Patent Publication Number: US-6709059-B1

Title: Adjustable non-biased positioning mechanism

Description:
BACKGROUND OF THE INVENTION 
     A wide variety of applications call for the ability to adjust and maintain the position of two objects relative to each other. Ease of adjustment and ability to hold a position once set are desirable. Additional desirable characteristics of a positioning device include high reliability, compact size and ease of manufacture. 
     Known positioning and adjustment devices have typically involved the use of a biasing means, such as a spring to control positioning. Springs often increase the effort required to adjust position of objects, because invariably, the operator is working against the spring, often multiple times, during adjustment. Springs are troublesome in that they are prone to wearing out or breaking. Spring failures can result in catastrophic failure of the entire positioning means. Assembly of a positioning device involving a spring can also be problematic and dangerous due to the high forces typically required to compress a spring during assembly of the positioning device. 
     One application of positioning devices involves furniture, and more specifically, chairs. Adjustment of chair components has long been known to increase comfort and efficiency of workers seated for long periods. A variety of adjustment devices have been used to allow for adjustment of chair components, such as seats, backrests and armrests. However, these devices have typically suffered from the drawbacks involved with reliance on a biasing means. 
     Similarly, adjustment of machines to adapt to different worker sizes is desirable to increase worker comfort and efficiency. Such applications are also typically disadvantaged by the use of a biasing means. 
     A need exists for a positioning device that does not involve a biasing means, thereby providing increased usability, reliability and efficiency in manufacture. 
     SUMMARY OF THE INVENTION 
     According to one embodiment of the invention, a positioning mechanism is provided, having a first member defining a channel, a second member, slidably mounted to the first member along an axis, a substantially non-biased cog, rotatably mounted to the second member, such that the channel and the cog interact to inhibit motion of the second member in a first direction relative to the first member until the second member has traveled substantially in a second direction. 
     A further, optional aspect of the invention includes a positioning mechanism involving an entry channel, continuous with the channel, to permit entry of the cog into the channel by slidable movement between the first and second members along the axis. 
     According to a second embodiment of the invention, an adjustment mechanism is providing, having a first member defining a channel, a second member mounted to the first member to be slidable with respect to the first member along an axis, a cog, substantially free of a biasing member and mounted between the first and second members and adapted to rotate with respect to the second member, such that the channel is formed to create locking positions, enabling the cog to inhibit motion of the second member in a first direction relative to the first member. 
     An optional aspect of the second embodiment of the invention is an undulating surface formed in a side of one of the first and second members, facing an other of the first and second members and oriented parallel to the axis, and a tab, mounted to the other of the first and second members and biased toward the one of the first and second members, adapted to travel along the undulating surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be more fully understood by reference to the following detailed description in conjunction with the attached drawings in which like reference numerals refer to like elements through the different views. The drawings illustrate principles of the invention and, although not to scale, show relative dimensions. 
     FIG. 1 is a perspective view of a chair incorporating a positioning mechanism of the present invention; 
     FIG. 2 is a exploded view of a positioning mechanism according to an embodiment of the invention; 
     FIG. 3A is a top view of a cog according an embodiment of the invention; 
     FIG. 3B is a side view of the cog shown in FIG. 5A; 
     FIG. 4 is a cut-away side view illustrating a positioning member according to an embodiment of the invention; 
     FIG. 5 is an end view of the positioning mechanism shown in FIG. 3; 
     FIG. 6 is a top view of a first member of a preferred embodiment of a positioning member according to the invention; 
     FIG. 7 is a cross-sectional view of a tab mounted to the first member shown in FIG. 6; 
     FIG. 8 is a cross-sectional view of an undulating surface formed in a second member; 
     FIG. 9 is a chair backrest configured to work with an embodiment of the invention; and 
     FIG. 10 is an exploded perspective view of an embodiment of the invention for use with a chair armrest. 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The invention is useful in a variety of applications involving adjustment or positioning of two items relative to each other. In the workplace, a variety of items can be configured for use by a wide variety of workers or tasks. For example, in a factory, worktables or manufacturing equipment can often be adjusted for height, thereby accommodating different optimal operating heights among workers. Other applications involve adjustment of equipment for varying workpiece sizes. Processing guides and safety guards are examples of objects that may require repositioning frequently. A common application involving positioning of objects involves positioning of furniture components, such as the seat, backrest and armrests of a chair. Although not limited to adjustment of chair component position, the invention will now be described in relation to use in a chair. 
