FIELD OF THE INVENTION

The invention relates to an actuator mechanism for a chair and to a chair. The invention relates in particular to an actuator mechanism for integration in a chair seat. BACKGROUND OF THE INVENTION

For a wide variety of applications, chairs are nowadays provided with one or more functions that can be actuated by a person sitting on the chair. Such functions may for example include adjustment of a height of the chair, adjustment of a tilt angle of a seat part of the chair, adjustment of a tilt angle of a back part of the chair, or locking or releasing a tilt movement of the chair. By way of example, one or more of such functions may be provided in an office chair.

For controlling such functions, the chair needs to be provided with one or more actu- ating elements, such as levers or knobs. To enable comfortable usage of such actuating elements, these are preferably arranged at locations which are easily accessible to a person sitting on the chair, e.g., below the seat part of the chair. However, in some cases there may be only limited space available for incorporating an actuator mechanism which mechanically translates motion of the actuating elements into operation of the corresponding seat function. On the other hand, increasing the size of seat components or adding additional seat components to accommodate the actuator mechanism might not be desirable from a design or cost perspective.

Accordingly, there is a need for user-friendly actuator mechanisms for chair functions which can be efficiently integrated into chair structures.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an actuator mechanism according to claim 1 and a chair according to claim 15. The dependent claims define further embodiments. Accordingly, an actuator mechanism according to an embodiment has the purpose of being used in a chair, for controlling a function of the chair. Examples of such function are adjustment of a height of a chair seat, adjustment of a tilt angle of a chair seat of the chair, adjustment of a tilt angle of a back of the chair, shifting of a seat of the chair with respect to a back of the chair, or locking or releasing a tilt movement of the chair. The actuator mechanism comprises a screw shaft having an external thread. Further, the actuator mechanism comprises a lever configured to rotate the screw shaft and a shuttle engaged with the external thread of the screw shaft. By the engagement of the shuttle with the external thread of the screw shaft, rotation of the screw shaft caused by the lever translates into a linear motion of the shuttle along the screw shaft. The function of the chair is controlled by the linear motion of the shuttle. By using the screw shaft to convert the rotary motion caused by the lever into a linear motion, the actuator mechanism can be built with a compact configuration which is substantially confined to a plane including the direction of the linear motion of the shuttle. Further, also forces acting within the actuator mechanism can be confined to a plane including the direction of the linear motion of the shuttle, which facilitates building the actuator mechanism with sufficient mechanical strength. By way of example, the actuator mechanism could be integrated in the chair seat, using the space provided within the horizontal plane of the chair seat. In this case, the lever could be arranged at the edge of the chair seat, so that it can be easily reached and operated by a person sitting on the chair. The screw shaft could then be arranged in parallel to the edge of the chair seat, which means that the lever can be conveniently operated by an upward pulling action.

According to an embodiment, the actuator mechanism further comprises a spring ar- ranged to be tensioned by the linear motion of the shuttle. By tension in the spring by the linear motion of the shuttle, a force required to operate the lever can be adjusted to a desired level.

According to an embodiment, the actuator mechanism further comprises a Bowden cable coupled to the shuttle and configured to control said function of the chair. By using the Bowden cable, the function of the chair can be efficiently controlled, even if a mechanism for implementing the function of the chair is located remotely from the actuator mechanism. However, in addition to or as an alternative to a Bowden cable, the actuator mechanism could also comprise a linkage mechanism configured to con- trol the function of the chair. For example, a mechanism for implementing the function of the chair could be located in the vicinity of the actuator mechanism and this mechanism and the actuator mechanism could be coupled directly by the linkage mechanism. According to an embodiment, the actuator mechanism comprises a further screw shaft having an external thread, a further lever configured to rotate the further screw shaft; and a further shuttle engaged with the external thread of the further screw shaft. In this case, rotation of the further screw shaft caused by the further lever translates into a linear motion of the further shuttle along the further screw shaft, and a further function of the chair can be controlled by the linear motion of the further shuttle. In this way, the actuator mechanism can be enhanced to support multiple functions of the chair. At the same time, a compact configuration of the actuator mechanism may be maintained because both screw shafts may be arranged in the same plane, e.g., parallel to each other. By way of example, if the actuator mechanism is arranged in a chair seat of the chair, both screw shafts could be arranged in parallel to an edge of the chair seat.

