HK1188695A - Ergonomic adjustable chair mechanisms - Google Patents

Description

Ergonomic adjustable seat mechanism

Technical Field

The present invention relates to seat and stool mechanisms, including seat and stool mechanisms suitable for use in a work environment.

Background

Among the objectives of ergonomic chairs, particularly work chairs, there is a need to support the user in a posture that reduces stress and tends to maintain the spine in a "neutral" position, i.e., a posture in which the spine is aligned so that a seated user can comfortably work for longer periods of time. Most chairs are configured to support an occupant at least initially at a position where the thigh to torso angle is between about 90 and 110 degrees. Maintaining such a posture for a long time may be fatiguing and even painful, depending to some extent on the physical condition of the user. Sitting at seating angles that increasingly spread closer to the optimal on-center position, which is about 130 degrees, is comfortable and more comfortable. If a chair is not suitable for the user to increase his sitting angle, he may try to compensate, for example by sliding forward on the chair, thus leaving the lower part of the back unsupported. Over time, this can lead to discomfort and even injury. If the user wants to maintain a straight posture, he can sit on the front edge of the seat to angle his thighs downward to increase the seating angle. However, in such a position, the user cannot benefit from the back support of the chair, and over time, this position can be uncomfortable as the front edge of the chair is not typically designed to support the full load of the seated user.

Many chairs are designed to support the back by providing a back that can move back with the torso of the user to allow for an increased seating angle, the increased angle between the back and the seat providing support for a more comfortable seating angle. Such chairs typically have any of a variety of complex arrangements, such as linkages using heavy springs to react the back support, such as found in the allen-type chairs from helmann miller. Another back tilting device is a recliner lifting device, such as provided by the freestyle chair from hourse or the easy chair from nier, which uses the weight of the user to balance the reclining back and allow the user to recline their torso away from their thighs.

Such back-rest recliners tend to have deep seats making it difficult or impossible for a user to lower their thighs, with the result that the seating angle decreases if the user wishes to lean forward toward the countertop. In addition, there is often little or no back support for users in a forward leaning position. The mechanisms in such chairs are typically designed to allow the occupant to tilt away from the work surface, making access to the work surface and tools difficult in the reclined position.

Disclosure of Invention

Within the general object of the present invention, it is desirable to provide a seating mechanism by which a seat or leg support can be fully tilted forward under the control of a user while the user's spine and pelvis remain in a vertically aligned position, and do so without the use of springs or other force balancing devices. The present invention allows the user to maintain proper spinal and pelvic posture by controlling his sitting angle with his thighs. In addition, the present invention allows the user to change positions toward the countertop as the seating angle increases. Another object of the present invention is to provide a chair that maintains the position of the seat with a gradual reduction in thigh power as the seating angle increases.

In one aspect of the invention, a seating mechanism includes a frame supporting a seat having two sections including a thigh support and a receptacle adapted to receive a pelvis of a user. The thigh support is pivotally mounted to the front of the frame in a rocking up and down (seeslow) manner between its ends, mounted at a first pivot. The thigh support has front and rear extensions located forward and rearward of the first pivot axis, respectively. The pelvis bracket is pivotally suspended about a second pivot axis at about the rear of the thigh support. The front end of the thigh support is adapted to support a user's thighs, while the pelvis bracket is adapted to receive a user's pelvis and support the torso in vertical alignment with the pelvis. The seating angle can be adjusted by the user changing the degree to which his thighs exert pressure on the front of the front section. The first and second pivots and the front length of the first section are arranged to provide a mechanical advantage (mechanical advantage) sufficient for the user to balance the weight of his torso and pelvis with the weight of the thighs throughout the sitting angle. As the seating angle increases, the pivot of the support bracket rises and moves forward, causing the bracket to rise slightly and move the user forward closer to the countertop. As the pivot approaches vertical alignment, the force of the thigh necessary to maintain position is gradually reduced. In one embodiment of the invention, the bracket is allowed to pivot freely about the second pivot. In another embodiment, the brackets are connected to the frame by stabilizing links that cooperate with the thigh supports to form a somewhat parallel linkage by which the pelvic brackets maintain a substantially constant posture throughout the entire range of movement of the chair. By maintaining the bracket in a constant posture, the spine can be aligned with the pelvis throughout the entire range of movement of the mechanism. The mechanism may be used in a stool structure or may include a chair back and arm rests connected to a bracket.

