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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) on U.S. provisional patent application No. 60/602,387 filed Aug. 17, 2004, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an anti-tilting mechanism for a pivotable, sliding panel made from any rigid material such as glass, wood, or fiber structure intended for use such as on balconies, verandas, piscine, wall separation, etc. 
     2. Brief Description of Prior Developments 
     Traditional glazing for balconies or the like consists of a plurality of sash glass panels mounted on upper and lower guide rail and adapted to slide laterally past one another. A major disadvantage with this type of glazing is that at most only 50 percent of the glazed-in area can be opened. Furthermore, the outer surface of the pane is awkward to clean. 
     Glazing structures have been proposed in which the panes can be stacked against a side wall of the balcony by pivoting about a vertical axis. In WO 89/05389 this is achieved by means of a double upper rail arrangement having a straight outer rail and an inner rail. Within the curved portion of the inner rail the trailing edge of the pane turns inwards and the pane can opened against the side wall of the balcony. Such an arrangement is, however, not particularly aesthetically pleasing and friction can arise in the system and still be a lot of effort to clean 
     In an effort to eliminate these drawbacks, WO 90/121183 proposes a structure in which the top edge pivot pin of the glass pane is held stationary, no curved guide rail for the trailing edge is required. Whilst eliminating some of the disadvantages of the prior systems, the arrangement according to WO 90/121183 introduces its own drawbacks; one being that the pane must be tilted to disengage the upper trailing wheel from its guide rail before pivoting can commence. Since the leading edge of the pane is locked first only when pivoting has commenced, there is a risk that the trailing wheel may not disengage should the pane topple back before pivoting commences. The fact that the leading edge is locked only once rotation has commenced further implies that a flange protruding from the upper guide rail adjacent the opening for the trailing wheel is required to support the trailing wheel during the initial opening operation. Such protruding flanges hinder the possibility to mount curtains or blinds across the glazing. In addition, because only the upper leading pivot pin is immobilized, the pane cannot be opened through more than 90 degree, due to the fact that the lower leading pivot pin would otherwise be forced along the lower guide rail as a result of the change in position of the center of gravity of the pane. 
     SUMMARY OF THE INVENTION 
     The solution to problems described above and the invention can comprise interlocking air-tight panels that are able to slide laterally guided by an upper and a lower rail, while simultaneously pivoting on their axis. It offers many benefits such as easily glass cleaning, frictionless sliding panels, pivoting the panels to serve as doors at any point of the rail, and stacking the panels at any point of the rail. 
     In accordance with one aspect of the invention, a panel movement system is provided including top and bottom rails having racks with registration teeth along their lengths; top and bottom rail attachments movably attached to respective ones of the rails for lateral movement along lengths of the rails; and a gear movement synchronization system. Each rail attachment includes a rotatable gear engaging the registration teeth on respective ones of the rails. The gear movement synchronization system connects the rotatable gear of the top rail attachment to the rotatable gear of the bottom rail attachment such that the top and bottom rail attachments move along the rails in unison. The top and bottom rail attachments are adapted to have a panel connected therebetween. 
     In accordance with another aspect of the invention, a panel movement system is provided comprising top and bottom rails; a panel mounted to the rails by top and bottom movement sections to longitudinally slide along the rails, wherein the movement sections comprise rotatable platforms connected to respective top and bottom ends of the panel for allowing the panel to rotate relative to the rails; and a rotation synchronization system connecting the rotatable platform of the top movement section to the rotatable platform of the bottom movement section to rotate the top and bottom rotatable platforms in unison when the panel is rotated relative to the rails. 
     In accordance with one method of the invention, a method of manufacturing a movable panel system is provided comprising connecting top and bottom movement systems to top and bottom ends of a panel; connecting the movement systems to respective top and bottom rails such that the movement systems can traverse along the rails; and connecting the movement systems to each other such that the top and bottom movement systems operate in registration with each other and traverse along the rails in unison with each other. The movement systems are connected to the panel by rotatable top and bottom platforms to allow the panel to rotate relative to the rails. The method further comprises connecting the movement systems to each other comprises limiting rotation of the top and bottom platforms relative to each other such that the platforms are rotatable in unison with each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a movable panel assembly incorporating features of the invention; 
         FIG. 2  is a perspective view of a portion of one of the rails of the frame of the assembly shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of components of the assembly shown in  FIG. 1 ; 
         FIG. 4  is a perspective view of the components of the assembly shown in  FIG. 3  from an opposite side; and 
         FIG. 5  is a perspective view of the components of the assembly shown in  FIGS. 3 and 4  in a gear box frame. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , there is shown a perspective view of a movable panel assembly  10  incorporating features of the invention. Although the invention will be described with reference to the exemplary embodiment shown in the drawings, it should be understood that the invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The panel assembly  10  in this embodiment is a window or glass door for use in a building. However, in alternate embodiments the invention could be used in any suitable type of assembly where panels are intended to be moved relative to each other. The assembly  12  comprises two panels  12 ,  14  which are window panes. Non-window panels could be provided. More or less than two movable panels could be provided. The assembly  12  also comprises a frame with two rails  16 ,  18 , top and bottom movement sections  20 ,  22  for each panel  12 ,  14 , and a synchronization system  24  for each panel  12 ,  14 . 