According to an embodiment, the external thread of the screw shaft has a first pitch and the external thread of the further screw shaft has a second pitch which is higher than the first pitch. In this way, different pitches on the screw shafts may be used to compensate for different ranges of linear motion required to control different functions of the chair. For example, control of the above-mentioned function of the chair may require a first range of said linear motion of the shuttle, while control of the above- mentioned further function of the chair requires a second range of the linear motion of the further shuttle, the second range being higher than the first range. This may be compensated for by making the second pitch higher than the first pitch. As a result, a range of motion of the lever which causes the first range of linear motion of the shuttle may be equal to a range of motion of the further lever which causes the second range of linear motion of the further shuttle. This is desirable from the perspective of user experience, because control of different functions of the chair can be achieved by lev- ers having similar characteristics.

According to an embodiment, the actuator mechanism having the screw shaft and the further screw shaft further comprises a first spring arranged to be tensioned by said linear motion of the shuttle and a second spring arranged to be tensioned by said linear motion of the further shuttle. In this case, the first spring may have a higher spring constant than the second spring. In this way, a force required to operate the lever and a force required to operate the further lever can be adjusted with respect to each other. Specifically, a force required for moving the lever to cause the first range of linear motion of the shuttle may be adjusted to be equal to a force required for moving the further lever to cause the second range of linear motion of the further shuttle. This is desirable from the perspective of user experience, because control of different func- tions of the chair can be achieved by levers having similar characteristics.

According to an embodiment, the actuator mechanism further comprises a support structure on which the screw shaft, the lever, and the shuttle are supported. If the actuator mechanism is integrated in a chair seat, the support structure may be different from an outer shell of the chair seat. For example, the support structure could be attached to the outer shell of the chair seat by screw attachment or gluing. By using the separate support structure, sufficient mechanical strength for supporting the elements of the actuator mechanism may be achieved without compromising the appearance of the outer shell of the chair seat. For example, if the outer shell of the chair seat is moulded from a plastic material, it can be avoided that the support structures are molded as part of the outer shell, which may adversely affect the appearance of the outer shell, because typically even structures which are arranged on the interior side of the outer shell will be visible due to "sinking" of the plastic material in the molding process.

According to a further embodiment, a chair is provided, e.g., an office chair. The chair has one or more functions, e.g., adjustment of a height of the chair, adjustment of a tilt angle of a seat of the chair, adjustment of a tilt angle of a back of the chair, shifting of a seat of the chair with respect to a back of the chair, or locking or releasing a tilt movement of the chair. The chair comprises a chair seat and at least one actuator mechanism as described above. The at least one actuator mechanism is integrated the chair seat. The at least one actuator mechanism is used for controlling the function^) of the chair. For controlling multiple functions of the chair, the chair may comprise multiple actuator mechanisms as described above, and/or one or more actuator mechanisms having multiple levers as described above.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will be described with reference to the accompanying drawings. Fig. 1 illustrates a chair with an actuator mechanism according to an embodiment of the invention.

Fig. 2 schematically illustrates components and operation of the actuator mechanism.

Fig. 3 illustrates an actuator mechanism according to an embodiment of the invention.

Figs. 4A and 4B illustrate operation of the actuator mechanism of Fig. 3. Fig. 5 illustrates an actuator mechanism according to a further embodiment of the invention.

Fig. 6 illustrates an actuator mechanism according to a further embodiment of the invention

DETAILED DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the invention will be described with reference to the drawings. While some embodiments will be described in the context of specific fields of application, such as in the context of an office-type chair, the embodiments are not limited to this field of application. The features of the various embodiments may be combined with each other unless specifically stated otherwise.

