FIELD OF THE INVENTION 
     The present invention pertains generally to an ergonomic chair that improves strength, endurance, and flexibility of the user. The present invention is more particularly, though not exclusively, useful as a chair which is designed to avoid work station related back pain and neck pain for people sitting for a long period of time at work by adopting a dynamic hemispherical seat to allow the harmony of the spine, muscles, ligaments, and discs. The present invention also provides an ergonomic chair that can be used as an office stretch GYM ball, when a back support and folding hinges are folded under the chair. 
     BACKGROUND OF THE INVENTION 
     Recent studies show that many cases of back pain and neck pain in a modern society are related to work stations that require people to sit for an extended period of time, since the human spine is not originally designed to sit for more than 10 to 15 minutes. Sitting for a long period of time puts a lot of strain on discs of the lumbar, or lower back, and the pressure on the discs increases dramatically when people lean forward while sitting, to write or use a computer. This bad posture exerts uneven forces to the intervertebral discs that lie between each of the vertebral bodies, and results in a loss of anterior longitudinal ligaments. 
     It has been known that a majority of back pains are caused by strains and/or sprains of the lordotic curve consisting of muscles, ligaments and tendons. People with jobs that require sitting at a work station for a long period of time tend to have their muscles become lax and lose the ability to support the spine correctly, due to the stress on the cervical spine. As a result, the ligaments and tendons in such people can also lose the ability to function properly. Unfortunately, sitting on a regular chair at work does not usually support the lordotic curve, and thus, various types of ergonomic chairs have been developed. 
     Ergonomic seating units adopting a gas-filled ball or a balloon which allows lateral movement and deformation when a user sits on the chair have been invented and widely used. These ergonomic chairs may be helpful to adjust sitting comfort, balance, and endurance. However, people on the ball-shaped chairs tend to forget about their sitting posture during work and currently available ergonomic chairs include seats which deform to accommodate the user&#39;s poor posture. Thus, currently available ergonomic chairs are not able to properly maintain the user&#39;s posture upright. The currently available ergonomic chairs can support the user&#39;s back only when the user leans on the chair, but not when the user leans forward towards the desk to write or type on the computer. 
     In light of the above, it would be advantageous to provide an ergonomic chair that can subconsciously adjust the user&#39;s position for a better posture as the user sits, by maintaining the spine of the user in the same alignment as when the user stands. It would also be advantageous to provide an ergonomic chair with a seat which does not allow any deformation on the seat. It would further be advantageous to provide an ergonomic chair that helps the nerve system to transmit 100% of the signals to the user&#39;s organs for a better internal function, through the correct posture. In addition, it would be advantageous to provide an ergonomic chair that can be used as a stretch GYM ball at the office, and which is simple to use, and comparatively cost effective. 
     SUMMARY OF THE INVENTION 
     The present invention includes an ergonomic chair that improves strength, endurance, and flexibility of the user. The present invention is useful for people who sit for an extended period of time at work and minimizes work station related back pain and neck pain. The present invention incorporates a hemispherical seat which can be locked in position and comprises a fixed inner hemisphere, a movable outer hemisphere, and a circumferential shroud. The inner hemisphere is fixed to a support pole which absorbs the load from the user, and a movable cuter hemisphere of the hemispherical seat is positioned over the fixed inner hemisphere and attached to tension springs which maintain the movable outer hemisphere in place. The movable outer hemisphere may be equipped with elastic ends or springs having hydraulic or pneumatic resistance devices, forming a rigid frame for a balanced movement of the outer hemisphere. The rigid outer hemispherical of the present invention does not allow deformation on the hemispherical seat when a user sits on the chair and the present invention keeps the spine of the user in the same alignment as when the user stands, further improving the internal function of the user&#39;s organs. Furthermore, the present invention can also be used as an office stretch GYM ball, when the folding hinges and a back support are folded and slid in under the chair. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The nature, objects, and advantages of the present invention will become more apparent to those skilled in the art after considering the following detailed description in connection with the accompanying drawings, in which like reference numerals designate like parts throughout, and wherein: 
