BACKGROUND OF THE INVENTION

This invention relates to covering open top containers such as paper and plastic cups used in the Quick Service Restaurant (QSR) and Beverage Industries. It has been the practice to cover these cups with a disposable pre-formed plastic lid in order to prevent spillage of the contents.

These plastic lids however, can leak if not properly placed or matched with an exact and specific cup size or fall off altogether if inadvertently disturbed. They are difficult to apply without touching the food contact surface of the lid and possibly contaminating it. When packaged in boxes, lids occupy a relatively large volume that can have significant cost impact on shipping, storage and handling. In order to function properly the plastic lid needs sufficient rigidity provided in part by the thickness of plastic material. The result can be plastic litter that lasts for a long time and negatively affect the environment. A number of solutions have been proposed to replace the problematic plastic lid. Most of these solutions fall into two general categories, both of which employ a thin, polymer film and require a source of continuous and constant heat in order to achieve a welded or shrink lid closure.

In the context of a restaurant, it is not possible to predict the timing and the number of cups that may require lidding. For example, this may vary from a single cup in two hours to twenty cups in five minutes. It can be appreciated that maintaining a constant temperature of, for example 375 degrees F, will be costly, deleterious to the environment, and difficult to achieve.

These technologies work well in an industrial setting where the continuous throughput of products can be controlled and thereby utilize the heat energy efficiently. One such category originated in the field of thermoplastically sealed polymer film covers on flat rimmed or flanged polymer containers such as yogurt cups, individual coffee creamers and packaged food trays. Examples of these solutions are described in U.S. Patents: 4 078 360; 4 771 935 and 5 039 001. Appropriately shaped lids, which may be polymer coated foil and the like, are pre-cut from a web at the sealing station. A heated platen under pressure softens the polymer of the lid and "welds" or fuses it to the flange of the polymer container. The thermoplastic seal created is an effective leak proof closure. The process however, is slow and requires special containers. Similar techniques are used to apply tamper-evident film barriers as described in U.S. Patent #5 182 896, however without providing a strong leak proof seal.

The other category of solutions relates to polymer shrink film covers for open top containers. Examples of these can be found in the following U.S. Patents: 3 703 066; 3 783 582; 3 838 805 and 4 184 310. Like the welded lid, the resultant shrink lid is more spill resistant, sanitary, using less plastic material and occupying less storage volume than the pre-formed plastic lid. However these devices and methods have also not replaced the pre-formed plastic lid. This is attributed to the problems associated primarily with their operation. The necessary film shrinkage is the result of the blowing hot air on the film. This requires equipment that by their nature are slow to respond, difficult to control, bulky, noisy and expensive to operate. This equipment is better suited for a continuous production line operation rather than the random cup lidding requirements of a restaurant.

Additionally, the need for a shrink lid for hot beverages has not been addressed. These lids need to withstand the shrink force from hot beverages such as coffee and tea and provided with access means other than a straw. Hot beverages are a large and growing portion of the QSR Industry.

U.S. Patent # 5 249 410 resolves some of these difficulties by providing a novel method of shrinking film without the use of hot air. This has resulted in devices that are faster, more responsive and operationally more stable than the prior art of both categories of solutions.

Despite these improvements, the primary user of pre-formed plastic lids, the QSR Industry, has not yet adopted the shrink lid product. Unresolved problems, such as the inability to suitably cover hot beverages persist. There are also additional new problems associated with the technology that shrinks film with the radiant energy of a halogen bulb. The invention described in the above patent and subsequent refinements is bulky, expensive, complex and wasteful of film and requires a level of maintenance expertise not possible in many QSR facilities.

Although the shrink lid of these devices provide some significant improvements over the pre-formed plastic lid, the plastic lid has the singular advantage of not requiring any equipment. The need for equipment has been a major stumbling block to the general adoption of the shrink lid system. To minimize the intrusive impact and gain acceptance of the equipment, it needs to be faster, simpler, smaller, less expensive to purchase and operate than the devices previously offered.

