HK1142783B - Office chair - Google Patents

Description

Office chair

The patent application is a divisional application; the original application date is 7/8/2005, the application number is 200580030132.8, and the invention name is 'office chair'. The original application is an international application with the international application number of PCT/US2005/024213, the international application date of 7/8 2005, and the national phase entry date of 3/8 2007.

Technical Field

The present invention relates to an office chair and, more particularly, to a molded office chair frame having a mesh fabric support.

Background

There are a variety of office and work chairs on the market, many of which have tilt control structures. The object of the present design is to provide a comfortable and ergonomic seating arrangement for the user which simultaneously provides the necessary support to the user for his comfort, even when the user is sitting in the chair in different positions, regardless of the height, weight or other physical characteristics of the user.

A typical office or task chair has a base, typically mounted on casters or fixed slides that rest on the floor, and has attached a support column to support the seat thereon. Mounted on the support column between the seat and back is a tilt control housing containing various controls, knobs and means for adjusting the height, tilt angle and various other adjustments of the chair to allow the user to personalize the chair to his or her preference. The chair may or may not include armrests, which may be fixed or adjustable in various positions. There are many devices for controlling the tilt angle of an office chair and such control devices are typically spring operated, operatively connected to the chair back and actuated by movement of the chair back. The springs may be of any configuration, such as leaf springs, coil springs or the like, and the tilt of the chair is generally controlled by the weight of the user pressing against the back portion. The chair is generally biased toward a substantially upright position such that the user must apply considerable pressure to tilt the back of the chair to a reclined position. The degree of tilt and the difficulty of operation of the tilt can be controlled by adjusting the tension of the spring so that as long as the user moves forward, the back of the chair generally moves forward pushing the user's back forward. Thus, the user feels pressure against his or her back when moving backwards in the chair, typically causing the user to feel that he or she is being pushed forward by the chair.

Preferably, the chair also has a lumbar support which is adjustable to the size or height of the user. There are many lumbar supports on the market, but most are permanently affixed to the chair. It is desirable that the lumbar support be easily detachable from the chair so that it can be removed when the user does not want such support on the chair back. The lumbar support may be attached to the front or back of the chair, or may be hidden within the upholstery of the chair. However, when the lumbar support is unlined, it is preferred that there be infinite adjustment of the fabric surface, which may include a mesh fabric from the lumbar region of the user's body to the pelvic region. It is further desirable that the armrests be adjustable so that the chair can accommodate users of any height. Many chairs have adjustable armrests that should be inclined in proportion to the seat and back of the chair so that the user feels comfortable in any position of the chair, while the user's arms remain level with the floor.

Finally, the chair fabric should provide adequate support for the user's weight and sufficient airflow around the chair and the user's body to maximize user comfort. It is common to use a padding with foam inside to provide support and comfort to the user, and to use a mesh weave to allow increased air circulation around the user. The mesh woven or net fabric must be pulled tight to comfortably support the user's weight while comfortably conforming to each user's unique body shape.

What is then needed is a fully adjustable office or work chair that is more adaptable to the user when the user wishes to recline without attempting to push the user's back upright.

Disclosure of Invention

It is therefore an object of the present invention to provide an adjustable office or work chair that can be reclined in an easily controlled manner at the user's will.

It is a further object of the present invention to provide an adjustable office chair that reclines according to the weight of the user, rather than according to the pressure exerted by the user on the chair back.

It is a further object of the present invention to provide an office chair that is fully adaptable to any individual user.

According to a first aspect of the invention, a chair includes a base, a seat supported by the base, a tilt mechanism between the seat and the base, a backrest coupled to at least one of the seat and the tilt mechanism, the tilt mechanism having a tilt spring, the tilt mechanism coupled to the seat such that the seat is movable relative to the tilt mechanism, wherein movement of the seat actuates the tilt spring to cause at least one of the seat and the backrest to tilt; the chair further comprises a tilt limiter movable between a first position in which the chair is tiltable and a second position; in the second position, the chair is not tiltable and the tilt limiter has a magnetic portion that facilitates full movement of the tilt limiter to at least one of the first and second positions.

According to a second aspect of the invention, the chair comprises: a base; a seat supported by the base; a tilt mechanism interposed between the seat and the base; a back coupled to at least one of the seat and the tilt mechanism, the back having a front side and a rear side; a lumbar support including a front pad and a rear frame, the front pad being freely positionable on the front side of the seatback and the rear frame being freely positionable on the rear side of the seatback; and the lumbar support is movable relative to the seat back because the front cushion and the rear frame maintain opposing positions on opposite sides of the seat back by an attractive force between at least one magnetic element disposed at a back of the front cushion and at least one magnetic element disposed at a front of the rear frame.

Drawings

Various other objects, features and advantages of the present invention will become apparent from the following description of the invention, taken in conjunction with the accompanying drawings, which are set forth by way of example only, and in which:

FIG. 1 is an isometric view of an office chair according to an embodiment of the present invention.

Fig. 2 is a left side view of the office chair shown in fig. 1.

Fig. 3 is a right side view of the office chair shown in fig. 1.

Fig. 4 is a front view of the office chair shown in fig. 1.

Fig. 5 is a rear view of the office chair shown in fig. 1.

Fig. 6 is a top view of the office chair shown in fig. 1.

