Abstract:
An ergonomic chair comprising a saddle seat, frame, and shin supports that are adjustable in position and orientation with respect to the saddle seat. The saddle seat is adjustable in terms of the width of the portion of the seat supporting the user&#39;s thighs. The shin supports are adjustable with respect to the position of the saddle seat in three degrees of freedom and freely rotate in a fourth degree of freedom. In one embodiment, the frame comprises a rocking mechanism allowing the seat to rock forward and back.

Description:
RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Patent Application No. 61/271,325, entitled “Adjustable Ergonomic Seat,” by Jay Stuart Wallace, filed Jul. 20, 2009, which is incorporated by reference herein. 
    
    
     BACKGROUND 
     In the modern workplace, many workers spend many hours at a desk or work surface in a seated position. Even with occasional breaks or periods away from the work area, spending several hours each day in the same or similar seated work position often leaves the worker with muscle and joint pain, especially lower back pain. It has become vital to the health and well being of workers that seating is provided for the work environment that promotes health, comfort, and ergonomics. Comfortable, ergonomic seating is of great importance to minimize the physical stresses associated with today&#39;s workplace. 
     In general, the present state of the art is incapable of providing users with the option to switch to different comfortable, healthy postures while keeping them within an ergonomic range of a work station in a manner that is non-disruptive to the task being performed. Particularly, the current state of the art does not provide an active sitting and proactive positioning system which incorporates the support of the various body parts and promotes healthy postures and comfort at work stations. 
     Numerous attempts have been made to provide seating devices that allow for adjustment of the user&#39;s position and distribute support of the user&#39;s weight across the buttocks, knees, shins, and back. There are three key features of any ergonomic seating system. First, ease of adjustability prior to use in order to fit users of various sizes. Second, adjustment of the seat bottom and other supports during use to relieve stress and engage different muscle groups. Third, the seating system preferably should allow flexible, natural movement during use to allow the user&#39;s upper body to orient to the work at hand and to allow the user&#39;s lower body to shift and stretch as desired. Information relevant to prior attempts to address these problems can be found in U.S. Pat. Nos. 3,541,313; 3,669,493; 4,589,699; 4,793,655; 4,832,407; 4,960,305; 5,667,278; 5,669,669; 5,782,534; and 7,367,623. However, each of these references either fails to allow user to shift weight to the user&#39;s thighs or fails to allow adequate adjustment of relative position and orientation between a seat bottom and a knee or shin support. For the foregoing reasons, there is a need for a seating system that a user can adjust to shift weight from the user&#39;s posterior to the user&#39;s shins and thighs in order to increase comfort and relieve stress. 
     SUMMARY 
     The present invention is based on previously unrealized objectives to successfully integrate the needs of worker productivity with comfort and health. Specifically, in the preferred embodiment, the invention implements principles of active sitting and proactive positioning in which the user of the chair is enabled and encouraged to change to various comfort and health postures while maintaining ergonomically compatible access and reach to a work station at all times. 
     The present invention is directed to a saddle chair that satisfies these needs for adjustability both prior to use to accommodate a user&#39;s size as well as during use to alter the user&#39;s weight distribution between the user&#39;s buttocks, thighs and shins, while allowing flexible movement of the user&#39;s upper body during use. A saddle chair having features of the present invention has a saddle-shaped seat and position-adjustable shin supports. The shin supports are positioned below the apex of the seat in a comfortable position to receive the user&#39;s knees or shins. The position of the shin supports relative to the seat are adjustable both laterally and vertically relative to the seat in order to provide a comfortable fit for the user. 