Fig. 1 shows a chair 10 according to an embodiment. The chair 10 is illustrated to be an office-type chair and has a chair seat 20, a chair back 30 and components to interconnect the chair seat 20 with the chair back 30. As further illustrated, the chair 10 also includes a base assembly with a pedestal column 50, support legs extending radially from the pedestal column 50, and castors arranged on the outer ends of the support legs. As further illustrated, a mechanism 40 is arranged on the pedestal column 50. The mechanism implements a number of functions of the chair 10, e.g., adjustment of a height of the chair 10, adjustment of a tilt angle of the chair seat 20 with respect to the pedestal column and/or with respect to the chair back 30, adjustment of a tilt angle of the chair back 30 with respect to the pedestal column 50 and/or with respect to the chair seat 20 of, shifting of the chair seat 20 with respect to the chair back 30, or locking or releasing a tilt movement of the chair 10. This tilt movement may for example involve concurrent tilting of the chair seat 20 and the chair back 30 in response to rocking movements of a person sitting on the chair 10. The adjustment of the height of the chair seat 20 may involve telescoping of the pedestal column, and this telescoping may be controlled by a gas cylinder which is pressurized when lowering the chair seat 20 and depressurized when lifting the chair seat 20. For controlling the functions of the chair 10, the chair is provided with actuating levers 1 10, 1 1 1 which are arranged at an outer edge of the chair seat 20. Accordingly, the actuating levers 1 10, 1 1 1 can be easily reached by a person sitting on the chair 10. By pulling the actuating lever 1 10, 1 1 1 upward, the corresponding function of the chair 10 can be activated. By way of example, in response to pulling the actuating lever 1 10 upward, the mechanism 40 may release a lock of the telescoping movement of the pedestal column 50, thereby enabling the person sitting on the chair 10 to adjust the heat of the chair seat 20. When releasing the actuating lever 1 10, it returns to its original position and the mechanism 40 locks the telescoping movement of the pedestal collagen 50 in the currently set position. In a similar manner, pulling the actuating lever 1 1 1 upward, the mechanism 40 could release a lock of the tilt movement of the chair 10.

The actuating lever 1 10 and the actuating lever 1 1 1 are each part of a corresponding actuating mechanism which is integrated in the chair seat 20. With reference to the actuating lever 1 10, structures and operation of such actuating mechanism 100 are schematically illustrated in Fig. 2. However, it is noted that a similar actuating mechanism could also be used for the actuating lever 1 1 1 or any other actuating lever of the chair 10. As illustrated in Fig. 2, the actuating mechanism 100 includes a screw shaft 120. The lever 1 10 is connected to the screw shaft 120 so that the screw shaft 120 is rotated about a longitudinal rotation axis (illustrated by a dotted line) when the lever 1 10 is operated, as illustrated by a solid arrow. The screw shaft 120 has a helix-shaped external thread. A shuttle 130, which is supported to be movable in a direction along the screw shaft 120, is engaged with the external thread of the screw shaft 120. For example, the shuttle 130 could be provided with an internal thread which matches the external thread of the screw shaft 120. However, it is also possible to utilize other features of the shuttle 130 to achieve engagement with the external thread of the screw shaft 120, e.g., one or more fixed protrusions of the shuttle 130, or balls or rollers which are rotatably supported on the shuttle 130. Accordingly, a rotation of the screw shaft 120, caused by operation of the lever 1 10, translates into a linear motion of the shuttle 130 along the screw shaft 120, as illustrated by an open arrow. In typical implementations, the range of rotation of the screw shaft 120 caused by operation of the lever 1 10 is between 30° and 180°. The corresponding linear displacement of the shuttle 130 may be in the range of 10 - 20 mm. The linear motion of the shuttle 130 is used for mechanically controlling a function of the chair.

As further illustrated, the actuator mechanism 100 includes a Bowden cable 140. The Bowden cable 140 has the purpose of transmitting the falls associated with the linear motion of the shuttle 130 to the remotely located mechanism 40, which implements the function of the chair 10 to be controlled by the lever 1 10. The Bowden cable 140 may for example extend through the chair seat 20 and through the pedestal column 50, so that it is not visible from the outside.

As illustrated, a wire of the Bowden cable 140 is coupled to the shuttle 130, while an outer sheath of the Bowden cable 140 is anchored on a support structure 160 of the actuator mechanism 100. In the illustrated example, the support structure 160 includes a first support element 161 , which is used for anchoring the outer sheath of the Bowden cable 140. Further, the first support element 161 and a second support element 162 of the support structure 160 are used for rotatably supporting the screw shaft 120. Addi- tional support structures may be provided as well, e.g., one or more support structures for guiding the linear motion of the shuttle 130. In the example of Fig. 2, the linear motion of the shuttle 130 releases tension in the Bowden cable 140. However, it is noted that in other implementation the linear motion of the shuttle 130 could also have the effect of increasing tension in the Bowden cable 140.