Fig. 7 is a bottom view of the office chair shown in fig. 1.

Figure 8 is an exploded view of one embodiment of the office chair shown in figure 1.

Fig. 9 is an exploded view of the housing and tilt mechanism of the office chair shown in fig. 1 with the cover removed.

Fig. 10 is an exploded view of one embodiment of the housing and tilt mechanism shown in fig. 9.

FIG. 11 is a side view of one embodiment of a linkage arrangement by which the tilt mechanism and housing are attached to the seat and back of the office chair shown in FIG. 1 with the chair linkage in a substantially upright position.

Figure 12 is a side view of the same linkage arrangement as shown in figure 11, except with the chair in a fully reclined position.

Figures 13 through 15 are motion system diagrams of one embodiment of the parallel arms connecting the tilt mechanism to the seat and back.

Figure 16 is an isometric view of a preferred embodiment of the lumbar support of the office chair shown in figure 1.

Figure 17 is an isometric view of the opposite side of the lumbar support shown in figure 16.

Fig. 18 is an isometric view of the office chair of fig. 1 showing the front of the lumbar support device of fig. 16 and 17.

Fig. 19 is an isometric view of the office chair of fig. 1 showing the rear of the lumbar support device of fig. 16 and 17.

FIG. 20 is an enlarged view showing the structure of the mesh material that can be used for the seat cushion and the seat back.

Fig. 21 is an exploded view of an embodiment of a seat of the office chair shown in fig. 1.

Figure 22 is an exploded view of the back of the office chair shown in figure 1.

FIG. 23 is a partial cross-sectional view of one embodiment of the seat fabric and a peripheral portion attached thereto.

FIG. 24 is a partial cross-sectional view as in FIG. 23, further showing the over-molded portion.

Figure 25 is a cross-sectional view of the overmolded portion of figure 24 as it may be attached to a frame of a seat or backrest in accordance with embodiments of the present invention.

FIG. 26 is a cross-sectional view as in FIG. 25, except with portions cut away to show how the molded plastic portion attaches to the frame of the seat or the frame of the back in an embodiment of the present invention.

Detailed Description

Turning now to the drawings in detail, wherein like reference characters denote like elements, fig. 1-8 illustrate one embodiment of an adjustable chair, such as an office or task chair, according to the present invention. Fig. 1-7 show an isometric view (fig. 1) and right, left, front, rear, top and bottom views (fig. 2-7, respectively) of the chair 10. The exploded view shown in fig. 8 best illustrates the components of the chair 10, which generally includes a seat 12 and backrest 14 operatively mounted by parallel arms to a tilt control housing 16, with the tilt control housing 16 attached to a base 18 by a vertical support post 20. The base 18 preferably includes a set of radial extension legs 22 (e.g., 5 extension legs) that are preferably mounted with casters 24 to facilitate movement of the chair 10 about a work site. Alternatively, a fixed skid (not shown) may be used in place of the casters.

Preferably, the height of the vertical support column 20 is adjustable in a manner well known in the art, and a pair of adjustable armrests 26 are also preferably included. The armrest 26 may be similar to the adjustable armrest in applicant's U.S. patent application 10/769,061, which was granted as U.S. patent No. 6,824,218 on month 11 and 30 of 2004, to which reference will be made later. Alternatively, the chair 10 need not have the armrests 26.

The seat 12 and backrest 14 are each preferably formed of a resilient mesh material. Both the seat 12 and the backrest 14 are rotatably attached to the tilt control housing 16 by parallel arms 30, 32 so that the seat 12 and/or backrest 14 can be tilted relative to the tilt mechanism and/or each other, as will be described in greater detail below in connection with the figures.

Figures 9 and 10 best illustrate the construction of the tilt control housing 16, incorporating a tilt control mechanism 35, various knobs and handles for adjusting the chair 10 to allow the user to adjust the chair 10 as desired to provide a comfortable sitting position. For example, the tilt control structure 16 may include the enclosed tilt control structure 35, a tilt rate adjustment knob 38, a tilt lever 41, and a seat height adjustment lever 44.

The preferred embodiment of the present tilt control mechanism 35 includes first 46 and second 48 pivot shafts which are preferably hexagonal in shape and which are connected to first 52 and second 54 pairs of parallel links. The two pairs of parallel links are rotatable and connect the opposite side of the seat 12 to the tilt control structure. The first 52 and second 54 pairs of parallel links form the parallel arm 30, i.e. the first of the two pairs of parallel arms 30, 32 in figures 2 and 3. The seat 12 is connected to the parallel links 52, 54 by a seat bracket 61, and the seat bracket 61 can be injection molded into the underside of the inner frame of the seat 12, as will be described in more detail below. To provide a more secure engagement of the parallel links with the seat 12, the sleeve 53 and compression bushing 55 may be used with screws 57. This allows the screws 57 to be tightened sufficiently to securely connect the parallel links 52, 54 to the seat bracket 61 without binding the ends of the parallel links 52, 54 to the seat bracket 61, thereby allowing the parallel links 52, 54 to rotate freely relative to the seat bracket 61.

