Abstract:
A Collapsible Rotary Blister Sealer with Improved Heating Plate Assembly is disclosed. The disclosed blister sealer comprises a lightweight, tubular frame, detachable legs and a lightweight, modular turntable. Further disclosed is a sealer that is mountable on a table-top or other horizontal surface. Said disclosed turntable is height-adjustable; easily removable, and further includes an indexing means for stopping said turntable at predetermined angular positions. The disclosed press of the present blister sealer may be height- and pressure-adjustable, and said frame may further include a strut to further strengthen said frame when greater pressures are desired from said press. It is further disclosed that said sealer include a unique heater plate assembly that permits easy access to the heating coils and further may include a protective sheath to prevent damage to said heater plate assembly. Still further disclosed is a protective guard to protect the user from the heater plate assembly by a guard comprising a metal top and three plastic side panels that are easily replaceable. In a further embodiment of the present invention, a rotary collapsible blister sealer that can seal clamshell packages around items is also disclosed.

Description:
This application is a continuation-in-part of application Ser. No. 08/746,298, filed Nov. 8, 1996; U.S. Pat. No. 5,997,688. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to blister sealers and, more specifically, to a Collapsible Rotary Blister Sealer with Improved Heating Plate Assembly. 
     2. Description of Related Art 
     Blister packaging has become one of the most prevalent means for packaging small- to medium-sized items for retail sale. A blister package comprises a backing card, many times made from cardboard, with designs or other information labeled thereon; a clear plastic “blister” is then sealed (over the retail item) to the backing card. These blister packages are extremely convenient and cost-effective and are particularly well-suited for hanging from the backing card. These backing cards may also be made from plastic, with a paper or cardboard insert placed in the blister with the retail item. 
     Prior blister sealers are adequate for the sealing task. They generally comprise at least one nesting tray on which the blisters are staged facing back-side up (i.e. the inside of the blister is up). The retail items are then placed on top of the blister (i.e. inside of it), with the face-down backing card then being laid atop the blister. The nesting tray is then placed under a heated plate; the heated plate is pressed down upon the back of the backing card for the requisite amount of time, which causes the blister to bond to the backing card, usually by melting a special bonding agent previously applied to either the backing card or the blister. 
     These prior blister sealers are generally very large machines that have more than one work station, typically arranged about a rotatable turntable, such that one set of parts can be staged by one employee coincident with the sealing of another set of parts by another employee. The problem with these large machines is that they are not a feasible purchase for a business having medium- to low-volume packaging needs. For one thing, they are prohibitively expensive; they are also so big that they consume excessive shop space. Furthermore, they are extremely difficult to ship, move or relocate. What is needed is a compact, lightweight blister sealer that can handle low- to medium-work flow. Also, if the unit had detachable legs, such that the unit could not only be easily shipped, but also placed on an existing table-top, the unit would be even more beneficial. 
     Another difficulty with the prior blister sealers is the design of the turntable. The typical prior turntable is a solid circular board or sheet with apertures cut therein for receiving the nesting trays. When it is necessary to conduct periodic maintenance or repairs, it is extremely difficult to remove these turntables, because of their extreme weight and size, as well as the fact that they are not designed to be easily removed. What is needed is a rotary blister sealer that includes a light-weight, quickly-detachable turntable, to facilitate maintenance on the unit. If the turntable was also collapsible, it would be of farther benefit, particularly if the unit was to be shipped to another location. 
     Another important part of the blister sealer is the heating plate assembly. The typical prior heating plate assembly comprises a solid metal block, through which passages are drilled. Electric heating coils are then inserted into the passages; when the coils are heated, the block will heat by conduction. One problem with this prior design relates to the need for maintenance on the heater; if a coil fails, many times the entire heating block must be discarded or sent out for repair. If the heating plate assembly included provisions for easy access to the heating coils in the event of coil failure, the user could easily complete repairs without the need to send the heater out for special help. 
     A further problem with the prior heating plate assembly is that of wear to the face of the heating plate. It is fairly common that the face of the heating plate becomes fouled or otherwise damaged through prolonged use. The prior heating plate assembly must be completely replaced in such an event, creating excessive delays and expense. If there were some sort of shield over the face of the heating plate that could be easily and cheaply replaced when it became worn or damaged, there would be no need to dismantle the entire heating plate assembly for repairs; this would be very helpful. 
