Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to a chair with a reclining back assembly and, more particularly, to a chair that includes a more efficient mechanism for adjusting resistance to the recline of a chair back assembly, a simple apparatus for limiting the angle of recline and a tilt mechanism that results in a more comfortable passive tilt adjustment of a chair back in various chair recline positions.
2. Description of the Related Art
Reclinable office chairs are ubiquitous and appear in many different styles and designs and with many different functions. Most, if not all, include some mechanism to resist a reclining back. See for example, U.S. Pat. No. 6,053,574 which includes movable springs. Some chairs also include adjustable stops to control the angle of recline. See for example, U.S. Pat. Nos. 6,616,231 and 6,193,314. Still other chairs include tiltable backs. See for example, U.S. Pat. Nos. 1,756,825 and 3,938,858 and Reissue 36,335. Adjustable office chairs are sometimes complicated to operate or are overly complex in structure and are often expensive, unreliable or difficult to use.
The difficulties encountered with previous devices have been over come by the present invention. What is described here is a chair with a reclining back including a seat assembly, a back assembly, a pivot forming structure defining an axis of rotation for allowing the back assembly to rotate relative to the seat assembly and a biasing structure for resisting the rotation of the back assembly, the biasing structure being spaced from the axis of rotation and also being movable forwardly and rearwardly relative to the axis of rotation with specific structural elements as a way of controlling resistance to the rotation of the back assembly. The invention here also includes a limit control apparatus having specific structure including a first structure having a step configuration, a second structure including an abutment surface for engaging the first structure and an actuator for moving either the first or second structures. The present invention further includes a tilt mechanism for the back of the back assembly including a first bracket, a second bracket, a first pair of links, a second pair of links, a first rod and a second rod so as to allow the second bracket which is connected to the chair back to pivot in a plane generally perpendicularly to the axes of the rods so as to provide a stable but passive adjustment of the chair back as the back assembly reclines.
A complete understanding of the present invention and other objects, advantages and features thereof will be gained from a consideration of the present specification which provides a written description of the invention, and of the manner and process of making and using the invention, set forth in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same in compliance with Title 35 U.S.C. section 112 (first paragraph). Furthermore, the following description of a preferred embodiment of the invention read in conjunction with the accompanying drawing provided herein represent an example of the invention in compliance with Title 35 U.S.C. section 112 (first paragraph), but the invention itself is defined in the Claims section attached hereto.
While the present invention is open to various modifications and alternative constructions, the preferred embodiment illustrating the best mode contemplated by the inventors of carrying out their invention is shown in the various figures of the drawing and will be described herein in detail, pursuant to Title 35 U.S.C. section 112 (first paragraph). It is understood, however, that there is no intention to limit the invention to the particular embodiment, form or example which is disclosed herein. To the contrary, the intention is to cover all modifications, equivalent structures and methods, and alternative constructions falling within the spirit and scope of the invention as expressed in the appended Claims section attached hereto, pursuant to Title 35 U.S.C. section 112 (second paragraph).
Referring now to
The illustrated chair 10 is of an office type which swivels, adjusts vertically, glides easily on a floor or carpet pad and includes reclining and tilt back features. The reclining and tilt back features are shown by comparing
The backrest 38 may include a support panel 42 and a back cushion 44, the frame 40 may include a pair of parallel tubular frame members 46, 48, and the back assembly 12 may include a tilt mechanism 50 connecting the support panel 42 and the frame members 46, 48. The seat assembly 14 may include a seat pan 52 and a seat cushion 54. It is noted that the back assembly may include only a panel of flexible and/or resilient material such that a cushion is not needed. The same may be true of the seat assembly where only a seat panel of flexible and/or resilient material is used.
The base 24 may include five arms 60, 62, 64, 66, 68 and a hub 70, and the base rigidly supports the column 22 in the hub 70. The support column may include a gas cylinder for allowing vertical adjustment of the seat and back assemblies.
