the height position of the front wheels 3 can be implemented in the different embodiments of the chair relying on several different principles, such as by using muscular strength of the caring person, hydraulically, in a motorised manner, or by means of spring force, such as with mechanical springs or positionally lockable gas springs.

When shifting from the transfer position of the chair back to the stable standing position of the chair, depending on the embodiment, gravity can also be used to provide the paths of the mechanism for changing the height position of the front wheels of the chair.

As an alternative motorised embodiment, the backward tilting of the chair can be performed with a mechanism equipped with an actuator, in which case the caring person activates the actuator via operating switches. In this embodiment, for the use of the actuator, the chair is equipped with an energy source, such as a chargeable battery, as well as operating switches and an arrangement for the actuator.

In another alternative embodiment, the backward tilting of the chair can be performed with a hydraulic actuator, in which case the caring person activates the actuator, for example, with hydraulic pressure generated by the movement of a foot pedal using a technical solution known per se.

The mechanism for changing the height position of the front wheels 3 of the chair may also be implemented separately for each wheel. The operation of the mechanism for changing the height position of the front wheels 3 of the chair and examples of different types of mechanisms are illustrated in more detail in Figures 3, 4, 5 and 6. In Phase D, the chair is supported to the front wheels 3 and the rear wheels 2 in the transfer position of the chair and the chair can be moved to a desired destination by the caring person.

The seat part and the backrest are supported to the chair frame 14 and the chair frame 14 forms the seat part and/or the backrest partly or completely. In the transfer position, the chair frame 14 is tilted backwards by 2 to 10 degrees from the fixed standing position. In Phase E, the chair has been moved to a desired destination and the caring person releases the height position lock of the front wheels 3 of the chair, whereupon the chair tilts forward onto the fixed standing supports by the gravity of the person sitting in the chair and the chair. In an alternative motorised embodiment, the caring person activates the actuator to return the mechanism for changing the height position of the front wheels to the position required by the fixed standing position of the chair. The chair can be equipped with an energy source, such as a chargeable battery, and an electrically operated mechanism including switching devices and actuators for changing the height position of the front wheels 3 using a technical solution known per se, where the caring person performs the tilting of the chair via the operating switch of the actuator. For example, a motor-driven screw mechanism or a linear motor drive can be used as an actuator.

In all of the Phases A to E of Figure 1, the centre of gravity of the chair and the person sitting in the chair is located in the area between the front wheels 3 and the rear wheels 2 of the chair so that stability is secured in all of the Phases A to E.

Figure 2 illustrates the positioning of fixed standing supports 1 and wheel constructions that bear load in the transfer position of the chair, of an embodiment of the chair. The fixed front standing supports 1 are located in front of the front wheels 3 and are fastened below the front part of the chair frame 14, to the chair frame 14. In the fixed standing position of the chair, the chair is supported to the floor surface 5 resting on the fixed standing supports 1 and the rear wheels 2 of the chair. When the chair frame 14 is tilted backward either by the caring person or with a motorised mechanism by shifting the height position of the front wheels, the rear wheels 2 of the chair are supported to the floor as fulcrums and the fixed front standing supports 1 of the chair are detached from the floor surface 5. In the transfer position of the chair, the chair leans to the floor resting on the front wheels 3 and the rear wheels 2. In addition to the fixed standing supports 1 located in front of the front wheels 3, the chair can also be equipped with fixed standing supports 13 installed in front of the rear wheels 2, under the rear part of the chair frame 14.

In this embodiment, the width of the seat part of the chair is 48 cm at the widest point. The chair has two front wheels 3 and two rear wheels 2. The chair frame 14 is an antibacterial, monolithic plastic construction and the axles of all of the front wheels 3 and rear wheels 2 are below the chair frame; that is, inside the plane determined by the sides of the frame 14, in all operating positions. The distance between the front wheels 3 is 24 cm and the distance between the rear wheels 2 is 29 cm. The thickness of the plastic construction of the frame 14 is 4 cm. The distance between the axles of castor-type front wheels 3 and rear wheels 2 is 35 cm when the transfer direction of the chair is forward towards the sitting direction of the chair. When the chair is moved backward to the opposite position with the backrest first, the distance between the axles of the front wheels 3 and the rear wheels 2 is 45 cm. The diameters of the front wheels 3 and the rear wheels 2 are 10 cm. The front wheels 3 and the rear wheels 2 are almost completely under the chair frame 14. Only the outer edge of the rear wheels 2 extends by about 2 cm over the frame 14 so that the centre of gravity of the chair and the person sitting in it constantly remains between the rear wheels 2 and the front wheels 3 and, if necessary, the chair can be easily tilted completely by the caring person in such a way that the backrest is against the floor.

