Abstract:
An apparatus, system and process for simultaneously imaging a number of articles, each of which has applied thereto a unique encoded symbology distinguishing each article from every other article in the number of articles. The symbology encoding for all the articles, in an array of such articles, is simultaneously illuminated and imaged by one or more CCD type cameras. The resulting images of the array of encoded symbologies is thereafter assembled and decoded. The symbology encoded articles may, for example, be test tubes disposed in a rack and the CCD imaging may be effected by four cameras which are disposed to image the array of such symbologies.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Application  
           [0002]    This invention relates to apparatus and processes for handling of a plurality of encoded articles; and, more particularly to the simultaneous handling of symbology encoded articles.  
           [0003]    2. Description of the Prior Art  
           [0004]    It is quite often necessary to handle or process a plurality of similar, but in some ways different, articles. To process articles serially, that is one after the other, is conventional and common; but time consuming and costly. Apparatus is, accordingly, available to gather a plurality of articles together, in an array, in a rack, tray, or carrier and to then handle the articles in the array, individually, serially, or possibly all at once, depending upon the process and how the articles are to be processed. One example of handling an array of articles, in this instance, test tubes for immunochemical determinations, is shown and described in U.S. Pat. No. 4,284,603 patented on Aug. 18, 1981 to G. K. Korom for “Test Tube Decanter Rack”. However, while the articles in this instance, test tubes, are in a 5 by 12 array for processing there is no provision for correlating and tracking the individual test tubes and the tests to be performed on the substance(s) in the test tubes.  
           [0005]    G. P. Kalmakis, et al, on the other hand, in U.S. Pat. No. 6,171,554, patented on Jan. 9, 2001, for “Apparatus And Method For Alphanumerically Identifying And Arranging Test Tubes” alphanumerically marks the test tubes to correspond to respective positions in the wells of a rack for a conventionally arranged 8 by 12 test tube array. Reading of the test tube identification, however, appears to require human intervention to either remove and read individual test tube identification or to lift the entire rack to do so. Once filled with the substance to be processed such handling of the test tubes may create difficulties and removal of the test tubes from the array may result in their return to incorrect well locations and improper processing.  
           [0006]    Apparatus and systems for automated processing of articles, such as cuvettes, specimen carriers, and test tube cassettes are shown respectively in U.S. Pat. No. 5,098,661, patented on Mar. 24, 1992, to J. A. Froehlich for “Coded Cuvette For Use In Testing Apparatus” (utilizing multiple optical facets); U.S. Pat. No. 5,427,743, patented on Jun. 27, 1995 to R. S. Markin, for “Specimen Carrier” (utilizing bar coded strips); and U.S. Pat. No. 5,009,316, patented on Apr. 23, 1991, to D. C. Klein for “Test Tube Cassette System And Cassettes For Use Therein”. However, even though encoded for automated decoding of the identification and processing, the various articles are decoded individually and/or the article carriers (such as those of R. S. Markin and D. C. Klein are encoded and not the individual articles (test tubes) to be carried by the article carriers. The constructions of the respective article carriers are not capable of permitting individual symbology encoded articles to be read and decoded. The respective articles, (test tubes, etc.) if removed from the carrier foe processing, may also be replaced in incorrect positions in their respective carriers.  
           [0007]    U.S. Pat. No. 5,357,095, patented on Oct. 18, 1994 to B. Wevrauch, et al, for “Reagent Bottle Identification And Reagent Monitoring System For A Chemical Analyzer” and U.S. Pat. No. 5,397,709, patented on Mar. 14, 1995, to K. W. Berndt for “System For Detecting Bacterial Growth In A Plurality Of Culture Vials” each utilize encoded symbology on the underside of the articles (reagent bottles and vials respectively). Reading of the symbology is, however, accomplished serially one article at a time by a single CCD type camera. Such a process is time consuming and inefficient.  
         SUMMARY OF THE INVENTION  
         [0008]    It is therefore an object of this invention to provide new and novel apparatus to read encoded symbology carried by a plurality of symbology encoded articles.  
           [0009]    It is another object of this invention to provide new and novel methods to capture encoded symbology carried by a plurality of symbology encoded articles.  