In another aspect of the invention, a chair includes a chair seat and a chair back. The chair seat pivots at a first pivot to provide front and rear extension sections. The chair back pivots the second pivot to the rear portion of the seat and the stabilizing link is pivotally connected at one end to the frame and at the other end to the chair back. In this arrangement, the seat can be tilted forward under the influence of pressure applied by the user's thighs to support the user in a position with the spine and pelvis properly aligned vertically, while the parallelogram linkages maintain the chair in an upright position throughout its entire range of movement.

In a further aspect of the invention, the seat mechanism includes a seat or thigh support supported by a scissors mechanism having a parallelogram link extending from the frame to the rear of the bracket or seat back to maintain the bracket and seat back in an upright position with the spine aligned with the pelvis. A second control link connects the rear of the frame and the forward portion of the seat or thigh support to guide the front end of the seat in a downwardly arcuate path to enable the user to increase the seating angle while the parallelogram connection between the frame and the pelvic cradle or seat back maintains the cradle or seat back in a constant posture. In this embodiment, the thigh support or seat may be considered to have a movable virtual (virtual) pivot point throughout the entire range of movement of the chair.

Drawings

The present invention will be more fully understood in light of the following further description of the invention, in which:

FIG. 1 is a schematic view of a bracket mechanism according to the present invention;

FIG. 2 is a schematic view of a bracket mechanism incorporated into a chair with variable lumbar support;

FIG. 3 is a schematic view of the chair shown in FIG. 2 with an expandable membrane covering the seat and back portions of the chair;

FIG. 4 is a schematic view of a chair similar to FIG. 3, wherein the chair is covered by an elastic fabric or film;

FIG. 5 is a schematic view similar to FIG. 1, wherein the expandable membrane is integrated with the pelvic support and the front seat;

FIG. 6 is a schematic view of another embodiment of the chair of the present invention wherein the expandable membrane is integrated with the seat back and the pelvic bracket;

fig. 7a-7c are side views of a stool embodying the invention and illustrating the stool in the rest, forward tilt and neutral positions, respectively;

FIGS. 8a and 8b are side views of a drafting height stool (a drafting height stool) showing the embodiment of the present invention mounted on a higher base with a foot pedal in the rest and forward tilted positions, respectively;

figures 9a-9d are side views of an ergonomic working chair embodying the present invention and illustrating the chair and user in the unloaded (off-load), resting, forward leaning, and neutral positions, respectively. The chair comprises a contour belt;

FIGS. 10a and 10b are schematic views of the stool mechanism with additional linkages to stabilize the posture of the pelvic brackets throughout the mechanism's entire range of operation;

figures 11a and 11b are schematic views of a chair mechanism with additional links to stabilize the integrated armrests, backrest and pelvic cradle, and illustrating a rest position and a forward tilt position;

figures 12a and 12b are schematic views of a chair having a single piece contoured seat and integrated armrest and backrest assembly with the frame and integrated armrest and backrest connected by a stabilizing link, showing at rest and forward tilted positions, respectively;

figures 13a and 13b are schematic views of another embodiment of the chair mechanism of the present invention in the at rest and forward tilted position wherein the user maintains a proper sitting position while controlling the seating angle by thigh pressure, the mechanism comprising a pair of parallel rearwardly extending stabilizing links and a forwardly extending guide link controlling the position of the front of the thigh support;

figures 14a and 14b are schematic views of a chair mechanism having a one-piece contoured seat and integrated armrest and backrest assembly, the chair mechanism including a front guide link and a pair of rearwardly extending stabilizing links; and

fig. 15a and 15b are schematic views of a stool having a mechanism similar to that shown in fig. 13, showing the stool in the rest and forward tilted positions, respectively.