Although the term "sealed" has been commonly used in conjunction with shrink film lids of prior art, there is no actual heat sealing taking place in the sense of fusion of polymer to polymer. The temperature necessary to achieve a thermoplastic melting or softening sufficient to bond the polymer shrink lid to a polymer cup, or the waterproofing polymer coating of a paper cup, does not occur.

The "seal" of the shrink film lids of the prior art is a tight mechanical compressive engagement of the shrunken film wrapped around the rim of the cup. Although a leak proof union results, the maximum potential strength of this engagement can only be achieved by the additional thermoplastic fusion of the lid to a cup and thus able to withstand the effect of heat and steam generated by hot beverages or the distortion caused by dropping a filled cup.

The shrink lid equipment of prior devices have been designed with the assumption that there is a QSR Industry requirement to shrink lids on potentially all sizes of cup diameters using one standard width of shrink film web regardless of large or small cup diameters. This is not necessarily a valid assumption in the whole industry and leads to significant unnecessary extra cost for equipment and film.

In order to cover a large diameter cup, a relatively large piece of shrink film is required. In prior art devices this same size piece is also used to cover the smaller diameter cups. However, the large cups may typically represent less than 10% of a restaurant's business or none at all, and consequently all the smaller sizes, representing all or the majority of the cups, use more shrink film than necessary. In addition to the waste, the result can be an unattractive partially shrunk appendage of film around and below the cup rim.

Speed of service is a critical component in the very competitive QSR industry, the speed that an operating crew in a restaurant Drive-Thru can complete a customer order is measured in seconds. Restaurant operators are aware that potential customers will go elsewhere if the wait time to be served is long. The lidding machine operation must be at least as fast as and preferably faster than the current hand placement of pre-formed plastic lids. This requirement is not likely to be sacrificed by a QSR operator in order to gain the other benefits of the shrink film lid.

The overall size and especially the width of the lidding device is a critical consideration for the QSR operator. The optimum place for the device is adjacent to the cup filling station, typically on or part of a counter. These counters are already crowded with other machines and the work stations that are necessary to operate a QSR. The difference between a 12" wide and a 7" wide lidding device can be a factor in an acquisition decision.

The ease of reloading the equipment with a fresh roll of film is another consideration for the QSR operator. A machine that will likely be positioned closely adjacent to other appliances may need to be pulled completely forward in order to access a side loading opening for a new roll of film. A top loading machine can resolve this problem.

In the event of a radiant energy source such as a halogen bulb becoming defective, it is desirable that it can be identified and replaced quickly without the use of tools and without having to dismantle a portion of the lidding machine by a trained service person. Restaurant food handling regulations require machine components subject to food and beverage spillage be cleaned at least on a daily basis. It is essential that these

components are readily accessible for cleaning and sanitizing.

Some of the largest users of cups are the coffee shop style restaurants. Incidents of accidental hot drink spillage and injury due to failure of the pre-formed plastic lids are legendary. There is a need for a spill resistant lid such as the shrink lid, but one that can withstand the heat of the hot beverage and also be easily accessible for normal consumption of hot beverages.

SUMMARY OF THE INVENTION

The overall objective of the present invention is to provide an improved cup lid and lidding method that meets the needs and concerns of the QSR and Beverage Industries. In particular the invention offers a superior, hygienic cup lid product that has the strongest possible seal with the cup and can withstand rough handling and hot beverages, yet is still easy to access when required. The lid readily adapts to the variances inherent in paper disposable cups without negatively affecting its performance. The lid's appearance is attractive and substantially free of wrinkles.

Only as much film is used as is required to make a lid with no waste or losses.

The device of the invention minimally impacts the restaurant environment by being small, easily portable and requiring no special power supply. Routine maintenance, refilling and cleaning requires no special training or tools. There are a minimum number of moving components that could increase complexity and potential for breakdowns. Sufficient space inside the machine is allocated for the film supply roll to hold 5 000 equivalent lids. Reloading is easy, rapid and measured in seconds, not minutes.