     An ergonomic chair having features of the present invention includes a saddle seat having a plurality of shin support mount points on each side, in one exemplary embodiment, these mount points are holes in the surface of the saddle seat shaped to accept a pin on the shin support and allow it to pivot in the hole. Because there are several mount points on each side of the saddle seat, each shin support may be mounted in one of several mount points. Much like a pegboard for securing items to a wall with hooks, each mount point hole provides a different relative position between the shin support and the saddle seat. The saddle seat also includes a means for adjusting the width of the seat for purposes of providing the user suitable adjustment for comfort as well as dynamic adjustment of weight distribution between the user&#39;s buttocks, thighs and shins. In a preferred embodiment, the ergonomic chair also includes a spring-loaded pivoting joint in the chair frame that allows the user to rock the saddle seat forward and back. The setting of a knob allows the user to lock or unlock the pivoting joint and thus enable or disable the rocking motion that is provided by the spring-loaded pivoting joint and a second knob permits adjustment of a damping mechanism. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the following description, appended claims, and the accompanying drawings where: 
         FIG. 1  is a perspective view of a saddle chair in accordance with the principles of the present invention; 
         FIG. 2  is a perspective view of a shin support of the saddle chair of  FIG. 1 ; 
         FIG. 2   a  is a perspective view of the shin support and mount points of the saddle chair of  FIG. 1 ; 
         FIG. 2   b  is a perspective view of an alternate implementation of the shin support and mount points of the saddle chair of  FIG. 1 ; 
         FIG. 3  is a perspective view of a means for adjusting the width of said saddle seat of the saddle chair of  FIG. 1 ; 
         FIG. 3   a  is a perspective view of an alternate implementation of the means for adjusting the width of said saddle seat of the saddle chair of  FIG. 1 ; 
         FIG. 4  is a perspective view of the chair of  FIG. 1  being used by a person in an office environment; 
         FIG. 5  is a cutaway view of the base frame of the chair of  FIG. 1 ; and 
         FIG. 6  is a perspective view of an embodiment of a saddle chair in accordance with the principles of the present invention having an alternative shin support mount frame. 
     
    
    
     DESCRIPTION 
     Definitions 
     A “saddle seat” is an object designed and intended to support a person in a sitting position where a portion of the seat extends between the person&#39;s thighs or knees when the person sits on the “saddle seat” and where the person&#39;s weight is not solely supported by the person&#39;s buttocks but also by the person&#39;s thighs. Examples of a “saddle seat” include: a motorcycle seat, a saddle used on a horse, and the seats depicted in U.S. Pat. Nos. 3,541,313 and 6,709,052. 
     A “shin support” is a structure suitable for use to support a person&#39;s leg between the knee and ankle, inclusive. 
     Overview 
     As shown in  FIGS. 1-4 , a saddle chair embodying features of the present invention comprises a base frame  101 , a saddle seat  110  attached the base frame  101 , a first and second shin support  112  attached to the saddle seat  110  at a first and second shin support mount point  111 , and a plurality of alternate mounting points  111  where the first and second shin supports  112  may be mounted so as to provide a plurality of relative positions between the saddle seat  110  and the first and second shin supports  112 . As shown in  FIG. 2 , a preferred embodiment of a saddle chair incorporating features of the present invention includes a means for adjusting the width of the saddle seat so as to provide easy adjustment of a seated person&#39;s position and weight distribution. 
     Detailed Description of the Invention 
     Referring to  FIG. 1 , there is shown a perspective view of a saddle chair embodying features of the present invention. A base frame  101  comprises a support post  102  and casters  103   a,    103   b,    103   c,  and  103   d.  Optional foot supports  104  are shown attached to the support post  102  but may be attached to any appropriate area of the base frame  101 . A saddle seat  110  is attached to the base frame  101 . The saddle seat  110  comprises a plurality of mount points  111  suitable for attachment of a shin support  112 . A shin support  112  is shown attached to the saddle seat  110  at one of a plurality of shin support mount points  111 . In the preferred embodiment of  FIG. 1 , said plurality of mount points  111  are holes through the surface of saddle seat  110 , which holes are substantially round in shape and include a keyway groove. 
     Referring to  FIG. 2 , a shin support  112  is shown in perspective. When a person is seated in the chair of  FIG. 1 , the person&#39;s shins rest in the curved and preferably padded shin stirrup  131 . Depending on a person&#39;s physical characteristics and how the chair has been adjusted, the shin supports may support the person&#39;s knee, ankle, or any portion of the shin or leg between the knee and ankle. A typical configuration for a seated person on a saddle chair having features of the present invention is also shown in  FIG. 4 . Shin support  112  is attached to saddle seat  110  by inserting shin support pin  132  into one of plurality of mount points  111 . Shin support pin  132  may be a detent pin of one of the types commonly available, such as the pin disclosed in U.S. Pat. No. 6,872,039. 