The tilt control structure 35 includes a torsion activated tilt spring 58. the tilt spring 58 may be associated with either of the pivot axes 46 or 48, but is preferably associated with the rearmost axle 46 (hereinafter referred to as the "drive" axle 46). The second frontmost shaft 48 will be referred to hereinafter as the "driven" shaft 48. Actuation of the tilt spring 58 from the drive shaft 46 at the rear provides a relatively small moment arm, meaning the effective distance at which a pair of parallel arms at the rear connect to the seat 12 and to the drive shaft 46. The relatively small moment arm allows for a tilt spring 58 that uses less and lower stiffness than tilt springs in conventional tilt control arrangements. The tilt spring 58 may be a conventional torsion-activated spring that includes a stiff outer cylindrical flat surface 60 that is adhered (e.g., glued) to a cylindrical inner resilient spring element 62. The center of the inner resilient spring member 62 has a bore 64 which is preferably hexagonal in shape to fit the hexagonal shaped drive shaft 46. The hexagonal shaped drive shaft 46 is passed through the bore 64 so that rotation of the drive shaft 46 causes the interior of the resilient spring member 62 to rotate. Since the outer portion of the resilient spring member 62 is held by the hard outer surface 60, the rotation of the inner portion creates a torsional force in the resilient spring member 62 that resists the tilting action of the seat 12 and backrest 14.

Referring now to fig. 11 and 12, side views show the parallel arms 30, 32, which connect the seat 12 to the tilt control housing 16 in a fully raised (upright) and fully lowered (reclined) position, respectively. As shown in these two and other figures, the tilting of the seat 12 and backrest 14 is accomplished by a plurality of sets of parallel links 52, 54 and 70 which form the parallel arms 30, 32 described above and which are rotatable and pivotally connect the seat 12 and backrest 14 to the tilt control housing 16. The seat 12 is preferably attached to the tilt control housing 16 by the first two pairs 52, 54 of links, with the first pair 54 of links being driven links attached to the front of the chair 10 and the second pair 52 of links being drive links operatively connecting the tilt control housing 16 to the rear of the chair 10. Each pair of links consists of (parallel) links attached to opposite sides of the tilt control housing 16 and the seat. The drive link 52 connects the seat 12 to a tilt spring 58, as described in more detail below. As best shown in FIG. 8, a single Y-shaped link 70 connects the lower middle portion of the backrest 14 to the tilt control housing, while the sides of the backrest 14 are rotatably connected to the connection points of the rearmost seat bracket 61 to which the drive link 52 is attached.

The tilt spring 58 controls the rate of tilt of the seat 12 and backrest 14. In the drive links 52, one end of each link is operatively attached to the tilt control housing 16, while the other end is pivotally mounted to the seat bracket 61.

Additional details of the tilt control structure 35 are best shown in fig. 9 and 10. The driven link 54 and the drive link 52 are rotatably connected at their ends to the seat bracket 61 and at their other ends to the driven shaft 48 and the drive shaft 46, respectively, through opposite sides of the tilt control housing 16. Preferably, the follower shaft 48 and the drive shaft 46 are hexagonal rods, which allow for either a tight connection with the links 52, 52 or rotation within the tilt control housing 16. The hexagonal shaped drive shaft 46 also facilitates actuation of the tilt spring 58 as it engages a hexagonal bore 64 through the center of the resilient spring member 62.

While the hexagonal shafts 46, 48 may be attached to the housing in any particular order, in the preferred embodiment shown, the drive shaft 46 is mounted at the rear of the seat 12 and the follower shaft 48 is mounted at the front of the seat 12. The follower shaft 48 is freely rotatable relative to the housing and has attached thereto a rotary washer, and a stop structure. The stop structure may include a washer 77 attached to and rotating with the follower shaft 48. The washer 77 may have a shoulder 78 that engages a flange 79 disposed on the interior of the tilt control housing 16. This stop structure is not a tilt control stop, but facilitates assembly of the tilt control mechanism 35. The drive shaft 46 may also have a similar stop feature, again using a similar washer 80 with shoulder 81. However, the shoulder 81 can also cooperate with a separate stop element 82, which is inserted over the drive shaft 46 and is held on the edge of the tilt control housing 16 by means of a spacer 83. This stop element is a full stop element which prevents further rotation of the drive shaft 46 at the point when the tilt mechanism 35 reaches full travel.

As shown, the drive shaft 46 is attached to and extends through the tilt control housing 16 and is operatively engaged with a tilt spring disposed at the rear of the tilt control housing 16 to shorten the moment arm as much as possible. The drive shaft 46 has a stop feature that engages a flange disposed on the interior of the tilt control housing 16 and acts as one of the stop, limiting elements of the tilt control mechanism 35. The tilt spring 58 controls the rate and amount of tilt of the seat 12 and backrest 14. When the drive link 52 is rotated (e.g., when a person sits on the seat), the drive shaft 46 rotates, causing the spring member 62 to rotate relative to the rigid cylindrical outer surface 60, thereby creating a torsional force on the tilt spring 58. The cylindrical surface 60 is, however, tethered to the interior of the tilt control housing 16 and generally prevents the spring from rotating. When the force urging rotation of the drive shaft 46 is removed (e.g., when the user is standing up from the chair 10), the tilt spring 58 will "unwind" restoring the drive link 52 and the seat 12 (and back) will return to the original upright position as the tilt spring 58 returns to the original position.