     Another drawback of the prior blister sealers relates to control of the turntable positioning. The typical prior (manual) blister sealer doesn&#39;t have any sort of stopping or indexing system for stopping the turntable when a freshly loaded nesting tray is in position for pressing. As a result, misalignments and/or delays may occur while proper positioning is achieved. If the turntable included a series of stops, such that it simply needs to be rotated until a stop is encountered in order to be in correct alignment with the press, it would greatly facilitate the blister sealing process. 
     The blister sealing process and equipment is closely related to another process, known as “clamshell packaging”. The clamshell package is plastic on the front and back side of the packaged item. The conventional manufacturing process creating the clamshell package involves gluing or sealing the edges of the two plastic halves to one another. The conventional clamshell packaging equipment suffers from the same defects as the conventional blister sealing equipment, namely, its extreme bulkiness and high cost. What is needed is a low-cost, collapsible, rotary blister sealer for creating clamshell packages. 
     SUMMARY OF THE INVENTION 
     In light of the aforementioned problems associated with the prior devices, it is an object of the present invention to provide a Collapsible Rotary Blister Sealer with Improved Heating Plate Assembly. The blister sealer comprises a lightweight, tubular frame, detachable legs and a lightweight, modular turntable. It is a further object that the blister sealer be mountable on a table-top or other horizontal surface. Said turntable should be height-adjustable; easily removable, and further inched an indexing means for stopping said turntable at predetermined angular positions. The press of the present blister sealer should be height- and pressure-adjustable, and said frame may further include a strut to further strengthen said frame when greater pressures are desired from said press. It is a further object that said sealer include a unique heater plate assembly that permits easy access to the heating coils and further may include a protective sheath to prevent damage to said heater plate assembly. It is a still further object that the user be protected from the heater plate assembly by a guard comprising a metal top and three plastic side panels that are easily replaceable. It is a further object that the present invention provide a rotary collapsible blister sealer that can seal clamshell packages around items. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which: 
     FIG. 1 is a perspective view of a preferred embodiment of the present invention; 
     FIG. 2 is a perspective view of the embodiment of FIG. 1 showing the Frame and Legs; 
     FIG. 3 is a cutaway side view of the Frame of the embodiment of FIG. 1; 
     FIG. 4 is a top view of a preferred Turntable of the present invention; 
     FIG. 5 is an exploded perspective view the structural layers of a preferred Heating Plate Assembly of the present invention; 
     FIG. 6 is a partial cutaway of the Heating Plate Assembly of FIG. 4; 
     FIG. 7 is an exploded perspective view of a preferred Indexing Means of the present invention; 
     FIG. 8 is a block diagram of a preferred Control Circuit of the present invention; 
     FIG. 9 is a partial perspective view of another preferred embodiment of the present invention wherein clamshell packages may be formed; and 
     FIG. 10 is a partial perspective view of an alternate embodiment of the blister packaging device of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a Collapsible Rotary Blister Sealer with Improved Heating Plate Assembly. 
     The present invention can best be understood by initial consideration of FIG.  1 . FIG. 1 is a perspective view of a preferred embodiment of the rotary blister sealer  10  of the present invention. As can be seen, the rotary blister sealer  10  comprises a frame  12  which is supported by legs  14 . In a preferred form, the frame  12  and legs  14  are made from rectangular and/or circular tubing, such as from steel, aluminum or other strong, lightweight material; other cross-sections may be used, depending upon the application involved. The legs  14  may be quickly detached from the frame  12  if it desirable to place the sealer  10  on a raised horizontal surface, or for shipping or moving, for example. 
     Also shown in FIG. 1 is a preferred turntable  16 . Ideally, the turntable  16  will be lightweight, such as from aluminum or other type of tubing. Furthermore, the preferred turntable  16  will be removable and be constructed in a modular manner, such that it may be dismantled or collapsed when desired. A strut  18  is shown in FIG. 1 protruding upwardly through the turntable  16  and to the upper portion of the frame  12 . This strut  18  is an optional element that may be desired for further rigidity to the sealer  10 , particularly where greater pressing forces are used in the sealing process. As might be appreciated, the turntable  16  is easier to remove from a sealer  10  that does not include the strut  18 , and therefore both embodiments are disclosed. Further detail regarding each structure is provided below in connection with the other drawings and the Provisional Application Ser. No. 60/006,356, filed Nov. 8, 1996, incorporated herein by reference. 
     If we turn now to FIG. 2, we might gain a better understanding of the frame  12  and legs  14 . FIG. 2 is a perspective view of the embodiment of FIG. 1 showing only the frame  12 , legs  14  and strut  18 . As can be seen, the frame  12  comprises a base portion  20 , a back portion  22 , and a top portion  24 . In this example, the base portion  20  is constructed substantially from tubing of a rectangular cross-section, however other shapes may be used, depending upon the application. The back portion  22  and the top portion  24  comprise tubing of a circular cross-section, such as from steel or other metal; again, other strong, lightweight materials and cross-sections may be used. 
