Abstract:
Diagnostic strips of the kind which are exposed to biological fluids such as blood or urine to detect or monitor medical conditions are cut sequentially from elongated cards by a reciprocating shear blade. The cards may be ones which exhibit defective areas that should not be included in the finished strips. Blade motion seats each newly cut strip on a movable strip carrier which abuts the blade during the cutting operation. The carrier then travels a nondefective strip to a pickup location where it is precisely positioned and picked off of the carrier for emplacement in a housing. A strip with a defective area is carried further to a discharge location where it is released into a waste receptacle. This enables more economical manufacture of diagnostic strips by efficiently making use of nondefective areas of cards that have defective areas.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the manufacture of diagnostic strips of the kind used for diagnosis or monitoring of medical conditions. More particularly the invention relates to mechanism for transverse cutting of elongated cards to form a plurality of such strips and for separating out defective strips following the cutting operation. 
     Diagnostic strips are strips of paper, plastic or other sheet material which are coated with reagents that react to particular substances which may be present in biological fluids such as blood or urine. Typically such strips change color after being immersed in the biological fluid if the particular substance is present in the fluid. This enables a very quick, convenient and economical detection of many medical conditions and facilitates monitoring of patients. As one example, strips sensitive to glucose oxidaise are used in the diagnosis and monitoring of diabetes. Strips sensitive to certain hormones are used to detect pregnancy. Strips having other compositions detect a variety of other physiological conditions. Similar strips are also used for non-medical purposes such as for detecting the presence of particular chemical compositions in a fluid. 
     The diagnostic strip typically has a backing material formed of paper, plastic or the like to which the chemically sensitive coating material is applied. The coating material may be contained in one or more very thin tissues which are laminated on to the backing material. Applying the coating to each small strip individually would result in undesirably high manufacturing cost. This is avoided during manufacture by applying one or more long ribbons of the coating material to a lengthy piece of the backing material to form what is called a card. Cutting of the card along transverse cut lines produces the strips. 
     In some prior manufacturing processes the strips are produced by making simultaneous transverse cuts across the card using a rotary cutter having a row of spaced apart cutting disks disposed along an axis of rotation. The groups of strips which are produced simultaneously in this manner are then packaged or passed on to other mechanism for further processing. Prior U.S. Pat. No. 5,067,309 and prior U.S. Pat. No. 5,816,030 disclose examples of rotary strip cutting mechanism of this kind. In other prior manufacturing processes the strips have been produced sequentially by cutting successive strips from the card using a reciprocating cutting blade. Prior cutting mechanisms of either form do not enable performance of certain post cutting operations in a desirably efficient and economical manner. 
     Cards can on occasion have areas with visible manufacturing defects or areas which have been inadvertently contaminated with a foreign substance. Finished strips formed from such areas or containing portions of such areas may not function in the intended manner. The prior practice does not provide desirably efficient and economical arrangements for assuring that finished strips are free from defective areas of this kind. Individual inspection of each cut strip is at best a costly complication of the manufacturing process. Discarding of an entire card because of a small localized defective area results in wastage of other portions of the card material. 
     In many cases individual strips are emplaced in a housing formed of plastic or other material to form a kit which facilitates use of the strip. The housing may have openings for admitting fluid and for observing the effects of the fluid on the strip. Any mechanism for moving the cut strips from the cutter to the housings must bring the strips into precise registration with the housings as the strips typically are tightly fitted into recesses in the housings. The prior art does not provide desirably efficient and economical mechanism for this purpose. 
     The present invention is directed to overcoming one or more of the problems discussed above. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the present invention, apparatus for cutting transverse strips from an elongated card and for sorting defective strips from non-defective strips includes a die member having a shear zone defining edge across which successive transverse portions of the card may be traveled. A reciprocatable shear blade is adjacent to the die member and has a cutting edge which is positioned to cut transverse strips from the card at the shear zone defining edge in a sequential manner. A strip transporting carrier is supported for movement between a first location at which a front end of the carrier abuts the die member in position to receive and support strips which are cut from the card, a second location at which non-defective strips are removable from the carrier and a third location at which defective strips are released from the carrier. 