As shown in fig. 8 and 11-12, the backrest 14 is connected to the seat 12 at a common connection point with a drive link 52, the drive link 52 connecting the seat 12 to the tilt control housing 16. The seat back 14 is also rotatable via the Y-shaped link 70 and is connected to the tilt control housing 16. The Y-shaped link 70 and the drive link 52 combine to form the second parallel arm 32 between the seat 12/backrest 14 and the tilt control housing 16. The single pronged end 85 of the Y-shaped link 70 can be pivotally connected to the seat back in a variety of ways, such as by a T-shaped projection member 72 embedded in the lower middle portion of the seat back 14 that cooperates with a receiver member 74 embedded or fitted into the end 85 of the Y-shaped link 70. The receiver member 74 may have a T-shaped opening that pivotally receives the T-shaped protrusion member 72. The receiver member may be attached to the end of the Y-shaped link 70 using, for example, fasteners 76, and a resilient member 78 may be attached to the end of the T-shaped projection member 72, which allows the T-shaped member 72 to pivot within the T-shaped opening of the receiver member 74. In this manner, the backrest 14 may pivot substantially relative to the end 85 of the Y-shaped link 70 as the backrest 14 tilts.

The other end of the Y-shaped link 70 is a bifurcated end 87 which is rotatably attached at two points to the rear-most portion of the tilt control housing 16. Each of the bifurcated ends 87 of the Y-shaped link 70 is attached to an opposite face of the rearmost portion of the tilt control housing 16, which may be accessed using bolts 80 or other fasteners that provide a rotatable connection. Parallel arms 30, 32 connect the seat 12 and backrest 14 to the tilt control housing 16 to allow rotation, for example, the seat 12 and backrest 14 can tilt relative to the tilt mechanism 35 and each other. In this way, the inclination of the seat 12 can be varied with the inclination of the backrest 14. Preferably, when the parallel arms 30, 32 are in the fully upright position (as shown in FIG. 11), the seat 12 and/or backrest 14 are both tilted slightly forward. When a person sits down, the seat 12 and backrest 14 move back and down to a position where the seat 12 and backrest 14 are substantially horizontal or slightly rearward, depending on the weight of the person. As the user reclines, more weight is placed on the backrest 14 and the seat 12 and backrest 14 will further tilt to a fully reclined position, corresponding to the position shown in FIG. 12. The Y-shaped link 70 functions to assist in supporting the backrest 14 and assisting in reclining the backrest 14 in a controlled manner relative to the seat 12.

The parallel links 52, 54, Y-shaped link 70, seat 12 and backrest 14 of figures 13 through 15 are shown in kinematic diagram relation to the tilt control housing 16. The chair 10 is shown in a fully upright position in fig. 13, a fully reclined position in fig. 14, and both positions in fig. 15. The preferred embodiment of the invention developed and tested, the parallel arms 30, 32 have the dimensions and angles shown in figures 13-15 so that the seat 12 and backrest 14 can be tilted in a satisfactory manner as described herein.

The chair 10 appears to be horizontal in the vertical and rest positions. In practice, however, the seat 12 is preferably tilted forward, e.g., about 3 degrees forward. Thus, as the chair 10 is seen to be unoccupied, the seat 12 is generally tilted slightly forward. While this appears counterintuitive, each time a person sits in a chair designed with the linkage of the present invention, the chair 10 becomes level or slightly reclined, depending on the weight of the seated person. As previously discussed, when the user leans back on the backrest 14 to further tilt the chair 10, the parallel arms 30, 32 are designed to "open" slightly as the chair 10 tilts back. This arrangement is desirable because it prevents the seat 12 and backrest 14 from "closing," i.e., a clam-shell effect, in which the backrest 14 pushes the user's back forward, resulting in an uncomfortable feeling.

Because the drive link 52 and the follower link 54 are operatively connected to the tilt control housing 16 and the seat 12, rather than to the backrest 14 as is conventional, the reclining motion of the chair 10 of the present invention is directly related to the weight applied to the seat 12. I.e., the tilting motion of the chair 10 is controlled by the weight of the user more than the force exerted by the user on the backrest 14 of the chair 10. Thus, when the user moves from the reclined position to the vertical position, the user does not feel as strongly that the seatback 14 is pushed against the back of the user, even if the seatback 14 is in close contact with the back of the user. The reclining motion of the chair 10 has a "rest" in such a way that the chair maintains its position for a short period of time as the user returns to the upright position, thereby preventing the user from feeling as if they were being driven out of the chair. Thus, the chair tilt motion is "seat-driven" rather than "back-driven".

In addition, when a user sits down on the chair 10, the weight of the user causes the seat 12 to initially move downward, allowing the tilt spring 58 to store some level of energy. This potential energy is released when the tilt spring 58 is deployed, i.e., when a user attempts to stand up from the chair 10. This is actually to assist the user in standing up. Thus, the chair 10 is more comfortable for a person to sit or stand. In conventional chairs, pushing the back of the chair activates the tilt spring (i.e. back drive) and the only "aid" in standing up from the chair is the back pushing the person's back, which however is not helpful for the act of standing up from the chair. Conversely, it is uncomfortable and annoying for the back of the user to push back on the user's back when the user is sitting down or standing up.