An important element that enables some of the innovations of the present invention is the choice of a standard cup diameter for use with the lidding device. The most practical choice is the most commonly used cup size of 3 ½"diameter which is also the ancient, traditional size dictated by human ergonomics and the preferred diameter for the lid and cup standardizing activity of the QSR Industry. This activity seeks to reduce the multiplicity of cup and lid diameters to one diameter by accommodating the traditional cup volumes of large, medium and small with a corresponding variance in cup heights. As a result of this and other efficiencies to be described, a portion of film that is, for example 5" x 5" can be used to make a lid, rather than a 7" x 7" portion typically used in prior shrink lid devices and required to accommodate a range of cup diameters.

With a rectangular piece of specially adapted shrink film more closely matching the cup diameter, with improved means of directing radiant energy and optimum configuration of adapted film, it is now possible to create a round lid on a round cup from a rectangular piece in which the corners will shrink under the rim of the cup and match the attractive appearance of a round cut film piece. This eliminates the need for rotating cutter and rotating radiant energy sources and their inherent complexity. Additionally, the film is fused to the cup providing a far stronger bond than merely wrapping the cup rim. In the context of the present invention, radiant energy sources are typically halogen bulbs. The present invention uses a rectangular portion of shrink film in its entirety as a lid, eliminating trim loss. This is cut from the end of a roll of film web unwound and positioned in a novel way that eliminates the need for an additional web brake, tension controller, motor operated rewind spindle and grippers.

Shrink films are typically thin, limp and pliant, lacking the stiffness and rigidity to be pushed. Controlling the movement or positioning of a portion of these materials with these characteristic properties requires holding them under tension. In order to obtain tension, a minimum of two holding points is required. Typically the unwinding web is held in tension by means of nip rollers and a supply roll brake until the material is cut. Gripper bars or belts grasp the cut film web at its edges and move it to a new position. An example of this is found in U.S. Patent # 3 703 066. A more elaborate method of controlling the positioning of the limp film is described in U.S. Patent # 7 395 645. In this application, only a round portion within the web is cut to create a lid and the web remains uncut. Control of the web tension includes the rewinding of this unused trim portion. In the context of a lidding device for the restaurant industry using open top containers full to the brim with perhaps sugary beverages, and in close proximity to the intricate mechanical film advance mechanisms and belts, these methods are not practical, fast or efficient.

In the example of cutting a round portion within the web, about one half of the shrink material is left over as trim is removed, and subsequently wasted and lost to useful usage. The present invention provides a novel and improved method of controlling the film web with a simpler, more economic alternative and no film wastage.

In order to move the limp film web forward in position to be cut, it is made temporarily rigid and controllable by forming longitudinal corrugations into the film. From a mechanical perspective, the equivalent of a structural beam is created by forming these indentations into the limp film material oriented parallel to the forward movement of the film. This beam will have a characteristic resistance to the bending stresses exerted by gravity when in a cantilever position, and the enhanced compression strength of a column when pushed. This permits the film to be pushed rather than pulled through the opening of a guillotine cutter and be positioned above a holding tray.

These corrugations are formed in the present invention by two rotating meshed fluted rollers that act simultaneously as both corrugation formers in the material and as nip rollers that assist in unwinding the rolled web material. This arrangement is faster and more efficient than the method described in U.S. Patent # 3 838 805 since there is no friction resistance to the movement of the material in the formation of the corrugations. Consequently, many more corrugations can be introduced and create a firmer and more controllable film piece that can be moved with precision at a greater forward speed.

