Abstract:
A single-piece flexure and flexure apparatus according to an embodiment allows movement along two perpendicular axes. The flexure is made from a single continuous material having a first and second flexure sections, with the second flexure section allowing translational movement in a direction perpendicular to that allowed by the first flexure section. Two-dimensional flexure assemblies may then be manufactured using these flexures. The flexure apparatus is made from a single contiguous material fashioned to provide a base section and a plurality of legs extending perpendicularly from the base section, with each leg having a first and second flexure sections, with the second flexure section allowing translational movement in a direction perpendicular to that allowed by the first flexure section.

Description:
BACKGROUND OF THE INVENTION 
     Mechanical devices often require an assembly that allows linear motion with essentially no static friction involved. In many instances, such functionality has been provided via flexures, which consist primarily of two or more semi-rigid elastic members attaching a stable base to a plate or other object that is to be allowed to move in some specified direction. For example, FIG. 1 shows a one-dimensional flexure assembly  100 , having a base plate  110 , to which four flexures  120  are attached using screws  130 . At the opposite end of each flexure  120  is attached the moving object, which in this case is a moving plate  50 . Each flexure  120  is thin enough to allow translational movement of moving plate  50  perpendicular to flexures  120 , as indicated by the arrow displayed in FIG.  1 . Additionally, the object to be moved is not limited to a plate such as the moving plate  50 , but may be something rigidly attached to the moving plate  50 , or may replace the moving plate  50  entirely. 
     At times, two-dimensional movement of the object may be desired, depending on the particular application involved. In such cases, a two-dimensional flexure assembly, such as an assembly  200  shown in FIG. 2, is employed to allow such motion. Again, a base plate  110  is typically used, to which the ends of four flexures  120  are attached. At the opposite end of each of the flexures  120  is attached an intermediate plate  210 , which moves one-dimensionally as allowed by the four flexures  120  attached to the base plate  110 . A second set of four flexures  120  is then attached at one end to intermediate plate  210 , and oriented perpendicular to the first four flexures  120  attached to base plate  110  so that the movement allowed by the second four flexures  120  is essentially perpendicular to that allowed by the first four flexures  120 . The ends of the second four flexures  120  opposite those attached to intermediate plate  210  are connected to a moving plate  50 , thus allowing the moving plate  50  to translate two-dimensionally in any direction parallel to base plate  110 , as indicated by the arrows shown in FIG.  2 . 
     Unfortunately, two-dimensional flexure assemblies such as assembly  200  shown in FIG. 2 require multiple components, which in this case are two plates, eight flexures, and a multitude of screws, bolts, rivets, or equivalent connectors. Such a high part count typically results in increased cost, prolonged assembly time, and a possible decrease in assembly reliability. 
     Therefore, from the foregoing, a new two-dimensional flexure and flexure apparatus comprised of fewer components, thus enhancing reliability while diminishing part cost and assembly time, would be advantageous. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention, to be discussed in detail below, allow for a two-axis flexure and flexure apparatus, each of which is made of a single contiguous piece of semi-rigid material. The flexure has a first and second flexure section, with the second flexure section being oriented so that the direction of translational motion allowed by that second flexure section is essentially perpendicular to that allowed by the first flexure section. Such flexures may be used in various multi-piece two-dimensional flexure assemblies. 
     A single-piece flexure apparatus, according to an embodiment of the invention, has a base section, and two or more legs extending substantially perpendicularly from the base section. Each of the legs has a first and second flexure section, with the first flexure section being positioned between the base section and the second flexure section. The second flexure section of each leg is oriented so that the direction of translational motion allowed by that second flexure section is essentially perpendicular to that allowed by the first flexure section. An object coupled to the second flexure section of each leg would then be allowed to move in two dimensions perpendicular to the legs. 
     Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a one-dimensional flexure assembly from the prior art. 
     FIG. 2 is a perspective view of a two-dimensional flexure assembly from the prior art. 
     FIG. 3 is a perspective view of a two-dimensional flexure assembly utilizing a set of two-dimensional flexures according to an embodiment of the invention. 
     FIG. 4 is a perspective view of a two-dimensional flexure apparatus according to an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments of the invention, which are described below, allow movement of an object in two dimensions with essentially no static friction by way of either a flexure or flexure apparatus composed of a single contiguous piece of semi-rigid material, thereby limiting the number of components required, resulting in brief assembly times and enhanced apparatus reliability. 
     Shown in FIG. 3 is a particular embodiment, a two-dimensional flexure  320 , of the present invention, which is utilized as part of a flexure assembly  300 . Each of the four flexures  320  is attached to a base plate  110  by way of screws  130  (as shown in FIG.  3 ), bolts, rivets, or equivalent connectors. 
     Each flexure  320  is fashioned from a single piece of semi-rigid material, including, but not limited to, sheet metal, metal, or plastic. For example, in the case of sheet metal, the flexures  320  may be formed by stamping out the proper shape required, followed by bending the metal into its final configuration. If metal is utilized, the flexures  320  may be formed by way of metal injection molding (MIM), among other techniques. If plastic is employed, the proper shape required for the flexure  320  and other embodiments of the invention can be attained by way of injection molding, shaping by way of heating and bending, or other means typically used for plastic materials. Additionally, the materials used in any particular application, the thickness of that material, and the geometry of the flexures  320  are determined by the rigidity and motion requirements of the apparatus. 