Detailed Description

As shown in fig. 1 and 2, one embodiment of the seating mechanism includes a two-piece structure 10, the two-piece structure 10 including a pelvis bracket 12 and a thigh support 14, the pelvis bracket 12 being mounted to the thigh support 14. The thigh support 14 is pivotally mounted at a pivot 18 between its ends on the fixed frame 16, and can be viewed with respect to the pivot 18 as having front and rear portions 20, 22. As shown, for example, the thigh support 14 may include a pair of laterally spaced members 24 connected at their front ends by a laterally extending crossbar 26. The rear portion of the thigh support comprises a pair of lugs 28, the lugs 28 having a pair of laterally spaced apart axles (pivots) 30 forming a second pivot axis. The pelvic cradle 12 comprises side members 32, the cradle being pivotally mounted to the shaft 30 by the side members 32, such that the cradle can pivot about the second pivot axis 30-30. The side members extend forwardly by the transverse back and front members 34, 36 to provide support that is not disturbed by the ability of the user's thighs. The lateral front member 36 of the pelvic cradle can be considered to be somewhat in the shape of a bicycle seat, with a concave or cut-out region 35 formed on each side of the lateral front member 36. It should be understood that other bracket configurations may be used. A stop 37 is provided on one of the frame 10 or the rear portion of the thigh support to limit the extent to which the thigh support can pivot rearwardly.

The distance between the pivot axis 18 and the area in front of the thigh support 14 where the resultant thigh force is applied (center of force) is sufficiently greater than the distance between the first and second pivot axes 18, 30 to provide sufficient mechanical advantage to enable a user sitting on the pelvic cradle to balance the weight of the torso accordingly by the weight force applied to the thigh support by the user. By way of example only, suitable dimensions may be found to be about 2.25 inches of horizontal distance between the first and second pivots, about 3.75 inches of vertical distance between the first and second pivots, and 6.75 inches (or more) of horizontal distance from the first pivot to the center of force. The pelvis cradle is mounted on its pivot 18 so that it tends to assume a relaxed position where a user seated in the cradle can be supported with his torso and pelvis in vertical alignment while allowing the user's hip and thighs to move freely to change the seating angle as desired. The ability of the pelvic support to pivot freely in this embodiment allows the user to fine tune the portion used by the weight applied to the rod. As the knee moves downward, the bracket rises and moves forward as the thigh support pivots forward, increasing the seating angle while allowing the user to maintain vertical alignment of his spine and pelvis. It should be noted that as the pivot moves closer to vertical alignment with the pivot 18, the thigh applies less force. The thigh force required to maintain the selected increased seating angle is reduced.

Fig. 2 illustrates a chair embodying the present invention, particularly of the type described in U.S. patent publication No. 7,695,067 entitled "ergonomically adjustable seat" and published on 4/13/2010, the disclosure of which is incorporated by reference in its entirety. In this embodiment, the frame 38 includes an upright back portion 40 and a cross bar at the top end. As described in the aforementioned patents, the chair includes a pair of elongated profile strips 44 extending downwardly from the upper end of the back portion of the frame 38. In the embodiment shown in fig. 2, the lower end of the profile strip is connected to the pelvis bracket, preferably to the upper part of the pelvis bracket, at 46. The contoured strip 44 is held in longitudinal compression and serves as a support for the lumbar region of the user by an elastic fabric or membrane attached to the contoured strip and spanning the back of the chair. In other applications of the invention, such as that shown in FIG. 3, a more robust and expandable membrane 48 may be provided. In this embodiment of the chair, the profile strap and the seat back connected to the strap provide the user with back support throughout the movement of the device from rest to the forward tilted position as shown. The contour bands may vary in shape, as described in further detail in the aforementioned patents, as the user adjusts his or her position on the chair to give the user's back a corresponding support contour.