           [0010]    It is yet another object of this invention to provide new and novel apparatus to simultaneously read encoded symbology carried by a plurality of symbology encoded articles.  
           [0011]    It is still another object of this invention to provide new and novel methods to simultaneously capture encoded symbology from a plurality of symbology encoded articles.  
           [0012]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices to read encoded symbology carried by a plurality of symbology encoded articles.  
           [0013]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices, each reading encoded symbology from a selected portion of a plurality of symbology encoded articles.  
           [0014]    It is still further an object of this invention to provide new and novel apparatus to read encoded symbology carried by a plurality of symbology encoded vials.  
           [0015]    It is yet still another object of this invention to provide new and novel methods to capture encoded symbology carried by a plurality of symbology encoded vials.  
           [0016]    It is yet still a further object of this invention to provide new and novel apparatus to simultaneously read encoded symbology carried by plurality of symbology encoded vials arranged in an array.  
           [0017]    It is yet still a further object of this invention to provide new and novel methods to simultaneously capture encoded symbology from a plurality of symbology encoded test tube vials arranged in an array in a rack.  
           [0018]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices to simultaneously read encoded symbology carried by a plurality of symbology encoded articles.  
           [0019]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices, simultaneously operated but so that each reads encoded symbology from a selected portion of a plurality of symbology encoded articles.  
           [0020]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices to simultaneously read encoded symbology carried by a plurality of symbology encoded vials, test tubes and the like.  
           [0021]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices simultaneously operated but so that each reads encoded symbology from a selected portion of a plurality of symbology encoded vials, test tubes and the like.  
           [0022]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices to simultaneously read encoded symbology carried by a plurality of symbology encoded vials, test tubes and the like arranged in an array.  
           [0023]    It is yet still a further object of this invention to provide new and novel apparatus and methods utilizing a plurality of symbology reading devices to simultaneously each read encoded symbology from a selected portion of a plurality of symbology encoded vials, test tubes and the like arranged in an array carried by a rack on a tray.  
           [0024]    It is yet still another further object of this invention to provide new and novel symbology decoding apparatus and methods to correlate encoded symbology carried by respective articles, such as vials, test tubes and the like, read by a plurality of reading devices simultaneously operated but so that each reads a selected portion of the encoded symbology from a selected portion of the symbology encoded articles.  
           [0025]    It is yet still an even further object of this invention to provide new and novel automated apparatus and systems to individually encode each one of a plurality of articles, simultaneously read selected portions of such encoded symbology carried by selected portions of articles from a larger array of such articles when carried by an article carrier and to provide an output for utilization by a system processing such articles.  
           [0026]    Other objects, features and advantages of the invention, in its details of construction, arrangement of parts and methods of operation, will be seen from the above and from the following detailed descriptions of the preferred embodiments when considered in conjunction with the accompanying drawings and the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    In the drawing:  
         [0028]    [0028]FIG. 1. is a perspective view of an upper portion of an encoded symbology reader incorporating the instant invention for simultaneously reading the encoded symbology from each one of a plurality of articles (vials) arranged in an array in a rack for such vials;  
         [0029]    [0029]FIG. 2. is a perspective view of the symbology reader of FIG. 1, somewhat reduced in size from that of FIG. 1, and showing the rack of articles removed from atop the symbology reader and with the rack support window removed to better show mechanisms internal to the reader;  
         [0030]    [0030]FIG. 3. is a perspective view of an array of articles, in the form of vials, arranged in a rack and with the rack cover removed to better show details of the vials;  
         [0031]    [0031]FIG. 4. is a perspective view of the symbology reader of FIG. 1 with the rack of vials and housing removed to better show details of the internal mechanisms;  
         [0032]    [0032]FIG. 5. is a plan view of the symbology reader of FIG. 4;  
         [0033]    [0033]FIG. 6. is a front elevation view of the reader of FIGS. 1 and 4 with a rack for articles (such as the rack and vials of FIG. 3), shown in phantom, positioned thereon;  
         [0034]    [0034]FIG. 7. is a left side elevation view of the symbology reader of FIG. 5;  
         [0035]    [0035]FIG. 8. is a perspective view of the symbology reader of FIG. 2;  
         [0036]    [0036]FIG. 9. is a plan view of the symbology reader of FIG. 8;  
         [0037]    [0037]FIG. 10. is a block diagram incorporating the instant invention for the described symbology reader and process.  
