MOTION MECHANISM FOR A CHAIR AND CHAIR

Abstract

A motion mechanism for a chair effects a coordinated movement of a chair seat and chair back. The motion mechanism comprises 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, and a second back support configured to couple the chair back to the mechanism. A first end of the first back support and a first end of the second back support are coupled via rotary connections to the mechanism. A second end of the first back support and a second end of the second back support are configured for coupling to the chair back. An axis of rotation of the first rotary connection extends in a front-rear direction of the chair and an axis of rotation of the second rotary connection extends in the front-rear direction.

Claims

1-18. (canceled)

19. 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; 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.

20. The motion mechanism of claim 19, 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.

21. The motion mechanism of claim 20, wherein the first flexible connection is arranged spaced from the second flexible connection in the left-right direction.

22. The motion mechanism of claim 19, wherein the first rotary connection is arranged spaced from the second rotary connection in the left-right direction.

23. The motion mechanism of claim 19, 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.

24. The motion mechanism of claim 19, 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.

25. The motion mechanism of claim 19, further comprising 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.

26. The motion mechanism of claim 25, wherein the spherical joint is arranged, in the front-rear direction, between a center and the rear side of the chair seat.

27. The motion mechanism of claim 19, further comprising: a third sliding connection coupling the chair seat to the chair back, wherein the third sliding connection is arranged at a left side of the chair seat and chair back, and a fourth sliding connection coupling the chair seat to the chair back, wherein the fourth sliding connection is arranged at a right side of the chair seat and chair back.

28. The motion mechanism of claim 27, wherein the third 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 fourth sliding connection is configured to enable a coordinated sliding movement in the front-rear direction and the up-down direction.

29. The motion mechanism of claim 28, wherein the third sliding connection comprises a guiding slot extending in the front-rear and up-down directions and a third pin slidingly supported in the guiding slot, and wherein the fourth sliding connection comprises a guiding slot extending in the front-rear and up-down directions and a fourth pin slidingly supported in the guiding slot.

30. The motion mechanism of claim 29, 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.

31. The motion mechanism of claim 30, wherein the locking mechanism comprises a lock plate movable in the front- and 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.

32. 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 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; 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.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0032] Embodiments of the invention will be described with reference to the accompanying drawings.

[0033] FIG. 1 is a schematic isometric exploded view of a chair having a chair motion mechanism according to an embodiment.

[0034] FIG. 2 is a schematic cross-sectional side view of the chair of FIG. 1 in a zero tilt position.

[0035] FIG. 3 is a schematic isometric view of the chair of FIG. 1 viewed from a rear right side.

[0036] FIG. 4 is a schematic isometric view of the chair of FIG. 1 viewed from a front left side.

[0037] FIG. 5 is a schematic side view of the chair of FIG. 1 in a zero tilt position.

[0038] FIG. 6 is a schematic side view of the chair of FIG. 1 in a back tilted position.

[0039] FIG. 7 is a schematic front view of the chair of FIG. 1 in a position tilted to the left.

[0040] FIG. 8 is a schematic front view of the chair of FIG. 1 in a position tilted to the right.

[0041] FIG. 9 is a schematic rear view of the chair of FIG. 1 in a position tilted to the left.

[0042] FIG. 10 is a schematic rear view of the chair of FIG. 1 in a position tilted to the right.

[0043] FIG. 11 is a schematic partial isometric view of the chair of FIG. 1 in a position tilted to the right.

[0044] FIG. 12 is a schematic partial isometric view of the chair of FIG. 1 in a position tilted back and to the left.

[0045] FIG. 13 is a schematic isometric exploded view illustrating details of a locking mechanism of the chair motion mechanism of FIG. 1.

[0046] FIG. 14 is a schematic partial isometric view of the locking mechanism of FIG. 14.

[0047] FIG. 15 is a schematic partial isometric view of the locking mechanism of FIG. 14 in an unlocked state.

[0048] FIG. 16 is a schematic partial isometric view of the locking mechanism of FIG. 14 in a locked state.

DETAILED DESCRIPTION OF THE INVENTION

[0049] 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 noted otherwise. Same reference signs in the various drawings refer to similar or identical components.