     One application of the invention is directed to use with a chair backrest  5  and is shown in FIG. 1. A positioning mechanism  100  is located between the chair backrest  5  and a chair seat  6 . The positioning mechanism  100  allows the chair backrest  5  to be located at different heights relative to chair seat  6 , thereby allowing a person sitting in the chair to locate the chair backrest  5  in an ideal position. 
     FIG. 2 provides an exploded view of one embodiment of the invention. A positioning mechanism  100  includes a first member  110  and a second member  120 . The first member is preferably formed with a first substantially planar surface  115 . A channel  130  is formed in first member  110 , preferably in the first substantially planar surface  115  of first member  110 . The channel  130  is preferably formed in a loop including locking positions  140  along one side of the loop and a return channel  150  formed along an opposing side of the loop. 
     Second member  120  is preferably formed with a second substantially planar surface  125  for sliding engagement with the first substantially planar surface  115  of first member  110 . 
     First and second members  110 ,  120  are not required to have a substantially planar surface. However, first and second members  110 ,  120  are to be configured to allow for movement in relation to each other. 
     Second member  120  is preferably provided with at least one flange  160  forming a guide groove  170  in which edges of side member  110  can be accommodated. Flanges  160  and guide groove  170  are preferably configured to ensure that first member  110  slides linearly with respect to second member  120  along an axis  180 . As one example of an alternative embodiment, the direction of travel of first and second members  110 ,  120  may be guided by the movement of objects to which each of the first and second members  110 ,  120  are mounted. In such an embodiment, grooves or flanges may be omitted from the first and second members  110 ,  120 . 
     Another variation of first and second members  110 ,  120  involves integrally forming one or both of first and second member  110 ,  120  as part of a component to which they would otherwise be mounted. Such a configuration is often more efficient to manufacture. For example, first and second member  110 ,  120  may each be integrally formed into a chair backrest  5 , chair seat  6 . 
     As shown in FIG. 2, second member  120  is preferably formed with a receptacle  190  beginning at and extending below the substantially planar surface  125 . The receptacle  190  is preferably formed in the shape of an arc extending from a recessed portion  200  of receptacle  190 . In a preferred embodiment of the invention, the arc extends 53°. 
     The recessed portion  200  of receptacle  190  is formed to provide an axis of rotation  210  within receptacle  190 . 
     First and second members  110 ,  120  may be made of a wide variety of plastics or metals. In a preferred embodiment of the invention, first and second members  110 ,  120  are constructed of a nylon, such as Kisso. One of skill in the art will appreciate that many manufacturing processes are available for creating first and second members  110 ,  120 , such as, by way of example, injection molding, casting or machining. 
     A cog  220  is located within receptacle  190  and formed to rotate about the axis of rotation  210 . The cog is also formed to interface with channel  130  of first member  110 , preferably with a cog tooth  230 . The cog  220  is preferably mounted to second member  120  by placing the cog  220  within receptacle  190 . If cog  220  is formed with a protrusion  225 , shown in FIG. 3B, the protrusion  225  preferably rotatably mates with recessed portion  200  of receptacle  190 . In a preferred embodiment of the invention, the cog tooth  230  has a circular cross-section and a width of channel  130  is approximately equal to the diameter of the circular cross-section of cog tooth  230 . 
     FIGS. 3A and 3B provide views of a preferred cog  220  configuration. The cog  220  may be made of a wide variety of plastics or metals. A preferred configuration involves a cog made metal, such as aluminum. One of skill in the art will appreciate that many manufacturing processes are available for creating cog  220 , such as, by way of example, injection molding, casting or machining. 
     First member  110  and second member  120  are designed to be slidably mounted to each other, preferably accommodating linear relative movement along axis  180 . During relative motion between first member  110  and second member  120 , cog  220  rotates along axis of rotation  210  so that a portion of cog  220 , extending above substantially planar surface  125 , travels within channel  130  of first member  110 . 
     As shown in FIG. 4, channel  130  is configured so that a portion of cog  220 , such as, for example as described herein, cog tooth  230 , can travel into locking positions  140  or past locking positions  140 , depending on the direction of relative motion between first and second members  110 ,  120 . 