         FIG. 1  is a perspective view of the Ergonomic Göbelek Chair of the present invention, showing a hemispherical seat, a pair of folding hinges having a pair of armrest supports, a back support, a base support, and a pedestal; 
         FIG. 2  is a vertical cross-sectional view of the Ergonomic Göbelek Chair of the present invention, consisting of multiple layers of hemispheres and a shroud connected through tracks of ball bearings or a sheet of soft and breathable foam, wherein an inner hemisphere is attached to the support pole, an outer hemisphere attached to a series of tension springs is freely movable while maintaining its orientation over the inner hemisphere and also can be locked in position, and a shroud encircles the outer hemisphere and is equipped with a pair of folding hinges to support a pair of armrests; 
         FIG. 3  is a perspective view of a movable outer hemisphere equipped with resistance elements, such as elastic ends or springs, and hydraulic or pneumatic resistance devices at its bottom, forming a rigid frame structure to the hemispherical seat; 
         FIG. 4  is a bottom view of a movable outer hemisphere equipped with resistance elements, such as elastic ends or springs and hydraulic or pneumatic resistance devices; 
         FIG. 5  is a top view of a fixed inner hemisphere permanently equipped with ball bearings placed on the circular tracks; 
         FIG. 6  is a top view of a fixed inner hemisphere permanently equipped with ball bearings, with an alternative placement on the tracks in a radial arrangement; 
         FIG. 7  is a top view of a fixed inner hemisphere with grease bearings placed on the circular tracks; 
         FIG. 8  is a top view of a fixed inner hemisphere with polymer bearings consisting of a circular strip on the top of the inner hemisphere, and multiple strips attached to the circular strip and extended radially therefrom; 
         FIG. 9  is a detailed vertical cross-sectional view depicting the inner hemisphere, bearing layer, and outer hemisphere and a shroud connected through the ball bearings with rows of balls for a fixed inner hemisphere and a movable outer hemisphere, and a soft and breathable foam for a movable outer hemisphere and a shroud; 
         FIG. 10  is a detailed top view of the horizontally cut shroud, where a top of a soft and breathable foam is visible through the center circular cutout of the shroud; 
         FIG. 11  is a cross-sectional view of the Ergonomic Göbelek Chair of the present invention depicting an installment of a bottom cover to the base frame of a shroud, with the support pole inserted through the circular opening on the bottom cover; 
         FIG. 12  is a detailed cross-sectional view of the left-end edge of the Ergonomic Göbelek Chair of the present invention shown in  FIG. 11 , when the outer edge of a shroud is installed to a bottom cover; 
         FIG. 13A  is a cross-sectional view of the Ergonomic Göbelek Chair of the present invention with a support ring attached to fix the locking system to the support pole; 
         FIG. 13B  is a top view of the locking system in the Ergonomic Göbelek Chair of the present invention attached to the support ring as installed on the support pole; 
         FIG. 14A  is a detailed cross-sectional view of the left-end edge of the movable outer hemisphere equipped with a locking system extending underneath the movable outer hemisphere to lock the hemisphere in place to prevent movement; 
         FIG. 14B  is a detailed cross-sectional view of the locking system attached and fixed to the support pole through the support ring, illustrating bores extending radially outwards through the support ring and corresponding to holes formed in the support pole for such attachment; 
         FIG. 15A  is a diagrammatic view of the locking system in the Ergonomic Göbelek Chair of the present in an unlocked configuration; 
         FIG. 15B  is a top view of the locking system in the Ergonomic Göbelek Chair of the present invention in the unlocked configuration, illustrating the locking bar shafts pulled back into the tubing posts; 
         FIG. 16A  is a diagrammatic view of the locking system in the Ergonomic Göbelek Chair of the present invention in a locked configuration; 
         FIG. 16B  is a top view of the locking system in the Ergonomic Göbelek Chair of the present invention in a locked configuration, illustrating the locking bar shafts extended underneath the movable outer hemisphere, locking the chair from tilting; 
         FIG. 17  is a diagrammatic view of the Ergonomic Göbelek Chair of the present invention when it is equipped with a base support having a shock absorber, a height adjustment lever, and a pedestal; 