     A variety of mechanisms suitable for pivotable mount points  111  and compatible pins  132  are known in the art and any of these would be suitable for use in the present invention, including but not limited to the following three described options. First, a cotter key where the cotter key is inserted through the rotating pin  132  on the opposite side of the shin support  112 . Second, a threaded knob may be to the hold an inserted pin  132  in place while permitting the pin  132  to rotate. A third, preferred option is as shown in  FIGS. 2 and 2   a : a keyway system where the shin support pin  132  is round with a short lengthened key blade on the tip of the pin  132  that must be inserted into the receiving mount point holes  111  which are circular with a keyway groove at the top to receive the blade on the shin support pin  132 . The key blade and keyway would be oriented such that the shin support  112  must be rotated upside down in order to insert the pin  132  into the selected mount point  111 . Then after the blade passes through the mount point hole  111 , as the pin  132  is fully inserted, the shin support  112  can be rotated back down and pivots in its normal operating range. 
     In  FIG. 2   b  is shown an alternative embodiment of the shin support  112  of  FIG. 2 . A shin support  112  is attached to the saddle seat  110  at a mount point  111 . A motor  120  is mounted on the inner surface of the saddle seat  110  and aligned with the same mount point  111  in which the shin support  112  is mounted. In this embodiment, the shin support pin  132  is inserted into offset plate  121 , which provides an offset, rotatable connection to the motor  120  at mount point  111 . The operation of the motor-driven shin support  112  is similar to a common BBQ rotisserie unit. The motor&#39;s  120  rotation speed is adjustable, and when operating it rotates the offset plate  121  which in turn moves the shin support pin  132  in a circular motion analogous to the movement of a carriage on a Ferris wheel. The user&#39;s shins are slowly moved in a circular motion up, down, forward and back within the small range of the offset plate  121 . This motion facilitates a constant readjustment of the user&#39;s seating position, allowing greater comfort over extended periods of time in the seated position. 
     In the embodiment of  FIG. 1 , shin supports  112  are shown attached directly to saddle seat  110 . An advantage of this arrangement is that a single means for adjusting the width of the saddle seat  110  also functions to adjust the distance between the shin supports  112 . This direct attachment is not required to practice the present invention, however. The shin supports  112  may also be attached to the base frame  101  such as to the support post  102 , provided their position is near the lower portion of the saddle seat  110  and oriented appropriately to accept a seated user&#39;s shins. The adjustment of the width of the saddle seat  110  as well as the distance between the shin supports  112  functions to transfer some of the user&#39;s weight from the user&#39;s buttocks to his thighs or shins. The wider the adjustment of the saddle seat  110 , the more weight is borne by the user&#39;s thighs and shins and the less is borne by the user&#39;s buttocks. 
     Referring to  FIG. 3 , there is shown a lower front view of the saddle chair of  FIG. 1 . A preferred embodiment of a means for adjusting the width of said saddle seat is shown as the combination of structures threaded shaft  130 , push bars  135 , spreader bars  136 , brackets  132 , and threaded cylinder  133 . The brackets  132  allow rotation of the spreader bars  136  while holding them against the sides of saddle seat  110 . In this embodiment, said means for adjusting the width of said saddle seat  110  is operated by turning a manual crank  134  to rotate threaded shaft  130 , thereby driving threaded cylinder  133  down threaded shaft  130 , which causes push bars  135  to force the sides of saddle seat  110  outward thus increasing the width of said saddle seat  110 . To narrow the width of saddle seat  110 , threaded shaft  130  is turned the opposite direction, driving threaded cylinder  133  up threaded shaft  130 , which causes push bars  135  to pull the sides of saddle seat  110  inward thus decreasing the width of saddle seat  110 . In alternative embodiments, the width adjustment caused by operation of crank  134  may be adjusted by activation of a motor, a ratcheting lever, or other suitable means known in the art. 
     The present invention is not limited to the particular implementation of the means for adjusting the width of a saddle seat shown in  FIG. 3 . Any suitable structure or mechanism for effectuating adjustment of the distance between the two sides of saddle seat  110  may be used to selectively adjust the distance between the sides of the saddle seat  110  and also between the shin supports  112 . Other suitable structures known in the art include the following examples. 
