Abstract:
A therapeutic chair having a seat, a base configured to rest on a surface, and a seat support mechanism configured to couple the seat to the base and to enable the seat to be rocked in any direction while resisting rocking of the seat. Ideally the seat-support mechanism permits universal motion in all directions about a vertical axis, including 360 degrees of rotation, 40 degrees of side-to-side flexion, and 35 degrees of front-to-back flexion on a universal-type joint. The joint includes a first support member having a projecting post and a second support member having a housing with first and second resilient members mounted therein and configured to slidably receive the post. A unique seat design in combination with the universal seat connector reduces pressure on the legs and facilitates therapeutic exercise when seated.

Description:
TECHNICAL FIELD 
     The present invention pertains to a therapeutic chair, and, more particularly, to a unique seat design and universal seat connector that reduces pressure on the back of the legs, especially the veins, and facilitates therapeutic exercise when seated. 
     BACKGROUND OF THE INVENTION 
     Mobile tissue, and, in particular, the spine, is susceptible to a variety of disorders resulting from active misuse and sedentary neglect. It has been shown that approximately 90% of chronic pain is located in the musculoskeletal system, with the prevalence of pain in individuals up to 59 years of age commonly occurring in the head, neck, shoulders, low back, legs, and pelvis. Some form of acute and chronic spinal pain will affect almost 80% of individuals in the western world. Musculoskeletal conditions have been recognized as a major cause of health and economic problems, with spine-related disorders second only to the common cold as a reason for absence from work. 
     Sleep disorders are also related to back pain, such as restless leg syndrome, periodic limb movement disorders, and sleep apnea. Backaches and leg pains are considered a major cause of sleep deprivation and have been attributed to a substantial loss of work productivity and work-related injuries. 
     While it has been assumed that lifting and bending accidents were the common cause of back injuries, approximately 80% of the U.S. population now have sedentary jobs requiring them to sit for up to eight hours per day. Factoring in the additional sitting time for work-related travel and resting or watching television, individuals may be sitting up to fifteen hours per day. While bending and lifting accidents can occur suddenly with known causes, a sedentary worker&#39;s back-related problems will occur gradually with no apparent identifiable cause. 
     After about age 12, the vascular supply system to spinal disks will begin to atrophy. The aging disks need just as much daily nutrition intake, metabolic waste, and algogenic inflammatory exudate elimination as they did before becoming avascular. It is generally accepted that a daily full range of motion, identified as “osmosis and imbibition” is absolutely essential for daily metabolic interchange. That is, nutrition intake and elimination of waste products must occur in order to maintain healthy, well-hydrated spinal disks, ligaments, and tendons. 
     In contrast, it has been found that up to 500 days is required for metabolic interchange by patients who are sedentary and patients who do not engage in a daily full-range spinal workout. The full-range workout is necessary to mix the glucosaminoglycans, chondroitin sulfate, and the proteoglycan aggregates that then nourish the disks and other avascular tissues. 
     Clinical observations have established the deleterious effects of the immobilization of joints and tissues in patients. It has also been observed that early active motion as opposed to prolonged immobilization of diseased and injured parts provides beneficial local effects. In addition, active and passive motion of the spine and extremities will reduce a patient&#39;s susceptibility to necrosis resulting from prolonged immobilization. 
     Thus, the best treatment and maintenance of healthy mobile tissue, such as the spine, is motion. It is well known that the biomechanics of the spine involve six degrees of motion (flexion, extension (right and left), rotation (right and left), lateral bending, and long-axis distraction and compression (load/unload cycling)). 
     During the normal gait or walking cycle, the spine is in a lordotic position, wherein portions of the spine receive a circumductive load-and-unload force. This cycle occurs each time a step is taken as gravity forces the body downward. The pumping action creates a load/unload cycle along with a slight rotational component as the arms swing and the legs alternately step. Patients confined to wheelchairs, those suffering from spinal injuries, or otherwise healthy individuals subjected to prolonged immobilization are unable to actively put the spinal column in motion and achieve the required circulation of blood and intercellular fluids through the spinal region, including the disks and legs. 
