Abstract:
An orbital shaker which provides a shaking motion that is both stable and accurate to allow repeatability is provided, which allows for ease of cleaning of the shaking platform due to its mounting on a drive platform that keeps the entire drive system in an assembled state even if the shaking platform is removed for cleaning. A vibration sensor can also be provided that senses an unbalanced load on the orbital shaker and communicates with the orbital shaker controller to reduce the shaking speed in a pre-determined, trackable manner so that shaking of samples can be continued at a vibration level that is below a threshold value. Additionally, an incubating enclosure can also be provided in which a uniform heat is created throughout the entire incubating chamber in order to assure minimum temperature fluctuations between samples being processed regardless of their position on the shaking platform.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/842,698, filed Sep. 6, 2006, which is incorporated by reference herein as if fully set forth. 
    
    
     BACKGROUND 
     The present invention relates to an orbital shaker and in one particular aspect, to an incubating orbital shaker. 
     Orbital shakers are known for use in a laboratory environment to agitate an assay or test samples with a generally orbital motion. Certain orbital shakers also include a heated chamber in order to keep certain materials at a predetermined temperature during the agitation. 
     In the past, devices for achieving such orbital motion and heating have not provided sufficient stability and accuracy for the drive speed, which result in sample-to-sample differences that introduce additional error and uncertainty into production or test results. Additionally, for incubating orbital shakers, the incubation chambers in some known devices lack generally uniform heating resulting in test samples located in different areas of the shaking platform being heated at different temperatures. This also results in sample-to-sample variations that can be unacceptable in various types of testing. 
     In addition, some known orbital shakers do nothing to address unbalanced load conditions which can result in the samples being damaged and/or the orbital shaker itself walking off the edge of a laboratory table if unobserved. Additionally, in the event of spillage it is often difficult to clean the shaking platform, since it is typically directly mounted to the drive system and requires disassembly beyond that which should typically done by a user and/or can result in the drive system being unbalanced upon reassembly. 
     SUMMARY 
     The present invention provides an orbital shaker which provides a shaking motion that is both stable and accurate to allow repeatability. Additionally, it allows for ease of cleaning of the shaking platform. 
     In another aspect, the invention also includes is a vibration sensor that senses an unbalanced load on the orbital shaker and communicates with the orbital shaker controller to reduce the shaking speed in a pre-determined, trackable manner so that shaking of samples can be continued at a vibration level that is below a threshold value. 
     In another aspect of the invention, an incubating orbital shaker is provided in which a uniform heat is provided throughout the entire incubating chamber in order to assure minimum temperature fluctuations between samples being processed regardless of their position on the shaking platform. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the preferred embodiment of the present invention, will be further understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings an embodiment which is presently preferred. It is understood, however, that the invention is not limited to the precise arrangement and instrumentality shown. In the drawings: 
         FIG. 1  is a perspective view of an incubating orbital shaker in accordance with a first preferred embodiment of the present invention. 
         FIG. 2  is a top-front-right perspective view of the incubating orbital shaker of  FIG. 1 . 
         FIG. 3  is a top-front perspective view of the incubating orbital shaker of  FIG. 1 . 
         FIG. 4  is a partial cross-sectional view taken along lines  4 - 4  in  FIG. 3 . 
         FIG. 5  is an exploded perspective view of the incubating orbital shaker of  FIG. 1 , showing all of the preferred components in accordance with the invention. 
         FIG. 6  is a perspective view of the drive mechanism and drive platform without the shaking platform installed. 
         FIG. 7  is a greatly enlarged detail view, in perspective, of a sensor used to track the actual movements of the drive platform and shaking platform of the orbital shaker. 
         FIG. 8  is a perspective view similar to  FIG. 6  in which the drive platform has been removed to show the motor and drive pulley as well as the oscillating drive platform mounts. 
         FIG. 9  is a top view of the arrangement shown in  FIG. 8 . 
         FIG. 10  is an enlarged exploded perspective view of the drive assembly shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “right,” “left,” “top,” and “bottom” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the incubating orbital shaker and designated parts thereof. The words “a” and “one” are defined as including one or more of the referenced item unless specifically stated otherwise. This terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. 
     Referring now to  FIGS. 1-5 , an orbital shaker  10  in the form of an incubating orbital shaker in accordance with a preferred embodiment of the invention is shown. The orbital shaker  10  includes a base housing  12 , in which the drive assembly  20  is mounted, as shown in  FIG. 5 , and an upper housing assembly  14 , in which the incubating heater assembly  70  is provided. A pivoted cover  16  encloses the incubating chamber  75  in the upper housing assembly  14  over the shaking platform  60  where vials, test tubes, beakers and/or other containers holding test samples or other items to be shaken are placed. A control panel  100  is located at the front of the base housing  12  and is connected to a controller  102 , shown in  FIG. 5 , which controls all of the shaker and incubating functions as well as receives user inputs and provides a connection for outputting data with respect to the shaking, speed and temperature performance of the shaker  10  as it is processing a test sample or other item. 