     Referring also to  FIG. 2 , the two rails  16 ,  18  are identical to each other. In alternate embodiments the rails could be different. The rails  16 ,  18  extend in a general cantilever fashion from the frame  26 . Preferably, the rails  16 ,  18  extend substantially the entire width of the window. Each rail  16 ,  18  has a track section with upper and lower convex curved sections  32 ,  34  and a rack section  28  with registration teeth  30 . Referring also to  FIGS. 3 and 4 , the top and bottom movement systems  20 ,  22  are identical to each other, but reversely oriented or flipped relative to each other. In alternate embodiments the movement sections could be different from each other. Each panel  12 ,  14  has the pair of the movement sections  20 ,  22  attached to its top and bottom ends. The top movement sections  20  are mounted on the top rail  16  and the bottom movement sections  22  are mounted on the bottom rail  18 . 
     Each movement section  20 ,  22  comprises a rail attachment  36 , a panel attachment  38  and part of the synchronization system  24 . The rail attachment  36  comprises rollers  40  and a rotatable gear  42 . Four rollers  40  are provided; two against the top convex curved section of the rail and two against the bottom convex curved section of the rail. However, in alternate embodiments more or less than two rollers on each top and/or bottom side could be provided. The rollers  40  have a general concave profile to mate with the convex shapes of the rail sections  32 ,  34 . However, in alternate embodiments, any suitable complementary shapes could be provided. The rollers are attached by shafts to a gear box frame of the movement sections  20 ,  22 . The rollers  40  are able to rotate to roll the movement sections  20 ,  22  along the rails  16 ,  18 . This allows the panel  12 ,  14  mounted to the rails by a pair of the top and bottom movement sections  20 ,  22  to longitudinally slide along the rails in general lateral directions as indicated by arrow  44  in  FIG. 1 . 
     The rotatable gear  42  is connected to a rotatable shaft  46 . The shaft  46  is rotatably mounted to the gear box. An intermediate gear  48  is also connected to the shaft  46 . Thus, intermediate gear  48  is rotated when the gear  42  is rotated. The gear  42  has its teeth engaged with the teeth  30  of the rack section  28 . The gear  42  forms a pinion in a rack and pinion system. When the panel  12 ,  14  is longitudinally moved along the rail  16 ,  18 , the gear  42  moves along the length of the rack section  28  and rotates because of interaction between the teeth. This causes the gear  48  to rotate. 
     The panel attachment  38  comprises a first section  62  adapted to be directly attached to one of the ends of one of the panels  12 ,  14 . The panel attachment  38  also comprises a second section  64  fixedly attached to the first section  62 . The second section  64  has a hole  66 . A rod  52  of the synchronization system  24  extends through the hole  66 . The rod  52  is rotatably mounted in the hole  66  by a bearing such that the rod can axially rotate in the hole. The axis  68  of rotation of the rod  52  is offset from the axis  60  of rotation of the panel attachment  38 . The panel attachment  38  can rotate about the axis  60  relative to the gear box. 
     Synchronization system  24  includes another intermediate gear  50  and the vertical axially rotatable rod  52 . The gear  50  is fixed to the gear box for axial rotational movement only about the axis  60 . The gear  50  has a top gear section  54  and a bottom gear section  56 . The bottom gear section  56  is engaged with the teeth of the gear  48 . The top gear section  54  engages teeth of a gear section  58  on the end of the rod  52 . The rod  52  has gear sections  58  at both its top and bottom ends. 
     The rod  52  provides two different types of movement synchronizations. For each panel  12 ,  14 , the respective rod  52  can help synchronize translation movement of the rail attachments  36  of the top and bottom movement sections  20 ,  22  relative to each other on their respective top and bottom rail  16 ,  18 . In addition, for each panel  12 ,  14 , the respective rod  52  can help synchronize rotational movement of the panel attachments  38  of the top and bottom movement sections  20 ,  22  relative to each other. 
