This invention relates to ergonomic seating, in particular, adjustable, reclining chairs.
Ergonomically designed office chairs are commonly configured so that the back can recline alone, the seat and back can recline as a unit, or the back can recline in a coordinated proportion with the seat. The latter are commonly known as “synchro-tilt” chairs. Most of these synchro-tilt chairs have a mechanism that loads a spring as the user reclines and a mechanism for adjusting the resistance to being reclined (also known as tilt or chair tension). In these chairs, the pre-load on the spring requires the user to input a high force or a large displacement in order to make any adjustments to the chair tilt tension. These adjustments often are difficult, awkward or require an extensive amount of user work to generate perceptible changes in the tension. In addition, most of these chairs provide no visual or tactile feedback to the user about the range of tension adjustment available and where, within this range, the chair is currently. As a result, many users don't take full advantage of the versatility of the chair in accommodating their comfort. For example, many of these chairs provide a rotatable knob or handle underneath the seat that includes plus and minus symbols. Rotation of this knob can require 30 revolutions or more to adjust the tension between the lowest and highest available levels.
The force applied to the chair back during reclining, as mentioned above, also may result in a shearing force between the user's back and the chair back. This shearing force may be perceived by the user as a tendency for the chair back to pull out the user's shirt tail, known as ‘shirt pull’ in the industry. In addition, reclining in these types of chairs may also cause a “pull-away” between the chair back and the user's back, such that the chair back does not remain in contact with the user's back as the chair reclines. As a result, the chair fails to provide proper support causing discomfort and dissatisfaction.
In addition to adjustment of the tilt tension, many of these chairs include a tilt lock to prohibit reclining of the chair, a seat height adjustment, arm adjustments, and/or seat position adjustments. Improvements in these other chair adjustments are also desirable to make them more user friendly and thereby encourage the user to take advantage of the various adjustments available to customize the chair for the user's personal comfort or work style.
The present invention overcomes the short comings of the prior art by providing an adjustable reclining chair including a seat configured to support a user, a chair back, a base and a control mechanism mounted on the base. The control mechanism couples the chair back to the seat with the chair back located generally adjacent to the user's back when the user is seated upon the seat. The control mechanism includes a resistance adjustment mechanism for varying the control mechanism's resistance to a reclining force applied by the user to the chair back in order to move the chair back rearward from an upright position. The resistance adjustment mechanism is activated by the weight of the user when seated in the chair, such that easy adjustment of the resistance is facilitated with the chair in an upright position.
The present invention also provides an adjustable reclining chair including a chair back, a seat, a base having a central axis and a control mechanism mounted on the base, the control mechanism coupling the chair back to the seat. The control mechanism is configured as a four-bar mechanism including a ground member and a pivot member pivotally coupled to the ground member at a pivot point forward of the central axis, the pivot member pivotally attached to the chair back at a back pivot. A reclining force applied by the user to the chair back results in the chair back moving rearward, pivoting the pivot member relative to the ground member about the pivot point and the chair back about the back pivot, with the chair back remaining generally in contact with the user's back due to reduced shear and pull-away forces.
The present invention also provides an adjustable chair back including a back frame, a resilient material attached to the back frame, the resilient material held in tension across the chair back and an adjustment mechanism coupled to the frame and engaging the resilient material. The adjustment mechanism is configured to modify a stiffness of the resilient material of the chair back.
With reference to the attached Figures, it is to be understood that like components are labeled with like numerals throughout the several Figures. Unless otherwise specified, the components described herein with respect to the present invention may be formed from any suitable material and by any suitable manufacturing method. For example, parts may be formed from plastic, such as glass-filled nylon or other moldable materials, or from die-cast aluminum.
In the first embodiment, the chair back 110 includes a frame 111 and an area of mesh fabric 112 attached to the frame 111. The back 110 attaches to the control mechanism 200 at back pivots 113. In the second embodiment, the chair back 115 includes a frame 116 and an upholstered portion 117. The back 115 attaches to the control mechanism 200 at back pivots 118. The backs 110, 115 will be discussed in more detail below.
The arms 140, in the first embodiment, are a fixed design that attach to the control mechanism 200. The arms 145 in the second embodiment are an adjustable design that attach to the control mechanism 200. The arms 145 include padded arm rests 146 and a mechanism 147 for raising or lowering them. In addition, the arm rests 146 are configured to move inward and outward and forward and backward. Alternatively, chairs 100, 105 may be provided without any arms. Numerous types and styles of chair arms 140 are also usable with chairs 100, 105, as would be known to one of ordinary skill in the art, including arms that are adjustable at an angle with respect to the seat. All such arm configurations are within the scope of the present invention.