Fig. 7a-7c illustrate a user seated on a stool embodying one embodiment of the present invention and depicted in a seated position with progressively increasing seating angles. This includes a rest position (fig. 7 a), a forward tilted position (fig. 7 b) and a position in the neutral position (fig. 7 c). The thigh supports are shown as being progressively inclined as a result of increasing seating angle. In all positions, the pelvic cradle adjusts itself about its pivot axis to provide support for the user's pelvis and torso in all positions. In the rest position (fig. 7 a), the user's thighs are parallel to the ground and the user can sit flat, or by tilting the pelvic cradle, his torso can easily be swung back and forth independently at the hip joints without raising the front of the seat. In the forward-leaning position (fig. 7 b), the user can increase the seating angle by tilting the thighs downward with respect to the thigh support. The mechanical advantage achieved by the relative positioning of the shafts 18, 30 and the forward extension of the thigh supports allows the change in thigh weight to raise or lower the user's torso relative to the user's legs, thereby increasing the seating angle. The pelvis support is contoured to cradle the user's pelvis and is pivotally connected to the rear portion of the thigh support to maintain it in a horizontal position independent of the position of the thigh support. As shown, by maintaining the planar positioning of the pelvic cradle, the user does not slide out of the cradle or slide down the seat even if the thigh support is angled downward. Further, to assist the user in accommodating different tasks, the user can easily pivot forward and backward without being affected by adjusting the angle of the torso on the pelvic bracket while the bracket is in a position that is elevated without changing the angle of the thigh support.

Fig. 7c illustrates a user sitting on the stool in a centered position. The frame of the stool may include a seat lift assembly, such as a standard pneumatic gas lift, to allow the user's thighs to be lowered further, thereby opening the seating angle further when desired.

Fig. 8a and 8b illustrate a drafting highstool embodying the present invention. The seating assembly is mounted on an upper base with foot pedals for accommodating a modified application (published applications) such as a drawing table or copyrighted surfaces.

Figures 9a-9d illustrate the present invention as incorporated into an ergonomic chair such as that described in connection with figure 2. Figure 9a illustrates the user sitting in the chair in an unloaded position wherein the user leans back to dump the weight of the torso against the backrest without raising the thigh support, the user's thighs being approximately parallel to the ground. Such movement is permitted by the independent pivoting capability of the pelvic bracket. In this position, vertical compressive stresses on the spine can be relieved. Figure 9b shows the user and the rest position, in which the user's thighs are substantially parallel to the ground and his back is supported by the profile strip. Fig. 9 illustrates a user and the chair in a forward tilted position, wherein the seating angle is increased by tilting the thighs downward with respect to the thigh support. Due to the mechanical advantage described above, the weight of the thighs can be used to balance the weight of the user's torso simply by lowering or raising the thighs. Furthermore, the profile band keeps the back support at a suitable angle. Figure 9d is a side view of the chair in the neutral position. Here, the chair may again include a pneumatic gas lift to raise the chair and allow the user's thighs to be lowered to further open the seating angle.

Fig. 10a and 10b illustrate the rest and forward tilt positions of a stool mechanism similar to that described above, further adjusted to include stabilizing links 50 to maintain the pelvic cradle in a constant posture throughout the full range of movement of the mechanism. The stabilizing link pivots at one end to the rear portion of the frame 16 at shaft 52. The other end of stability link 50 is pivoted at 54 to the bracket by a bracket 56 extending from the bracket or other suitable connection means. The links connecting the shafts 52, 54 and 18, 30 form a substantially parallel linkage that maintains the brackets in a constant attitude. Thus, as shown, the pelvis is supported in the cradle and the seated person can maintain the spine in alignment with the pelvis throughout movement between the rest and forward positions.

Fig. 11a and 11b illustrate the mechanism shown in fig. 10a and 10b adjusted to add an integrated backrest 55 and armrest 57 to the bracket, and wherein a stabilizing link 50 is provided to operate as described above.

Figures 12a and 12b illustrate another chair embodiment of the present invention in the rest and forward tilted positions, respectively, with the bracket omitted. Instead, the chair includes a single contoured seat 58 pivoted to the frame at the first pivot 18. A pair of laterally spaced lugs 28 integral with the rear portion of the seat 58 extend upwardly from the seat and are pivotally connected at pivots to a separate, integrated chair back and armrest unit 60. The chair back is movably connected to the frame by a stabilizing link 61 extending from a rear portion of the frame to a lower end of the overall chair back. The arrangement of the links and shafts 18, 30 and 52, 54 form a parallel linkage arrangement for maintaining the user in the proper position throughout the entire range of movement of the chair. The rear portion of the one-piece seat 58 is contoured to recess to provide support to the user's pelvis, particularly in a forward-leaning position (fig. 12 b) to prevent the user from sliding forward on the seat.