[0050] FIG. 1 shows a chair 100 which includes a motion mechanism 200. The chair 100 is illustrated to be an office-type chair having a chair base assembly 150 and a superstructure. The superstructure includes a chair seat 101, a chair back 102 and the motion mechanism 200 which connects the chair seat 101, the chair back 102 and the chair base assembly 150. The motion mechanism 200 may effect a coordinated motion of the chair back 102 and the chair seat 101. The chair base assembly 150 includes a pedestal column 151, a number of support legs 152 extending radially from the column 151 and a corresponding number of casters 153 supported on the outer ends of the support legs 152. Additionally, a gas cylinder 154 or other lifting mechanism may be supported by the column 151 to enable the height of the chair seat 101, and thus of the chair superstructure, to be adjusted by an occupant.

[0051] The terms front, rear, left, right, up and down, as used herein, have been defined above. It is to be understood that the terms forward, rearward and lateral as used herein, also each have a particular meaning that is defined in relation to a flat support surface beneath the chair 100 and in relation to an occupant of the chair. For example, the term forward refers to a direction moving away from the chair back 102 and in front of a chair occupant along an axis which extends parallel to such a flat support surface, while the term rearward refers to a direction opposite to the forward direction. The term lateral refers to a generally horizontal direction perpendicular to both the forward and rearward direction and extending parallel to the aforementioned flat support surface. For example, terms like to the left and to the right are lateral directions as seen from an occupant sitting on the chair.

[0052] The motion mechanism 200 comprises a base mechanism 201 which is arranged at the top side of the gas cylinder 154 and which is configured to support the chair seat 101. Furthermore, the motion mechanism 200 comprises a first back support 211 and a second back support 221. Each of the first and second back supports 211, 221 are L-shaped and extend from the base mechanism 201 to a rear side 108 of the chair back 102. The first and second back supports 211, 221 are mounted at a back support plate 207 of the base mechanism 201. The chair seat 101 is mounted at a seat support plate 206 of the base mechanism 201. The back support plate 207 and the seat support plate 206 are movably connected at the mechanism 201 such that the first and second back supports 211, 221 and the chair seat 101 may be tilted in a coordinated manner under the control of the base mechanism 201. For example, the chair seat 101 and the chair back 102 may be movable between a zero tilt position shown in FIG. 5 and a back tilted position shown in FIG. 6. In the zero tilt position, a seating surface 103 of the chair seat 101 may extend essentially in a front-rear direction 104 as indicated by a double arrow in FIG. 1 and in a left-right direction 105 as indicated by a double arrow in FIG. 1. In the zero tilt position, the back surface 108 of the chair back 102 may extend essentially in an up-down direction 109 as indicated by a double arrow in FIG. 1 and in the left-right direction 105. When moving from the zero tilt position to the back tilted position, an upper part of the chair back 102 may travel a longer distance in the rearward direction than a lower part of the chair back 102 thus inclining the chair back 102. The chair seat 101 may move in a coordinated manner together with the chair back 102, for example a rear side 111 of the chair seat 101 may be lowered and a front side 110 of the chair seat 101 may be raised when the chair back 102 is moving from the zero tilt position to the back tilted position. A movement from the zero tilt position to the back tilted position and reverse may be controlled by an occupant sitting on the chair 100. The occupant may control the chair 100 to take any position between the zero tilt position and the back tilted position shown in FIGS. 5 and 6, respectively.

[0053] The chair seat 101 is mounted at the seat support plate 206 via a spherical joint 202 and two elastic buffer elements 204 and 205, for example rubber pads. The spherical joint 202 may be arranged, viewed in the left-right direction, in the center of the chair seat 101. Viewed in the front-rear direction, the spherical joint 202 may be arranged between a center and the rear side 111 of the chair seat 101. The spherical joint 202 may comprise a bearing seat 203 arranged between the seat support plate 206 and a lower surface of the chair seat 101. The spherical joint 202 may allow the chair seat 101 to be tilted around an axis of rotation in the left-right direction 105 and an axis of rotation in the front-rear direction 104 with respect to the seat support plate 206. The elastic buffer elements 204 and 205 may be arranged near the front side 110 of the chair seat 101. For example, in the left-right direction 105, the buffer element 204 may be arranged between a center of the chair seat 101 and a left side of the chair seat 101, and the buffer element 205 may be arranged between the center of the chair seat 101 and a right side of the chair seat 101. As a result, the chair seat 101 is mounted at three positions at the seat support plate 206. The three positions constitute a triangle.