         [0038]    [0038]FIG. 11. is a flow diagram of the process; incorporating the instant invention, for the described symbology reader; and  
         [0039]    [0039]FIG. 12. is a view of the monitor display for the described symbology reader operations process; 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    With reference to FIGS. 1 and 2 there is generally shown at  20  an encoded symbology scanner, incorporating the instant invention, with the mechanisms thereof arranged with a housing  22 . Scanner  20  is to be associated with peripherals, to be hereinafter described, which together with scanner  20  comprise an encoded symbology reader  24 .  
         [0041]    A rack  30  (FIGS.  1 - 3 ) of symbology encoded articles, in this instance vials or test tubes  32 , is shown in FIG. 1 disposed in symbology sensing position on top of scanner  20  (FIG. 1), adjacent scanner  20  (FIG. 2) and all by itself (FIG. 3). Vials  32  are shown disposed in rack  30  in an array  34  of 8 rows  40  and 12 columns  42 . A cover  44  (FIGS.  1 - 3 ) is provided for vials  32  so that they may be covered to protect not only vials  32  while in array  34 , but any contents (not shown) therein.  
         [0042]    Each article, test tube, vial  32  and the like, carries, on an under or bottom surface  36  (FIGS. 2 and 3) thereof on encoded symbology  38 . In this instance such encoded symbology  38  is the conventionally available “DATA MATRIX”. Each such encoded symbology may merely encode an identification, such as a number or the like, peculiar to the respective vial; with the numbers of the array  34  following serially and consecutively for each vial  32  in rack  30 . Encoded symbology  38  may also include other information such as the characteristics of the substance in the respective vial  32 , or to be thereinafter placed in each respective vial  32 .  
         [0043]    Encoded symbology  38  may be applied to each vial  32  by conventionally available equipment and systems to do so, as by printing, etching or the like.  
         [0044]    An opening  46  (FIG. 2) with chamfered edges  48 ,  50  is formed through a top  52  of scanner housing  22 . A notch  54  is formed in each edge  48  to facilitate removal of rack  30  from its position within opening  46  and on top of a tempered glass window  60  (FIGS. 4, 5,  6  and  7 ) which is positioned just below window opening  46 . Window  60  not only forms a seat for rack  30 , but also serves to close off opening  46  into housing  22  to protect the contents thereof from dust, dirt and damage. Window  60  is made from tempered glass, but other materials, such as a suitable clear plastic may be utilized.  
         [0045]    A window retainer  62 , secured to a support plate  64  by suitable securing members such as threaded members  66  (FIG. 4), positions and retains window  60  in the above-described position. Window retainer  62  includes an opening  63  for window  60  and is formed with a recess  65  around the peripheral edges of opening  63  and up from a bottom surface of retainer  62  to hold window  60  in place.  
         [0046]    A number of spacers  68  (FIGS. 6 and 7) may be utilized between window retainer  62  and support plate  58  and, if so, held in place by threaded members  66 . Support plate  64  is, in turn, positioned and secured on top of support rods  70  (FIGS. 4 and 7),  72  and  74  (FIG. 7) as by threaded members  76  (FIGS. 4 and 5). Lower ends of support rods  70 ,  72  and  74  are, in turn, secured to a base plate  78  (FIGS.  4 - 9 ) by threaded members (not shown).  