As further illustrated, a spring 170 is arranged between the shuttle 130 and the support structure 161 . In the illustrated example, the spring 170 is assumed to be a helical compression spring. Accordingly, when the shuttle 130 moves in the illustrated manner toward the support structure 161 , the spring 170 is tensioned. The tensioning of the spring 170 provides a resistance against the operation of the lever 1 10. Further, by selecting the spring 170 with a suitable spring constant, the force required for operating the lever 1 10 can be adjusted to a desired level, which is different from the force which would be needed for controlling the function of the chair 10. In this way, it can achieved that the lever 1 10 has a desirable crisp feel of operation. Further, the spring 170 may also provide for restoration of the shuttle 130 and the lever 1 10, when the lever 1 10 is released. It is noted that providing the spring 170 in the form of a helical compression spring is merely exemplary, and that other kinds of springs could be used as an alternative or in addition, e.g., other forms of compression springs, such as a gas spring, or an extension spring provided between the support structure 162 and the shuttle 130. Fig. 3 shows an example of an actuator mechanism which is based on the principles as explained in connection with Fig. 2. In the example of Fig. 3, the actuator mechanism includes a first lever 1 10A and a second lever 1 10B. Further, the actuator mechanism includes a first screw shaft 120A and a second screw shaft 120B, each provided with a helix like external thread. A first shuttle 130A is engaged with the first screw shaft 120A, so that a rotation of the first screw shaft 120A causes a linear motion of the first shuttle 130A. Similarly, a second shuttle 130B is engaged with the second screw shaft 120B, so that a rotation of the second screw shaft 120B causes a linear motion of the second shuttle 130B. As explained in connection with Fig. 2, the actuator mechanism of Fig. 3 includes a first spring which is tensioned by the linear motion of the first shuttle 130A, and a second spring which is tensioned by the linear motion of the second shuttle 130B. A first Bowden cable 140A is coupled to the first shuttle 130A, and a second Bowden cable 140B is coupled to the second shuttle 130B. The elements of the actuator mechanism are supported by a support structure 160, which is attached by screw fixation into the interior of an outer shell of the chair seat 20. The outer shell of the chair seat 20 and the support structure 160 are both formed of a molded plastic material. However, since the outer shell of the chair seat 20 and the support structure 160 are molded as separate parts, the presence of the support structure 160 does not adversely affect the appearance of the outer shell of the chair seat 20, e.g., due to sinking of the outer surface.

In the example of Fig. 3, the linear motion of the first shuttle 130A is used for mechanically controlling a first function of the chair 10, and the linear motion of the second shuttle 130B is used for mechanically controlling a second function of the chair 10. By way of example, the linear motion of the first shuttle 130A could be used for adjustment of the height of the chair seat 20, whereas the linear motion of the second shuttle 130B could be used for locking or releasing a tilt movement of the chair 10. As can be seen, with respect to each of the first lever 1 10A and the second lever 1 10B, the actuator mechanism of Fig. 3 is configured for operation as explained in connection with Fig. 2. In the example of Fig. 3, the first screw shaft 120A and the second screw shaft 120B are co-linear and arranged in parallel to the outer edge of the chair seat 20. In this way, the multiple levers 1 1 OA, 1 1 OB and associated components of the actuating mechanism can be accommodated in a space efficient manner.

Fig. 4A and 4B illustrate operation of the actuator mechanism of Fig. 3. Specifically, Fig. 4A shows the actuator mechanism in an unactuated state, with both levers 1 10A, 1 10B in a rest position. Fig. 4B shows the actuator mechanism in an actuated state of the first lever 1 10A, while the second lever 1 10B is in its rest position. As can be seen, by pulling the lever 1 1 OA upward from its rest position, the first screw shaft 120A is rotated, thereby causing a linear motion of the first shuttle 130A and controlling the corresponding function of the chair 10. In a similar manner, the second lever 1 1 OB could be pulled upward, thereby causing a linear motion of the second shuttle 130B and controlling the corresponding function of the chair 10.

The range of motion of the first shuttle 130A which is required for control of the corresponding function of the chair 10 may be different from the range of motion of the second shuttle 130B which is required for control of the corresponding function of the chair 10. In view of user experience it is however desirable that the range of motion of the levers 1 10A, 1 10B as required for controlling the different functions is substantially the same. In the illustrated actuator mechanism, this may be achieved by selecting the pitches of the pitches of the screw shafts 120A, 120B in such a way that the required range of linear motion of the first shuttle 130A and the required range of linear motion of the second shuttle 130B are obtained by the same range of motion of both levers 1 10A, 1 10B. Accordingly, if for the first shuttle 130A higher range of linear motion is required than for the second shuttle 130B, the first screw shaft 120A may be provided with a higher pitch than the second screw shaft 120B. Similarly, if for the first shuttle 130A lower range of linear motion is required than for the second shuttle 130B, the first screw shaft 120A may be provided with a lower pitch than the second screw shaft 120B.