     A first example is a horizontal, spring loaded, telescoping, pneumatic piston with an air release button activated by a lever arm similar to those in a typical office chair height adjustment systems as shown in  FIG. 3   a . To adjust the sides, the user activates a lever arm  137  that presses the air release button on the pneumatic piston  138  by means of a cable system  139  and either squeezes his or her thighs together or allows the spring within the piston to push the sides apart until the correct width is achieved and then releases the lever. An example gas cylinder suitable for use on a chair having features of the present invention is described in U.S. Pat. No. 4,200,332. A second example is a pair of horizontal, geared arms attached one to each side of the saddle seat  110 . The arms completely overlap one another when the seat sides are down. The two arms pass through a locking mechanism located at the center of the seat between the two arms. A central gear within the locking mechanism engages both arms ensuring that each seat side is deployed in and out the same distance. The locking mechanism is released to adjust the seat sides in and out. When unlocked, the user can move the sides of the saddle seat  110  closer together or further apart as their shins are engaged in the shin supports  112 , then lock the sides in any desired setting within their range of movement. A third example is a horizontal, spring loaded, telescoping post with one end attached to each side of the saddle seat so as to push the sides of the seat apart. A user may push against the spring loaded action with the user&#39;s thighs in order to narrow the seat. When the seat is compressed to the desired width, the user can lock the spring loaded post into the selected position by operating a locking device to restrict the movement of said spring loaded post. A fourth option is to use an electric motor to drive the saddle seat side expanding arms. The desired width of the saddle seat  110  may be set by operation of the motor, which may further be set to cycle the width between a desired minimum and maximum setting. 
       FIG. 4  is a representative depiction of the chair of  FIG. 1  while in use by a typical user. As shown in  FIG. 4 , the user&#39;s upper shins just below the knees are resting in the shin supports  112 . The crank  134  is positioned between the user&#39;s knees and is easily reachable by the user to dynamically adjust the width of the saddle seat  110  and thereby also the distance between the shin supports  112 . 
     Referring now to  FIG. 5 , vertical support post  102  is mounted to the base frame  101  by means of a pivoting connection  151 . The vertical support post  102  on which a saddle seat  110  is mounted may rock forward and back on the pivoting connection  151  as shown by the arrows. When vertical support post  102  is rocked forward and back by a person seated on a seat mounted to the upper end of said support post  102 , the lower end  102   b  of support post  102  drives shaft  153  alternately against rear springs  156  and forward spring  157 . An adjustment knob  154  is positioned on the forward section of the base frame  101  along side a pin-knob  152 . The adjustment knob  154  is used to adjust the friction damping force imparted on the shaft  153  by friction plates  155 . The less resistance that is imparted on the shaft  153  by the adjustment knob  154 , the more freely the support post  102  is permitted to rock forward and back. The pin-knob  152  shown dashed, may be placed in the position indicated to block movement of shaft  153  and thereby prevent the vertical support post  102  from rocking. The pin-knob  152  may be placed in a stored position as shown to permit free movement of shaft  153  and thereby to enable rocking of vertical support post  102 . 
     In operation, the ergonomic chair may be adapted to support a seated user in a substantially neutral position in which the user&#39;s weight is supported by the user&#39;s buttocks, thighs, and shins. The ergonomic seat may be adjusted for fit to users of different physical sizes by adjusting the position of the shin supports relative to the saddle seat. Due to its saddle seat design, the ergonomic chair is easily mounted in comparison to previously known chairs designed to support the user&#39;s weight on the user&#39;s knees or shins. When seated on the ergonomic chair, the user is free to shift his weight by rocking forward and back about the pivot means in the chair frame against the rocker springs. This gentle rocking motion engages the user&#39;s abdominal core muscles and serves to reduce muscle tension and fatigue. The width of the saddle seat is also adjustable while in use to enable the user to dynamically adjust the distribution of weight from the buttocks to the thighs and knees. As one muscle group tires, another muscle group can be engaged by adjusting the seat width. As the seat is widened, more of the user&#39;s weight is borne by the thighs and shins and less by the buttocks. Conversely, as the seat is narrowed more weight is shifted to the buttocks. 
     Various modifications, substitutions, and changes may be made in the structure and embodiments shown without departing from the concept of the invention. Therefore, the scope of the appended claims should not be limited to the description of the preferred versions set forth above.