[0054] A first end 212, i.e. the lower end, of the first back support 211 is rotatably mounted at the back support plate 207 via a first rotary connection 214. A first end 222, i.e. the lower end, of the second back support 221 is rotatably mounted at the back support plate 207 via a second rotary connection 224. The axes of rotation of the first rotary connection 214 and the second rotary connection 224 are parallel to each other, extend in the front-rear direction 104, and are arranged spaced in the left-right direction 105. As shown in FIG. 1, the first rotary connection 214 may comprise a first pin 216 mounted at the back support plate 207 and a first hole 217 provided in the first end 212 of the first back support 211. The first pin 216 and the first hole 217 may cooperate as a plain bearing. The second rotary connection 224 may comprise a second pin 226 mounted at the back support plate 207 and a second hole 227 provided in the first end 222 of the second back support 221. The second pin 226 and the second hole 227 may cooperate as a plain bearing. The first and second rotary connections 214, 224 may be implemented in any other suitable way, for example by means of roller bearings, or by pins at the first ends and holes or bushings provided at the back support plate.

[0055] For example, as shown in more detail in FIG. 13, in each hole 217, 227 a corresponding bushing 220, 230 may be provided. The bushings 220, 230 may be made of metal or any other adequate material for constituting a plane bearing in connection with the pins 216, 226. For securing the first back support 211 at the first rotary connection 214, a first bolt 1312, for example a screw, may be provided at the free end of the first pin 216. The first bolt 1312 may be covered by a first cap 1313. For securing the second back support 221 at the second rotary connection 224, a second bolt (not shown in FIG. 13), for example a screw, may be provided at the free end of the second pin 226. The second bolt may be covered by a second cap 1323.

[0056] The motion mechanism 200 comprises furthermore a locking mechanism 1300. The locking mechanism 1300 comprises a lever 1301 which may be operated by an occupant to set the locking mechanism 1300 in either a locked state or an unlocked state. In the locked state, the locking mechanism 1300 engages with at least one of the first and second back supports 211, 221 to inhibit a rotation of the corresponding back support(s). In the unlocked state, the locking mechanism 1300 is disengaged from the first and second back supports 211, 221. Further details concerning the locking mechanism 1300 will be described in connection with FIGS. 13 to 16.

[0057] As further shown in FIG. 1, a second end 213, i.e. the upper end, of the first back support 211 is coupled to the back surface 108 of the chair back 102. The second end 213 may be coupled to the back surface 108 via a first sliding connection 215. The first sliding connection may enable sliding of the back surface 108 of the chair back 102 with respect to the second end 213 of the first back support 211 in the up-down direction 109. The first sliding connection 215 may comprise for example a sliding piece 218 mounted at the second end 213 of the first back support 211 and a track 219 mounted at the back surface 108 of the chair back 102. The sliding piece 218 may be engaged with the track 219 such that the sliding piece 218 is retained by the rail 219 and is slidable in the up-down direction 109 with respect to the rail 219. A second end 223, i.e. the upper end, of the second back support 221 is coupled to the back surface 108 of the chair back 102. The second end 223 may be coupled to the back surface 108 via a second sliding connection 225. The second sliding connection 225 may enable sliding of the back surface 108 of the chair back 102 with respect to the second end 223 of the second back support 221 in the up-down direction 109. The second sliding connection 225 may comprise for example a sliding piece 228 mounted at the second end 223 of the second back support 221 and a track 229 mounted at the back surface 108 of the chair back 102. The sliding piece 228 may be engaged with the track 229 such that the sliding piece 228 is retained by the rail 219 and is slidable in the up-down direction 109 with respect to the rail 229.

[0058] The second ends 213, 223 may be coupled to the back surface 108 of the chair back 102 in any other appropriate manner, for example by means of flexible connections, for example elastic elements configured to enable an elastic movement of the back surface 108 with respect to the second ends 213, 223 in the up-down direction 109. The elastic elements may be made of rubber or silicone and may be integrated, at least partially, in the back surface 108.