     One attempt to provide motion to seated workers is described in U.S. Pat. No. 5,113,851 issued to Gamba on May 19, 1992 for a chair equipped with a swinging seat. Gamba teaches the mounting of a seat to a base through an articulated ball joint mechanism with movement induced by a motor through a gear train assembly. Hence, Gamba provides passive motion, i.e., motion produced by an external force, using a complicated, expensive, and cumbersome motor and gear train assembly. Moreover, the articulated ball joint assembly provides no structure for resisting movement of the seat or maintaining the seat in a relatively horizontal position when no force is applied or when not in use. In addition, the seat of Gamba provides no relief for pressure on the legs of a user. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a therapeutic chair having a seat, a base for supporting the seat on a surface, and a seat support mechanism configured to couple the seat to the base and enable the seat to rock in any direction with respect to the base and to resist rocking of the seat. Ideally, the seat support mechanism returns the seat to a starting position, such as a horizontal position, when no force is applied or when not in use. 
     In accordance with another aspect of the present invention, the seat support mechanism includes a first support member configured for mounting to one of either the seat or the base and a second support member configured for attachment to the other of the seat and the base and further configured to receive the first support member in slidable engagement, the second support member including at least one resilient member configured to urge the first support member into alignment with a longitudinal axis of the second support member. 
     In accordance with a further aspect of the present invention, the first support member is a post having a longitudinal axis and the second support member is a housing with a longitudinal axial bore defining an interior, and further including at least one resilient member mounted in the housing interior with a central opening that is sized and shaped to receive the post. 
     In accordance with yet another embodiment of the present invention, a therapeutic chair is provided having a seat and a base for supporting the seat on a surface, the seat having a substantially triangular planform shape with an apex portion configured to be straddled by a user&#39;s legs and a base portion configured to support the user in a seated position. Ideally, the apex portion of the seat is upturned, as are first and second corners of the base portion. 
     In accordance with still yet another aspect of the present invention, the seat has a top surface and a bottom surface, and the top surface has a dished configuration such that the apex portion and first and second comers of the base portion are upturned. 
     In accordance with yet a further embodiment of the present invention, a therapeutic chair is provided having a hydraulic, adjustable-height seat with 360 degrees of rotation, 40 degrees of side-to-side flexion, and 35 degrees of front-to-back flexion on a universal-type joint to facilitate all possible combinations of exercise motion. 
     As can be readily appreciated from the foregoing description, the therapeutic chair of the present invention has a pyramid-shaped seat. The top of the pyramid faces forward. The seat rests on a universal joint that enables controlled motion by a user in all directions as the user moves, while simultaneously ensuring stability of the arms, back, and chair base. The unique seat is designed for freedom of leg motion and blood circulation. This design combined with user-controlled motion allows for continuous spinal, low back, and leg macro and micro-motions to prevent accumulative trauma injuries to the back, relief for aching legs, and prevention of varicose veins. The arms of the therapeutic chair are adjustable to three inches higher than ordinary chair arms, which the user&#39;s arms to rest when working. The higher arms minimize the user&#39;s arm weight, thus not only preventing but also relieving chronic aching in the neck, upper mid back and shoulders, as well as carpal tunnel aggravations of the wrist and hands. 
     The back of the chair is not as tall as other chairs, allowing for support of the user&#39;s rib cage and the upper part of the low back without interfering with breathing. The back and the seat of the chair are adjustable for tilting backward or forward in combinations for the comfort of the user. The seat bottom may be tilted forward while the chair back is tilted backwards, or vice versa. In addition, the chair sits on an adjustable-height gas cylinder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features and advantages of the present invention will be more readily appreciated as the same become better understood from the following description when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an isometric projection of a therapeutic chair formed in accordance with the present invention and showing the seat portion in alternative positions of articulation; 
     FIG. 2 is an isometric projection of a therapeutic chair formed in accordance with another embodiment of the present invention; 
     FIG. 3 is an isometric projection of the therapeutic chair of FIG. 2, with the seat portion removed; 
     FIG. 4 is an isometric projection of a seat support mechanism formed in accordance with the present invention; 
     FIG. 5 is a cross-sectional partially-exploded view of the seat support mechanism of FIG. 4; 
     FIG. 6 is a front elevational view of the chair of the embodiment of FIG. 3 without the seat; and 
     FIG. 7 is an isometric projection of the therapeutic chair of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, shown therein is a therapeutic chair  10  formed in accordance with one embodiment of the present invention. The chair  10  includes a seat  12  mounted to a base  14  by way of a seat support mechanism  16  that includes a coupling  18 . The base  14  has a plurality of legs  20 , each leg  20  having a distal end  22  configured to bear against a support surface (not shown) and a proximal end  24  connected to a lower end  26  of a vertical support member  28 . Wheels  27  or other surface contacts may be mounted on the distal end  22  of each leg  20  in a conventional manner known in the art. 