Although the back style 110, 115 and arm style 140, 145 varies between chair 100 and chair 105, the seat 120, base 130 and control mechanism 200 are all the same. These components will be referred to hereinafter with respect to only chair 100 for clarity during the discussion. However, it is to be understood that this discussion applies equally to the second embodiment chair 105 and any other variation described herein or contemplated based on this invention.
The base 130 includes a central column 131 supported by a plurality of outwardly projecting base legs 134. Each base leg 134 is provided with a caster 135 configured to swivel and roll so as to move the chair 100. In some embodiments, each caster 135 may include a locking mechanism. The central column 131 preferably includes a pneumatic or gas cylinder having a fixed outer cylinder 132 and a movable inner cylinder 133 attached to the control mechanism 200. Activation of a height adjustment lever 136 results in upward or downward movement of the control mechanism 200, and thus the backs 110, 115, seats 120 and arms 140, 145, as is known in the art.
Referring now to
A generally U-shaped, pivoting locking lever 150 is mounted to the underside 125 of the seat pan 122 at pivot mounting elements 129 using pivot blocks 151 and fasteners 152. (The pivot blocks 151 and pivot mounting elements 129 are described in more detail below.) The lever 150 includes a lever handle 153 interposed between two legs 154. The lever handle 153 is positioned near a front edge 126 of the seat pan 122 when the lever 150 is mounted to the seat pan 122. Each lever leg 154 includes a notched protrusion 155 provided on an end 156 opposite from the lever handle 153. Springs 157 are also provided to bias the lever 150 into a ‘locked’ position relative to the seat pan 122, such that the notched protrusions 155 are forced upward toward the underside 125 of the seat pan 122. Although shown as a U-shaped member, the locking lever 150 could alternatively be provided as an L-shaped member having a handle and only one leg, or another suitable configuration.
The control mechanism 200 includes a seat plate 210 having a top side 211 and a bottom or underside 212. On the top side 211, the seat plate 210 includes two pairs of T-shaped protrusions 213 and a center rib 214. In addition, there are two slots 215 formed through the seat plate 210 and positioned on either side of the center rib 214. Along each edge 216 are a series of teeth 217 formed on the underside 212 of the seat plate 210. An extended lip 218 is also provided on the underside 212 for connection of the seat plate 210 to the back upright 230 at pivot 201.
The seat 120 slidably mounts to the seat plate 210 of the control mechanism 200 by insertion of the seat posts 124 into the slots 215 in the seat plate 210, insertion of the T-shaped protrusions 213 into the T-slots 127 and insertion of the center rib 214 into the center channel 128. The locking lever 150 is then installed and attached to the seat pan 122, such that the two notched protrusions 155 are positioned to mate with and engage the teeth 217 on the seat plate 210, as shown in detail in
A user seated on the seat 120 may desire to adjust the seat position in a forward (F) or backward (B) movement, per directional arrows 101, in order to accommodate the user's size or preferred fit of the chair 100. As a result, the seat 120 moves relative to the control mechanism 200 and, thus, to the arms 140 and back 110, which are attached to the control mechanism 200. In order to make the adjustment, the user reaches under the front edge 126 of the seat 120 with either hand and lifts the lever handle 153, preferably by grasping the seat 120 and handle 153 and squeezing. The locking lever 150 pivots about the pivot blocks 151 resulting in the notched protrusions 155 disengaging from the teeth 217, as shown in detail in
Referring now to
Viewed from the side, the back upright 230 is a generally J-shaped, rigid unit extending from a central region of the chair back 110 at the back 102 of the chair 100, downward, under the seat 120, and forward, to the front 103 of the chair 100. In one embodiment, the back upright is split into an upper part 250 and a lower part 251 joined together at a joint 252 located near a rearward portion 222 of the seat 120. In this embodiment, the joint 252 is formed with a male portion 253 on the upper part and a female portion 254 in the lower part, which are held together by fastener 255. Providing the back upright 230 in multiple parts allows for more compact shipping of the chair 100. In addition, it facilitates more efficient (and thus cost effective) manufacturing and assembly.
As described in more detail below and shown in
When a user seated in the chair 100 reclines the chair 100, as shown in
Referring now to FIGS. 13 and 17-21, the back pivot 113 is shown in more detail. As stated above, the back upright 230 is attached to the chair back 110 at pivots 113. In this embodiment, the upper part 250 of the back upright 230 includes a tri-lobed pivot coupler 233 that mates with a C-shaped back bracket 114, and is connected to the bracket 114 by a pin 234 held in place by a clip 240 forming joint 241. This type of joint 241 is provided for structural and stability purposes, however, any pivot joint could be used in this application, as would be known in the art. All such pivot joints are within the scope of the present invention.