     In another aspect of the invention, apparatus for cutting transverse strips from an elongated card and for sorting defective strips from non-defective strips includes a die member having a horizontal slot into which successive transverse portions of the card may be traveled, the slot forming a shear zone defining edge. A shear blade is disposed against the die member and has a cutting edge positioned to cut transverse strips from the card at the shear zone defining edge as the blade is reciprocated in a vertical direction. The shear blade has an inclined surface which extends upward from the cutting edge and outward from the die member. A strip transporting carrier has a platen for supporting newly cut strips, the carrier being movable along a horizontal strip travel path which extends away from the shear zone defining edge of the die member. The carrier is movable from a first location at which a front end of the carrier is against the die member in position to receive and support a newly cut strip to a second location at which nondefective strips are removed from the carrier and is further movable to a third location at which defective strips are released from the carrier. The front end of the carrier is formed by a plurality of strip supports which are retractable into the platen portion of the carrier. The strip supports are urged into the platen by the inclined surface of the shear blade as the blade travels downward during a cutting operation. This moves the newly cut strip onto the platen. 
     The invention provides for economical and efficient sorting of defective diagnostic strips from non-defective strips after cutting of the strips from elongated cards which may include cards having defective areas. The strips are cut from the card in a sequential manner by a reciprocating shear blade. Each newly cut strip is received by a strip transporting carrier. The carrier moves non-defective strips to a first location at which they are picked off of the carrier for transfer to a housing or other processing. If the strip is a defective one continued motion of the carrier takes the strip to another location at which it is released into a waste receptacle. Structural features of the preferred form of the invention provide for precise positioning of the cut strips on the carrier at the pick up location thereby enabling precise registration of the strips with housings into which they are tightly fitted. 
    
    
     The invention, together with further objects and advantages thereof, may be further understood by reference to the following Detailed Description of the Invention and by reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of diagnostic strip cutting and sorting apparatus embodying the invention, certain components being shown in schematic form. 
     FIG. 2 is a top view of the apparatus of FIG.  1 . 
     FIG. 3 is a longitudinal section view of a portion of the apparatus of the preceding figures taken along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a cross section view of a portion of the apparatus of the preceding figures taken along line  4 — 4  of FIG.  2  and showing strip cutting components of the apparatus. 
     FIG. 5 is a top view of a strip transporting carrier component of the apparatus taken along line  5 — 5  of FIG.  3 . 
     FIG. 6 is a front elevation view of a portion of the strip transporting carrier taken along line  6 — 6  of FIG.  5 . 
     FIG. 7 is an elevation section view of a portion of the strip transporting carrier taken along line  7 — 7  of FIG.  5 . 
     FIG. 8 is a side elevation view of the strip cutting and sorting apparatus including suitable mechanism for removing cut strips from the apparatus. 
     FIG. 9 is a longitudinal section view of a portion of the apparatus corresponding generally to FIG. 3 except that the strip transporting carrier is shown shifted to a cut strip receiving position. 
     FIG. 10 is another longitudinal section view of a portion of the apparatus corresponding generally to FIG. 3 except that the strip transporting carrier is shown shifted to a reject strip discarding position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1 of the drawings, strip cutting and sorting apparatus  11  embodying the invention is designed to cut transverse strips  12  from elongated rectangular cards  13  in a sequential manner. The cards  13  may be of the known diagnostic form which are coated with reagents that change color upon exposure to specific substances in biological fluids. The reagents are typically contained in laminated ribbons  14  of thin tissue like material that extend along opposite boundary regions of one surface of a backing material  16 . The apparatus  11  may also be used to cut transverse strips from other types of card. 
     Cards  13  may on occasion exhibit visible defective areas  17  which can arise during manufacture or from exposure of the card to foreign substances. Strips containing such areas  17  or portions of such areas may not function properly and should not be present in the finished product. Cutting and sorting apparatus  11  enables efficient sorting of defective strips  12   a  from the nondefective strips  12 . 
     Each card  13  is fed end wise into a cutter unit  18  which cuts the strips  12 ,  12   a  from the card in a sequential manner. A movable strip transporting carrier  19  separately carries each newly cut nondefective strip  12  from a first location  21  at which the cutting operation takes place to a second location  22  at which the strip is picked off of the carrier by pickup mechanism  101  which will hereinafter be described. Defective strips  12   a  are carried further by the carrier  19  to a third location  23  at which the strip is released from the carrier into a waste receptacle  24 . 
     In this example of the invention, pickup mechanism  101  emplaces each non-defective strip  12  in one of a series of flat plastic housings  15  which are brought to a housing loading location  25  by a conveyer belt  108 . The housings  15  are subsequently provided with covers  25  to form test kits such as pregancy test kits, for example. The kits may be of the known form in which covers  25  have openings through which fluid may be admitted and for observing the central region of the strips. The strip  12  is emplaced in a recess  20  within housing  15  that has a rectangular configuration conforming with the outline of the strip. The strip  12  fits tightly into the recess  20  in order to prevent it from shifting position. This requires that the strip  12  be in precise register with recess  20  as it is being entered into the recess. That in turn requires that the strip  12  be precisely positioned and oriented at the pickup location  22 . 