     Channel  130  is formed to rotate the cog  220  toward each locking position  140 . Because channel  130  and locking positions  140  work together to guide the rotating of cog  220 , a biasing device is not required to bias the cog  220  toward the locking positions  140 .  10  Locking positions  140  are shaped to catch and hold a portion of cog  220 , preferably cog tooth  230 , by rotating cog  220  toward the locking positions  140  during relative motion between first and second members  110 ,  120  in a particular direction. Conversely, channel  130  is formed to inhibit engagement of cog tooth  230  in locking positions  140  during relative motion between first and second members  110 ,  120  in an opposite direction. 
     For example, as shown in FIG. 4, if first member  110 , in which channel  130  is formed, travels in direction A relative to second member  120 , to which cog  220  is rotatably mounted, the cog tooth  230  travels along channel  130  without engaging in locking positions  140 . 
     Relative movement between first and second members,  110 ,  120  in a direction opposite to direction A is inhibited by the shape of locking positions  140 . In the event first member  110  stops traveling in direction A, relative to second member  120 , and begins traveling opposite to direction A when cog tooth  230  is in channel  130  near locking positions  140 , the cog tooth  230  will enter a locking position  140 , preventing further relative movement opposite to direction A between first and second members  110 ,  120 . To continue further relative movement between first and second members  110 ,  120  opposite to direction A, first member  110  travels to a maximum limit in direction A, thereby positioning cog tooth  230  in reset position  132 . 
     Reset position  132  is positioned relative to axis of rotation  210  such that relative movement of first member  110  opposite to direction A results in cog  220  rotating to position cog tooth  230  into return channel  150 , preventing cog  220  from engaging locking positions  140 . First member  110  is then free to travel to a maximum limit of travel in a direction relative to second member  120 , opposite to direction A. 
     In a variation of the invention, the orientation of the locking positions  140  and return channel  150  may be reversed about a vertical axis as shown in FIG.  4 . For example, locking positions  140  may be formed on the right and return channel  150  formed on the left. 
     In an optional embodiment, an end limit  165  is formed in guide groove  170  or first or second members  110 ,  120  to limit travel of first member  110  in a maximum limit of travel in a direction relative to second member  120 , opposite to direction A. Such an embodiment absorbs impact forces as a maximum limit of travel is reached, thereby reducing strain on cog  220 . Typical examples of such an application include a chair backrest  5  being raised to an upper limit of travel and released to travel to a bottom limit of travel. An end limit  165  can be provided to absorb the impact of stopping the downward travel of the chair backrest  5 . As a further option, a dampening surface  167  can be provided on the end limit  165  at a location where the end limit  165  meets the first member  110 , in the case of the end limit  165  formed in or mounted to the second member  120 . The dampening surface can include a variety of impact-absorbing material, such as one or more rubber dowels or felt or various polymers. 
     An entry channel  240  is preferably provided to allow cog  220  to enter into channel  130  upon initial assembly. Entry channel  240  allows cog  220  to enter channel  130  by way of linear motion between first member  110  and second member  120 . Entry channel  240  joins channel  130  at an angle inhibiting cog  220  from re-entering entry channel  240  once cog  220  is within channel  130 . 
     FIG. 4 also illustrates an optional configuration allowing the second member  120  to be mounted to object  300 . An attachment device  310 , such as, for example, a bolt, screw or rivet, may be provided to secure either the first or second member  110 ,  120  of the invention to object  300 . A variety of attachment devices will be apparent to one of skill in the art for use with the invention. For example, object  300  may be configured with tabs to secure one end of either the first or second member  110 ,  120  of the invention and another attachment device employed to secure an opposite end of either the first or second member  110 ,  120  to object  300 . 
     FIG. 5 provides an end view showing flanges  160  and guide grooves  170  of second member  120  located around edges of first member  110 . Receptacle  190  and axis of rotation  210  are also illustrated in FIG.  5 . Object  300  is also shown having an indented volume  320  to accommodate first and/or second members  110 ,  120 . A mounting flange  127  is provided for mating with object  300 . Mounting flange  127  may also be formed so that object  300  does not need to have an indented volume  320 . 