Fig. 13a and 13b illustrate another embodiment wherein the chair comprises a pelvic bracket having an integrated chair back and armrests adapted to move as a unitary structure, and further comprises a thigh support 64 pivoted at its rear end to the unit 62 at pivot 68, preferably at a lower region of the back or rear portion of the integrated bracket. The thigh support 64 and the unitary chair back and bracket 62 are supported by the linkage 66 which maintains the unitary structure 62 in a constant posture while the thigh support 64 is urged downward to increase the seating angle. The mechanism includes a pivotal connection 68 between the rear of the thigh support 64 and the unitary structure 62. The pivot 68 is located at the interface between the bracket and the backrest of the unitary structure 62. The overall structure 62 maintains a constant attitude throughout the entire range of chair movement by means of a parallel linkage comprising a pair of parallel links 70, 72 connected at one end to the front portion of the frame 16 at axes 74, 76. The other ends of the links 70, 72 are connected to the unit 62 at the lower rear portions thereof at the shafts 68, 78. The mechanism 66 also includes a guide link 80, the guide link 80 connecting a rear portion of the frame 16 at an axis 82 to a front end of the thigh support 64 at an axis 84. The guide link 80 guides the front end of the thigh support 64 along an arc that is different from the arc along which the integrated structure 62 is guided by the parallel linkage. It is noted that guiding the ends of the thigh support 64 along different arcs creates an effective virtual pivot point under the thigh support about which the thigh support rotates. The virtual pivot point itself is spatially displaced with the operation of the mechanism throughout its entire range of movement.

Fig. 14a and 14b illustrate a mechanism similar to fig. 13a and 13b but with the bracket portion of the unitary structure 62 removed. Instead, the chair has a full contoured seat 58 connected directly to the unitary back and arm rest structure at shaft 68. The operation of the mechanism 66 is the same as described above in connection with fig. 13a and 13b, except that a depression is formed in the rear region of the seat when in the forward tilted position to maintain support for the user's pelvis.

Fig. 15a and 15b illustrate a chair mechanism similar to the stool mechanism of fig. 13a and 13b without an integral back rest and armrest structure.

It is understood that the foregoing description of the invention is merely illustrative and that other embodiments, modifications and equivalents will be apparent to those skilled in the art without departing from the scope of the invention.

Claims (14)

1. A seat mechanism comprising:

a frame;

a thigh support pivotally mounted to the frame along a transverse first pivot axis, the thigh support having a portion extending forward of the first pivot axis and a portion extending rearward of the pivot axis;

a pelvic cradle pivotally mounted to the rearward extension of the thigh support at a transverse second pivot axis, the cradle adapted to pivot relative to the thigh support and to receive a pelvic region of a human being to support the pelvic region and torso of the user in vertical alignment independently of tilting of the forward portion of the thigh support, the second pivot axis being movable upwardly and forwardly as the forward portion of the thigh support tilts forwardly;

the thigh support and the first and second pivots are arranged and arranged to provide a mechanical advantage sufficient for a user to control the position of the thigh support about the first pivot to change the seating angle of the user while balancing the weight of the user's pelvis and torso by applying thigh pressure to the front portion of the thigh support.

2. The seat mechanism of claim 1 wherein the second pivot is located rearwardly and upwardly of the first pivot such that when the thigh support is tilted forward, the second pivot is moved forward, approaching vertical alignment with the first pivot and reducing the force on the thigh support required to maintain the position of the mechanism.

3. The seat mechanism as claimed in claim 1, further comprising a brake member disposed on the frame and engageable with the thigh support to limit a range of rearward rotation of the thigh support.

4. The seating mechanism of claim 1, further comprising the bracket having a seat portion and a back portion, the seat portion having leg cutouts on sides thereof.

5. The seating mechanism of claim 1, wherein the pelvic cradle is free to pivot about the second pivot axis independent of the position of the thigh support.

6. The seating mechanism of claim 1, wherein the pelvic bracket is connected to the frame by a stabilizing link pivoted at one end to the frame and at the other end to the bracket, whereby the bracket is fixed in a constant posture throughout the entire movement of the seating mechanism.