The parallel arms 30, 32 connecting the seat 12 and backrest 14 to the tilt control housing 16 may be designed to provide a 1.2 to 1 ratio between the tilt angle of the seat 12 and the tilt angle of the backrest 14. When the chair 10 is reclined, the rear portion of the seat 12 moves downward relative to the front portion of the seat 12, reclining the seat 12. Since the angle of inclination of the seat 12 is a function of the user's weight, the tilting action is much smoother and more controlled. In addition, because the weight of the user is responsible for the tilting of the seat 12, gravity also assists the tilting action of the chair 10 so that the user can recline comfortably without having to exert more force on the back 14 of the chair 10.

The tension adjustment knob 38 is used to increase or decrease the initial tension applied to the tilt spring 58, i.e., to adjust the preload on the tilt spring 58. To make it more difficult or easier for a user to tilt the seat 12 and backrest 14 (depending on the weight of the user), the user may twist the tension knob 38 to increase or decrease the tension on the tilt spring 58.

Fig. 10 best illustrates the rotatable tensioning knob 38 described above, which is connected to a tensioning device connected to a tilt spring 58. As shown, the tension knob 38 is disposed below the tilt control housing 16 for convenient manual manipulation thereof by a user.

The tension control device is connected to a threaded rod 90 that extends from the tension knob 38 and is encased in the tilt control housing 16. The end of the screw 90 cooperates with a nut 92 and washer 94 that operatively engage the screw 90 and the hard outer surface 60 of the tilt spring 58. The retaining detent 96 ensures that the nut 92 never completely drops off the end of the screw 90. In the illustrated embodiment, a cantilever arm 98 extends outwardly from the outer surface 60, which may be integral with the stiff outer surface 60 of the tilt spring 58. Twisting the tension knob 38 (e.g., clockwise) draws the nut 92 toward the knob 38, and the nut 92 draws the cantilever arm 98 downward as well, rotating the tilt spring 58, thereby increasing the tension on the spring 58, which makes it more difficult to further compress the tilt spring 58, thereby making tilting of the seat 12 and backrest 14 more difficult and slower. Twisting the tension knob 38 in the opposite direction allows the tilt spring 58 to return to the initial position, even beyond the initial set position, thereby reducing the tension and allowing one to more easily tilt the seat 12 and backrest 14. Thus, by adjusting the tension knob 38, the user can preset the tension of the tilt spring 58 to adjust the degree and/or difficulty of the tilting motion of the seat 12 and backrest 14 when reclining the backrest. The drive shaft 46 is connected to the seat 12 by the drive link 52, the seat 12 and the backrest 14, so that the tilt spring 58 is also connected to the seat 12 through the drive shaft 46. Thus, the chair may tilt more or less depending on the weight of the user. This tilting action is "seat driven".

In addition, in tension adjustment, the use of a pair of rotatable parallel arm linkages rotatably connecting the seat 12 to the torsion spring allows for a lower rate tilt spring 58, a smaller moment arm, and an enhanced function of the tension adjustment knob 38. In particular, because the tilt spring 58 may have a lower spring rate, adjustment of the tension knob 38 is easier. In contrast, conventional tilt adjustment mechanisms use a stiffer tilt spring, which for simplicity reasons is easier to increase the tension of a stiffer spring than a stiffer spring.

The reason for the greater stiffness of the tilt springs is generally required is that conventional tilt chairs attach the tilt springs to the back of the chair rather than to the seat. The moment arm is increased due to the large distance between the connection to the back of the chair and the connection to the tilt spring (which is usually located just under the seat of the chair). The moment arm in conventional chairs is significantly longer and a higher stiffness tilt spring is required because the force applied to the spring is a function of the force applied to the end of the moment arm and the length of the moment arm. Thus, the tension adjustment for a higher stiffness tilt spring requires a relatively large amount of force to rotate the tension knob to preload the spring. One way to reduce the large amount of force required to rotate the tension knob is to use a longer cantilever arm extending from the tilt spring. However, a longer cantilever may require a larger tilt control housing. It will thus be appreciated that the great advantage of actuating the tilt spring through the seat rather than through the back is that this enables the moment arm to be shorter and therefore the stiffness of the tilt spring to be lower.

For user convenience, the tilt housing may have markings 40 or other indicators that cooperate with markings on the tension knob 38 to indicate different settings relative to the weight of different users. The user can quickly and easily rotate the tilt tension knob 38 to the appropriate setting using a weight setting that approximates his or her weight. Alternatively, the user may set the tension to a lighter weight to recline the seat 12 more quickly, according to the user's preference; or set at a higher weight to recline the seat 12 slower. For example, a person weighing 175 pounds may adjust the knob 38 to 175 pound setting, or may adjust to a higher or lower weight to make the tilting action more difficult or easier, respectively. In addition, the full tilt of the seat 12 can be defined by the position of the tilt lever 41.

The upper drive shaft 46 is also operatively connected to the tilt lever 41. The tilt lever 41 may define or set the degree of tilt for reclining when the seat 12 and back of the chair 10 are pulled outward by a person. Pulling the tilt lever 41 outward releases the restraining means.