     The base portion  20  further comprises a center brace  26 , a medial brace  28  and a outer brace  30 . The function of the center brace  26  is to strengthen the base portion  20  in the area of the turntable (see FIG.  1 ). The medial brace  28  may include a guide (not shown) on its top surface, upon which the turntable (see FIG. 1) may rest. The guide (not shown) may be made from some sort of plastic or other material that will permit the turntable (see FIG. 2) to slide over it without wearing either the turntable (see FIG. 1) or the medial brace  28 . The outer brace  30  is very similar to the medial brace  28 , but is positioned at or near a location that corresponds to the periphery of the turntable (see FIG.  1 ). The outer brace  30  may also include a guide upon which the turntable (see FIG. 1) may rest and slide. The center brace  26 , medial brace  28  and outer brace  30  are preferably made from a lightweight, strong material and are rigidly attached to the frame  12  by a conventional means that may or may not permit removal of each piece when collapsing the sealer (see FIG.  1 ). 
     The top portion  24  may include a top brace  32 , which is configured to support the press assembly (see FIG. 3) and to provide further rigidity to the frame  12 . The top brace  32  is rigidly attached to the top portion  24  by a conventional means, such as welding or bolting, that also may or may not permit its removal in order to collapse the sealer (see FIG.  1 ). 
     Each leg  14  is preferably removeably attached to the frame  12 , such as by insertion into a leg receiver  34 . Each leg receiver  34  might include a set screw (not shown) which can be tightened onto a leg  14 , to retain the leg  14  once it is inserted into the leg receiver  34 . In this manner, the legs  14  can be removed simply by first removing the set screws (not shown) and then sliding the legs  14  out of the leg receivers  34 . 
     In order to understand the cooperation of the press  36  and turntable  16 , one should now consider FIG.  3 . FIG. 3 is a cutaway side view of the Frame  12  of the embodiment of FIG.  1 . As described above, the press  36  is preferably attached to the top brace (see FIG.  2 ), and further includes a shaft  38  that is extended and retracted by the press  36 . The press  36  may be operated to extend and retract the shaft  38  by electrical, pneumatic, hydraulic, magnetic or other means well known in the art. 
     Attached to the distal end of the shaft  38  is the heating plate assembly  40 . Further detail regarding the heating plate assembly  40  may be found below in connection with the discussion under FIGS. 5 and 6. As may be appreciated, therefore, when the shaft  38  is extended, the heating plate assembly  40  is biased towards the turntable  16 , where backing cards and blisters to be sealed would rest. As also can be seen, the medial brace  28  and outer brace  30 , and their respective guides (not shown) are aligned such that they straddle the width of the heating plate assembly  40  when the heating plate assembly  40  is lowered onto the turntable  16 . The present invention may also permit the stroke of the shaft  38  and/or the height of the heating plate assembly  40  to be adjusted by the user to allow for different nesting tray and packaging configurations. 
     In its preferred form, the heating plate assembly  40  is surrounded on its sides by a guard  42 . This guard  42  may be in a variety of styles, with a preferred form including a sheet metal top with three strips of shatter-resistant plastic surrounding it on the three exposed sides. This design is particularly efficient, because it permits the easy and cheap replacement of individual plastic strips (rather than the entire guard  42 ) in the event that the guard  42  is damaged in some way. 
     Also shown in FIG. 3 is an indexing means  44 . The indexing means  44  provides a positive stop to the rotation of the turntable  16  when a nesting tray (see FIG. 4) is aligned properly for pressing/heating. The indexing means  44  may allow for some adjustment of the angular position of each stop, to allow for operator adjustment for special nesting trays (see FIG.  4 ), for example. Further detail regarding the indexing means  44  may be found below in connection with the discussion under FIG.  7 . 
     FIG. 4 provides additional detail regarding the preferred turntable  16 . FIG. 4 is a top view of a preferred turntable  16  of the present invention. In the center of the turntable  16  is a block  46 , preferably from a light-weight, strong material, such as steel. In the center of the block  46  is a center aperture  48 , through which the strut (see FIGS. 1,  2  and  3 ) may pass, if so equipped. If no strut is included in the particular embodiment, the center aperture  48  may be excluded. Centered on the block  46  and extending away therefrom may be a pair of mounting bars  50 , for rigidly attaching the turntable  16  to the block  46 . 