     Referring jointly to FIGS. 2 and 3, the cutter unit  18  of this particular example of the invention includes a vertically extending rectangular die member  26  and a reciprocating rectangular shear blade  27  disposed against the back surface of the die member in parallel relation ship with the die member. Track members  28  of right angled cross section extend from each side of die member  26  and along edge regions of the back of shear blade  27  to hold the blade against the die member. Referring to FIGS. 1 and 2, die member  26  is supported by a downward extending portion  29  of the framing of the apparatus  11  which also supports an electrical servomotor  31 . Servomotor  31  turns a crank wheel  32  within framing portion  29  through a speed reducing gearbox  33 . The lower end of a crank arm  34  is pivoted to wheel  32 , at an off center location on the wheel, by a pivot pin  36 . The upper, end of crank arm  34  is coupled to shear blade  27  through another pivot pin  37 . Thus operation of servomotor  31  causes vertical reciprocation of shear blade  27  relative to die member  26 . 
     Referring to FIGS. 3 and 4 in conjunction, the shear zone at which successive strips are cut from the cards  13  is defined by the lower edge of a horizontal slot  38  in die member  26  into which the cards are fed. The upper edge  39  of a trapezoidal opening  41  in shear blade  27  is a cutting edge of the blade and is sloped so that each cutting of a strip proceeds progressively along a transverse cut line on the card. The shear blade  27  has a surface  42  immediately above the cutting edge  39  which is inclined to extend outward from die member  26 . The inclined surface  42  urges cut portions of the strip outward from the die member  26  as cutting of the strip progresses in a manner which will hereinafter be further described. Three spaced apart vertical grooves  43  in the back surface of shear blade  27  extend upward from the inclined surface  42  to enable entry of strip transporting components into the blade as will also hereinafter be further described. 
     The die member  26 , including slot  38 , and shear blade  27  of this example of the apparatus are considerably broader than the particular cards  13  which are being cut. This facilitates adaptation of the apparatus for cutting cards of different widths. 
     Referring jointly to FIGS. 3 and 5, the strip transporting carrier  19  of this example of the invention has a platen  44  which is traveled towards the strip cutter  18  and away from the strip cutter along a strip travel path  46  which extends horizontally from the shear zone  38  at die member  26 . The platen  44  rides on a pair of spaced apart rails  48  which are engaged by sliding shoes  49  at the underside of the platen. Rails  48  are secured to a horizontal portion  51  of the framing of the apparatus  11 . 
     Referring jointly to FIGS. 3,  5  and  6 , parallel thin slots  52  in platen  44  extend from the front end  53  of the platen  44  to a location near the back end of the platen. Platen  44  is formed to have raised ribs  54  which extend along each side of the top of each slot  52  and which also extend outward towards die member  26  at the front of the platen. Another raised rib  56  extends along the top of the platen  44  at a location which is midway between the pairs of ribs  54 . Newly cut strips  12  which are being traveled by the carrier  19  rest on the ribs  54  and  56 . 
     A pivot arm  57  extending along each slot  52  has an upwardly directed strip containment finger  58  at its front end, the finger being immediately in front of the ribs  54  which bound the slot. Arms  57  are coupled to the platen  44  by a pivot axle  59  which extends transversely within the platen thereby enabling fingers  58  to be moved in a vertical direction by pivoting of the arms. A cross link rod  61  extends between the arms  57  at a location forward from pivot axle  59  to enable joint raising and lowering of the fingers  58  by a single actuator  62  of the type having an extensible and retractable rod  63 . Actuator  62 , which may be any of the pneumatic, hydraulic or electrical type, is pivoted to a bracket  64  which extends down from platen  44  and the extensible and retractable rod  63  engages cross link rod  61 . As best seen in FIG. 6, fingers  58  are proportioned to be flush with the tops of ribs  54  and  56  when in the lowered position and to extend above the ribs when in the raised position. 