     The vertical support member  28  has an upper end to which is mounted the seat support mechanism  16  with coupling  18 , which is further mounted to the seat  12 . The coupling  18  is configured in a preferred embodiment to permit tilting of the seat  12  in any direction about a vertical axis X. As shown in FIG. 1, in this particular embodiment, the seat  12  has a range of motion that includes 360 degrees of rotation about the vertical axis X, 40 degrees of side-to-side flexion, and 35 degrees of front-to-back flexion to facilitate all possible combinations of exercise motion. The coupling  18  urges the seat  12  to an initial position wherein the seat  12  is in a substantially horizontal orientation. 
     The vertical support member  28  may include a hydraulic actuator that permits a user to raise or lower the seat  12  with respect to the base  14 . Such hydraulic actuators are readily commercially available and may be used in a conventional manner with the chair  10 . As such, the hydraulic actuator will not be described in detail herein. 
     The seat  12  in this embodiment has a pyramid or triangular planform shape. More particularly, the seat  12  has a forward portion  30  with an apex  32  formed by the intersection of first and second sides  34 ,  36  that are configured to allow a user&#39;s legs to straddle the apex  32  and a rearward portion  38  that is configured to support a user in a seated position. In the illustrated embodiment, the rearward portion  38  has a substantially rectangular planform shape with left and right rearward comers  40  and  42 , respectively, and left and right intermediate corners  44  and  46 , respectively, located between the rear corners  40 ,  42  and the sides  34 ,  36 , respectively, of the apex  32 . Ideally, the apex  32  and the left and right rearward corners  40 ,  42  are formed to project upward or include an upward projection  47 . The seat  12  may be formed to have a concave top surface  48  with the apex and the left and right rearward corners  40 ,  42  curved upward. The bottom surface  50  of the seat  12  can assume a convex shape to match the concave shape of the top surface  48  or it may be formed to be substantially flat. 
     Referring next to FIGS. 2 and 3, illustrated therein is another embodiment of a therapeutic chair  52  formed in accordance with the present invention. This chair  52  has a seat  54  mounted to a base  56  through a vertical support mechanism  58 . A transverse member  60  is mounted to the vertical support mechanism  58  to extend outward horizontally. The transverse member  60  has upwardly-curved left and right vertical ends  62 ,  64 , respectively. Slidably mounted to the left and right vertical ends  62 ,  64  are left and right arm rests  66 ,  68 , respectively (shown more clearly in FIGS.  6  and  7 ). The height of the left and right arm rests  66 ,  68  may be individually adjusted using a conventional mechanism that is readily commercially available and which will not be described in detail herein. 
     Referring to FIGS. 6 and 7, shown therein in greater detail is the transverse member  60  attached to the vertical support mechanism  58 . Projecting at substantially a right angle from the transverse member  60  is a backrest support assembly  70  having a backrest  72  attached thereto. The backrest support assembly  70  is of a conventional construction that is readily commercially available and will not be described in detail herein. In one embodiment, the backrest  72  is shorter than conventional backrests. The shortened backrest facilitates support of the us&amp;r&#39;s rib cage and the upper part of the low back without interfering with breathing. 
     As shown more clearly in FIGS. 3 and 7, the seat  54  has been removed to reveal a seat support mechanism  74 . The seat support mechanism  74  includes a first support member  76  mounted to a bottom surface  78  of the seat  54 , as shown in FIG. 3, and a second support member  80  attached to a top surface  82  of the backrest support assembly and to a flange  84  on the transverse member  60 . 
     The first support member  76  is comprised of a plate  86  mounted to the bottom surface  78  of the seat. Projecting from the plate  86  is a post  88 . In this embodiment, the post has a substantially circular cross-sectional configuration and is elongated along a longitudinal axis. The second support member  80  is comprised of a mounting plate  90  to which a coupling assembly  92  is attached, in this case by welding. However, the coupling assembly  92  may be integrally formed with the mounting plate  90 . Conventional fasteners  94  attach the mounting plate  90  to the flange  84  on the transverse member  60  and to flanges extending from the backrest support assembly  70 . 