The joint 241 is spring loaded with a predetermined pre-load by compression of spring 235 positioning the back 110 in the upright position by default and providing a resistance to rotation during reclining of the chair 100. In the upright position, as shown in
The pivot axis 242 of the back 110 relative to the back upright 230 runs through the joint 241 at pins 234. This axis 242 is positioned near the center of force 243 of the seated user in the vertical direction, as shown in
The purpose for the horizontal positioning of the pivot axis 242 relative to the user's spine (as represented by item 246) is to promote proper spinal positioning as the chair back 110 rotates. If it were horizontally behind the user's spine 246, the chair back 110 would improperly lift the user's lower back and push the user out of the chair 100. If it were horizontally off in either direction it would cause slipping between the chair back 110 surface and the user's back.
The control mechanism 200 and the back pivot 113 of the present invention, as described above, combine together to provide a chair 100 in which shear and pull-away forces on the user's back, as encountered in other reclining chairs, have been substantially reduced, if not eliminated. As a result, the user experiences a comfortable and customized fit, including proper back support both in an upright and reclined position. Increased comfort of a work chair will aid in producing higher productivity and reduced discomfort, fatigue or other negative physical issues for the user.
Referring now back to
The control body 260 includes a spring 261 which acts between the rear link 290 and the ground 260. Upon removal of the reclining force, the chair 100 returns to its upright and forward position due to the action of the spring 261 in combination with the weight of the user. In one embodiment, the spring 261 is provided as a steel coil spring that is pre-loaded. The rear link 290 includes a generally flat under surface 295 positioned to engage the coil spring 261. The size, spring strength, location and style of the spring 261 allow it to provide the desired return effect while adding minimal resistance to the recline of the chair 100.
The control body 260 also includes a second spring 262 that acts between the rear link 290 and the ground 260. This second spring 262 is formed from a block of resilient material having a varying resistance to compression. By adjusting the location of the second spring 262 within the control body 260 relative to the rear link 290, the chair's resistance to the reclining of the chair back 110, that is, the chair's tilt tension, can be varied.
In this embodiment, the varying resistance to compression of the spring 262 is provided by changing the geometry of the spring 262, such as by changing the amount of resilient material that resists compression within the spring 262. This change results from the removal of a wedge-shaped volume of material 263 from the interior of the block of resilient material. Alternatively, this change could be achieved by changing the material, such as by varying the density, formulation or other material characteristics of the spring. Other methods of varying the resistance to compression of the spring 262 may also be utilized, as are known in the art, and all such embodiments are contemplated by and within the scope of the present invention.
The rear link 290 also includes a downwardly protruding element 296 positioned over the resilient second spring 262. In this embodiment, the element 296 is generally configured as a trapezoidal prism having a radiused end that engages the resilient spring 262. The curved shape of the protrusion 296 provides a discrete area of contact with the resilient spring 262, thereby more accurately conveying the changes in resistance as the spring 262 is moved relative to the protrusion 296. In addition, the curved shape prevents the sliding of the spring 262 with respect to the protrusion 296 since the resilient material can wrap around this protrusion 296 as it is compressed.
The resilient spring 262 is held within a slider 264 that is mounted upon a track 265 in the control body 260, as shown in
Alternatively, instead of sliding the resilient spring having a varying resistance to compression, such as spring 262, forward and backward relative to the rear link 290, the spring could be moved from side to side. Another option would be to rotate the resilient spring to present a greater or smaller resistance to compression. Further, the protrusion 296 could also be movable with respect to the main portion of the rear link 290, as well as the spring, in order to obtain even more adjustment of the tilt tension. Referring now to
When a user sits down in the chair 100, the four-bar control mechanism 200 of the present invention biases the mechanism 200 forward against an upright stop 205 due to the weight of the user. As a result, a minimal load is placed on the first and second springs 261, 262, thereby allowing for quick and easy adjustments of the reclining resistance or tilt tension. Coupled with the limited motion tension adjustment slider 264 described above, the present invention provides an adjustment mechanism that is easier to locate, operate, and utilize to provide changes to the tilt resistance by any user of the chair 100.