     In conjunction with other structure to be described, fingers  58  assure that a newly cut strip is precisely positioned on the platen  44  in a transverse orientation and remains at that position during travel towards the strip pickup location  22 . As may be seen in FIG. 9, the fingers  58  are within the shear blade  27  when cutting of a new strip begins. The fingers  58  are in the lowered position and are within shear blade opening  41  at that time. The previously described vertical grooves  43  in the shear blade  27  allow fingers  58  to remain in the blade as the blade descends and the cutting operation continues. Descent of the inclined surface  42  of the blade  27  moves the newly cut strip out of the blade and on to platen  44 . Fingers  58  are then raised to contact the adjacent edge of the newly cut strip and thereby maintain it in a transverse orientation as it is traveled away from the blade by the carrier  19 . 
     In the absence of preventive measures, the shear blade  27  would tend to wedge strips downward between fingers  58  and die member  26  as cutting of the strip progresses. This is avoided by a series of spaced apart retractable strip supports  66  at the front end  67  of carrier  19 , there being four such strip supports in this example of the invention. Referring jointly to FIGS. 3,  5  and  7 , the strip supports  66  extend outward from platen  44  except when cutting of a strip is progress. During a cutting operation, the descending inclined surface  42  of the shear blade  27  forces the strip supports  66  into notches  68  in platen  44 . This moves newly cut portions of the strip on to platen  44  without the wedging effect discussed above. 
     The strip supports  66  are retractable as the supports have stems  69  which extend into openings  71  in the front of platen  44 . Compression springs  72  in openings  71  act against steps  73  on the stems  69  to urge the supports in an outward direction. Stops  74  at the inner ends of the stems  69  limit the outward movement. 
     Movement of the strip transporting carrier  19  can be effected with a motor or actuator of any various kinds. In this example, with reference to FIG. 1, an arm  76  extends downward from the carrier  19  to an internally threaded sleeve  77 . Sleeve  77  engages on a horizontally extending lead screw  78  which is turned by an electrical servomotor  79  to travel the carrier  19  between the above described locations of the carrier. 
     Referring jointly to. FIGS. 2 and 9, precise positioning of each strip  12  on the carrier  19  is further provided for by a top containment plate  81  which extends horizontally between the cutting unit  18  and the strip pickup location  22 . Spacing of the bottom surface of top containment plate  81  from the top of carrier  19  is just slightly greater than the thickness of the strips  12 . Longitudinal grooves  82  in the bottom surface of top containment plate  81  are entered by the tops of the strip containment fingers  58  of carrier  19  when the fingers are in the raised position. 
     Movement of strips  12  at right angles to the direction of travel is blocked by strip end guides  83  and  84  which extend along opposite sides of the strip travel path. End guides  83  and  84  extend down from top containment plate  81  to a level which is slightly below the level of the tops the platen ribs  54  on which the strips rest. End guide  83  is a fixed end guide fastened directly to the top containment plate  81 . The other end guide  84  is a retractable end guide which is movable towards the fixed end guide  83  and away from the fixed end guide within a small range of travel in order to accommodate to slight variations in the length of strips  12 . Retractable end guide  84  has a tab  86  which extends up to a location which adjacent to a spring housing  87  situated at the top of containment plate  81 , and is secured to a horizontal rod  88  which extends into the housing at right angles to the path of travel of carrier  19 . A spring  89  within housing  87  urges rod  88  and thus retractable end guide  84  in the direction of the fixed end guide  83 . The retractable end guide  84  is positioned to be urge slightly away from the fixed end guide  83  by strips  12  entering the region between the end guides and thus exerts a light pressure against the strip which acts to hold the other end of the strip in abutment against the fixed end guide  83 . This assures precise positioning of the ends of strips  12  on carrier  19 . 
     Referring to FIGS. 2 and 3 in conjunction, positioning of nondefective strips  12  at the pickup location  22  is completed by transversely extending front edges of a pair of spaced apart registration guides  91  which are components of a lift gate assembly  92 . Assembly  92  has a vertically oriented rectangular fixed frame  93 , secured to the previously described framing portion  51  of the apparatus, which extends around the path of travel of carrier  19 . A lift gate  94  which is also a vertically oriented rectangular frame, is disposed against fixed frame  93 . The lift gate  94  has vertically extending rails  96  of angled cross section which are entered into conforming grooves  97  in the fixed frame  93 . This enables vertical movement of the lift gate  94  relative to the fixed frame  93  and relative to the strip transporting carrier  19 . Referring to FIG. 1, vertical movement of the lift gate  94  is effected by another actuator or cylinder  98  of the form having an extensible and retractable rod  99  and which may be of the pneumatic, hydraulic or electrical type. 