Rather than being pivotally mounted on a free-wheeling spindle coupled with a braking device, as in many of the prior inventions, the film supply roll of the present invention is lowered into position on two bottom rollers. One roller is powered by an electric motor that simultaneously powers the corrugating rollers. When a new section of film is called for, the powered bottom roller rotates the film supply roll and unwinds the film. This film is gripped by the meshed corrugating rollers and pulled at a slightly greater speed than the rate the film roll is being unwound by the powered bottom roller. This maintains the tautness required to supply a consistently uniform piece of film. When the motor stops, the powered bottom roller also stops and acts as a brake to the film supply roll's rotational momentum. The rate of film unwinding is constant and is a function of the number of rotations the bottom roller makes. The diminishing diameter of the supply roll or the increasing diameter of a trim windup roll found in other devices has no bearing on the rate of speed of the film that is unwound. Consequently, no variable portion length occurs.

The position of a printed film relative to the cup is important. This is controlled by a photo electric sensor that detects registration marks at the edge of the film, and stops the motor when required and triggers the cutting of the film web. Another object of the present invention is to minimize the overall time it takes to complete the lidding process. In order to accomplish this, the time required for each function in the process is incrementally reduced by improvements over prior art or novel new methods and devices.

The lidding process starts with the entry of the cup into the lidding machine. The machine under most circumstances will rest on a counter in a restaurant environment, close by or adjacent to the cup filling station. The height of the entry point is sufficient to place or slide a filled cup into position. The higher the entry point is, the further the distance and the longer it takes for the cup to enter the machine and thus the greater the chance of spillage. Although a number of entry means are possible, fixed entry guides, made possible by the standardized cup diameter, eliminate the need for the lateral position adjustment provided by the centering devices of prior machines. This permits a smooth upward motion with no jerk or hesitation for the cup entry that can cause spillage. The operator maintains continuous control of the cup, and no time is lost in the operator's hand leaving and reacquiring the cup.

The upwardly moving cup engages the precut film and both continue into the sealing chamber, comprising a round glass former which drapes the film downwardly. The burn cycle of the bulbs of approximately one second duration commences at the end of the upward travel and results in the film fusing to the cup.

In order to reduce the time required for the operator to respond and remove the cup upon the completion of the burn cycle, an auditory signal is triggered just as the bulbs are turned off. Another advantage of an auditory signal is that operators need not watch the machine to see when the bulbs turn off and can direct their attention elsewhere during the sealing cycle. Cup removal initiates the next film piece to move into place.

Film is unwound and moved forward by means of the corrugated rollers while the sealing chamber is raised. Upon the required film passing through a guillotine cutter, a photoelectric sensor stops the advance and activates the guillotine cutter. This single straight cut can be accomplished faster with much less complexity than a rotating blade assembly.

The freshly cut film piece, now completely unsupported, drops into a tray comprising three raised edges and a centrally located access aperture of sufficient size for a cup to pass through. The raised edges and guillotine housing form a rectangular enclosure the same size as the film piece. The film piece drops into the tray, and if askew, it is laterally adjusted by the enclosure. The film piece is now centered in relation to the cup entry aperture and the film piece corners are correctly positioned adjacent to each of the radiant energy sources. The replenishing process as described is accomplished in less time it takes to position the next cup for entry into the device, and a rapid lidding sequence is possible as a pre-cut film piece is always ready and a separate triggering means is not required.

It is another object of the present invention to provide a safe and sanitary lidding system that ensures the potential for contamination or the transmission of pathogens is minimized. Throughout the system, the film contact surfaces are direct or indirect food contact approved by appropriate regulatory or industry authorities. The film is completely wound throughout the system and hand contact is only required in initiation of a new roll of film. This contact is limited to the leading edge portion of the film of the first lid which is subsequently discarded.

Another object of the present invention to create a cup cover that will function for hot beverage cups and otherwise greatly improve the spill resistance of lids on all cups. In order to do so, it is necessary to bond the film by fusion to the cup rim and not merely wrap the rim with shrunken film. The temperature of the hot beverage can be in the 200F degree range and within the minimum shrink temperature that initiates the shrink process of shrink films. This can result in the normally unshrinking central portion of the film lid to shrink and pull the film inwardly, unwrapping the previously shrunk film periphery away from around the cup rim causing failure.