Fig. 10 best shows the structure of the tilt lever 41, which is disposed, for example, to the left of the tilt control housing 16 (as shown), and includes a lever end 42 on the interior of the tilt control housing 16 and which cooperates with a tilt lock assembly. The tilt lock assembly 104 cooperates with the magnetic member 100 (and detent/stop 108) that allows the tilt lever 41 to move from a position in which it is released and allowed to tilt (where the tilt lever 41 is pulled outwardly from the tilt housing 16) to a position in which it locks and prevents tilting (where the tilt lever 41 is pushed inwardly into the tilt housing 16). The action of pushing the tilt lever 41 inwardly actuates the tilt lock assembly 104. the assembly 104 includes a tilt limiter member 105 that prevents the hexagonal follower shaft 48 from rotating when the assembly is actuated by the tilt lever 41. The tilt limiter element 105 is fixed in position inside the tilt control housing 16 by means of an inner bushing 106 and an outer bushing 107, operatively close to the magnetic element 100 and the positioning groove 108. The detent 108 cooperates with the magnetic element 100 as described below. The magnetic element 100 is disposed at or near the tip of the rod end 42 of the tilt lever 41. The detent 108 separates the opposing sidewalls 109, 110 and the magnetic element 100 has a segment 112 that is operatively disposed between the opposing sidewalls 109, 110. The sidewalls 109, 110 are made of a magnetically attractive material so that the magnetic element 100 will contact one of the faces if it is near the sidewalls 109, 110. When the tilt lever 41 is pushed in to lock the hexagonal follower shaft 48, the magnetic element 100 enters the innermost side wall 110 adjacent the detent 108, and the side wall 110 attracts the magnetic element 100, pulling it into contact with the side wall 109. In this position, the tilt lever 41 is fully moved to the lock position. The attraction of the magnetic member 100 to the detent 108 not only pulls the tilt lever 41 fully inward to ensure full inward movement, but also produces an audible cue, i.e., a "click," when the magnetic member 100 contacts the side wall 109. This "click" can be used to inform the user that the tilt lever 41 has been fully moved to the locked position. Conversely, pulling the tilt lever 41 outward causes the magnetic member 100 to enter the opposing side wall 110 proximate the detent 108, and the side wall 110 will likewise pull the magnetic member 100 into contact with the side wall 110, thereby ensuring that the tilt lever 41 is moved fully outward to the released position. As above, the contact of the magnetic member 100 with the side wall 110 also produces an audible "click" indicating that the tilt lever 41 has indeed been fully moved to the released position permitting tilting.

For greater comfort to the user, the backrest 14 preferably includes a lumbar support member. Referring to fig. 16-19, an embodiment of a lumbar support 200 for a chair 10 according to the present invention includes a front lumbar pad 202 and a rear lumbar frame 204. The lumbar pad 202 is intended to contact the user's body, while the rear lumbar frame 204 is tied to the lumbar pad by magnetic elements, such as magnets. The front pad 202 and the rear frame 204 are separable and preferably held in a magnet-cooperative relationship with each other on opposite sides of the seat back 14. Preferably, six magnets 208a to 208f are mounted on the front of the rear lumbar frame 204 and these are matched to the other six magnets 208a to 208f mounted on the front pad 202 and will attract the magnets on the lumbar frame 204. In this manner, the mesh fabric of the backrest 14 is sandwiched between the front pad 202 and the rear frame 204 of the lumbar support 200. Because there is no permanent connection between the lumbar support 200 and the backrest 14, the lumbar support 200 is vertically (and horizontally) adjustable along substantially the entire surface of the backrest 14. Thus, the lumbar support 200 is essentially infinitely adjustable from lumbar to pelvic support according to the user's preference. If desired, the user can move or adjust the lumbar support 200 at any time by moving the front pad 202 and the rear frame 204 will move due to the magnetic forces therebetween.

As shown in detail in FIG. 18, the front pad 202 may be made of injection molded plastic and is slightly curved to generally fit the user's lumbar region. The facing surface, i.e., the front surface of the lumbar pad 202 that contacts the user, is preferably made of a relatively comfortable material, such as a thermoplastic elastomer (TPE), gel or rubber, which is more comfortable for the user to rest his or her back against the backrest 14 and lumbar support 200. Both the front and back sides of the front liner 202 may be injection molded. In a preferred embodiment, the back surface is stiffer than the front surface, but still bendable. In this manner, when a user sits in the chair 10 and rests his or her back against the lumbar support 200, the back flexes along the mesh fabric 28 to support the user for comfort. The front pad 202, which contacts the back 14 of the chair, may have a fully molded portion of the holding magnet.

As mentioned above, the seat 12 and backrest 14 are preferably formed from the upper mesh material 28. It should be understood, however, that the material from which the seat back 14 is made may be any suitable and relatively thin material. Thus, the magnetic elements of the front pad 202 and the back frame 204 of the lumbar support 200 can be held in a cooperative relationship on either side of the material as the lumbar support 200 is adjusted.