Further, the functions controlled by the first lever 1 10A and the second lever 1 10B may require different forces exerted by the corresponding shuttle 130A, 130B. Further, also using different pitches on the first screw shaft 120A and on the second screw shaft 120B may result in different forces being required to move the shuttle 130A, 130B by rotation of the lever 1 10A, 1 10B. In view of user experience it is however desirable that the force which is required for operation of the levers 1 10A, 1 10B is substantially the same. In the illustrated actuator mechanism, this may be achieved by selecting the springs which are tensioned by the linear motion of the shuttles 130A, 130B in such a way that the force which is required for operation of the levers 1 10A, 1 10B is substantially the same. Accordingly, if for the first shuttle 130A a higher force is required to generate the linear motion than for the second shuttle 130B, the first spring, which is tensioned by the linear motion of the first shuttle 130A, may be selected with a lower spring constant than the second spring, which is tensioned by the linear motion of the second shuttle 130B. Similarly, if for the first shuttle 130A a lower force is required to generate the linear motion than for the second shuttle 130B, the first spring may be selected with a higher spring constant than the second spring.

As can be seen, even if multiple functions controlled by the actuator mechanism have different mechanical characteristics, this can be compensated for by appropriate selection of the pitches of the external thread of the screw shafts 120A, 120B and/or appropriate selection of the first and second springs.

In the above examples, it was assumed that the linear motion of the shuttle 130, 130A, 130B is transmitted via the corresponding Bowden cable 140, 140A, 140B to the remote mechanism 40 which implements the function of the chair 10. However, in some implementations, other mechanisms could be used for controlling a function of the chair 10 by the linear motion of the shuttlel 30, 130A, 130B. By way of example, one or more of the illustrated Bowden cables 140, 140A, 140B could be replaced by a linkage mechanism which is coupled to a mechanism located in the vicinity of the actuator mechanism. A corresponding example of an actuator mechanism is illustrated in Fig. 5.

As can be seen, the actuator mechanism of Fig. 5 is similar to that of Fig. 3 and includes the first lever 1 10A, the second lever 1 10B, the first screw shaft 120A, the second screw shaft 120B, the first shuttle 130A, and the second shuttle 130B. However, rather than including the first Bowden cable 140 a and the second Bowden cable 140 B, the actuator mechanism of Fig. 5 includes a first linkage mechanism 150A coupled to the first shuttle 130A, and a second linkage mechanism 150B coupled to the second shuttle 130B. In the illustrated example, the first linkage mechanism 150A is based on an internal lever which is in sliding engagement with a sloped face of the first shuttle 130A. Similarly, the second linkage mechanism 150B is based on an internal lever which is in sliding engagement with a sloped face of the second shuttle 130B. The first linkage mechanism 150A may for example be used for operating a mechanism which controls a function for shifting of the chair seat 20 with respect to the chair back 30. The second linkage mechanism 150B may for example be used for operating a mechanism which controls tilting of the chair seat 20 with respect to the chair back 30. These mechanisms may be implemented within the chair seat 20, in the vicinity of the actuator mechanism, so that direct coupling of the mechanism to the corresponding linkage mechanism is possible.

Further, while in the above examples it was assumed that elements of the actuator mechanism are supported on the support structure 160 which is different from the outer shell of the chair seat 20, it may in some implementations also be possible to support at least some of the elements of the actuator mechanism directly on the outer shell of the chair seat 20, thereby simplifying construction of the chair 10. A corresponding example of an actuator mechanism is illustrated in Fig. 6. As can be seen, the actuator mechanism of Fig. 6 is similar to that of Fig. 3 and includes the first lever 1 10A, the second lever 1 10B, the first screw shaft 120A, the second screw shaft 120B, the first shuttle 130A, and the second shuttle 130B. For a better overview, the first Bowden cable 140A and the second Bowden cable 140B are not illustrated. However, rather than including the support structure 160 as a separate component, the levers 1 1 OA, 1 10B, the screw shafts 120A, 120B, and the shuttles 130A, 130B are supported directly on molded parts of the outer shell of the chair seat 20.

While exemplary embodiments have been described in the context of office-type chairs, the actuator mechanisms and chairs according to embodiments of the invention are not limited to this particular application. Rather, actuator mechanisms as explained above may be employed in a wide variety of chairs. Further, it is noted that the illustrated actuator mechanisms may be modified in various ways. By way of example, the actuator mechanism could also include more than two levers and corresponding screw shafts and shuttles, thereby enabling support of more than two functions of the chair by the same actuator mechanism. Still further, a shuttle coupled to a Bowden cable and a shuttle coupled to a linkage mechanism could be combined in the same actuator mechanism.