One practical method to prevent this from happening is to fuse the film thermoplastically to a polymeric surface of the cup. In the instance of a paper cup, the inner surface is typically coated with a very thin layer of waterproofing material such as low density polyethylene (LPDE). In the cup manufacturing process, the cup rim is formed by rolling the top edge of the sidewall inside-out, this then exposes the coating to the outside of the cup and is available as a polymeric heat seal surface.

By appropriate design or selection of material used in the treatment of the cup, there are other opportunities to improve the security of the film/lid system for both paper and plastic cups. This may include modifying the rim shape, applying adhesion promoters or modifying the surface texture or colour of the rim area.

It is another object of this invention however, to provide a film/lid system that is immediately useful and adaptable to existing cup constructions now in general use. This will allow the QSRs to quickly adopt the system with a minimum disruption and cost. The majority of the QSR cups are polymer coated paper with a rolled rim. The shrink film is heated by the radiant energy sources and radiant energy absorbent inks to a temperature not only higher than what is required to shrink the film but, is also sufficient to soften the film to thermoplastically fuse to adjacent cup polymer.

The rotating lights of U.S. Patent # 5 249 410 and the array of fixed lights energized sequentially by switching means as described in U.S. Patent # 6 775 472 are unable to achieve sufficient temperature in the shrink film to cause both shrink and thermoplastic fusion. One reason for this, among others, is that the effect of momentary pulses of radiant energy is only sufficient to shrink the film in successive stages. There is no opportunity for the film to achieve a temperature beyond what is needed to merely shrink the film.

The energy of a tubular quartz halogen lamp described in U.S. Patent # 6 775 472 as an alternative to the array of sequentially powered fixed lights is equally distributed around the rim of the cup and cannot direct the radiant energy to where it is most required which are the corners of the rectangular portion of shrink film. As is the case with the rotating lights, it is better suited for shrinking a round cut portion of film.

Each of the fixed halogen bulbs and the special configuration of their respective reflectors direct the radiant energy proportionately to the amount and position of the film draped downwardly and outwardly from the cup rim between the glass former and the cup. The distance from the bulb/reflector radiant energy source to the cup is consistent due to only the standard size cup diameter being permitted entry into the present invention. As a result the focal point of the radiant energy can now be accurately and optimally positioned to effect shrinkage and fusion of the four film corners and, shrinkage of the adjacent film draped over the rim between said corners. There is no necessity for a more diffuse focus or a complete encirclement of fixed or rotating radiant energy sources as required in prior devices to shrink a lid on a wide range of cup diameters. The result achieved is a more rapid and higher temperature rise that, in conjunction with the specially adapted shrink film, permits the polymer of the cup to fuse to the shrink film.

In addition to the requirement for a specifically focused energy source impinging on the shrink film, is the requirement for the film to be modified with an energy absorbent material in appropriate locations. The energy absorbent material on the shrink film piece extends outwardly to the perimeter of the rectangular piece from inside the circular top of the cup rim in order for the periphery of the film to shrink and the four corners to fuse around and under the rim of the cup.

This again is aided by the standardized cup diameter since it is now possible to determine and predict where this adsorbent material needs to be located with respect to the cup rim. The essential elements of thermal bonding thermoplastic materials are heat and pressure. In the present invention the contact pressure is uniquely provided by the shrinking force of the film drawing rapidly inward towards and under rim of the cup. At the same time the comparatively long sections of exposed film in the corners provides enough surface, despite shrinking, to heat up and soften the polymeric surfaces of film and cup to promote fusion.

The simultaneous energizing of the four opposing radiant energy sources balances the shrink force and prevents the lid from moving askew. Additionally a portion of the energy adsorbent material of the film extends over the top portion of the bead, shrinks and tightens the film cover to form a wrinkle free surface.