         [0047]    Four CCD camera assemblies  80  (FIGS. 8 and 9),  82 ,  84  and  86  respectively are supported within housing  22  each by its own camera support bracket assembly  90 ,  92 ,  94  and  96  respectively. Cameras  80 - 86  may be of conventional construction and may be ones such as those provided by Sensor Technologies America under their model number STC- 170 . Each camera assembly  80 ,  82 ,  84  and  86  includes a pair of printed circuit boards  100  (FIGS. 6 and 8) and  102  respectively attached together by suitable members (not shown) and separated from each other by spacers  104 . Camera printed circuit boards  102 , 104  are secured to each camera  80 ,  82 ,  84  and  86  respectively in a suitable and appropriate manner, function for each respective camera in a conventional manner to operate same and facilitate operation thereof and to connect the respective cameras to control circuitry for and otherwise with respect to encoded symbology reader assembly  24 . Each camera also includes a lens assembly  106  consisting of a “C” mount, an extension  108  which in this embodiment is selected to be 5.5 mm, and an 8.5 mm lens  109  with locking screws (not shown). Other lens assembly arrangements may also be selected depending upon the positioning of camera assemblies ( 80 - 86 ) and the target image to be captured.  
         [0048]    Camera support bracket assemblies  90 ,  92 ,  94  and  96  respectively are each substantially identical in construction and operation so only one such assembly, camera support bracket  90  will be described in detail. A body portion  110  (FIGS. 6 and 8) of camera support bracket  90  includes a pair of spaced arms  112  extending outwardly therefrom. An opening  114  (FIGS. 8 and 9) formed through body portion  110  receives a conventional ball joint assembly  116  including ball joint bearings (not shown). Ball joint standoffs  118  interconnect body portions  110  of each camera support bracket assembly  90 ,  92 ,  94  and  96  to base plate  78 . Each body portion  110  also includes three openings  120  (FIGS. 4, 8 and  9 ) that receive threaded adjustment members (not shown) with each such adjustment member extending through its respective opening and into base plate  78 . The underside  122  of each body portion  110  is formed with counterbores  124  surrounding each opening  120  sized and configured to receive an upper end of a spring  126  the other end of which rests upon base plate  78 . Springs  126  are each positioned to surround a respective one of each such threaded adjustment members. The threaded adjustment members are rotated either clockwise or counter-clockwise to pivot respective camera support bracket assemblies ( 90 - 96 ) about their respective ball joint assemblies  116  and by doing so adjust the position of the cameras ( 80 - 86 ) carried thereby with respect to window  60  and a rack  30  of symbology encoded  38  vials  32  that may be disposed thereupon; all as will be explained in greater detail hereafter. Ball joint assemblies  116 , their bearings and standoffs  118  function in a substantially conventional manner to facilitate pivoting and rocking movement of their respective camera assemblies ( 90 ,  92 ,  94  and  96 ) to position such camera assemblies in manners and for purposes to be hereinafter explained in further detail.  
         [0049]    Suitable and appropriate attaching items, such as a threaded member  130  (FIGS. 4 and 9) is extended through each spaced hole (not shown) formed through each of the spaced arms  112  of each camera support bracket assembly ( 90 - 96 ). Each such threaded member  130  is then extended through a spacer  132  camera printed circuit board  102 , spacer  104  and camera printed circuit board  100 . A nut (not shown) is thereafter utilized to secure the above items in place. Each camera ( 80 - 86 ) is thus secured to its respective support bracket assembly ( 90 - 96 ) when all four threaded members  130  have been so utilized to connect camera circuit boards  100  and  104  to arms  112  of the support bracket assembly ( 90 - 96 ).  
         [0050]    An “L” shaped locking bracket  140  (FIGS. 4, 5, and  9 ) is provided for cooperation with each camera support bracket assembly ( 90 - 96 ). Each bracket  140  is disposed proximate an outward side  142  of each body portion  110  of each camera support bracket assembly ( 90 - 96 ) as shown in FIGS. 4, 6 and  8 . A pair of threaded members  144  are used to securely attach an outwardly extending leg  146  of each bracket  140  to base plate  78 . An upwardly extending arm  148  of each such bracket  140  is disposed proximate outward side  142  of the respective cooperating camera support bracket assembly ( 90 - 96 ). An upwardly extending slot  150  is formed through each such arm  148  to receive a pin  152  that extends out from side  142  of each support bracket assembly for purposes to be hereinafter described. Locking bracket  30 , through its disposition adjacent body portion  110 , and due to the coaction of pin  152  and slot  150  permits camera bracket assembly ( 90 - 96 ) and its respective camera ( 80 - 86 ) to rotate about horizontal axis “x”, or “y” but prevents rotation about a vertical “z” axis.  