[0059] In any way, the coupling between the second ends 213, 223 and the back surface 108 may be configured such that a traveling distance in the up-down direction 109 of the few millimeters, for example at least 5, 10 or 20 mm is achieved. The coupling of the second end 213 to the back surface 108 is arranged spaced from the coupling of the second end 223 to the back surface 108 in the left-right direction 105. A movement of the second end 213 with respect to the back surface 108 may be independent from a movement of the second end 223 with respect to the back surface 108.

[0060] FIG. 2 shows a sectional side view of the superstructure of the chair 100 in an assembled state. In particular, FIG. 2 shows a sectional view through the spherical joint 202 and a sectional view through the second rotary connection 224 and the second sliding connection 225. Although these components are not located within the same sectional plane, they are shown commonly in FIG. 2 for reasons of clarity and brevity.

[0061] As furthermore shown in FIGS. 1 and 2, a lower side of the chair back 102 is coupled to the rear side 111 of the chair seat 101, for example via sliding connections. For example, a sliding connection 250 (named third sliding connection in the claims) may be arranged at the left side of the chair 100 between the lower side of the chair back 102 and the rear side 111 of the chair seat 101, and a further sliding connection 260 (named fourth sliding connection in the claims) may be arranged at the right side of the chair 100 between the lower side of the chair back 102 and the rear side 111 of the chair seat 101. Each of the sliding connections 250, 260 may be composed of a corresponding long hole or slot 251, 261 provided in the lower side of the chair back 102, and a corresponding pin 252, 262 provided at the rear side 111 of the chair seat 101. The pin 252 is arranged within the slot 251. The pin 262 is arranged within the slot 261. The slot 251 defines a traveling path for the pin 252 in the up-down and front-rear directions 104, 109. Likewise, the slot 261 defines a similar traveling path for the pin 262 in the up-down and front-rear directions 104, 109. As a result, the lower side of the chair back 102 is movable with respect to the rear side 111 of the chair seat 101 along the traveling paths. Furthermore, rotation of the lower side of the chair back 102 with respect to the rear side 111 of the chair seat 101 is achieved by a cylindrical shape of the pins 252, 262. It is to be noted that traveling of the pin 252 in the slot 251 at the left side of the chair is independent from traveling of the pin 262 in the slot 261 at the right side of the chair.

[0062] FIG. 3 shows a perspective view of the chair 100 of FIG. 1 in an assembled state in a rear right view. The chair 100 is in a zero tilt position, i.e. the chair back 102 is essentially in an upright position and the chair seat 101 is essentially in a plane position.

[0063] FIG. 4 shows a perspective view of the chair 100 of FIG. 3 in a front left view. Handlebars, for example for adjusting the height of the chair 100 or controlling tilting of the chair back 102 and/or the chair seat 101 are not shown in the figures for reasons of clarity.

[0064] The functioning of the motion mechanism 200 will be explained in the following with respect to FIGS. 5 to 12.

[0065] FIG. 5 shows the chair 100 in the zero tilt position. The chair back 102 is essentially in an upright position and the chair seat 101 is essentially in a plane position. When an occupant is sitting on the chair 100, the occupant may lean back against the chair back 102. Upon the force being exerted on the chair back 102 by the occupant in the rear direction, the chair back 102 may be tilted as shown in FIG. 6. The tilting motion is communicated by the first and second back supports 211, 221 via the back support plate 207 to the base mechanism 201. Within the base mechanism 201, the back support plate 207 is mechanically coupled to the seat support plate 206 such that a coordinated movement of the back support plate 207 and the seat support plate 206 is achieved. As a result, the chair seat 101 is moved by the seat support plate 206 in the rearward direction and at the same time tilted such that the rear side 111 of the chair seat 101 is lowered and the front side 110 of the chair seat 101 is raised as shown in FIG. 6. The base mechanism 201 may provide a restoring force, for example by means of a spring arrangement within the base mechanism 201, which urges the chair back 102 and the chair seat 101 back into the zero tilt position when the force exerted by the occupant on the chair back 102 is released. As can be seen in FIGS. 5 and 6, when moving from the zero tilt position to the tilted position, the second ends 213, 223 of the first and second back supports 211, 221 may move in the up-down direction with respect to the back surface 108 of the chair back 102. The first and second sliding connections 215, 225 enable such movement. Furthermore, the lower side of the chair back 102 moves and rotates with respect to the rear side 111 of the chair seat 101 as enabled by the sliding connections 250, 260.