         FIG. 18  is a back view of the Ergonomic Göbelek Chair of the present invention when it is equipped with an alternative pedestal having a heavy base and side wheels for easier movement of the chair when tilted; 
         FIG. 19  is a diagrammatic view of the Ergonomic Göbelek Chair of the present invention equipped with a pedestal having wheels and a back support when the back support is positioned beneath the chair such that the Ergonomic Göbelek Chair of the present invention is used as an office stretch GYM ball; 
         FIG. 20  is a partial vertical cross-sectional view of an alternative embodiment of the Ergonomic Göbelek Chair of the present invention when it is equipped with a shroud and a movable outer hemisphere which sits on five (5) single bearings; 
         FIG. 21  is a side view of an alternative embodiment of the Ergonomic Göbelek Chair of the present invention equipped with ergonomic armrests installed with springs inside for easier movement of the armrests depending on the users need; and 
         FIG. 22  is a diagrammatic view of the alternative embodiment of the Ergonomic Göbelek Chair of the present invention when the back support and the armrests are positioned beneath the chair such that the Ergonomic Göbelek Chair of the present invention is used as an office stretch GYM ball. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to  FIG. 1 , a perspective view of a preferred embodiment of the Ergonomic Göbelek Chair of the present invention is depicted and generally designated  100 . The preferred embodiment  100  of the Ergonomic Göbelek Chair of the present invention depicted in  FIG. 1  shows a hemispherical seat consisting of multiple layers of hemispheres and a shroud  118  including a sheet of soft and breathable foam  110  attached on top of a movable outer hemisphere  108  (not shown) for the user&#39;s comfort while sitting on the chair, a pair of folding hinges  126  equipped with a pair of armrest supports  127 , a back support  132 , a base support  130  and a pedestal  134 . A back support  132  is equipped with a lumbar cushion  133  for the user&#39;s comfort. 
     Now referring to  FIG. 2 , a vertical cross-sectional view of a preferred embodiment of the Ergonomic Göbelek Chair of the present invention is depicted. The preferred embodiment  100  of the Ergonomic Göbelek Chair of the present invention consists of multiple layers of hemispheres (a fixed inner hemisphere  102  and a movable outer hemisphere  108 ) and a shroud  118  connected through tracks of ball bearings  106  and a sheet of soft and breathable foam  110 . The preferred embodiment  100  of the present invention further comprises a support pole  104 , round mounting ring  112 , a circular metal or plastic sheet  114 , a bottom cover  140  (shown in  FIG. 11 ), a series of tension springs  116 , support bars  122 , a pair of folding hinges  126  equipped with a pair of locking hinges  124  and a pair of armrest supports  127 , a shock absorber  128  (shown in  FIGS. 17 ,  18 , and  19 ), a base support  130  (shown in  FIGS. 1 ,  17 ,  18 , and  19 ), a back support  132  (shown in  FIGS. 1 and 19 ), a pedestal  134  (shown in  FIGS. 1 ,  17 , and  19 ), and a locking system  200  (shown in  FIGS. 13A ,  13 B,  14 A,  14 B,  15 A,  15 B,  16 A, and  16 B). 
     With regard to the fixed inner hemisphere  102 , a support pole  104  is secured to an inner center and sides of the fixed inner hemisphere  102 , through a circular opening  138 , to support the load from the user. The tracks of ball bearings  106  are permanently attached to the fixed inner hemisphere  102 . The movable outer hemisphere  108  is then placed on top of the tracks of ball bearings  106 . A sheet of soft and breathable foam  110  is attached on top of the movable outer hemisphere  108 , and the support pole  104  is inserted into the round mounting ring  112 . The outer surface of the round mounting ring  112  is attached to a circular metal or plastic sheet  114  where the movable outer hemisphere  108  is connected by a series of tension springs  116 . 
     Through such connections, when the movable outer hemisphere  108  rotates, the series of tension springs  116  helps the circular metal or plastic sheet  114  rotate together. Indeed, the outer hemisphere  108  rotates about its center on fixed inner hemisphere  102 . The tension springs  116 , by allowing tension only, not compression, help the movable outer hemisphere  108  about its center (tilts on the “Y” axis) yet maintains the orientation of the hemispherical seat during such movement. On top of the movable outer hemisphere  108 , a shroud  118  having a larger diameter than those of the fixed inner hemisphere  102  and the movable outer hemisphere  108 , is added covering the foam layer  110  over the fixed inner hemisphere  102 , and the movable outer hemisphere  108 . 