The central portion of the film cover is not required to shrink and can be utilized as an information panel. The rotating radiant energy sources of the prior art and the sequentially powered fixed array and tubular lamp of U.S. Patent 6 773 472 cannot effectively develop the necessary selective energy intensity in the film to both shrink and fuse it to the cup.

Another objective of the present invention is to provide a means for accessing the contents of the lidded cup by means other than a straw and with the capability of re- sealing the cup. An example of the utility of such a means is the ability to sip a cup of coffee and manually re-seal the cup with the same lid. This can be accomplished with the use of a pull tab that can pull back at least a small portion of the film from the rim of the cup and replacing said portion by pulling it back over the rim. This works exceptionally well with hot drinks in that the heat keeps the film flexible and somewhat elastic.

A pull tab is created in the preferred embodiment by reducing or eliminating the energy absorbing material of the extremity of one corner of the rectangular lid piece. This leaves a small portion of the film corner beyond the rim of the cup unaffected by the shrink process and available to use as a pull tab.

In the instances where a straw is preferred, entry can be made with either a slanted straw that pierces the film or a regular straw that enters through a small slit. This slit is produced by a piercing tool that may also produce pin holes required to vent carbonation or steam. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a sectional side view of the device according to the present invention in use. Figure 2 is a sectional side view of the sealing chamber with container partially inserted. Figure 3 is a sectional side view of the container fully inserted with the radiant energy sources activated.

Figure 4 is a sectional view of the sealing chamber with the sealed container about to be completely removed.

Figure 5 is a sectional view with the platen raised to permit the advance of the film. Figure 6 is a top partial (2) figures sectional view showing the relationship of the film holding tray, heating chamber and radiant energy sources.

Figure 7 is a sectional front view of film moving forward from corrugated rollers.

Figure 8 is a top view partially in cross section of the container opening relative to printed film and pull tab feature before fusion.

Figure 9 is a top view of a sealed cup with a pull tab feature.

Figure 10 is a partial sectional top view of a reflector, bulb, cup and sealing chamber.

Figure 11 is a partial cross sectional side view of a reflector, bulb and cup.

Figure 12 is a partial cross sectional front view of the container guide posts and tray.

Figure 13 is a partial cross sectional view of the tray, guide posts and container.

Figure 14 is a partial cross sectional top view of platen and solenoid plunger. DETAILED DESCRIPTION OF THE INVENTION

A detailed description of the preferred embodiments of the present invention with reference to the drawings will now be made. This invention is directed to open top containers such as cups. Those with ordinary skill in the art will appreciate that it is equally applicable to other open top containers.

Briefly, as illustrated in Fig.l, cup 1 is lifted upward into aperture 2 of device 17. Cup 1 engages cut film portion 4 and platen 5 and subsequently into sealing chamber 31 until no further upward motion is possible. At this point, a timed, focused radiant energy source is activated and directed to the periphery of the cut film portion 4 extends from platen 5 and cup 1. It results in film portion 4 fusing to cup 1.

The newly covered cup 1 is lowered through aperture 2 and withdrawn from device 17. Platen 5 is held in the upward position by solenoid 33 until a new piece of film 4 is positioned in tray 3 in preparation for the next cup. Platen 5 is subsequently lowered to rest on top of newly cut film piece 4.

Turning now to the preferred embodiment of the cup, used in the present invention. Cup 1 in Fig.1 is a typical configuration used by the beverage industry. It is tapered to a narrower diameter at the base of the cup to permit nesting of multiple cups and thus reduce storage and shipping space. Typical construction is paper or plastic and includes a shaped rim at the brim of the cup. This rim provides lateral stiffness to the upper portion of the cup, a more comfortable edge for the consumers' mouth and an anchor for holding lids in place. The preferred embodiment for the rim shape of the present invention is an outwardly turned or rounded brim that provides a relatively large surface area for fusion of film 4 to rim 6 of a polymer or polymer coated cup as depicted in Fig.11. The vast majority of cups in the Beverage Industry are paper and have this type of rounded rim.