     As shown in  FIGS. 1-5 , and in particular in  FIG. 5 , the base housing assembly  12  can be formed of a plurality of pieces which are assembled via mechanical fasteners, adhesives or any other suitable means in order to form the base housing assembly  12 . In a preferred embodiment, lower side panels  24 ,  25  are connected to a base panel  26 . A front panel  28 , which is preferably a molded plastic or a cast metal housing which includes the control panel  100  and holds the controller  102 , is connected to the front of the lower side panels  24 ,  25  and base panel  26 . A rear panel  30  is connected the back sides of the lower side panels  24 ,  25  and the base panel  26  and preferably also extends upwardly a sufficient distance to also provide the rear panel of the upper housing assembly  14 . 
     The drive assembly  20 , which is shown in detail in  FIGS. 5-10 , includes a base platform  32  with three preferably integrally formed support wells  34  for receiving eccentric bearing assemblies  36   a - 36   c . A drive motor  38  is also mounted to the base platform  32  and includes a pulley  39  which drives a belt  40  that is connected to a weighted drive pulley  42 , having an offset weight to counter vibration, connected to a first eccentric bearing assembly  36   a . The eccentric bearing assemblies  36   a - 36   c  include a bearing with an off center post  44 . The drive platform  46  is connected to the offset posts  44  of the eccentric bearing assemblies  36   a - 36   c  by bearings  48  located in bearing housings  49  that are connected to the drive platform  46  via fasteners  50 . Fasteners  52  are used to secure the bearings  48  to the off center posts  44  of the eccentric bearing assemblies  36   a - 36   c . The motor  38  drives the drive pulley  42  on the first eccentric bearing assembly  36   a , which is connected to the other eccentric bearing assemblies  36   b ,  36   c  via the drive platform  46  to generate the shaking motion. 
     As shown in detail in  FIG. 7 , an encoder disc  54  is connected to the second eccentric bearing assembly  36   b . An encoder sensor  56  is used to read the encoder disc  54  and transmits data regarding the actual movement of the drive platform to the controller  102 . 
     The motor  38  is preferably a brushless DC motor with a Hall Effect sensor and therefore can be controlled to provide a desired speed. The encoder disc  54  and encoder sensor  56  preferably are a beam break optical sensor combination which detect the actual speed of the drive platform  46  rotations so that data on both the speed of the drive motor  38  and the actual movement of the drive platform  46  can be determined in order to account for slippage of the belt  40 . In the preferred embodiment, the controller  102  can calculate the amount of belt slip, if any, and adjust the tray speed to be stable to plus or minus one rpm at speeds below 100 rpm and between plus or minus 1% of speeds between 101-500 rpm. This allows an extremely precise control of the shaker speed to be obtained according to the invention through the use of the two sensors in communication with the controller  102  to achieve the desired speed with both stability and accuracy. The controller  102  can also maintain the desired speed within the above-noted ranges throughout the entire cycle of a given test run therefore providing enhanced repeatability to the extent that multiple tests need to be run and compared with accuracy. 
     While the preferred motor  38  is a dc brushless motor, and the preferred sensor is an encoder disc  54  with an encoder sensor  56 , those skilled in the art will recognize that other types of motors can be used and that other types of sensors can be employed to detect both the motor speed and actual speed of the drive platform  46  so that feedback adjustments can be made by the controller  102  to achieve the high stability and accuracy provided by the present invention. 
     Referring now to  FIG. 6 , stand-offs  58  are provided on the drive platform  46 . The shaking platform  60  is mounted on the stand-offs  58 , which preferably extend through openings  74  in the lower housing wall  72  of the upper housing assembly  14 . The shaking platform  60  can therefore be easily removed, preferably by removing four fasteners, such as screws, which extend through the shaking platform  60  and into the stand-offs  58 . This allows two further benefits of the incubating orbital shaker  10  according to the present invention in that the shaking platform  60  can be easily removed for cleaning without the need for disturbing the balance of the drive assembly  20 . In the prior known shakers, the drive assembly is connected directly to the shaking platform and therefore if the shaking platform is removed it must be precisely reinstalled so that it is not out of balance and such that none of the eccentric bearing assemblies  36  are misaligned, which would result in an unstable movement as well as premature wear on the bearings to the extent that one may lead or lag the others in their movement. According to the present invention, the shaking platform  60  can be easily removed and the drive platform  46  maintains its connection with all three eccentric bearing assemblies  36   a - 36   c  ensuring that the precise alignment is maintained. Additionally, by allowing the user to easily remove the shaking platform  60 , cleanup of spills can be easily performed in hard to reach areas, unlike the prior known shakers, without any effect on the performance of the equipment or requiring rebalance of the drive mechanism. This not only provides a savings in down time for cleaning spills but also eliminates unnecessary service calls or returns to the vendor for repair or rebalancing of a shaker drive assembly. 