     The shroud  118  is used as a shell for the chair and it is horizontally cut along the line A-A in  FIG. 2 , leaving the top (above the line A-A) of the shroud  118  open, yet concealing the tracks of ball bearings  106  and tension springs  116 . By adopting a seat consisting of multiple layers of rigid hemispheres and a rigid shroud, the present invention does not allow any deformation on the seat when a user sits on the chair. Even though a sheet of soft and breathable foam  110  is used as a cushion for the user&#39;s comfort while sitting on the chair, such a cushion forming on the foam  110  does not results in any deformation on the hemispherical seat of the chair. In addition, a support pole  104  where the fixed inner hemisphere  102  is supported absorbs the load from the user. 
     At the base frame of the shroud  118 , the bottom cover  140  (shown in  FIGS. 11 and 12 ) of the chair is installed and the bottom cover  140  is formed with a groove (shown in  FIG. 12 ) to receive the outer edge of the shroud  118 . The support bars  122  are attached underneath the circular metal or plastic sheet  114  and they prevent the circular metal or plastic sheet  114  from bending when the movable outer hemisphere  108  is pushed or pulled in the Y-direction by user&#39;s movement. Each of the folding hinges  126  is connected to an armrest support  127 , and an extension  129  can be extended for an extra length. For each of the folding hinges  126 , one end of the folding hinge  126  is locked and stands vertically, and the other end of the folding hinge  126  is unlocked. The folding hinge  126  is then folded 90 degrees out and partially slid into the rails. By moving freely both to the right and left sides, in direction of arrows  144  and  146  respectively, as depicted in  FIG. 2 , the folding hinges  126  connected to the armrest supports  127  can be positioned under the chair. 
       FIG. 3  depicts a movable outer hemisphere  108  equipped with elastic ends or springs  150  and hydraulic or pneumatic resistant devices  152 . The elastic ends or springs  150  equipped with hydraulic or pneumatic resistance devices  152  are connected to the hub  154 . As a result, a rigid frame is created on the elastic ends or springs  150 , allowing a balanced movement of the movable outer hemisphere  108  while maintaining the orientation upon the application of the load on the chair. 
       FIG. 4  is a bottom view of the movable outer hemisphere  108  equipped with elastic ends or springs  150  having hydraulic or pneumatic resistance devices  152 . Multiple elastic ends or springs  150  in the same length equipped with hydraulic or pneumatic resistance devices  152  are connected to the hub  154  at the center. 
     Referring to  FIG. 5 , a top view of the fixed inner hemisphere  102  permanently equipped with the ball bearings  106  on the circular tracks, is depicted. As shown in  FIG. 5 , in a preferred embodiment, the ball bearings  106  are placed on a series of circular tracks, on top of the fixed inner hemisphere  102 . 
       FIG. 6  is a top view of the fixed inner hemisphere  102  permanently equipped with the ball bearings  106  with an alternative placement. In this alternative placement, the ball bearings  106  can be placed on the tracks in a radial arrangement. 
     Referring to  FIG. 7 , the Ergonomic Göbelek Chair of the present invention can also alternatively adopt grease bearings  107 . As shown in  FIG. 7 , the grease bearings  107  can be placed on top of the fixed inner hemisphere  102 , in a series of circular arrays. Similar to the alternative arrangement for the ball bearings of  FIG. 5 , the grease bearings  107  can also be alternatively adopted on top of the fixed inner hemisphere  102 , either on the tracks in a radial arrangement or in an orthogonal arrangement. 
       FIG. 8  depicts a top view of the fixed inner hemisphere  102  with polymer bearings. The polymer bearing is a strip or strips made of polypropylene, polyethylene, or Delrin®, which allows metal parts to easily slide with low friction. By adopting polymer bearings, the movable outer hemisphere  108  can slide easily over the fixed inner hemisphere  102 . As shown in  FIG. 8 , a circular strip  109  is placed at the top of the fixed inner hemisphere  102  and the ends of a number of rectangular strips  111  are screwed to the circular strip, with an aid of screws  113 . A number of rectangular strips  111  are extendedly and radially positioned on top of the fixed inner hemisphere  102 . 