The upright stop 205 is formed from the interface between the control body 260 and back upright 230. In this embodiment, the stop 205 is provided by two rectangular protrusions 244 on the lower back upright 230, as shown in
The chair 100 of the present invention also includes a tilt lock 271 provided to lock the chair back 110 in the upright position, as shown in
In this embodiment, the tilt lock 271 includes a generally U-shaped tilt-lock slider 272 mounted within the control body 260. The tilt-lock slider 272 is coupled to a tilt-lock lever 273 extending outward from the control body 260 on the side of the chair 100. The lever 273 is pivotally mounted to the control body 260 at pivot 274, in the same manner as pivot 267 for tension lever 266 described above. The lever 273 is then moveably coupled to the tilt-lock slider 272 at interface 275, also in the same manner as the slider 264 is coupled to tension lever 266 at interface 268. In operation, the user moves the tilt-lock lever 273 forward to move a lock portion 276 of the tilt-lock slider 272 into the tilt-lock recess 245 on control body 260, as shown by the dashed lines in
As described above, the forward motion of the chair 100 is limited by the upright stop 205. The rearward reclining motion of the chair 100 is limited in the locked configuration by the tilt lock 271. In an unlocked configuration, however, the rearward limit of the chair's reclining motion is provided by a full recline stop occurring when recline stop surface 247 on the lower part 251 of the back upright 230, shown in
As shown in
While the function of the height adjustment lever 136 is similar to adjustments provided on other chairs, the pivotal mounting of the lever 136 is unique, improving and simplifying the assembly process. Referring now also to
A spring 289 is provided and interposed between the control body 260 and the lever 136 so as to bias the lever in an un-activated position, keeping the activation portion 138 in contact with the cylinder and eliminating any vibration or rattling between the lever 136 and the cylinder. Activation of the lever 136, as described above, requires the user to pivot the lever 136, such that gravity returns the lever 136 to its un-activated position upon release of the lever 136 by the user.
As described, the pivotal mounting of lever 136 is accomplished with components that are all assembled on the same side of the control body 260, thus simplifying the assembly process. In the same manner, the two pivots on the seat locking lever 150 include similar components, such as pivot mounting elements 129 and pivot blocks 151, so as to simplify assembly of this pivoting lever as well. The design of this pivotal mounting structure may be utilized in many situations. The major advantages of this pivot joint assembly method and structure are that it is quick, easy and low cost to assemble, yet very effective in operation.
Referring again to
In this embodiment, in order to provide adjustable back support for users of different sizes and needs, the present invention provides a tensioning device 160 that changes the stiffness of the mesh 112 across the back, in particular, such as in the lumbar region. This is different from other mesh back supports because they usually provide a solid brace or cushion or other additional member attached to the back 110 or frame 111 in the lumbar region, which causes discontinuities in the pressure gradient applied to the user's back.
The tensioning device 160 includes a pair of assemblies 161 mounted on either side of the frame 111. These assemblies 161 contain three components, a front piece 162, a rear piece 163 and a fastener 164. Although shown with three components, it is to be understood that the assemblies 161 may be formed with more or less components as desired to provide the same functionality. The assemblies 161 are affixed to a feature on the frame 111 that guides the motion of the assembly 161 as it travels vertically on the frame 111. The guide feature in this embodiment is a slot 165 that also limits the vertical travel of the assemblies 161. Alternatively, the guide feature could be a protrusion, and it could run the full height of the frame 111.
In this embodiment, the front piece 162 is configured with a generally convex front surface 166 and suitable structure to engage with the rear piece 163 and fastener 164. The rear piece 163 includes a pair of posts 167 configured to be positioned within the guide slot 165 and received within the rearward structure of the front piece 162. The rear piece 163 also includes a handle 168 that provides a grasping region for the user when adjusting the assemblies 161.
The location of the assemblies 161 on the sides of the frame 111 provides improved adjustability and user comfort. As shown in
Optionally, the high points 166 of the assemblies 161 could also be adjusted. This would allow the user to change the amount of tension seen in the mesh 112 and, therefore, the pressure on the user's back. This depth adjustment of the assemblies 161 would still cause continuous tension gradients throughout the mesh 112, adding another level of adjustment and customization.
Referring now to
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. In addition, the invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention. In addition, the embodiments and associated components described herein are to be taken to be cumulative, such that one or more of these components may be removed or mixed and matched in different combinations with the resulting configurations still within the scope of the present invention.
This application is a continuation of U.S. patent application Ser. No. 11/388,331, filed on Mar. 24, 2006, which is incorporated herein by reference in its entirety for all purposes.
Number | Date | Country | |
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Parent | 11388331 | Mar 2006 | US |
Child | 12907856 | US |