The other methods of fusion bonding disclosed in the prior art are not suitable for rounded rims, especially paper rims since only the uppermost extremity of the round rim is available as a fusion contact surface. This may be sufficient for a tamper-evident cover but not for a robust spill resistant seal. These methods employ a compressive heat that functions well on flat, supported polymer surfaces such as a flanged rim that can provide sufficient surface area to create an effective seal. An adjustable mechanical means is required to ensure that the compressive pressure is consistent between containers and unlike the present invention, a hand supported, manual presentation is not possible.

In the present invention the required fusion pressure is uniquely provided by the shrink force inherent in the polymer film when heated and no additional mechanical pressure is required. This force is evenly spread over the relatively large surface area of the round rim without the possibility of crushing the rim. When unrolled, this rim at approximately ¼ inch wide is comparable to the area of the flat flanged rim of prior art containers. The present invention does not preclude the use of the flat, flanged rim of polymer cups used by the other methods. The underside of the flange can also be a suitable surface for fusion.

The preferred cup may be completely polymer or of a paper construction, provided that in the case of a paper cup at least the outward surface of the rounded rim is coated with a thermoplastic polymer and available for contact with the polymer film cover. In the instance of a paper cup, the vast majority of disposable cups requiring lids, this is normally provided by the thermoplastic water proof coating of the inside paper surface. To form the round rim, the paper is rolled outwardly at the brim in the manufacturing process, thus exposing the inside polymer coating outwardly. In the instance of a cold drink paper cup, this coating may be on both sides to eliminate the damaging effect of condensation on the outside paper surface.

One of the most widely used water proof coating for paper cups is a Low Density Polyethylene (LDPE). Applied at a rate of between 5 and 151bs./ream on inner and/or outer surfaces, it provides a very thin coating that softens at 92 degrees C and melts at 1 15 degrees C. The low softening temperature aids in the thermoplastic fusion of the coating to the film cover. Although when a heated, softened polymer pressed against most surfaces, including glass and metal, will provide some adhesion. By far the strongest bonds are developed when both contact surfaces are softened or molten to intermingle and form an inseparable bond between the two polymers. Due to its very thin coverage, waterproof coating on a paper cup has an opportunity to soften or melt quickly and completely to provide the strongest thermoplastic bond using the methodology of the present invention.

It will be appreciated by those of ordinary skill in the art that other polymer cups and polymer coatings, whether of polyethylene, polypropylene or other polymers may also provide suitable surfaces for a thermoplastic bond between shrink film cover and cup. The operator is able to verify a fused bond by simply pulling the film off at the cup rim. There will be a significant resistance to removal and in the case of a paper cup there will be evidence of paper fibers being pulled off with the poly coating. Film piece 4 originates from roll 10 in Fig. 1 and Fig. 2 and is a biaxially oriented shrink film having a thickness of between 40 and 120 gauge. Any film capable of shrinking with sufficient shrink force when heated such as polypropylene (PP), low density polyethylene (LDPE) and co-polymers of LDPE and high density polyellylene (HDPE) may be suitable.

Good results have been achieved with 75 gauge Bemis Clysar copolymer ABL shrink film with a shrink force of 130 grams/inch @100 degrees C according to test method ASTM D2838 and Bemis Clysar XPL film.

The shrink film is adapted to absorb radiant energy, creating heat and subsequently film shrinkage. This is primarily accomplished by printing the film with energy absorbing inks as described in US Patent 5 993 942 and 7 089 718.

The effectiveness of the seal of film 4 to cup rim 6 can be adversely affected by a number of factors. For example, cold carbonated beverages or beverages with ice floating at the brim level may affect the amount of energy required from the radiant energy source 23. Normal variations between batches of film and cups such as the thickness of film, printing and polymer are also examples of factors that can affect the seal.