The set of controls 16 are located in and about a lower mount box 74,
Pivotally mounted to the box 74 may be a U-shaped upper mount plate 126,
The pivot forming structure of the control box 74, the plate 126 and the pivot rod 140 creates an axis of rotation 142,
Located within the box 74 may be a low friction plastic slide plate 150,
Extending from lever opening 82,
The actuator lever 180 may include a handle portion 190,
The spring assembly 152 is a biasing structure and may include a spring carrier 200,
The recline control mechanism 154 has a “lost motion” feature and may include the actuator of lever 182 having a handle portion 220,
The crank 224 may include a fastener receiving opening 240,
In operation, the actuator lever 182 is able to rotate a short distance, about 3-4 degrees about the bolt 259 in a first step so as to remove any restraint on the lock ball 254 exerted by the bridge wall 234. As shown in sequence in
The purpose of the spring assembly 152 is to resist rotation of the back assembly 12 about the rotation axis 142. The further the spring assembly is from the rotation axis, the greater is the moment arm and the higher is the resistance to the reclining back assembly. By moving the spring assembly closer to the rotation axis, the moment arm is decreased and recline of the back assembly is more easily accomplished. This arrangement for altering the tension applied to the back assembly is simple, robust, reliable and very easy to use. The control may be accessed from the side of the chair instead of from under the chair and operation merely requires a lever to be pivoted with an attendant mechanical advantage instead of a knob to be rotated. This feature also provides a user easy feedback to easily judge the current tension or resisting force and then to alter the force, if desired. Also, moving the lever forward to decrease tension and rearward to increase tension may be displayed graphically on the handle portion 220 which is easily seen by a chair user. This compares favorably to an under chair knob without any indication of the correct direction of rotation and with the great difficulty in determining the comfort level of the recline once an adjustment is made.
The user determines his/her comfort level by moving the lever forward or rearward while attempting to recline. When the amount of resistance force is found to be suitable, the user releases the handle portion 220 of the actuator lever 182. The wire spring 256 returns the actuator lever to an at-rest position where the bridge wall 234 is positioned over the lock ball 254 causing the lock ball to be depressed into one of the six lock openings 103. This locks the crank 224, and the actuator lever 182, and thereby the spring assembly 152, into position relative to the rotation axis 142. The distance of the spring assembly from the pivot axis defines the amount of resistance that the spring assembly offers to oppose the rotation of the back assembly 12. Movement of the actuator lever 182 and the spring assembly 152 is shown in
The lock structure may take any of a number of forms. For example, a lock structure may be formed by a detent arrangement like that used with the actuator lever 184 as explained below in relation to the detent recesses 168 in the slide plate 150. Or, a lock structure may be formed of high friction material or friction increasing surface textures. The rotation or recline force applied by a chair user is somewhat oblique thereby creating a force component acting in the direction of the rotation axis 142. The greater the recline angle, the greater will be the force component. The lock structure must be sufficient to resist the force component and any one of various mechanisms may prove satisfactory.
It is also noted that the amount of force needed to compress the spring 218 is a function of the distance between it and the rotation axis 142. In addition, the further the distance from the rotation axis, the greater must be the deflection or compression of the spring to reach a desired recline. This greater compression distance adds a component to the total force resisting recline of the back assembly.
The chair 10 may also include a limit control apparatus 270,
The limit control apparatus 270 may include an actuator structure or lever 184 with a handle portion 274 and a link portion 276, a slide block 278, a brace 280 and a stepped abutment structure 282. The link portion 276 has a first end portion 284 with a fastener receiving opening 286 connected to the handle portion 274, and a second end portion 288 with a slot 290. The fastener receiving opening accommodates a shoulder bolt 292,
The upstanding projection 300 of the slide block 278 may include an abutment surface 304, and the abutment structure 282 includes three complementing abutment surfaces 306, 308, 310, each abutment surface of the abutment structure being at a different elevation from the other two surfaces. The abutment surfaces are generally horizontal when the chair is in an upright position, however, because of the recline of the back assembly, the shorter abutments topped by the surfaces 308, 310 are slanted at about 3.5 and 7 degrees, respectively so that contact is made along generally the entire surfaces. It is noted that the abutment structure 282 may be mounted on the box and the slide block 278 may be mounted on the back assembly 12, if found desirable.
In operation, the limit control apparatus 270 functions by pivoting the handle portion 274 through a maximum arc of about 21 degrees about the pivot axis 294. Rotation of the handle portion is translated to linear motion of the slide block 278 and moving the slide block allows selective placement of the upstanding projection 300 opposite one of three abutment surfaces 306, 308, 310 of the abutment structure 282. Because the abutment structure is affixed to the back assembly 12, rotation of the back assembly is selectively limited. When the abutment surface 306 of the abutment structure 282 is aligned with the abutment surface 304 of the upstanding projection 300, the back assembly will not be able to recline. When the abutment surface 308 is aligned with the upstanding projection 300, the back assembly will be able to be reclined about 3.5 degrees. When the abutment surface 310 is aligned with the upstanding projection 300, the back assembly will be able to be reclined fully, about 7 degrees. The limit control apparatus is very easy to operate, is very reliable and is robust.