     Now referring to  FIG. 9 , a detailed cross-sectional view of a portion of  FIG. 2 , depicting layers of the fixed inner hemisphere  102 , ball bearings  106 , the movable outer hemisphere  108 , soft and breathable foam  110 , and the shroud  118 , is shown. The ball bearings  106  comprise rows of balls which allow the movable outer hemisphere  108  to move freely in any direction. Specifically, as shown in  FIG. 9 , there is a fine gap of approximately 2 mm, between the foam  110  covering the movable outer hemisphere  108 , and the shroud  118 . This gap prevents the movable outer hemisphere  108  and the shroud  118  from contacting each other, and minimizes the space for clothing to be pinched between the movable outer hemisphere  108  and the shroud  118 . It is to be appreciated that this gap can be increased or decreased for any particular chair design, and the specific measurement of 2 mm in a preferred embodiment is not to be considered limiting. 
       FIG. 10  is a detailed top view for the horizontally cut shroud  118  placed on top of a medium of soft and breathable foam  110 . As shown in  FIGS. 9 and 10 , the shroud  118  is installed on top of a medium of soft and breathable foam  110 , which covers the movable outer hemisphere  108 , with a fine gap of approximately 2 mm between the foam  110  and the shroud  118 . This provides a soft seating surface for the user, while also providing a rigid chair structure with the shroud  118  for stability. 
       FIG. 11  is a cross-sectional view of Ergonomic Göbelek Chair of the present invention depicting an installment of a bottom cover  140  to the base frame of the shroud  118 , when the support pole  104  is inserted through the circular opening  138  on the bottom cover  140 . The circular opening  138  does not rotate and is placed on the bottom cover  140  for an installation of the upper part of the chair to the base part of the chair. The bottom cover  140  is made with a groove for a proper installation of the shroud  118  into the bottom cover  140 .  FIG. 12  is a detailed cross-sectional view of the left-end edge of the Ergonomic Göbelek Chair of the present invention, when the outer edge of the shroud  118  is installed with a bottom cover  140 . As shown in  FIGS. 11 and 12 , the bottom cover  140  is formed with a groove at the outer edge to receive the edge of the shroud  118 , and the base frame of the shroud  118  is pushed up when the bottom cover  140  is installed. 
       FIG. 13A  is a cross-sectional view of the Ergonomic Göbelek Chair of the present invention depicting a support ring  220  attached to the support pole  104  to attach and fix the locking system  200 . Since the locking system  200  is attached to the support ring  220  and the support ring  220  is fixedly attached to the support pole  104 , when the cone shape cylinder  212  moves up forcing the locking bar shafts  216  to extend outwards underneath the movable outer hemisphere  108  to lock the movable outer hemisphere  108 , the movable outer hemisphere  108  is accordingly prevented from tilting.  FIG. 13B  is a top view of the locking system  200  in the Ergonomic Göbelek Chair of the present invention, when it is attached to the support ring  220 . 
       FIG. 14A  is a detailed cross-sectional view of the left-end edge of the movable outer hemisphere  108  shown in  FIG. 13A , equipped with a locking system  200  which extends outwards underneath the outer hemisphere  108 , when it is locked. As the locking bar shafts  216  in the locking system  200  extend outwards underneath the movable outer hemisphere  108 , the movable outer hemisphere  108  is prevented from tilting. 
       FIG. 14B  depicts a detailed cross-sectional view of the locking system  200  attached and fixed to the support pole  104  through the support ring  220 . As shown in  FIG. 14B , the tube  104  is formed with apertures  224  which align with bores  222  formed in support ring  220  such that the locking bar shaft  216  of the locking system  200  can penetrate through the support ring  220 . The support pole  104  also includes A roller bearing  210  formed on the end of the bar shaft  216 . The roller bearing  210  has an outer diameter that is less than or equal to the diameter of bar shaft  216  such that when the bar shaft  216  is urged outwards from tube  104 , the roller bearing  210  can pass through the aperture  224  in tube  104  and into bore  222  of support ring  220 . The locking system  200  is attached to the support ring  220  and the support ring  220  is further attached to the support pole  104  with an aid of screws or bolts  226 . 
     Referring to  FIGS. 15A and 15B , the locking system  200  for the Ergonomic Göbelek Chair of the present invention is depicted. The locking system  200  is placed under the movable outer hemisphere  108  and primarily consists of two (2) tubing posts  202 , and a cylinder cover  206 . The tubing posts  202  further consist of compression springs  208  and the locking bar shafts  216  equipped inside the tubing posts  202 . The locking bar shafts  216  are attached to the compression springs  208  on one (distal) end and the wheel or roller bearings  210  on the other (proximal) end. The diameter of the locking bar shaft  216  is equal or greater to that of the wheel on the wheel bearing  210 . The cylinder cover  206  consists of a cone shape cylinder  212  and is inserted into the support pole  104 . A locking handle  214  which is equipped on the support pole  104  moves up and down to lock or unlock the system. 