In Figure 3, the transfer position of an embodiment of the chair is shown by illustrating the position of the chair frame 14 with a dash-dotted line as well as the tilting angle K between different positions. The fastening frame 6 included in the height position adjustment mechanism of the front wheels 3 is fastened to the chair frame 14 with a hinge joint 15. The hinge joint 15 is located in front of and above the rear wheels 2 in such a way that the tilting of the chair frame 14 and the height position change of the front wheels provide a change of position to the fastening frame 6, whereupon the castor angle of the castor-type front wheels 3 fastened to the fastening frame 6 correspondingly changes relative to the normal of the floor surface. The castor angle change improves the transfer properties of the chair in the transfer position of the chair. In the stable standing position of the chair, the castor angle of the front wheels 3 is parallel to the normal of the floor surface 5.

Figure 4 illustrates an embodiment of the mechanism for adjusting the height position of the front wheels of the chair as a basic solution. A fastening frame 6, to which the castor-type front wheels 3 of the chair are fastened, is connected to the frame construction 14 of the chair 6 with a hinge joint 15. In the embodiment of the figure, the swinging motion of the fastening frame 6 performed relative to the hinge joint 15 is provided with gas springs 16, which are fastened with an articulated joint 17 to the chair frame 14 at one end and connected by a joint to the fastening frame 6 at the other end. The gas springs 16 are of a valve-controlled type. The caring person controls the functions of the gas springs via an operating button 18 located in the backrest of the chair. The operating button 18 is located in the backrest of the chair, near a gripping element placed in the upper part of the backrest, enabling for the caring person to easily push and pull and tilt the chair by gripping it, the operating button 18 thus being easily close at hand for the caring person.

Figure 5 depicts another embodiment of the mechanism for adjusting the height position of the front wheels of the chair as a basic solution. In the embodiment of the figure, the swinging motion of the fastening frame 6 performed relative to the hinge joint 15 is provided with a hydraulic cylinder 19. The hydraulic pressure is provided by the caring person using a pump 21 operated by a foot pedal 20. Hydraulic hoses 22 are mounted between the pump 21 and the cylinder 19 through a valve 23. The caring person controls the functions of the mechanism with the valve 23 and the foot pedal 20. A corresponding basic solution can also be used in connection with a motorised actuator, in which case, for example, an actuator based on a screw principle or a linear motor is installed instead of a hydraulic cylinder and the chair is equipped with a chargeable electrical energy source and operating switches for the actuator. Operating switches for the actuator can be located, for example, in the upper part of the backrest of the chair, thus being under the control of the caring person. The actuators used have a position lock feature enabling a stepless selection of the tilting angle "K" of the chair in the transfer position of the chair within defined limit values.

Figure 6 shows an embodiment of the height position adjustment mechanism of the front wheels of the chair based on the use of mechanical springs for providing the movement of the fastening frame 6. The fastening frame 6 and the construction of the front wheels 3 of the chair fastened thereto are identical with the basic solutions described above. The swinging motion of the fastening frame 6 is provided with mechanical spring-operated actuators 24. The actuators 24 comprise a tubular frame, guided by the inner surface of which it is possible to move helical springs 25 and push bars 26 in the axial direction by spring force or an external force within a desired operating range. The actuators 24 are equipped with a spring-operated locking mechanism 27, which can be released, for example, with a solenoid 28 or a mechanical lever assembly, controlled by the caring person. The caring person tilts the chair backward, whereupon the helical springs 25 provide the swinging motion of the fastening frame 6. The spring-loaded locking mechanism 27 locks the push bar 26 and the fastening frame 6 connected by a joint thereto in the position required by the transfer position of the chair and the caring person allows the chair to tilt forward onto the wheel constructions, to the transfer position of the chair. When shifting to the static standing position of the chair after performing the transfer of the chair and the person, the caring person releases the lock of the push bar 26 of the actuator 24 with an arrangement related thereto and the chair returns by gravity to the static standing position, to rest on the fixed standing supports 1.

The purpose of use and the operating principle of the invention as well as some practical solution examples of the technical solution principles of different functions and mechanisms are described above. The structural details of the care chair according to the invention are not restricted to the basic solutions described above but may vary in many ways within the limits of the characteristic features of the independent claim.

For example, in the embodiments where, instead of changing the height position of the front wheels of the chair, the height position of the rear wheels or the front wheels and the rear wheels or the standing supports is changed for shifting the chair between operating modes, in the technical implementation of the mechanism, it is possible to use electrical, hydraulic, pneumatic or spring-operated actuators described above or other structural details known to a person skilled in the art within the limits of the characteristic features of the independent claim.