     Referring again to FIGS. 2 and 3, registration guides  91  are integral portions of the lift gate  94  that extend down to carrier ribs  54  when the gate is at the lowered position. The lowered guides  91  are abutted by nondefective strips  12  as the strips arrive at the pickup location  22  along the strip travel path. Referring to FIG. 8, nondefective strips  12  are lifted away from the pickup location  22  by the pickup mechanism  101 . In this example of the invention the pickup mechanism  101  has a pair of vertically oriented suction tubes  102  which extend downward from a vacuum housing  103 . Housing  103  and tubes  102  are movable in a vertical direction to bring the bottom ends of the tubes  102  into contact with nondefective strips  12  which have arrived at the pickup location  22 . A flexible conduit  106  is connected between housing  103  and a vacuum source  107  through a valve  104 . Valve  104  is opened when the tubes  102  arrive at the pickup location  22  to create suction which causes the strip  12  to cling to the bottoms of the tubes  102 . Housing  103  and tubes  102  are then traveled upward and then horizontally and then downward to emplace the strip  12  in a housing  15  in the previously described manner. The housings  15  are brought to the loading position  25  by conveyor belt  108  which is driven by another servomotor  110 . Closure of valve  104  at that time releases the strip  12  from the suction tubes  102 . 
     The pickup mechanism  101  includes a horizontal rail  109  which extends in the direction of travel of housing  103  and a support block  111  is slidable along the rail. Housing  103  is secured to an arm  112  which extends in parallel relationship with rail  109  below the rail. Spaced apart vertical rods  113  extend up from arm  112  through vertical passages  114  in block  111 . The above described vertical motion of housing  103  and suction tubes  102  is effected by another extensible and contractible actuator  116  connected between arm  112  and slidable block  111 . The block  111  is traveled along rail  109  to provide the horizontal movement by a leadscrew  117  driven by another servomotor  118 . 
     Referring jointly to FIGS. 1 and 2, cards  13  which are to be cut into strips  12  are fed into the cutter unit  18  along a card guide  119  having a floor  121  and upward extending side walls  122 . In this example a ram member  123  abuts the end of the card  13  within guide  119  and is traveled along the guide to force the card into the cutter unit  18 . Ram member  123  is traveled by another lead screw  124  driven by another servomotor  126 . The card  13  is preferably traveled in a stepped manner with each increment of movement having a length equal to the desired width of the strips  12 . Servomotor  126  is preferably of the programable type to enable selective changing of the length of the stepping movements of ram member  123  in order to change the width of the strips  12  which are being produced. 
     The herein described operations of the servomotors  31 ,  79 ,  110 ,  118  and  126 , valve  104  and actuators  62 ,  98  and  116  can be preprogrammed and sequenced by automatic controls if desired. 
     Incipient entry of a defective area  17  of a card  13  into cutter unit  18  can be detected by an optical sensor  127  situated above guide  119  at the entrance to the cutter unit. A lamp  128  illuminates the region of the card  13  that is passing under sensor  127 . When an optical sensor  127  is used, the cards  13  are preferably manually inspected prior to being fed into the cutting and sorting apparatus  11  and defective areas  17  are emphasized by marks  129  made with a marking pen or the like, the markings being black or of some other color that contrasts with the color of the card. 
     Upon entry of a defective area  17  into the cutter unit  18 , with reference jointly to FIGS. 1 and 10, actuator  98  is operated to shift lift gate  94  including registration guide  91  to the raised position. Preferably, the next cutting operation at the cutter unit  18  is then delayed until the entire defective area  17  has passed through die member  26 . The strip transport carrier  19  is then traveled beyond the pickup location  22  to the third location  23  as depicted in FIG.  10 . This locates the defective portion  12   a  of the card, which is being transported by carrier  19 , beyond the registration guide  91 . Referring again to FIGS. 1 and 10, the lift gate  94  including registration guide  91  is then lowered by operation of actuator  98  to reposition the registration guide against ribs  54  of the carrier  19 . Strip containment fingers  58  are lowered by operation of actuator  62 . Servomotor  79  is then operated to return the carrier  19  to cutter unit  18  in preparation for receipt of another strip. 
     During the return motion of the carrier  19  the defective portion  12   a  of the card is scraped off of the back end of the carrier by the back surface of the lowered registration guide  91 . A chute  131  extends outward and downward from the back of carrier  19  to guide the rejected portion  12   a  of the card into waste receptacle  24 . 
     While the invention has been described with reference to a single preferred embodiment for purposes of example many modifications and variations are possible and it is not intended to limit the invention except as defined in the following claims.