     Preferably, the base platform  32  is made of iron or heavy material in order to provide stability to the shaker  10 . However, those skilled in the art will recognize they can be made from various other suitable materials and appropriate weights can be added to the base housing assembly  12 , if necessary. 
     Additionally, rubber feet  62  are preferably connected to the bottom of the base panel  26  to help absorb vibration and to maintain a more stable platform. While in the preferred embodiment the drive assembly  20  and the base housing assembly  12  are assembled using threaded fasteners, those skilled in the art will recognize that other suitable types of fasteners and/or adhesives can be utilized depending upon the particular assembly and maintenance requirements. 
     Referring again to  FIGS. 1-5 , the upper housing assembly with the incubator  70  is shown. The incubator  70  includes the lower housing wall  72  which is preferably formed from molded plastic or bent-up sheet metal that is able to resist temperatures of up to 65° C. Two side walls  76  extend upwardly from the lower housing wall  72  to the same height as the rear panel  30 , and a top wall  78  closes a top portion of the heating chamber  86 . The side walls  76  have angled portions which extend from a mid portion of the incubating orbital shaker  10  toward the front. Additional insulating panels  77 , shown in  FIG. 5 , can also be attached as desired. The pivoting cover  16  is connected to a front edge of the top wall  78  via a hinge  80  and extends forward with a top wall, two side walls and a front wall in order to form an enclosure over the shaking platform  60  having a sufficient height to hold flasks, beakers and/or test tubes with samples that are being tested, defining the incubating chamber  75 . A handle  18  is preferably provided on the front of the cover  16 . As shown in  FIG. 5 , seals  17   a ,  17   b  can be provided around the periphery of the opening for the cover  16 . Additionally, gas-spring holders  79  can be provided to hold the cover  16  in an open position. 
     A center wall  82  extends upwardly from the lower housing portion  72  to the front edge of the top wall  78  behind the shaking platform  60 . This center wall  82  includes two spaced apart upper openings which receive fans  83 ,  84  that draw air from the incubating chamber  75  into the heating chamber  86  formed between the center wall  82 , the rear panel  30 , the back portions of the side walls  76  and the top wall  78 . A heating coil  85  is located in the heating chamber  86  and heats the air drawn in by the fans  83 ,  84 . 
     As shown in  FIGS. 4 and 5 , a lower opening  88  is provided in the center wall  82  which allows the heated air to return to the incubating chamber  75  over the shaking platform  60 . A filter  90  is preferably located in the lower opening  88  and a baffle  92  is mounted in front of the opening and includes two bent side portions  93 ,  94  that direct the air flow sideways into the incubating chamber along the insides of the side wall  76  of the incubating chamber  75  and the side walls of the cover  16  as indicated by arrows in  FIG. 3 . A temperature sensor  96 , shown in  FIG. 5  is located in the incubating chamber  75  or the heating chamber  86  and provides a temperature signal to the controller  102 . Additionally, preferably a horizontal baffle  81 , shown in  FIGS. 3-5 , is located between the fans  83 ,  84  and the lower return opening  88 . 
     Through the use of the fan arrangement which draws air from the incubating chamber  75  into the heating chamber  86  as well as the baffle  92  which directs the air flow out of the heating chamber  86  back into the incubating chamber  75  along the side walls of the incubating chamber  75 , which rises upwardly due to heat convection, the present invention provides an extremely uniform heating throughout the entire incubating chamber and in particular through all areas on the shaking platform  60  so that uniform temperature can be achieved in all samples regardless of their position on the platform  60 . This is extremely important for repeatability of testing and accuracy in test results. In comparison, the prior known incubating shakers provide fan driven airflow into the center of the incubating chamber resulting in higher temperature heating of samples located directly in the path of the heated air flow. Testing of the present invention has shown stability and accuracy in temperature control to less than 0.7° C. for samples located at any position on the shaking platform  60 . In comparison, the prior known incubating shakers have temperature variations of plus or minus two degrees C. or more depending upon the location of the sample on the shaking platform. Thus, the present invention not only provides enhanced performance, but allows for higher accuracy testing of samples to be conducted. 