     Specifically,  FIG. 15A  is a diagrammatic view and  FIG. 15B  is a top view of the locking system  200  for the Ergonomic Göbelek Chair of the present invention when it is unlocked. As shown in  FIG. 15A , when the locking handle  214  moves up, the cone shape cylinder  212  moves down and the system is unlocked, rendering the movable outer hemisphere  108  to move freely. As a result, in its unlocked position, the compression springs  208  urge the locking bar shafts  216  to be pulled back into the post tubing  202 , in the direction of arrows  203  and  205 , respectively. Therefore, in its unlocked position, as shown in  FIG. 15B , there is no locking bar shaft extended underneath the movable outer hemisphere  108 . In addition, as shown in  FIG. 15B , the locking system  200  is attached to the support ring  220 , and the support ring  220  is further attached to the support pole  104 , as described above. 
       FIGS. 16A and 16B  illustrate a locking system for the Ergonomic Göbelek Chair of the present invention when it is locked. As shown in  FIG. 16A , when the locking handle  214  moves down, the cone shape cylinder  212  moves up forcing the locking bar shafts  216  attached to the wheel bearings  210  to be pushed out within the tubing posts  202 , in the direction of arrows  207  and  209 , respectively. As a result, as shown in  FIG. 16B , the locking bar shafts  216  are extended under the movable outer hemisphere  108  and prevent the movable outer hemisphere  108  from tilting. As shown in  FIG. 16B , the locking system  200  is attached to the support ring  220 , and the support ring  220  is further attached to the support pole  104 , as described above. 
       FIG. 17  depicts a diagrammatic view of the Ergonomic Göbelek Chair of the present invention with its base support  130  and a pedestal  134  equipped. A pair of the folding hinges  126  having armrest supports  127  are folded 90 degrees out in the direction  142  (shown in  FIG. 2 ), and slid in under the chair when the chair is used as an office stretch GYM ball, or upon any other needs of the user. The folding hinges  126  can also be extended by use of an extension  129  (shown in  FIG. 2 ) for an extra length, when the user needs longer folding hinges. The shock absorber  128  is attached to absorb any shock from an excessive load applied on the chair. The base support  130  is equipped with a height adjustment lever  120  which enables the chair to move up and down for the desirable height depending on the user&#39;s need. In addition, a locking handle  214  for the locking system  200  is equipped on the support pole  104 . Selectively, a wheel assembly can be installed at the end of the pedestal  134 . 
       FIG. 18  is a back view of the Ergonomic Göbelek Chair of the present invention with its base support  130  and an alternative pedestal  135  equipped. Differently from the pedestal  134  having legs described in  FIG. 17 , the alternative pedestal  135  may be formed with a heavy base which does not have any legs. The alternative pedestal  135  with the heavy base can provide more stability to the user when the chair does not need to be moved often, or the chair is used for over-weighted people. For easier movement of the chair with such a heavy base, a handle  131  is equipped. The handle  131  is placed at the top of a back support  132 , on the back of the lumbar cushion  133 . With an aid of the handle  131 , the user of the Ergonomic Göbelek Chair of the present invention can tilt the heavy chair when the chair needs to be moved to some other locations. When the chair is tilted, the side wheels  137  placed on the side of the alternative pedestal  135  enable the user to easily move the chair along the ground, by a rolling movement of the side wheels  137 . The use of the side wheels  137  along with the handle  131  further enables the user to move the Ergonomic Göbelek Chair of this invention along the slope. 
       FIG. 19  is a diagrammatic view of the Ergonomic Göbelek Chair of the present invention equipped with a back support  132 . The back support  132  for the Ergonomic Göbelek Chair of the present invention is folded 180 degrees out and positioned under the chair when the chair is used as an office stretch GYM ball, or upon any other need of the user. The lumbar cushion  133  is installed on top of the back support  132  for the comfort of the user. As shown in  FIG. 19 , a wheel assembly  136  may be attached to the end of the pedestal  134 , providing mobility of the chair. 