The tilt mechanism 50 is based on a four bar mechanism, and may include a first or frame bracket 322, a second or backrest bracket 324, a first or upper pair of links 326, 328, a second or lower pair of links 330, 332, a first or upper pair of structures, such as rods 334, 336, and a second or lower pair of structures, such as rods 338, 340. The tilt frame bracket 322 is secured to the frame members 44, 46 in any convenient fashion. The backrest bracket 324 is connected to the support panel 42 and allows the back to pivot in a plane generally perpendicular to longitudinal axes 342, 344, 346, 348 of the rods in reaction to the movement of a chair user's back.
The frame bracket 322 includes a first or upper pair of holes 350, 352 and a second or lower pair of holes 354, 356. The front upper rod 336 is pivotally connected to the frame bracket through the upper holes 350, 352 such that the pivot axis 344 of the rod 336 does not translate. The front lower rod 340 which is pivotally connected to the frame bracket through the lower holes 354, 356, such that the pivot axis 348 of the rod 340 is also restrained from translating. The frame bracket 322 may also include a first or upper pair of cutouts in the form of curved slots 358, 360 and a second or lower pair of cutouts in the form of slots 362, 364.
The back bracket 324 includes a first or upper pair of holes 366, 368, a second or lower pair of holes 370, 372, a first or upper pair of cutouts 374, 376 and a second or lower pair of cutouts 378, 380. Each link 326, 328, 330, 332 includes a first or front end portion 390, 392, 394, 396 and a second or rear end portion 398, 400, 402, 404.
The front end portions 390, 392 of the upper links 326, 328 may include rod openings 410, 412 which receive the front upper rod 336. The rear end portions 398, 400 of the upper links 326, 328 includes rod openings 414, 416 which receive the rear upper rod 334. The front lower rod 340 is received by openings 418, 420 in the front end portions 394, 396 of the lower links 330, 332 and the rear lower rod 338 is received by openings 422, 424 in the rear end portions 402, 404 of the lower links 330, 332.
The upper rear pivot axis 342 is allowed to travel within the arc generally defined by the pair of upper curved slots 358, 360 in the upper portion of the frame bracket 322. The lower rear pivot axis 346 is allowed to travel along an arc generally defined by the pair of curved lower slots 362, 364 in the frame bracket 322. The upper front rod 336 moves in the cutouts 374, 376 of the backrest bracket 324 and the lower front rod 340 moves in the cutouts 378, 380 of the backrest bracket 324. The upper links 326, 328 are able to pivot about the pivot axis 344 and the lower links 330, 332 are able to pivot about the pivot axis 348. The pivot axes 344, 348 allow the upper pair of links 326, 328 to rotate about 40 degrees downwardly until limited by the ends of the upper slots 358, 360, and the lower pair of links 330, 332 also rotate about 40 degrees downwardly. At rest, the ends of the lower slots 362, 364 limit rotation of the backrest bracket 324. These rotations combine to allow the backrest bracket 324 to pivot about 7 to 8 degrees in a plane generally perpendicular to the pivot axes 342, 344, 346, 348. This creates a stable, wobble-free platform for the backrest 38.
The effect of the two-dimensional movement of the backrest bracket 324 is that the chair back follows and supports the back of the chair user with little shear so that there is little or no “shirt pull” of the garment being worn by the chair user even when the user fully reclines the back assembly. This rotational adjustment feature of the back is very stable, passive and functions with chair users of various sizes.
The above specification describes in detail a preferred embodiment of the present invention. Other examples, embodiments, modifications and variations will, under both the literal claim language and the doctrine of equivalents, come within the scope of the invention defined by the appended claims. For example, different lever, link and mechanism designs are considered equivalent structures and will also come within the literal language of the claims. The same applies to the dimensions and physical charcteristics mentioned as well as the amount of recline and tilt. Still other alternatives will also be equivalent as will many new technologies. There is no desire or intention here to limit in any way the application of the doctrine of equivalents nor to limit or restrict the scope of the invention.