     The mounting plate  90  is sized and shaped to avoid interference with a vertical height adjustment lever  98  and backrest position adjustment lever  100 , shown more clearly in FIG.  7 . 
     Referring next to FIGS. 4 and 5, shown therein in greater detail, is the seat support mechanism  16  used with the first embodiment of the therapeutic chair  10  as shown in FIG.  1 . The first support member  76  is shown having the post  88  extending from a cylindrical tube  102 . The tube  102  is sized and shaped to be coupled to a hydraulic actuator for adjusting the height of the seat  12  through a lever  103 . This differs from the embodiment shown in FIG. 3, wherein the post  88  projects from the mounting plate  90 . 
     The coupling assembly  92 , as shown in cross section in FIG. 5, includes first and second resilient donut-shaped disks  104 ,  106 , sized and shaped to be slidably mounted in a longitudinal axial bore  108  of a cylindrical housing  110 . Each of the first and second resilient disks  104 ,  106  have a longitudinal axial bore  111 ,  113 , respectively, sized and shaped to allow the post  88  to be slidably inserted into the housing  110  and through the disks  104 ,  106 , preferably with a tight fit. A cylindrical spacer  112  holds the first and second disks  104 ,  106  apart when mounted inside the housing  110 . The first resilient disk  104  is retained in the housing  110  by a C-clip  114  that is retained within an annular groove  116  formed on an interior surface  118  of the housing  110  adjacent an open end  120  of the longitudinal axial bore  108 . The second resilient disk  106  bears against the plate  107 , which in the embodiment of FIG. 1 is attached under the seat  12 . 
     Each of the first and second resilient disks  104 ,  106  are formed of a hard yet compliant material, such as a hard rubber or, more preferably, material formed of neoprene, having a hardness in the range of 200 to 400 pounds maximum load. Such disks are readily commercially available and will not be described in greater detail herein. 
     The post  88  has a free end  122  that is slightly rounded such that when the post  88  is inserted into the coupling assembly  92 , the free end  122  will bear against the mounting plate  90 . The post  88  has sufficient length that the tube  102  (or plate  86  with the embodiment of FIG. 1) will not bear against or touch the housing  110 . In the assembled configuration, as shown in FIG. 4, the first and second resilient disks  104 ,  106  hold the post  88  in an initial orientation such that a longitudinal axis X of the post  88  is aligned with a longitudinal axis X of the housing  110 . Because the disks  104 ,  106  are formed of resilient material, a force exerted laterally on the post  88  will cause lateral compression of the disks  104 ,  106 , allowing the post  88  to tilt at an angle with respect to the longitudinal axis of the housing  110 . Lateral travel of the post  88  is limited by the disks  104 ,  106  and, ultimately, by the size of the housing  110 . 
     In use, with either embodiment of the chair a user would straddle the apex of the seat with their legs while resting on the remaining portion of the seat. Hence, the user&#39;s legs are relieved of upward and inward pressure that impedes circulation while seated. The seat can then be tilted by the user as shown in FIG.  1 . 
     The seat support mechanism or universal joint formed in accordance with the present invention enables controlled motion in all directions as the user moves. In the embodiment with the arms and backrest, stability of the arms and back are ensured during user-controlled motion. Ideally, a user performs a regimen of exercises using the therapeutic chair. Such exercises can include four sessions of full-range motion workouts necessary for the lower spinal disks during an eight-hour day. Full-range workout sessions consist of a total of 25 repetitions of side-to-side flexion and front-to-back flexion that carry the chair seat and low back through its full range of motion. Use of the chair with the stable back and higher arms during the workout will provide a user with a greater sense of security if needed. Full breathing during the exercises will improve vital capacity and the user&#39;s sense of well-being. Ideally, each set of twenty-five repetitions should take two minutes. 
     While a preferred embodiment of the invention has been illustrated and described, it is to be understood that various changes may be made therein without departing from the spirit of and scope of the invention. For example, the resilient disks  104 ,  106  may be replaced by a single resilient disk that extends the length of the housing  110 . However, two resilient disks  104 ,  106  are used in the preferred embodiment because two disks allow the desired lateral flexion and rotation producing one combined motion that closely mimics normal spinal motion. Hence, the invention is to be limited only by the scope of the claims that follow and the equivalents thereof.