Motion mechanism for a chair and chair

1 . A motion mechanism for a chair, the motion mechanism being configured to effect a coordinated movement of a chair seat and chair back of the chair, wherein a seating surface of the chair seat extends essentially in a front-rear direction and a left-right direction of the chair, wherein the chair back is arranged at a rear side of the chair seat, the motion mechanism comprising:

a mechanism configured to support the chair seat and to couple the chair seat to a chair base assembly;

a spherical joint configured for coupling the chair seat and the mechanism at a central position in the left-right direction of the mechanism and the chair seat;

a first back support configured to couple the chair back to the mechanism, wherein a first end of the first back support is coupled via a first rotary connection to the mechanism, wherein a second end of the first back support is configured for coupling to the chair back; and

a second back support configured to couple the chair back to the mechanism, wherein a first end of the second back support is coupled via a second rotary connection to the mechanism, wherein a second end of the second back support is configured for coupling to the chair back;

wherein an axis of rotation of the first rotary connection extends in the front-rear direction and an axis of rotation of the second rotary connection extends in the front-rear direction, and wherein the second end of the first back support comprises a first flexible connection for coupling to the chair back, and wherein the second end of the second back support comprises a second flexible connection for coupling to the chair back.

2 . The motion mechanism of claim 1 , wherein a back surface of the chair back essentially extends in the left-right direction and an up-down direction perpendicular to the seating surface, wherein the first flexible connection comprises a first elastic element configured to enable an elastic movement of the back surface of the chair back with respect to the second end of the first back support in the up-down direction, and wherein the second flexible connection comprises a second elastic element configured to enable an elastic movement of the back surface of the chair back with respect to the second end of the second back support in the up-down direction.

3 . The motion mechanism of claim 2 , wherein the first flexible connection is arranged spaced from the second flexible connection in the left-right direction.

4 . The motion mechanism of claim 1 , wherein the first rotary connection is arranged spaced from the second rotary connection in the left-right direction.

5 . The motion mechanism of claim 1 , wherein the first rotary connection comprises a first pin extending in the front-rear direction, wherein a first end of the first pin is mounted at the mechanism and a second end of the first pin is rotatably inserted in a hole in the first end of the first back support, wherein the second rotary connection comprises a second pin extending in the front-rear direction, wherein a first end of the second pin is mounted at the mechanism and a second end of the second pin is rotatably inserted in a hole in the first end of the second back support.

6 . The motion mechanism of claim 1 , wherein the first back support has an L-shape extending from the first end of the first back support to the second end of the first back support, and wherein the second back support has an L-shape extending from the first end of the second back support to the second end of the second back support.

7 . The motion mechanism of claim 1 , wherein the spherical joint is arranged, in the front-rear direction, between a center and the rear side of the chair seat.

8 . A motion mechanism for a chair, the motion mechanism being configured to effect a coordinated movement of a chair seat and chair back of the chair, wherein a seating surface of the chair seat extends essentially in a front-rear direction and a left-right direction of the chair, wherein the chair back is arranged at a rear side of the chair seat, the motion mechanism comprising:

a mechanism configured to support the chair seat and to couple the chair seat to a chair base assembly;

a first back support configured to couple the chair back to the mechanism, wherein a first end of the first back support is coupled via a first rotary connection to the mechanism, wherein a second end of the first back support is configured for coupling to the chair back; and

a second back support configured to couple the chair back to the mechanism, wherein a first end of the second back support is coupled via a second rotary connection to the mechanism, wherein a second end of the second back support is configured for coupling to the chair back;

a first sliding connection coupling the chair seat to the chair back, wherein the first sliding connection is arranged at a left side of the chair seat and chair back, and

a second sliding connection coupling the chair seat to the chair back, wherein the second sliding connection is arranged at a right side of the chair seat and chair back;

wherein an axis of rotation of the first rotary connection extends in the front-rear direction and an axis of rotation of the second rotary connection extends in the front-rear direction, and wherein the second end of the first back support comprises a first flexible connection for coupling to the chair back, and wherein the second end of the second back support comprises a second flexible connection for coupling to the chair back.

9 . The motion mechanism of claim 8 , wherein the first sliding connection is configured to enable a coordinated sliding movement in the front-rear direction and an up-down direction perpendicular to the seating surface, and wherein the second sliding connection is configured to enable a coordinated sliding movement in the front-rear direction and the up-down direction.

10 . The motion mechanism of claim 9 , wherein the first sliding connection comprises a guiding slot extending in the front-rear and up-down directions and a first pin slidingly supported in the guiding slot, and wherein the second sliding connection comprises a guiding slot extending in the front-rear and up-down directions and a second pin slidingly supported in the guiding slot.

11 . The motion mechanism of claim 10 , further comprising a locking mechanism mounted at the mechanism and configured to engage with at least one of the first and second back supports for inhibiting a rotation of the at least one of the first and second back supports upon actuating the locking mechanism.

12 . The motion mechanism of claim 11 , wherein the locking mechanism comprises a lock plate movable in the front-rear direction, wherein the lock plate comprises a protruding lock form configured to engage into a corresponding recess provided in the at least one of the first and second back supports in a locked state of the locking mechanism, and to disengage from the corresponding recess in an unlocked state of the locking mechanism.

13 . A chair, comprising:

a chair base assembly;

a chair seat;

a chair back; and

a motion mechanism to support the chair seat and to couple the chair seat to the chair base assembly, the motion mechanism comprising

a first back support configured to couple the chair back to the mechanism, wherein a first end of the first back support is coupled via a first rotary connection to the mechanism, wherein a second end of the first back support comprises a first sliding connection for coupling to the chair back; and

a second back support configured to couple the chair back to the mechanism, wherein a first end of the second back support is coupled via a second rotary connection to the mechanism, wherein a second end of the second back support comprises a second sliding connection for coupling to the chair back;

wherein an axis of rotation of the first rotary connection extends in a front-rear direction and an axis of rotation of the second rotary connection extends in the front-rear direction;

wherein the motion mechanism is attached to the chair base assembly, the chair seat being attached to the mechanism of the motion mechanism, and the chair back being attached to the first and second back supports of the motion mechanism.