     Attached to the mounting bars  50 , and surrounding the block  46  is the center panel frame  52 , which is the base structure to which the nesting tray receiver members  54  attach. Each nesting tray receiving member  54  may be configured to be removable from the center panel frame  52 , thereby making the turntable  16  collapsible; one preferred means of attachment is by conventional bolts, etc. A preferred material of construction for the center panel frame  52  and the nesting tray receiving members  54  is rectangular tube, such as from steel or other lightweight, strong material. The aperture formed by the cooperation of each nesting tray receiving member  54  and the center panel frame  52  is ideally formed to receive a nesting tray  56 . These nesting trays  56  are old in the art and comprise a flat sheet with apertures therethrough to receive a specific shape of blister. Each aperture may also have some sort of gasket surrounding it to assist in the sealing process, and the sheet may also include some alignment pegs to align the backing cards with the blisters. 
     In its preferred form, adjacent nesting tray receiver members  54  are connected to one another by an handle  58 . The preferred handles  58  comprise a smooth, lightweight material, such as tubing, bolted to the nesting tray receiving members  60 , such that they are also removable. These handles  58  assist an operator in turning the turntable  16  to advance the nesting trays  56  to the next set of items to be sealed. 
     In the center of the turntable  16 , a center panel  60  may cover the open area in the center of the center panel frame  52 . The center panel  60  provides a flat surface upon which operators may stage parts for sealing, such as backing cards, blisters, and the retail items. If a strut (see FIGS. 1,  2  and  3 ) is included, the center panel  60  will include an aperture (not shown), corresponding to the center aperture  48 , through which the strut may pass. If no strut is included, the center panel  60  surface is undisturbed for part staging. 
     FIG. 5 presents another unique aspect of the present invention. FIG. 5 is an exploded perspective view the structural layers of a preferred heating plate assembly  40  of the present invention. As can be seen, a base plate  62 , preferably made from aluminum, is attached to the distal end of the shaft (see FIG.  3 ). Below the base plate  62  may be a reflective layer  64 , for reflecting heat energy away from the base plate  62 . The reflective layer  64  may or may not be included in all embodiments, depending upon the particular application involved. 
     Below the reflective layer  64  is an insulating layer  66 . The material comprising the insulating layer  66  may be any of several conventional insulating materials. Below the insulating layer  66  is the outer plate  68 . The outer plate  68  is preferably very similar to the base plate  62 . All of the aforementioned layers are pressed and held together, such as by bolts. In one preferred form, a shield  70  may be attached to the heating plate assembly  40  to cover the outer plate  68 . The shield  70  may be a thin metallic layer that is heat-resistant and possibly even including a coating, such as a non-stick material, on its outer surface. The role of this shield  70  is to protect the outer plate  68  from damage which may result through prolonged use of the heating plate assembly  40 . The shield  70  is designed to be easily removable and replaceable for periodic or corrective maintenance. 
     FIG. 6 gives indicates how the improved heating plate assembly  40  appears when it is assembled. FIG. 6 is a partial cutaway of the heating plate assembly  40  of FIG.  4 . As can be seen, heating coils  72  are pressed between the insulating layer  66  and the outer plate  68 . When connected to an electrical power source, the heating coils  72  will heat up and subsequently cause the outer plate  68  (and shield  70 , as appropriate) to heat up by conduction. Since the heating coils  72  are not embedded within the outer plate  68 , if any of the coils fail they can be easily repaired or replaced by removing the outer plate  68  (and shield  70 , as appropriate). 
     Another unique aspect of the present invention may be appreciated by consideration of FIG.  7 . FIG. 7 is an exploded perspective view of a preferred indexing means  44  of the present invention. In one form, the indexing means  44  comprises an index disc  74 , which is attached to the underside of the turntable (see FIGS. 1,  2  and  3 ) at the block (see FIG. 4) via the apertures  76 . The index disc  74  may be made from a variety of materials, including high-density plastic, and includes a plurality of depressions  78  formed around its circumference. The index disc  74  is permitted to rotate on the spindle  80  which passes through its center and is attached to the center brace (see FIG.  2 ). The spindle  80  and/or index disc  74  may be adjustable in the direction  82 , such that the height of the turntable (see FIGS. 1,  2  and  3 ) will also be adjustable. 