     According to a preferred embodiment of the invention, as shown in FIGS. 6 and 7, a tab  250  may be provided on substantially planar surface  125  of second member  120  or a substantially planar surface  115  of first member  110 . A corresponding undulating surface  260 , shown FIG. 8, may be provided on the opposing substantially planar surface of substantially planar surface  125  of second member  120  and or substantially planar surface  115  of first member  110 . Tab  250  and undulating surface  260  are configured to interface with each other and provide feedback to a user during operation of positioning mechanism  100 . Feedback may include sound, such as a clicking sound during motion between first member  110  and second member  120 . Clicking sounds may preferably be created in association with the cog  220  entering each of locking positions  140  by properly forming undulating surface  260 . Additional or alternative forms of feedback may include motion resistance. By the interaction of tab  250  and undulating surface  260 , noticeable resistance may be provided to the user of the location of each of locking positions  140  by increased resistance to linear movement between first member  110  and second member  120 . 
     Optionally, undulating surface  260  may be formed so as not to indicate locations of each of locking positions  140 , instead providing noise or physical resistance during any movement, or a predetermined amount of movement, between first member  110  and second member  120 . 
     Although various applications of the positioning mechanism  100  of the present invention are possible, several applications include furniture, such as chairs, as shown in FIGS. 9 and 10. FIG. 9 illustrates a chair backrest  5 , optionally formed with an integral second member  120 . Alternative variations include integrally forming a first member  110  in a chair component or providing accommodation for rapid mounting of either first member  110  or second member  120  to a chair component. By modification of the structure of chair backrest  5 , a chair backrest may be optimized to provide a thin backrest and/or ideal location of cushioning by allowing positioning mechanism  100  to be located in a preferred location within chair backrest  5 . 
     FIG. 10 illustrates an example of implementing the present invention within an application involving an armrest of a chair. Although FIG. 10 illustrates an embodiment involving an upright arm  290  formed as a second member  120  of the invention, the invention is not so limited and an upright arm  290  may alternatively be formed as a first member  110  or formed so that a separate component resembling either a first member  110  or a second member  120  may be mounted. In the configuration shown in FIG. 10, an armrest cushion is preferably attached at mounting location  270 . As illustrated in FIG. 10, additional hinges or other adjustment devices may be provided at many locations. 
     A variation of the invention, described in relation to FIG. 10 involves forming the first member  110  as a sleeve to be placed over second member  120 . In such a variation, the appearance and safety of the invention can be enhanced. Locations at which guide groove  170  and flange  160  meet would be encapsulated, hiding an elongated seam formed by the proximate locations of second member  120  and flange  160  with guide groove  170  and first member  110 . Furthermore, access to portions of guide groove  170  not occupied by flange  160  would be prevented. 
     FIG. 10 also illustrates a variation of the embodiment shown in FIG. 2 in that first member  110  is formed with guide grooves  170 , while second member  120  is formed with flanges  160 . 
     The embodiment of the invention shown in FIG. 10 further illustrates an optional entry channel plug  280 . Entry channel plug  280  is used in an alternative embodiment of the invention to preclude cog  220  from entering entry channel  240 , thereby exiting channel  130 , during operation. Entry channel plug  280  is preferred in locations where an entry channel as illustrated in FIG. 3 cannot be provided. 
     The positioning mechanism  100  of the present invention is also suitable for other applications requiring adjustable positioning of various components. By way of example, the positioning mechanism of the present invention could be used to adjust the height of a chair seat  6 , illustrated in FIG. 1, or a writing surface mounted to the chair, typically found in academic settings. Further examples include lamps that are adjustable for positioning, such as a reading lamp. Other stands, such as jack stands or stands used for positioning of laboratory equipment such as magnifying glasses or lamps or electrical leads. The invention is not limited to positioning by human effort; the invention can be used in applications involving a variety of other devices proving positioning force, such as, for example, hydraulic cylinders. These examples are meant to be illustrative and not limiting. As described herein, the terms positioning mechanism and adjustment mechanism are considered to be interchangeable. 
     The present invention has been described by way of example, and modifications and variations of the exemplary embodiments will suggest themselves to skilled artisans in this field without departing from the spirit of the invention. Features and characteristics of the above-described embodiments may be used in combination. The preferred embodiments are merely illustrative and should not be considered restrictive in any way. The scope of the invention is to be measured by the appended claims, rather than the preceding description, and all variations and equivalents that fall within the range of the claims are intended to be embraced therein.