         [0051]    Each camera  80 ,  82 ,  84  and  86  is positioned by its respective support bracket assembly  90 ,  92 ,  94  and  96  respectively for optimum and efficient capture of encoded symbology  38  carried by vials  32  when properly positioned and disposed on window  60 . Such positioning of each of cameras  80 ,  82 ,  84  and  86  is individually accomplished by turning the threaded members (not shown), which extend through opening  120  of each camera support bracket assembly body  110  and into base  78 ; in either a clockwise or counter-clockwise direction until the respective camera ( 80 - 86 ) is optimally positioned. Springs  126  function to facilitate such positioning. In this particular instance such threaded adjustment members for each camera support bracket assembly ( 90 - 96 ) are adjusted so that the support bracket assembly positions its respective camera ( 80 - 86 ) at an angle of substantially three degrees (3°) to the horizontal and so that adjacent pairs of cameras  80 - 84  and  86 - 88  are tilted towards each other (FIG. 7) when observed from a side of scanner  20  for reasons to be hereinafter described in greater detail.  
         [0052]    Other adjusted positions for cameras  80 - 86  may be similarly accomplished depending upon the application and use for scanner  20 .  
         [0053]    If desired, a threaded blocking member (not shown) may be inserted into each opening  120  to limit access to respective adjustment members and/or to lock them in position after adjustment as described above.  
         [0054]    The four camera assemblies ( 80 - 86 ) are positioned, as described above, so that each captures a particular area of the underside of array  34  of vials  32 . More particularly camera assemblies ( 80 - 86 ) and provided with lens assemblies  106  and are so positioned so that each camera captures at least one quarter of the encoded symbology  38  carried vials  32  of array  34 .  
         [0055]    Other image capture arrangements may be provided depending upon the number, size, disposition, and other characteristics of the articles in an array of articles, the kind and disposition of the encoded symbology carried by such articles and the disposition of the other scanner components. The number of camera assemblies may also be varied with either more or less then four such camera assemblies utilized and with a corresponding number and disposition of camera support and positioning mechanisms. When less then four camera assemblies are so utilized, especially if only a single camera assembly is to be so employed, higher resolution camera assemblies may be required. The number and disposition of encoded symbologies  38  to be imaged by each such camera assembly as well as thye array arrangement will, of course, depend upon the number of such camera assemblies.  
         [0056]    An illumination assembly  180  (FIGS. 8 and 9) is provided for scanner  20 . Four printed circuit board mounting blocks  182 ,  184 , 186  and  188  respectively secure a pair of long illumination printed circuit boards  190 , 192  and a pair of short illumination printed circuit boards  194 , 196  into a substantially rectangular configuration as shown in FIGS. 8 and 9. A threaded member  200  (FIGS. 5, 8 and  9 ) is utilized to connect each mounting block  182 - 186  to the underside of support plate  64  as shown in FIGS. 4, 6 and  7 ; and to position illumination assembly  180  with respect to the underside of window  60 , and any encoded symbology  38  carried by vials  32  that may be positioned thereupon, as well as with respect to cameras  80 - 86 .  
         [0057]    Each long illumination printed circuit board  190 , 192  and each short illumination circuit board  194 ,  196  carries and positions a number of red, 636 nm LED&#39;s  210  and is selected to provide non-diffused, low angle, “dark field” illumination. LED&#39;s  210  are arranged horizontally but may be angled upward toward and under window  60 .  
         [0058]    A substantially “L” shaped back plate  216  (FIGS.  4 - 9 ) is secured to base plate  78  by threaded members or the like. A regulator printed circuit board  218  and a component printed circuit board  220  are each appropriately secured to a leg  222 ,  224  respectively of back plate  216 .  
         [0059]    An opening  230  (FIG. 4) is formed through base plate  78  to facilitate access to components within scanner  20  to facilitate servicing same. A cover plate  232  (FIG. 6) secured in place by threaded members  234  is utilized to close opening  230  when access into scanner  20  is not required. A set of feet  240  (FIG. 6), suitably secured beneath base plate  78  may be utilized to raise scanner  20  above a surface that it may be resting upon.  
