Abstract:
A reciprocating laboratory shaker ( 10 ) includes a platform ( 12 ) driven by a motor ( 62 ) which is constrained to move in a reciprocating fashion by a pair of flexible bands ( 30, 32 ) located on opposite sides of the platform ( 12 ). A frame ( 24 ), which preferably supports the drive motor ( 62 ), includes a pair of upright supports ( 28 ) which are attached to a pair of wide, but thin, flexible plastic bands ( 30, 32 ) at least at two locations. Each of the two flexible bands ( 30, 32 ) includes a pair of rollers ( 34, 36, 38, 40 ) attached to the inside surface ( 50 ) of the bands ( 30, 32 ). The laboratory platform ( 12 ) is attached to the remaining outside face ( 52 ) of the bands and is driven by the drive motor ( 62 ) having an appropriate crank mechanism ( 54 ). The two flexible bands ( 30, 32 ) constrain the motion of the platform ( 12 ) to substantially a single direction, x, while preventing it from moving in either the y or z directions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a laboratory shaker drive mechanism including a pair of flexible bands which restrain the movement of the shaker platform to a single dimension. 
     2. Description of Related Art 
     Laboratory shakers, and the like, are known in the prior art. See, for example, U.S. Pat. No. 5,593,228 issued on Jan. 14, 1997 and entitled “ROTARY SHAKER WITH FLEXIBLE STRAP SUSPENSION.” The inventor is Myron Tannenbaum, Cranbury, N.J., and the patent is assigned to New Brunswick Scientific Co., Inc., Edison, N.J., the assignee of the present application. That patent describes a shaker which produces motion in an orbital plane and in which the shaker platform is restrained by two pairs of flexible metal straps. 
     Another rotary laboratory shaker is described in U.S. Pat. No. 4,183,677 issued on Jan. 15, 1980 and entitled “MECHANISM FOR EFFECTING ORBITAL MOTION OF A MEMBER”. The inventor is Norman A. De Bruyne, Princeton, N.J. That disclosure also describes the use of flexible members to constrain the motion of a laboratory shaker platform to an orbital circuit. 
     Devices other than laboratory shakers also include flexible or reciprocating motion drivers. See, for example, U.S. Pat. No. 1,501,625 issued on Mar. 10, 1924 to Warren Sadorus and entitled “CORN-POPPING MACHINE.” That device includes a drive mechanism for constraining the motion of a corn-popping pan to a strictly single dimension. 
     Also of possible relevance is the disclosure in Russian Patent Application SU-588-167 entitled “LABORATORY, MULTI-BOWL FEEDER”. As described in that device a pair of animal feed bowls is driven by a single shaft through two pairs of flexible straps. 
     While the prior art appears to describe diverse drive mechanisms including flexible drive members, nevertheless, there does not appear to be any teaching or suggestion of an inexpensive and dependable reciprocating laboratory shaker suitable for use in a laboratory environment. 
     It was in the context of the above prior art that the present invention arose. 
     SUMMARY OF THE INVENTION 
     Briefly described, the invention comprises a laboratory shaker which includes a platform constrained to reciprocate in a single direction by a pair of flexible straps located on opposite sides of the platform. A frame, including a pair of upright supports, also supports a drive motor. Each of the upright supports is attached to the outside surface of a flexible strap or belt. The pair of flexible belts includes two rollers located at opposite ends thereof which contact the inner surface of the flexible belts. The other outer surface, distal from the side connected to the frame supports, is connected to the reciprocating platform. The laboratory flasks, or other laboratory items, are placed on the platform. The drive motor causes the platform to move only in a single dimension restricted by the flexible belts. 
     These and other features of the invention will be more fully understood by reference to the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of the flexible band reciprocating shaker platform invention according to the preferred embodiment thereof. 
     FIG. 2A is a perspective view of the flexible band reciprocating shaker platform illustrated in FIG. 1 with the chassis and flask support tray removed. 
     FIG. 2B is an exploded view of the flexible band reciprocating shaker platform. 
     FIG. 3 is a top plan view of the shaker platform with the tray and chassis removed. 
     FIG. 4 is a side elevational view of the platform mechanism with the tray and chassis removed. 
     FIG. 5 is a front elevational view of the platform with the tray and chassis removed. 