       FIG. 20  is a partial vertical cross-sectional view of an alternative embodiment  300  of the Ergonomic Göbelek Chair of the present invention. In the alternative embodiment  300 , the Ergonomic Göbelek Chair can be equipped with a movable outer hemisphere  308  and a shroud  318 , without an installation of the fixed inner hemisphere disclosed in the preferred embodiment. The movable outer hemisphere  308  simply sits on the five (5) single bearings  306 . Each of the single bearings  306  is equipped with a roller within a socket to allow the movable outer hemisphere  308  to move into various directions. The inside surface  309  of the movable outer hemisphere  308  rolls along the single bearings  306  which are installed at the end of the vertical support  303  and four (4) lateral supports  304 . The vertical support  303  primarily absorbs the load from the user, and may be made of materials having more strength for the structural durability and integrity of the chair. A series of tension springs  316  and a circular metal sheet  314  are also used as in the preferred embodiment. By doing so, when the movable outer hemisphere  308  rotates, the series of tension springs  316  helps the circular metal sheet  314  rotate together. Also as in the preferred embodiment, the tension springs  316  allow tension and help the movable outer hemisphere  308  move up and down and serve to maintain the orientation of the hemispherical seat during such movement. 
     As disclosed in the preferred embodiment, the movable outer hemisphere  308  is covered with a soft and breathable foam layer  310 , which is used as a cushion for the user&#39;s comfort while sitting on the chair. The shroud  318  placed on top of a soft and breathable foam layer  310  is used as a shell for the chair and it is horizontally cut as in the preferred embodiment. At the base frame of the shroud  318 , a bottom cover  340  of the chair is installed. In addition, as in the preferred embodiment, the vertical support  303  is inserted into a base support  330  which is further equipped with a pedestal  334  at its end and a height adjustment lever (not shown in  FIG. 20 ) for the desirable height adjustment for the user. 
     Referring now to  FIG. 21 , a side view of an alternative embodiment of the Ergonomic Göbelek Chair of the present invention is depicted and designated  400 . As shown in  FIG. 21 , similar to the preferred embodiment  100 , the alternative embodiment  400  of the Ergonomic Göbelek Chair of the present invention is formed with a shroud  402 , a sheet of soft and breathable foam  404 , a back support  410  equipped with a lumbar cushion  412 , a base support  416 , a height adjustment lever  418  and a pedestal  420 . The back support  410  is extendable in direction of arrow  422  for a desirable height of the back support  410 . Specifically, the alternative embodiment  400  of Ergonomic Göbelek Chair of the present invention includes a pair of folding hinges  406  equipped with ergonomic armrests  408 . The folding hinges  406  can extend in direction of arrow  424 , for an adjustable height of the armrests  408  depending upon the user&#39;s desire. The ergonomic shape of the ergonomic armrests  408  can provide for more comfort when the user leans his or her arms on the armrests.  FIG. 22  is a diagrammatic view of the alternative embodiment of the Ergonomic Göbelek Chair of the present invention when the back support  410  and the ergonomic armrests  408  are positioned beneath the chair. Both back support  410  and the ergonomic armrests  408  are foldable. As shown in  FIG. 22 , the back support  410  is folded 180 degrees out and the ergonomic armrests  408  are folded 90 degrees out to be positioned folded and slid in under the chair such that the alternative embodiment of Ergonomic Göbelek Chair of the present invention is used as an office stretch GYM ball. It is also convenient for the user of the Ergonomic Göbelek Chair of the present invention to store the chair in a smaller space by folding the back support  410  and the ergonomic armrests  408 . 
     While there have been shown that are presently considered to be preferred embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope and spirit of the invention.
The Ergonomic Gobelek Chair of the present disclosure is useful for avoiding work related back and neck pain associated with extended periods of time sitting by providing a hemispherical seat which promotes correct posture and spine alignment as a user sits. The hemispherical seat includes a fixed inner hemisphere, a movable outer hemisphere received by and positioned over the inner hemisphere, and a shroud enclosing a portion of the inner and outer hemispheres. Affixed to the inner hemisphere, between the inner hemisphere and the outer hemisphere, is a series of bearings which allow the outer hemisphere to move adjacent to the inner hemisphere. A locking system locks and unlocks the outer hemisphere. The Ergonomic Gobelek Chair further includes foldable back and arm rests capable of folding away from the hemispherical seat for use of the hemispherical seat as a stretch gym ball.