     Referring to  FIG. 5 , the controller  102  is preferably located in the base housing assembly  12  on a circuit board  104 , and is preferably a PLC or another known type of programmable controller. A vibration sensor  106  is preferably also mounted on the circuit board  104  and provides a vibration signal to the controller  102 . The controller  102  analyzes the frequency of vibrations to determine whether the vibration has risen above a threshold level where damage can occur to a sample and/or the shaker  10 . When excessive vibrations are detected by the controller  102 , the controller  102  generates an error signal and slows the shaking drive assembly  20  by lowering the motor speed to a lower rpm until the excessive vibration is no longer present. The unit  10  preferably notifies the user through the display panel  110  of the error. Preferably, the display panel  110  shows alternately that an error has been detected by showing the error code and alternately displays the actual speed of the shaking drive  20 . An audible alarm can also be sounded. This data can also be transmitted by a serial port connection from the shaker  10  to allow the actual data log tracking to occur for the actual speed, time and/or temperature. While the vibration sensor may be of any suitable type, in a preferred embodiment, a ball-and-tube sensor which chatters open and closed as it is tilted or vibrated is used. One preferred sensor is a SQ-SEN-200 sensor from SignalQuest. 
     Referring to  FIG. 1 , the display panel  110  preferably includes digital LCD or LED displays  112   a ,  112   b ,  112   c  for temperature speed and time as well as on-off switches for each of these functions  114   a - 114   c . Up-down buttons  116   a - 116   c  are also provided to control switches that adjust each of the functions for temperature, speed and time to desired values. An on-off button  118  is preferably provided for supplying power to the entire unit  10 . These buttons/switches are all connected to the controller  102  so that the various functions can be set and controlled, allowing a user to set a desired temperature and speed for tests, as well as a desired test time allowing the incubating orbital shaker assembly  10  to carry out a pre-programmed test on samples loaded on to the shaking platform  60 . Preferably, the control panel  100  is covered with a one piece spill-resistant cover  120  that allows the display  110  to show through and includes flexible portions over the buttons/switches so that in the event of any spill, nothing can enter through the cover  120  and into the switches and/or controller  102 . 
     The controller  102  will preferably signal the display panel  110  to display the last set points on the displays  112   a ,  112   b ,  112   c  for the temperature speed and time, even when the unit is shut off or power is interrupted. The controller  102  preferably also includes or is connected to a built in audible alarm when the elapsed time has counted down to zero so that a user is informed that the testing cycle has ended and the unit automatically shuts off. Additionally, the controller  102  will shut down the unit and activate an audible and visual alarm if the temperature limit is exceeded to prevent damage to the unit  10 . 
     In the preferred embodiment, the incubating orbital shaker can run in a speed range of 15 to 500 rpm. However, the range can be extended, as desired. Optional stands and covers may be provided for the shaking platform  60  in order to allow attachment of various different types of holders, such as test tube racks, clamps for flasks and/or beakers. Optionally, a non-skid rubber mat can be attached to or set on the shaking platform  60  that allows a petri dish or a cell culture flask to be set on the platform  60  and maintained in position. 
     Those skilled in the art will recognize that the present invention provides an improved orbital shaker with a high accuracy drive system which provides extremely accurate control with respect to both the stability and accuracy of the drive speed. This is adapted for use with any type of orbital shaker. Additionally, the vibration sensor according to the invention can also be used in any type of orbital shaker in order to provide for continued testing without damage to samples and equipment at safe speeds in the event that an unbalanced load condition occurs and it can also sound an alarm to alert a user who may not necessarily be closely monitoring the testing once it has begun. 
     Further, the invention provides a drive system which allows a user to remove the shaking platform  60  from any orbital shaker in accordance with the invention for cleaning of spills which may occur in use, without affecting the balance of the drive system which could then require outside repair, such as by a factory or dealer representative. In the case of an incubating orbital shaker, this also allows the incubating chamber to be cleaned to avoid contamination through residue of spilled materials which were not thoroughly cleaned from the chamber. 
     Additionally, in connection with the incubating orbital shaker of the preferred embodiment that incorporates the above features, it is also possible to provide an incubating orbital shaker with improved temperature control through the use of a fan/heating system with baffles which direct the airflow into the incubating chamber along the side walls along the lower portion of the incubating chamber  75  so that the heated airflow does not directly impinge upon samples. This results in a more uniform temperature throughout the entire incubating chamber regardless of the position of the samples on the shaking platform  60 . 
     Those skilled in the art will recognize that one or all of the above-referenced features can be used alone and/or in various combinations to provide an improved orbital shaker or incubating orbital in accordance with the present invention.