     FIG. 6A illustrates the shaker platform in its fully reversed mode. 
     FIG. 6B illustrates the platform in its central, or neutral, position between the positions illustrated in FIG.  6 A and FIG.  6 C. 
     FIG. 6C illustrates the shaker platform in its fully forward mode. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     During the course of this disclosure, like numbers will be used to identify like elements according to the different figures which illustrate the invention. 
     The preferred embodiment of the invention  10  is illustrated in an assembled perspective view in FIG.  1 . Invention  10  includes a reciprocating platform  12 , that only moves in a forward and backward direction, i.e., 1 dimension, not 2 dimensions, which supports a tray  14  which in turn supports a plurality of laboratory flasks  16  or Petri dishes or the like. A chassis cover  18 , or skin, surrounds the internal drive mechanism and protects it from dust and chemical spills and the like. Chassis  18  also supports a control panel  20  which may include a key pad  56  for controlling the speed, periodicity, and duration of the reciprocating shaking of the platform  12  and associated tray and flasks  16 . A control panel  20  could typically include a speed indicator  58  and a time indicator  60 . Power is provided to an electric drive motor  62  and the control panel  20  through a conventional electric cord  22 . In many respects the outward appearance of the invention  10  is similar to that of other prior art laboratory devices. 
     The internal mechanism that drives the platform  12  is best understood by reference to FIGS. 2A to  5 , which represent counter-respectively orthogonal views of the drive mechanism. Invention  10  is supported by a frame  24  which includes a base  26  and a pair of upright supports  28 . Base  26  would also typically support the electric drive motor  62 . Electric drive motor  62  is preferably connected to the underside of the platform  12  through a conventional crank mechanism  54 . A number of well known crank mechanisms, previously used in the art, would be satisfactory and accordingly, the specific crank mechanism  54 , illustrated in the drawings and described herein, is not intended to limit the universe of crank mechanisms potentially available for inclusion in this invention  10 . A crank mechanism  52  would allow for adjustable stroke settings, but is not intended to limit the universe of crank mechanisms or other push-pull mechanisms available for inclusion in this invention. Other types of drive mechanisms might include pneumatic drive mechanisms, solenoid drive mechanisms, audio speaker electromagnetic coil mechanisms, etc. 
     The pair of upright supports  28  each includes an inward facing surface  64 . The inward facing surfaces  64  are attached by at least two pair of attachment means, such as bolts, rivets, metal screws, etc.,  42  to the outside surface  52  of flexible belts  30  and  32 , respectively. The flexible belts  30  and  32  shown in the preferred embodiment of FIGS. 1-6C are two inches wide, 0.0625 inches thick and 22 inches long. Belts  30  and  32  are preferably fabricated from polyethylene or could be made from any other suitable, flexible, but not especially elastic material. While belts  30  and  32  have been described with respect to its preferred embodiment, it will be understood that belts  30  and  32  can be varied in thickness, width and length to accommodate different platform  12  loads and strokes. In addition, belts  30  and  32  can actually comprise two flexible discontinuous pieces of material rather than one single strap in view of the fact that the portions of the belts  30  and  32  between the attachment means  42  and  46  do not move. Moreover, it may be desirable to provide more than two sets of belts  30  and  32 , perhaps a pair on both sides, in order to accommodate heavier platforms and loads. Rollers  34 ,  36 ,  38 , and  40  as shown in FIGS. 1-6C, were made from sections of standard PVC pipe, 1 ¼ inch in diameter and 2 inches long. 
     The first flexible belt  30  includes a pair of rollers  34  and  36  located on the inside thereof, and contacting the inside surface  50  of the first flexible belt  30 . Rollers  34  and  36  respectively are attached to the first belt  30  by roller/belt attachments  44  which could comprise nails, machine screws, bolts, rivets or the like as shown in FIGS. 2B and 5. Similarly, the second flexible belt  32  includes a pair of rollers  38  and  40  located on the inside thereof and contacting the inner surface  50 . Rollers  38  and  40  are attached to the second flexible belt  32  by a suitable roller/belt attachment such as wood screws, machine screws, bolts, rivets, etc.  44 . Rollers  34 ,  36 ,  38 , and  40  can be made of any suitable durable, nonelastic material, such as wood, metal or plastic. 