     The flexure  320  is composed of a first flexure section  330  and a second flexure section  340 . In FIG. 3, the first flexure section  330  is positioned between a base plate  110  and the second flexure section  340 , which is coupled with a moving plate  50 . The two flexure sections  330  and  340  of each flexure  320  are positioned so that the direction of translational movement allowed by the first flexure section  330  is essentially perpendicular to the direction of translational movement allowed by the second flexure section  340 . The relative orientation of the flexure sections  330  and  340  allow movement of the moving plate  50  in two dimensions perpendicular to the general direction indicated by the flexures  320 . In the specific embodiment of FIG. 3, the first flexure sections  330  allow movement of the moving plate  50  perpendicular to the long axis of the base plate  110 . Also, the second flexure sections  340  allow movement parallel to the long axis of the base plate  110 . 
     Additionally, as can be seen from FIG. 3, the first  330  and second  340  flexure sections are detached from each other and extend in opposite directions beyond a portion of the flexure where the first flexure section is attached to the second flexure section. The first flexure section  330  has a first broad surface in relation to its thickness. The thickness of the first flexure section  330  is thin enough to allow translational motion perpendicular to the first broad surface and the first broad surface is wide enough to resist translational motion parallel to the first broad surface. Similarly, the second flexure section  340  has a second broad surface in relation to its thickness. The thickness of the second flexure section  340  is thin enough to allow translational motion perpendicular to the second broad surface and the second surface is wide enough to resist translational motion parallel to the second broad surface. The second flexure section  340  is oriented perpendicular to the first flexure section  330  so that the direction of translational motion allowed by the second flexure section  340  is essentially perpendicular to the direction of translational motion allowed by the first flexure section  330 . This allows for the two-dimensional translational motion of the flexure perpendicular to the length of the flexure. 
     In the embodiment of FIG. 3, four flexures  320  are employed. However, other embodiments of the present invention may utilize more or fewer flexures  320  depending on the requirements of the particular application involved. For example, if more rigidity in compression along the general direction defined by the flexures  320  is desired, more flexures  320  may be employed. However, if compression is not a significant concern, fewer flexures  320  may be called for. For example, using the embodiment of FIG. 3 as a starting point, one more flexure  320  could be added along each of the long edges of the base plate  110  to provide more rigidity. Alternately, only two flexures  320 , extending from opposite corners of the base plate  110 , may be employed if additional rigidity is not required. 
     Taking this concept further, an entire flexure apparatus  400 , as shown in FIG. 4, can be fashioned from a single portion of a semi-rigid material, using the same materials and methods described earlier for the flexures  320 . The apparatus  400  has a base section  410  that is employed to support the remaining portions of the apparatus  400 . In the embodiment of FIG. 4, the base section  410  is shown to be generally rectangular; however, other shapes, as dictated by the particular application in which the apparatus is to be employed, may be used. For example, the base section  410  could be formed in the shape of a square, especially if the object to be moved also exhibits that same general shape. 
     Extending substantially perpendicularly from the base section  410  are a plurality of legs  420  that are coupled with an object that is to be allowed to translate in two dimensions, such as the moving plate  50  from FIG.  1 . In FIG. 4, screws  130  are utilized to couple the legs  420  with the moving plate  50 , but other means, such as rivets, welds, or the like, such that the moving plate  50  is coupled with the legs  420  may be employed. Also, other objects that require the type of movement that a two-dimensional flexure assembly provides may either be connected to the moving plate  50 , or may be substituted for the moving plate  50  by being coupled directly to the legs  420 . 
     Each leg  420  of the apparatus  400  is composed of two flexure sections, as was the case for each flexure  320  described earlier. A first flexure section  330  is positioned between the base section  410  and a second flexure section  340  of leg  420 . 
     The two sections of each leg  420  are positioned so that the direction of translational movement allowed by the first flexure section  330  is essentially perpendicular to the direction of translational movement allowed by the second flexure section  340 . The relative orientation of the flexure sections  330  and  340  allow movement of the moving plate  50  in two dimensions perpendicular to the general direction indicated by the legs  420 . In the specific embodiment of FIG. 4, the first flexure sections  330  allow movement of the moving plate  50  perpendicular to the long axis of the base section  410 . Additionally, the second flexure sections  340  allow movement parallel to the long axis of the base section  410 . 
     In the embodiment of FIG. 4, four legs  420  are employed. However, other embodiments of the present invention may utilize more or fewer legs  420  depending on the requirements of the particular application involved, in a fashion similar to that described for the flexures  320  of apparatus  300  (from FIG.  3 ). For example, if more rigidity in compression along the general direction defined by the legs  420  is required, more legs  420  may be utilized. However, if compression is not a significant concern, fewer legs  420  may be employed. 
     From the foregoing, the embodiments of the invention discussed above have been shown to provide two-dimensional movement with essentially no static friction by way of a flexure and a flexure apparatus fashioned from a single contiguous piece of semi-rigid material. In addition, other specific devices embodying the invention are also possible. Therefore, the present invention is not to be limited to the specific forms so described and illustrated; the invention is limited only by the claims.