Preferably, the seat 12 and backrest 14 are comprised of a frame of mesh fabric 28 having elasticity attached thereto. Referring to FIG. 20, the mesh fabric 28 preferably comprises a plurality of different types of materials, such as multifilament yarns and monofilament fibers, that allow the seat 12 and backrest 14 to be woven in a grid weave pattern. This may provide a more comfortable seating arrangement for the user so that air may freely circulate around the chair 10 and the user's body. The seat 12 and backrest 14 each comprise a molded frame having a mesh fabric incorporated therein, preferably by injection molding or other conventional plastic forming techniques, as will be described in greater detail below. As shown, the mesh fabric 28 is woven in a grid weave pattern in which the multifilament and elastomeric monofilament materials are arranged in a mutually perpendicular fashion, in a leno weave pattern. A leno weave is defined as a process in which adjacent warp fibers (i.e., monofilaments) are laid side-by-side, and one yarn is twisted between each weft of a weft yarn, thereby locking each weft. In the figures, multifilament yarn 250 is laid vertically and monofilament material 255 is woven from a pair of monofilament threads, typically in an "over/under" pattern, which alternates once between each multifilament thread. The fabric 28 is thus significantly capable of being held in a sufficiently taut position to firmly support the user's body.

A presently preferred embodiment of the construction of the seat 12 and backrest 14 is shown in fig. 8 and 21-26. As shown in FIG. 8, the seat 12 generally includes an inner frame 310 to which an outer frame 308 is attached, with fasteners 314 tying the two together. As shown in fig. 21, the outer frame 308 is made of a molding 305 that encases the rim portion 300 to which the mesh fabric 28 is attached. As shown in fig. 8 and 22, the seat back 14 is similarly made from an outer frame 309 that is tied to an inner frame 311 with fasteners 314. Wherein the outer frame 309 is also made of a moulding 306 which encases the edge portion 301 to which the mesh fabric 28 is attached.

The structure and mode of assembly of the seat 12 will be described in detail below, it being understood that the structure and mode of assembly of the backrest 14 is substantially the same as the structure of the seat 12. Thus, the structure of the seat back 14 will not be repeated below.

The internal frame 310 is the primary structural element that includes the area to secure the seat 12 to the tilt control housing 16. The outer frame 308 is preferably integral with the mesh fabric as described above, as will be described below. Because the outer frame 308 is positioned over the inner frame 310, similar to a wreath, the upper edge 312 of the inner frame 310 engages the mesh fabric 28. When the outer frame 308 is nested into the inner frame 310 from above, the outer perimeter of the mesh fabric 28 is pulled down the upper edge of the inner frame 310, causing the mesh fabric 28 to be taut, as necessary and desirable to provide support to a user sitting in the chair 10. The inner frame 310 is then attached to the outer frame 308 by a set of fasteners (e.g., mechanical bolts or the like) that are threaded through aligned holes molded at intervals around the inner frame and threadably engage screw holes in the outer frame 308. This approach is best shown in fig. 26. This locks the inner frame 310 and the outer frame 308 together and holds the mesh fabric 28 in a taut condition. It should be understood by those skilled in the art that other fastening methods may be used to lock the inner frame 310 and the outer frame 308 together. For example, electrical bonding and/or chemical bonding techniques, which are well known in the art, may also be used herein. In a preferred embodiment, both the inner frame 310 and the outer frame 308 have corresponding planar surfaces that facilitate the connection of the two pieces of the frame.

Fig. 21-26 illustrate the hierarchy of the outer frames 308, 309 of the seat 12 and backrest 14, respectively, in accordance with a presently preferred embodiment of the invention. With particular reference to the seat, the expandable mesh fabric 28 is initially integral with the outer rim portion, at which stage the mesh fabric 28 is generally in a relaxed or unstretched condition. To attach the edge portion 300, the loose mesh fabric 28 is placed in a jig and placed in an injection molding machine, and the edge portion 300 is injected along the outer edge of the mesh fabric 28 in the desired shape of the seat 12. The rim portion 300 is preferably made of a copolyester elastomer or polypropylene material and is injection molded to form the outer perimeter of the mesh fabric 28. The material of the edge portion 300 is selected with consideration of the temperature required to melt the material, i.e., for subsequent use in the injection molding technique, which should not damage the mesh fabric 28. Preferably, the temperature does not exceed about 200 degrees Celsius. This enables a permanent bond between the material of the rim portion 300 and the expandable mesh fabric 28. The outer perimeter of the mesh fabric 28 may extend outward of the rim portion 300, which may be trimmed or otherwise retained during the final production of the outer frame 308.

As shown, the outer frame 308 is substantially rigid, and in the final fabrication, a rigid material of a particular mass and geometry is continuously injected around the outer perimeter of the mesh fabric 28 and around the rim portion 300 to produce a composite outer frame assembly 308 that is not susceptible to expansion or deformation during the frame construction process. The injection molding material preferably comprises glass-filled or non-glass nylon or neoprene or polypropylene that is injection molded at the edge portion 300 at a temperature of no more than about 220 degrees celsius. The temperature is selected during injection molding to avoid significant melting of the edge portion 300. Since the injection molding does not touch the mesh fabric 28 beyond the edge portion 300, this process does not pose a risk of damage to the mesh fabric 28.

The outer frame 309 of the backrest 14 is constructed in substantially the same manner as the outer frame 308 of the seat. Thus, both the seat 12 and backrest 14 include a structural inner frame 310, 311 having a cross-section of a continuous perimeter. The outer frames 308, 309 of the seat 12 and backrest 14 also have a continuous outer perimeter cross-section. The inner 310, 311 and outer 308, 309 frames are preferably aesthetically pleasing and may be molded to any contour during the injection molding process. For example, the front surface of the seat frame may be curved downward to make the thighs more comfortable for the user when seated in the chair. In addition, a resilient insert or pad 317 is also preferably positioned at the front edge of the seat frame, between the mesh and the inner frame. The pad further relieves the pressure on the user's legs at the edge of the seat, which greatly improves the comfort of the seat.