Claims

1. A convertible chair comprising

- a seat part with a front edge and a rear part, the sitting direction of the chair being from the rear part of the seat part towards the front edge,

- a backrest, and

- a chair frame (14) to which the seat part and the backrest are supported or which forms the seat part and/or the backrest partly or completely,

- fixed standing supports for supporting the chair in a first operating mode, which is a static standing position for a person with reduced mobility to sit,

- at least one rear wheel (2) and at least one front wheel (3) for supporting the chair in a second operating mode, and

- equipment for transferring a load from the standing supports to said front wheel and said rear wheel, that is, from the first operating mode to the second operating mode and back to the standing supports to the first operating mode, characterised in that

- said equipment for shifting the chair between the first and the second operating modes comprises operating means arranged to be operated by a caring person on the backrest side of the chair, and

- said equipment comprises tilting means for tilting the chair frame (14) about a fixed point formed by said rear wheel (2) between the first and the second operating modes to a tilting angle (K) of 1.5 to 25 degrees, most preferably 2 to 10 degrees.

2. A convertible chair according to Claim 1, characterised in that said equipment for shifting the chair between the first and the second operating modes comprises a height adjustment mechanism for changing the height position of said front wheel (3) between an upper and a lower height position and locking it in the lower height position, in which lower height position the chair is in the second operating mode and in which upper height position the chair is in the first operating mode.

3. A convertible chair according to Claim 1 or 2, characterised in that said equipment for shifting the chair between the first and the second operating modes comprises a height adjustment mechanism for changing the height position of said rear wheel (2).

4. A convertible chair according to any of Claims 1 to 3, characterised in that, when shifting between the first operating mode and the second operating mode, the height position of said front wheel (3) relative to the chair frame (14) is arranged to change more than the height position of said rear wheel (2).

5. A convertible chair according to any of Claims 1 to 4, characterised in that said equipment for shifting the chair between the first and the second operating modes comprises a height adjustment mechanism for changing the height position of said standing supports.

6. A convertible chair according to any of Claims 1 to 5, characterised in that, in the transfer position, the chair frame (14) is tilted backward by 1.5 to 25 degrees, preferably 2 to 10 degrees, from a fixed standing position.

7. A convertible chair according to any of Claims 1 to 6, characterised in that at least one standing support is formed from a rear wheel (2) equipped with a brake.

8. A convertible chair according to any of Claims 1 to 7, characterised in that, for the first operating mode, the chair is equipped with at least one separate fixed standing support (1) located in front of said front wheel (3) and, for the second operating mode, the chair is equipped with a load-bearing rear wheel (2) and a front wheel (3) maintaining the stability of the chair.

9. A convertible chair according to Claim 8, characterised in that the fixed standing support (1) of the chair is fastened to the chair frame (14) and equipped with a lockable height adjustment.

10. A convertible chair according to any of Claims 2 to 9, characterised in that, as the rear wheel (2), there is one or more directionally locked castor-type running wheels fixedly fastened to the chair frame and, as the front wheel (3), there is one or more castor-type running wheels, the height position of which relative to the chair frame (14) are arranged to be changed via a height adjustment mechanism fastened to the chair frame (14) when shifting between the operating modes of the chair.

11. A convertible chair according to any of Claims 2 to 10, characterised in that the height adjustment mechanism of the front wheel (3) includes a fastening frame (6), which is connected to the chair frame (14) with a hinge joint (15) and to which the front wheel (3) is fastened, where the swinging motion of the fastening frame (6) on the hinge joint (15) relative to the chair frame (14) provides the height position shift of the front wheel (3).

12. A convertible chair according to any of Claims 2 to 11, characterised in that the height adjustment mechanism of the front wheel (3) includes an electrical actuator.

13. A convertible chair according to Claim 12, characterised in that the height adjustment mechanism includes control equipment located in the upper part of the backrest.

14. A convertible chair according to any of Claims 2 to 11, characterised in that the height adjustment mechanism of the front wheel (3) includes a pneumatic or hydraulic actuator.

15. A convertible chair according to Claim 14, characterised in that the height adjustment mechanism includes a foot-operated pump equipment for operating the actuator.

16. A convertible chair according to any of Claims 2 to 11, characterised in that the height adjustment mechanism of the front wheel (3) includes a spring-operated actuator.

17. A convertible chair according to any of Claims 12 to 16, characterised in that said actuator is arranged to swing the fastening frame (6) on a hinge joint (15) relative to the chair frame (14).

18. A convertible chair according to any of Claims 1 to 17, characterised in that the chair frame (14) is a monolithic die-cast plastic construction, wherein the seat part and the backrest are in a fixed position relative to each other.

19. A convertible chair according to any of Claims 1 to 17, characterised in that the seat part and the backrest of the chair are separate structural components articulated with each other and the backrest tilting is adjustable to lockable positions.

20. A convertible chair according to any of Claims 1 to 19, characterised in that the chair is equipped with second fixed standing supports (13), which are installed under the rear part of the chair frame (14), in front of the rear wheel (2).

21. A convertible chair according to any of Claims 1 to 20, characterised in that the chair comprises a gripping element located in the upper part of the backrest for a caring person to grip the chair.

22. A convertible chair according to any of Claims 1 to 21, characterised in that the axles of the front wheel (3) and/or the rear wheel (2) are under the chair.