7. The seat mechanism as set forth in claim 6 wherein said stabilizing link and connecting structure between said first and second pivots comprise a four bar linkage.

8. The seat mechanism as claimed in claim 1, further comprising:

a frame including an assembly having a seat section and a back section; at least one elongated, flexible, resilient profile band mounted to the frame at least one fixed location on the frame and having a back portion extending along the back portion of the frame, each profile band having a lumbar portion adapted to project forward at a reference plane of the lumbar portion; the pelvic cradle is connected to the profile band to apply variable pressure to at least a portion of the profile band in a direction of elongation thereof such that the protrusion of the lumbar region of each profile band is controllable in response to the position of the thigh support.

9. The seating mechanism of claim 6, further comprising a seat back fixedly connected to the pelvic bracket and extending upwardly therefrom, the bracket and seat back being movable as a unit.

10. A seat mechanism comprising:

a frame;

a seat pivotally mounted to the frame along a transverse first pivot axis, the seat having a portion extending forward of the first pivot axis and a portion extending rearward of the pivot axis;

a heightwise extending seat back pivotally mounted to said rearwardly extending portion of said seat at a transverse second pivot axis, said seat back adapted to support a user's torso in vertical alignment with said user's pelvis independent of said tilting of said forward portion of said seat, said second pivot axis being movable upwardly and forwardly as said forward portion of said thigh support is tilted forwardly;

a stabilizing link pivoted at one end to the frame and at the other end to the seat back, thereby securing the seat back in a constant, substantially vertical position throughout movement of the seat mechanism;

the seat and the first and second pivots are arranged and arranged to provide a mechanical advantage sufficient for a user to control the position of the seat about the first pivot to change the seating angle of the user while balancing the weight of the user's pelvis and torso by applying thigh pressure to the front portion of the seat.

11. The seating mechanism of claim 10, wherein said rearward portion of said seat forms a recess.

12. A seat mechanism comprising:

a frame having front and rear portions;

a pair of generally parallel links each pivotally mounted to the front portion of the frame at first and second pivot axes and extending rearwardly and upwardly;

a seat member disposed above the frame for supporting the pelvic region of the user, the upper ends of the parallel links each being pivotally connected to a rear portion of the seat member at third and fourth pivots, such that pivoting the parallel links about their first and second pivots moves the seat member upwardly and forwardly while maintaining the seat member in a constant posture;

a thigh support having front and rear portions, the rear portion being pivotally connected to and extending forward of the seat member at the fourth pivot axis;

a guide link pivotally mounted to the rear portion of the frame and extending upwardly and forwardly, the guide link pivotally connected to a front end of the thigh support;

the parallel and guide links and their respective pivots are arranged such that a downward force can be applied to the thigh support by the user's thighs while maintaining the seat member in a constant posture, causing the thigh support to tilt forward, thereby increasing the seating angle while allowing the user's spine and pelvis to remain vertically aligned.

13. The seating mechanism of claim 12, further comprising a seat back secured to and extending upwardly from the seat member.

14. A seat mechanism comprising:

a frame having front and rear portions;

a pair of generally parallel links pivotally mounted to the front portion of the frame at first and second pivots, respectively, and extending rearwardly and upwardly;

a seat back disposed above said frame and having upper and lower portions, said upper ends of said parallel links pivotally connected to said lower portion of said seat back at third and fourth pivots, respectively, such that pivoting said parallel links about their first and second pivots moves said seat back upwardly and forwardly while maintaining said seat back in a constant attitude;

a seat disposed above the frame for supporting the pelvic region and thighs of the user, a rear portion of the seat being pivotally connected to the seat back at the fourth pivot and one of the parallel links;

a guide link pivotally mounted to the rear portion of the frame and extending upwardly and forwardly, the guide link pivotally connected to a front end of the seat;

the parallel and guide links and their respective pivots are arranged such that a downward force can be applied to the front portion of the seat by the user's thighs while maintaining the seat back in a constant, generally vertical posture, causing the seat to tilt forward, thereby increasing the seating angle while maintaining the user's spine and pelvis in vertical alignment.