[0066] Alternatively or additionally, an occupant sitting on the chair 100 may lean to the left or to the right. For example, when leaning to the left, the occupant may exert force on the left side of the chair seat 101 in the downward direction. As discussed above, the chair seat 101 is coupled to the base mechanism 201 via the spherical joint 202 and the buffer elements 204, 205. Upon a force in the downward direction on the left side of the chair seat 101, the chair seat 101 may tilt to the left as shown in FIG. 7. It is to be noticed that FIG. 7 is a front view such that the left side as seen from an occupant sitting on the chair 100 is at the right side in FIG. 7.

[0067] The chair seat 101 may rotate around an axis of rotation in the front-rear direction 104 with the axis of rotation passing through the spherical joint 202. Buffer element 204 may be compressed whereas buffer element 205 may be unloaded or stretched. An angle of rotation 701, i.e. the angle of the tilting to the left, may depend on the amount of force being exerted on the left side of the chair seat 101, and may be restricted by the spherical joint 202 and/or the buffer elements 204, 205. The buffer elements 204, 205 may provide a restoring force urging the chair seat 101 back in the zero tilt position when being unloaded.

[0068] When an occupant sitting on the chair 100 leans to the right, a force is exerted on the right side of the chair seat 101 in the downward direction. Upon the force in the downward direction on the right side of the chair seat 101, the chair seat 101 may tilt to the right as shown in FIG. 8. It is to be noticed that FIG. 8 is a front view such that the right side as seen from an occupant sitting on the chair 100 is at the left side in FIG. 8. The chair seat 101 may rotate around the axis of rotation provided by the spherical joint 202 in the front-rear direction 104. Buffer element 205 may be compressed whereas buffer element 204 may be unloaded or stretched. An angle of rotation 801, i.e. the angle of the tilting to the right, may depend on the amount of force being exerted on the right side of the chair seat 101 and may be restricted by the spherical joint 202 and/or the buffer elements 204, 205.

[0069] Simultaneously, the chair back 102 may be tilted to the left or right, for example upon a force exerted by the occupant's back on the chair back 102 or exerted via the sliding connections 250, 260 from the chair seat 101 on the lower side of the chair back 102. FIG. 9 shows the chair back 102 in a position tilted to the left by a tilt angle 702. FIG. 10 shows the chair back 102 in a position tilted to the right by a tilt angle 802. It is to be noticed that FIGS. 9 and 10 are front views such that, in contrast to FIGS. 7 and 8, the left side as seen from an occupant sitting on the chair 100 is at the left side in FIGS. 9 and 10, and the right side as seen from an occupant sitting on the chair 100 is at the right side in FIGS. 9 and 10. Tilting the chair back 102 to the left or to the right is enabled by the first and second rotary connections 214, 224 which enable rotation of the first ends 212, 222 of the first and second back supports 211, 221 with respect to the back support plate 207 as illustrated in FIGS. 9 and 10. As can be seen from FIGS. 9 and 10, contact points 901, 902 between the second ends 213, 223 and the back surface 108 of the chair back 102 may vary in the up-down and direction 109 when tilting the chair back 102 from a zero tilt position to the tilted positions, i.e. tilted to the left as shown in FIG. 9 or tilted to the right as shown in FIG. 10. For example, a distance 910 between contact point 901 and a reference line 920 at the back surface 108 of the chair back 102 becomes smaller when tilting the chair back 102 from the left to the right. A distance 911 between contact point 902 and the reference line 920 becomes larger when tilting the chair back 102 from the left to the right. This may be compensated by the sliding connections 215, 225 as discussed above or by corresponding flexible connections provided at the contact points 901, 902 between the second ends 213, 223 and the back surface 108 of the chair back 102.