     Lastly, the outside surface  52  of each of the flexible belts  30  and  32 , opposite the side attached to the upright supports  28 , are attached to the platform  12  by a plurality of suitable support/belt attachments  46  which again, might comprise common fasteners such as wood screws, machine screws, bolts, rivets, or the like depending upon the materials employed in the platform  12  or the upright supports  28 . For example, if the upright supports  28  and the platform  12  were made of wood, then wood screws would be suitable, or if the platform  12  and the upright supports  28  were made of thin gauge metal, then sheet metal screws, bolts or rivets might be suitable. 
     The reciprocating motion of the drive mechanism is illustrated in a progressive fashion in FIGS. 6A-6C. 
     In FIG. 6A, the platform  12  is shown in its most withdrawn, i.e., reversed, position with the platform  12  closest to the rear  68  of the machine and farthest from the front  66  of the machine. In this position the rollers  34 ,  36 ,  38  and  40  have rotated approximately 60 degrees such that the roller/belt fastener  44  are almost adjacent to the downward facing portions  70  of the platform  12 . The downward facing portions  70  of the platform  12  essentially ride on the rollers  34 ,  36 ,  38  and  40  which in turn ride against the inside surfaces of the two upright supports  28 . 
     As the crank mechanism  54  moves forward under the influence of drive motor  62 , the platform is driven towards the central, or neutral, position as illustrated in FIG.  6 B. This is the same mode that is also seen in FIGS. 3-5. In this case the platform  12  is effectively equi-distance between the front  66  and back  68  of the base  26 . Moreover, the roller/belt attachments  44  effectively face directly forward and backward respectively. 
     Finally, as seen in FIG. 6C, the crank mechanism  54  has advanced to its other extreme under the influence of drive motor  62  so that the platform  12  is closest to the front edge  66  and furthest from the back edge  68 . In t his mode the rollers  34 ,  36 ,  38  and  40  have rotated approximately 60 degrees in the opposite direction from neutral as seen in FIG. 6B, so that the roller/belt attachment means  44  almost come into contact with the pair of upward supports  28 . 
     During the t ravel from the extreme positions illustrated in FIGS. 6A and 6C, the platform  12  smoothly rotates under the influence of rollers  34 ,  36 ,  38  and  40  and the flexible belts  30  and  32 . Because the rollers are effectively in contact with the upright supports  28  and the flat lower portions  70  of the platform  12  all the time, the back and forth ride of the platform is very smooth. The flexibility of the belt, given its minor elastic characteristics, further helps to dampen any irregularities in the ride. 
     The invention  10  just described has several advantages over the prior art. 
     First, be cause the plat form  12  is supported by the belts  30  and  32  and the rollers  34 ,  36 ,  38  and  40  maintain the vertical rigidity of the belts  30  and  32  throughout the total movement and the fact that the rollers  34 ,  36 ,  38  and  40  move across flat surfaces separated only by the thickness of the belts  30  and  32 , the motion of the platform  12  is smooth, and not erratic. Additionally, the force required to move the platform  12  is virtually constant even though relatively increased platform  12  loads can be accommodated. Also, the full length of the platform  12  is maintained a constant horizontal plane throughout the total movement. 
     Second, the mechanism is very sturdy and dependable. This means that it has a long life, especially under adverse conditions. 
     Third, the snug fit between the belts  30  and  32  and the surrounding fixed and moving supports  28  and  70 , results in a motion devoid of undesirable or extraneous vertical motion or side play. 
     Fourth, the mechanism  10  is nearly noise free as compared to like devices using ball or sleeve bearings. Since many of these shaker devices are used in a laboratory setting on a continuous basis, a quiet running machine such as the present invention  10  is very desirable. 
     Fifth, the concept of the invention is easily adapted for scaling up in size and performance. Larger shakers can be made by increasing the belt thickness a nd width. The stroke length of the larger platform can be increased by making the roller diameters larger. 
     Sixth, the materials, fabrication and assembly costs are relatively inexpensive. The effort and time to repair or maintain the present invention  10  is minimal based upon its simplicity. Accordingly, the system can be provided to the public at a relatively reasonable and competitive cost. 
     While the invention has been described with reference to the preferred embodiment thereof, it will be appreciated by those of ordinary skill in the art that modifications can be made to the structure and function of the invention  10  with out departing from the spirit and scope thereof.