         [0060]    It should be understood that while the components of scanner  20  have been shown and described as being disposed within housing  22  and accessible through opening  230  closed by cover plate  232  that neither housing  32  nor cover  232  need be provided if the components of scanner  20  are to be otherwise positioned and housed.  
         [0061]    A photo-optical sensor  250  (FIGS. 4 and 5) is positioned on top of window retainer  62  to sense the presence, or absence, of a rack  30  of vials  32  on window  60 . Suitable and appropriate electrical conductors and components connect sensor  250  to the control circuitry of FIG. 10.  
         [0062]    A simplified control circuit assembly  260  for encoded symbology reader  24  is shown in FIG. 10. Camera assemblies  80 ,  82 ,  84  and  86  are symbolically shown disposed for coaction with illumination assembly  180  for scanner  20 . Suitable and appropriate electrically conductive cabling  262  interconnects scanner  20  with an I/O controller module of conventional construction; while other suitable and appropriate cabling interconnects scanner  20  with a machine vision processor board  264  for a computer  266 , which may be of the personal computer type. Panel  264  may be of a type sold by RVSI Acuity/CiMatrix under their designation AV2301.  
         [0063]    The operation of reader  24  and scanner  20  will be explained along with reference to the Flow Diagram of FIG. 11.  
         [0064]    A rack  30  Of articles, such as vials  32  each carrying encoded symbology  38 , such as a Data Matrix, is placed on window  60  at step  300 . Sensor  250 , coacting with rack  30  when so disposed, is held in its on position as long as rack  30  remains positioned as described for step  302 . At step  304  illumination assembly  180  is energized for an alloted time, which could be strobbing, while at step  306  camera assemblies  80 - 86  are activated each to image one quarter of the array of the encoded symbology  38  carried by vials  32 . The images may overlap a predetermined amount to facilitate proper image capture.  
         [0065]    At steps  308  and  310  the images are respectively decoded and a data array corresponding to the number of encoded articles, in this instance  96 , is made available for output. The combined images captured by cameras  8 - 86  may also be displayed on a monitor as shown in FIG. 12 as well as other desired displays.  
         [0066]    At steps  312  and  314  any duplicate encoded symbology content, if found, are shown to the operator and checking is done for the number of encoded symbologies to decode, respectively. If the number of encoded symblogies decoded does not match the expected number that is shown to the operator at step  316 . After the number of encoded symbologies are found to correspond to the number expected to be found the decode is considered to have been sucessfully accomplished and illumination assembly  180  is turned off a step  318 .  
         [0067]    At step  320  an encoded symbology label, not shown, if desired (which may include an 88×88 Data Matrix encoded symbology with, for example, 96 strings an a total of 1,055 characters) may be printed for application to cover  44  of rack  30 . A comma delimited text file for the number of encoded symbology articles (in this example 96), if desired may be created at step  322 . In addition and also if desired an PC speakers may be sounded to provide an audible indicator that reading is complete at step  324  and at step  326  an indication is provided that sensor  250  has been held on continuousely.  
         [0068]    At this juncture rack  30  may be removed (at step  328 ) and an indication is provided that rack  30  has been in place is removed. The process is now considered to be complete at step  330 .  
         [0069]    The encoded symbology may be used to identify each article as it is recorded in a data base so that different proceedures for different articles may be performed via a data base lookup. The encoded symbology as provided and utilized as herein above described insures that regardless of the position in the array, rack, carrier or the like, of the article (vial  32 ) that the proceedure information (test data) that is recorded for the respective article will be properly associated with that article. The particular proceedure to be performed for any particular may alsso be encoded in the encoded symbology so that a data base lookup is not required.  
         [0070]    From the above description it will thus be seen that there has been described new and novel apparatus and methods for handling a plurality of symbology encoded articles for proceedures to be employed with respect to each individual article to insure accuracy in associating the required proceedure with the article for that specific proceedure.  
         [0071]    Numerous alterations of the structure, components, controls and process herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to the preferred embodiments of the invention, which is for pruposes of illustration only, and not to be considered as a limitation of the invention. All modifications, which do not depart from the spirit of the invention, are intended to be included withinthe scope of the appended claims.