     Cooperating with the indexing disc  74  is a roller cam  84 , that is also slidingly mounted to the frame or center brace (see FIG.  2 ), such that the roller cam  84  may travel towards and away from the center of the index disc  74 . A biasing means  86 , such as a conventional spring, biases the roller cam  84  towards the index disc  74 . In operation, therefore, the roller cam  84  travels over the index disc  74  as the index disc  74  is rotated on spindle  80 . When the roller cam  84  encounters a depression  78 , it will be biased into it, thereby causing a positive stop on the index disc  74  and, consequently, the turntable (see FIGS. 1,  2  and  3 ). One need merely to exert slightly more angular force on the turntable (see FIGS. 1,  2  and  3 ) to overcome the force of the biasing means  86  and force the roller cam  84  out of the depression  78 . Either the alignment of the index disc  74  and/or the positioning of the roller cam  84  may be adjustable by the user in order to change the angular location of each stop, if desired. 
     Now turning to FIG. 8, one might better understand the preferred control circuit  88  of the present invention. As shown, the heating coils  72  are connected in series with a 120 VAC power source  90 , an adjustable thermostat  92 , and the main switch  94 . In this manner, the heating coils may be activated by closing the main switch  94 . 
     The press (see FIG. 3) is activated by a circuit comprising a timer  96  connected in series with a solenoid valve  98  and counter  100  that are connected to each other in parallel. The solenoid valve  98  is normally closed, and when opened, permits supply air to flow to the press (see FIG.  3 ), which causes the shaft (see FIG. 3) to be extended, causing the heating plate assembly (see FIG. 3) to travel downward. When this circuit is activated, the timer  96  will provide current to the solenoid valve  98  and counter  100  circuit for an adjustable time period, which corresponds to the “dwell time”, or the time that the user desires for the heating plate assembly (see FIG. 3) to be pressed against the items being sealed. The timer  96  is activated by a foot switch  102  that is connected in series to it and the power source  90  and main switch  94 . All a user needs to do, therefore, is depress the foot switch  102 ; when the dwell time expires, the press will retract, allowing the turntable (see FIGS. 1,  2  and  3 ) to be advanced to the next nesting tray of items to be sealed. Other control circuits  88  may be used, such as to include safety checks or other parameters and adjustments, including the ability to interface with presses (see FIG. 3) that operate on other than compressed air. 
     If we now turn to FIG. 9, we can examine yet another embodiment of the present invention. FIG. 9 is a partial perspective view of another preferred embodiment  104  of the present invention wherein clamshell packages may be sealed. In this embodiment  104 , the alternate nesting tray  57  comprises a plurality of sealing ridges  106  disposed around the surface. The sealing ridges  106  are configured to provide a metal edge upon which the articles to be sealed can be placed. When the conventional heating plate assembly  40  is then pressed onto the sealing ridges  106 , the upper plastic top of the package can actually be bonded to another piece of plastic or a plastic bottom. The result is what&#39;s known as a sealed clamshell package, or a plastic to plastic bond. The prior means for accomplishing this plastic to plastic bond was through RF sealing or UV activated glue, and where impulse sealers were used it was only for very thin materials. With the improved design  104 , conventional blister-type plastic materials can be sealed to one another quickly and cheaply. If we now turn to FIG. 10 we can examine another preferred embodiment of the present invention. 
     As indicated by FIG. 10, there are other possible embodiments for this clamshell sealing device. FIG. 10 is a partial perspective view of an alternate embodiment of the blister packaging device of FIG.  9 . FIG. 10 depicts an alternate improved clamshell packaging device  112  that embodies a part-time heating mechanism. As can be seen here, an alternate nesting tray  114  is defined by a plurality of sealing ridges  106 , however it further includes a plug assembly  108 . This plug assembly might be in a variety of designs in order to provide electricity to an external device placed in electrical contact with this plug assembly  108 . As can be seen, the alternate heating plate assembly  41  has a reciprocal receptacle assembly  110  for cooperating with the plug assembly  108  such that when the heating plate assembly  41  is pressed onto the alternate nesting tray  114 , electrical power is supplied to the alternate sealing ridges  107  which will result in their being heated. As can be appreciated, when the receptacle  110  loses contact with the plug assembly  108  (such as when the heating plate assembly  41  is lifted away from the nesting tray  114 ), the sealing ridges  107  will cool. This intermittent heating provides at least two benefits, one being safety aspect of not having a continuously heated device, and further the economic effect of only heating the ridge  107  when the heat is needed. As can be appreciated, since a fairly small surface area is involved when the sealing ridges  106  and  107  press one another, much less heat and pressure is needed in order to make the seal. As a result, thicker plastics can be used and need only be heated for a short time. 
     Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.