[0070] As explained above, the tilting of the chair back 102 may be effected by a force communicated via the sliding connections 250, 260 from the chair seat 101. However, it to be noticed that the tilt angle 702, 802 of the chair back 102 and the tilt angle 701, 801 of the chair seat 101 may be different and independent from each other. Due to the sliding connections 250, 260, there is a degree of freedom for the chair back 102 to vary its tilt angle with respect to the chair seat 101. For example, the tilt angle 702, 802 of the chair back 102 may be varied within the range of a few degree, for example 5 to +5, with respect to the tilt angle 701, 801 of the chair seat 101. In detail, the pin 262 of sliding connection 260 may vary its position within the slot 261 independent from a position of the pin 252 of sliding connection 250 within the slot 251.

[0071] For example, as shown in FIG. 11, sliding connections 250, 260 may effect that the chair back 102 is tilted to the right with respect to the chair seat 101. In another example, as shown in FIG. 12, the sliding connections 250, 260 may effect that the chair back 102 is tilted to the left with respect to the chair seat 101.

[0072] Additionally, as shown in FIGS. 11 and 12, the sliding connections 250, 260 allow an independent tilting of the chair seat 101 and the chair back 102 around an axis of rotation in the left-right direction 105, i.e. a tilt angle of the chair back 102 in the front-rear direction is independent from a tilt angle of the chair seat 101 in the up-down direction.

[0073] FIG. 13 illustrates details of the locking mechanism 1300. The locking mechanism 1300 is provided at the back support plate 207 of the base mechanism 201. The locking mechanism 1300 comprises a lever 1301 and a lock plate 1302. The lever 1301 can be rotated around an axis of rotation extending in the front-rear direction 104. Upon rotation of the lever 1301, the lock plate 1302 may be moved in the front-rear direction 104. For example, a peg 1303 may be provided at the lever 1301 which engages into a cam slot profile 1304 provided at the lock plate 1302. The lock plate 1302 has two protruding lock forms 1310 and 1320. The protruding lock form 1310 is configured such that it can engage into a matching recess 1311 provided at the first end 212 of the first back support 211, when the lock plate 1302 is moved in the rearward direction. The protruding lock form 1320 is configured such that it can engage into a matching recess 1321 provided at the first end 222 of the second back support 221, when the lock plate 1302 is moved in the rearward direction. When the lock form 1310 is engaged into the recess 1311 and the lock form 1320 is engaged into the recess 1321, rotation of the back supports 211, 221 in the left-right direction is inhibited. Thus, when the lock plate 1302 is moved in the rearward direction, the locking mechanism 1300 is in the locked state. On the other hand, when the lock plate 1302 is moved in the forward direction, the lock forms 1310, 1320 are disengaged from the recesses 1311, 1321 such that the back supports 211, 221 can be rotated in the left-right direction and the locking mechanism 1300 is in the unlocked state.

[0074] FIG. 14 shows the locking mechanism 1300 of FIG. 13 in an assembled state, wherein in FIG. 14 the back support 221 is not shown for reasons of clarity.

[0075] FIG. 15 shows the locking mechanism 1300 in an enlarged view in the unlocked state. The lock plate 1302 is in a forward position, for example upon a movement in the forward direction caused by the lever 1301. In the forward position, the lock plate 1302 is spaced apart from the first ends 212, 222 of the first and second back supports 211, 221 and close to the back support plate 207. In this forward position, the protruding lock forms 1310 and 1320 are disengaged from the recesses 1311, 1321 provided in the first and second back supports 211, 221, and the first and second back supports 211, 221 can be rotated in the left-right direction 105 around the axis of rotation provided by the first and second rotary connections 214, 224.

[0076] FIG. 16 shows the locking mechanism 1300 in an enlarged view in the locked state. The lock plate 1302 is in a rearward position, for example upon a movement in the rearward direction caused by the lever 1301. In the rearward position, the lock plate 1302 is close to or in contact with the first ends 212, 222 of the first and second back supports 211, 221 and spaced from the back support plate 207. In this rearward position, although not visible in FIG. 16, the protruding lock forms 1310 and 1320 are engaged with the recesses 1311 and 1321 provided in the first and second back supports 211, 221. As a result, a rotation of the first and second back supports 211, 221 in the left-right direction 101 is blocked.

[0077] While exemplary embodiments have been described in the context of office-type chairs, the tilt mechanism 100 and the chair 101 according to embodiments of the invention are not limited to this particular application. Rather, embodiments of the invention may be employed to effect a coordinated motion of a chair back and the chair seat in a wide variety of chairs.