     For synchronized translation movement of the rail attachments  36  of the top and bottom movement sections  20 ,  22  relative to each other on their respective top and bottom rail  16 ,  18 , the rod acts as a mechanical connection between the movement sections  20 ,  22 . The gears  42  of the two movement sections  20 ,  22  are connected to each other by the respective intermediate gears  48 ,  50  of the two movement sections  20 ,  22  and by the rod  52  and its gears  58  at its opposite ends. Thus, as the gear  42  of the bottom movement section  22  moves along the teeth  30  of the bottom rail  18 , the two sets of shafts  46  and gears  48 ,  50 ,  58 , and the rod  52  insure that the gear  42  of the top movement section  20  moves along the teeth  30  of the top rail  16  in the same direction and with the same amount of movement. Likewise, as the gear  42  of the top movement section  20  moves along the teeth  30  of the top rail  16 , the two sets of shafts  46  and gears  48 ,  50 ,  58 , and the rod  52  insure that the gear  42  of the bottom movement section  22  moves along the teeth  30  of the bottom rail  18 . This insures a synchronized movement of the top and bottom ends of the panel  12  or  14  along the width of the window. The panel  12 ,  14  is, thus, prevented from tilting and perhaps jamming during this lateral translation movement. 
     The panels  12 ,  14  can also be individually rotated inward and/or outward as indicated by arrows  70  in  FIG. 1 . For synchronized rotational movement of the panel attachments  38  of the top and bottom movement sections  20 ,  22  relative to each other, as the panel attachments  38  are rotated along axis  60  at each of the movement sections  20 ,  22  the gear  50  can remain stationary. The rod  52 , because of its connection at the hole  66  to the panel attachment  38 , rotates about the axis  60 . The teeth of the gear sections  58  rotate about the perimeter of the top gear section  58  resulting in axial rotation of the rod  52  about its axis  68 . Thus, as the panel  12  or  14  is rotated open or closed the gear section  58  at the bottom movement section  22  moves along the teeth of the gear  50  of the bottom movement section  22  and the rod  52  axially rotates to insure that the gear section  58  at the top of the rod at the top movement section  20  moves along the teeth of the gear  50  at the top movement section  20  for the top and bottom panel attachments  38  to move in synchronized unison rotation. The rotational movement can also occur at the same time as translational movement if desired. 
     The invention can comprise interlocking air-tight panels that are able to slide laterally guided by an upper and a lower rail. This can occur with simultaneous pivoting on their axes of rotation  60 . This was accomplished by the introduction of specialized gearboxes, located at the extremities of the panels, connecting it to the rails. In order to keep the panel stable while in motion, the gearboxes holding the panels preferably move synchronously else, the panel could be subject to tilting; since one end of the panel may be leading or lagging the other end. The synchronization of the gearbox movements is made possible using a solid beam; the rod  52 . The beam  52  connects gear or cog  58  of the lower gearbox with cog  58  of the upper gearbox, enabling them to rotate simultaneously. Rotation of the cog  58  is controlled by a series of other cogs which link it to the rack  28  that lines the rails on which the panel slides aided by the four rollers or pulleys  40 . 
     As the panel is moved laterally, the rack causes pinion  42  to rotate which, in turn, causes the other cogs to rotate relaying rotation to cog  58 . Solid beam  52  relays rotation to the upper gearbox. Similarly, the upper gearbox moves the exact distance as that covered by the lower gearbox. 
     When the panel needs to be rotated on its axis  60 , one can simply turn the panel by hand. Cog  58  would travel on the perimeter of cog  50 , since the panel is fixed on platform  38  which is secured onto axis  60  known as the synch axis, resulting in the rotation of cog  58 . This would cause the simultaneous rotation of both cogs, thus maintaining the vertical parallel position of the beam  52  with respect to the panel; avoiding collision of the beam with the panel while in rotation. The end result is a panel, made out of any rigid material, which can be moved laterally guided by rails, while being simultaneously rotated onto its axis. The panel&#39;s motion is smooth and easy to move regardless of its weight. With the invention, the panels  12 ,  14  can also rotate more than 90 degrees; such as 360 degrees for example. In the embodiment described above, the gears  48  only rotate when the panel laterally slides/rolls along the rails. The platform  38  does not rotate with the gear  48 . The platform  38  only rotates when the user pivots the panel and rotation of platform  38  cause gear  58  to circle around the gear section  54 . The panels  12 ,  14  can preferably overlap each other when then are slid towards each other, such as more than 50 percent overlap. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Summary:
A panel movement system including top and bottom rails having racks with registration teeth along their lengths; top and bottom rail attachments movably attached to respective ones of the rails for lateral movement along lengths of the rails; and a gear movement synchronization system. Each rail attachment includes a rotatable gear engaging the registration teeth on respective ones of the rails. The gear movement synchronization system connects the rotatable gear of the top rail attachment to the rotatable gear of the bottom rail attachment such that the top and bottom rail attachments move along the rails in unison. The top and bottom rail attachments are adapted to have a panel connected therebetween.