Likewise, the backrest 14 may be contoured to provide comfort to the lower back of the user, as well as to provide comfort to the upper back portion adjacent the user's shoulders. Regardless of the shape of the seat 12 and backrest 14, the mesh fabric 28 is stretched from a relaxed state prior to assembly to a final stretched state in which the fabric 28 is sandwiched between the inner 310, 311 and outer 308, 309 frames, in which position the fabric 28 is sufficiently taut to adequately and comfortably support the weight of the user.

The design described above allows the outer surfaces of the outer frames 308, 309 to define the outer surfaces of the seat and back frames, making the outer surfaces of the seat and back frames cleaner and more aesthetically pleasing. Some chair designs use mesh fabric as the back and seat support, which is first supported on a frame portion that is then inserted into a channel in the outer surface of the seat and back frame members so that the two seams of the channel are clearly visible. This may make the chair less aesthetically pleasing. Current attachment methods create only a single seam between the outer frames 308, 309 and inner frames 310, 311, visible only from under or behind the chair. As can be seen, the front and side views of the chair 10 do not exhibit any visible seams between the outer frames 308, 309 and the inner frames 310, 311, resulting in a cleaner and smoother appearance. The seam between the inner and outer frames is visible only in the bottom and rear views.

As is conventional in such chairs, the vertical column of the chair 10 has a height adjustment structure. Referring to fig. 9 and 10, a tubular receptacle 320 in the tilt control housing 16 is visible from the rear of the tilt spring 58. Extending through the tubular receptacle 320 is an upper portion of the vertically adjustable column 20 that generally connects the base 18 and the tilt control housing 16 together. Adjacent the tubular receptacle 320 is mounted a height adjustment actuator 322 which cooperates with the upper end of the vertical column 20 to initiate vertical adjustment of the adjustable column 20. The vertical cylinder 20 may be an adjustable cylinder such as a conventional pneumatic piston/cylinder. The actuator 322 is pivotally locked to the base portion by a pair of retainers 324,325. The distal portion of the actuator 322 slightly covers the tubular receptacle 320 and cooperates with the upper end of the vertical column 20 to enable vertical adjustment thereof. The rod end 45 of the vertical adjustment control rod 44 is in the tilt control housing 16 and is operatively associated with the actuator 322 to pivot, causing the vertical adjustment actuator 322 to pivot about the locked end, such that the distal portion of the actuator 322 actuates the vertically adjustable column 20, and thus the height of the seat 12, to be raised or lowered. An elastic member 326 may be disposed between the rigid outer surface 60 of the tilt spring 58 and the vertical adjustment actuator 322, wherein the elastic member 326 may bias the height adjustment actuator 322 to a position that disables vertical adjustment of the vertically adjustable column 20 such that a user cannot adjust the height of the vertical column 20. The other end of the vertical adjustment lever is a handle configured for easy manual manipulation to move the height adjustment actuator 322 to a second position where the vertical adjustment function of the vertically adjustable column 20 is activated. The upward movement of the handle preferably raises or lowers the vertically adjustable column, releasing the handle and causing the resilient member 326 to automatically bias the height adjustment actuator 322 back to a position where vertical adjustment of the column 20 is disabled.

A multi-function and positionable office or task chair 10 is described herein that can accommodate users of various body shapes and heights in a variety of ways.

While specific embodiments of the invention have been shown in the drawings and described in detail, it will be appreciated by those skilled in the art that various alternatives can be developed in light of the disclosure herein. Accordingly, the particular embodiments disclosed herein are illustrative only and are not limiting to the scope of the invention as claimed, which includes all ranges subsumed by the claims appended hereto and all equivalents thereof.

Claims (4)

1. A chair, comprising:

a base;

a seat supported by the base;

a tilt mechanism interposed between the seat and the base;

a back coupled to at least one of the seat and the tilt mechanism, the back having a front side and a rear side;

a lumbar support including a front pad and a rear frame, the front pad being freely positionable on the front side of the seatback and the rear frame being freely positionable on the rear side of the seatback; and is

The lumbar support is movable relative to the seat back because the front cushion and the rear frame maintain opposing positions on opposite sides of the seat back by an attractive force between at least one magnetic element disposed at a back of the front cushion and at least one magnetic element disposed at a front of the rear frame.

2. The chair of claim 1, wherein the chair back material comprises a resilient mesh material.

3. A lumbar support for a chair back, comprising:

a front cushion and a rear frame, the front cushion being disposed in a freely positionable manner on a front side of a seat back and the rear frame being disposed in a freely positionable manner on a rear side of the seat back; and is

The lumbar support is movable relative to the seat back because the front cushion and the rear frame maintain opposing positions on opposite sides of the seat back by an attractive force between at least one magnetic element disposed at a back of the front cushion and at least one magnetic element disposed at a front of the rear frame.

4. The lumbar support of claim 3 wherein said seatback material comprises a resilient mesh material.