It is another objective of the present invention to enable the operator to adjust the total energy output of radiant energy sources 23 to produce the optimum seal and provide the operator the most convenient means to do so. The means of radiant energy control as described in some prior art such as US Patent 7 089 718 are factory pre-set

microcontrollers and AC photo-couplers that are not accessible by ordinary means and not available or designed for the on site adjustments that may be necessary. Timer controls 34 are located on the front panel of housing 17 and provide the operator with the means to add or reduce the amount of time radiant energy sources 23 are activated by a total of 2 tenths of a second in either direction. Indicator light 55 incorporated as part of the timer controls, indicates whether or not the machine is ready for use.

It is an objective of the present invention to provide a more robust lid seal than that provided by prior art lidding systems. In order to measure the systems, the information provided in table 1 in US Patent 7 089 718 was compared to the present invention. No direct comparison was possible using the methodology described in US Patent 7 089 718 since the cup wall collapsed inwardly, without releasing the fused lids of the present invention.

The inventor of the present invention is co-inventor of prior art devices described in US Patent 5 249 410, 7 089 718 and others and as such has access to these devices enabling direct comparisons using the different methodologies.

A comparative test of the strength of the bond between the lid and the cup, which also has real life relevance, would be to subject the various methods of shrink film lidding with a hot liquid such as water. As shown in Table 1, empty paper cups lidded by each of the methodologies were subjected to 8 fl. oz. of 200 degrees F hot water. The three methods were US Patents 5 249 410, 7 089 718 and the present invention. The result was graded as either a complete failure in that the whole lid was pulled away from the rim, partial failure when one portion pulled away, or passed. TABLE 1

The selection of a single diameter cup as the preferred embodiment of the present invention permits a simple cup entry which assists the rapid, unimpeded and efficient motion of the cup. Prior art devices that accommodate variable diameter cups require a mechanism that will centrally locate the cup. Typically these positioning devices require horizontal motion of the cup inside the device before a centrally positioned upward motion is possible. This requires the stoppage of the horizontal motion with a perhaps fully filled open top beverage cup. Unless these motions are carried out slowly and deliberately, they will create spillage of the beverage. Elevating devices that elevate the cup requires the cup to be placed and removed manually. A process taking longer than maintaining continuous manual contact as in the preferred embodiment. A common element of these prior art devices is the likelihood for beverages to be spilled on the moving parts and create problems. When cup 1, as depicted in Fig. 1, Fig. 12 and Fig. 13, is pressed against the guide rails 22 and urged upwardly, it is prevented from moving in any other direction. The result is an accurate and reproducible placement of the cup. This is important in order to engage the energy absorbing printed periphery of film portion 4 in the required central position relative to cup rim 6. Fig. 12 illustrates the upper edges of guide rails 22 with a chamfer 27. This prevents the cup rim 6 from catching the rail tops upon the cups downward removal.

Tray 3 as depicted in Figs. 4, 5, 6, 12 and 13 consists of a food contact approved material such as High Density Polyethylene (HDPE) or similar materials that are readily washable. Tray 3 is quickly removable for cleaning and other purposes by pulling it outward along track 29 as shown in Figs. 12 and 13.

The function of tray 3 is to guide and hold cut film piece 4 in a centrally located position relative to aperture 2 in readiness for the entry of the cup. The film piece 4 advances through cutter 11 by being pushed by corrugated rolls 19 and 12. Cut film piece 4 is no longer controlled or constrained after being cut by cutter 11. The film piece drops downwardly into tray 3 and is prevented from floating into an off-centered position relative to aperture 2 by fences 30 fixed on 3 edges of the tray. The 4 ^th fence is the housing of cutter 1 1. This process commences immediately after a lidded cup is removed and while platen 5 is still in an elevated position. This elevated position as depicted in Fig. 5 is sufficient to provide unobstructed clearance between the sealing chamber 31 and platen 5 and tray 3 for film 4 advancing from cutter 1 1. The size of this clearance anticipates that the leading edge of advancing film 4 may deviate slightly from the horizontal plane. In the preferred embodiment of the invention this clearance is approximately 1".

The preferred embodiment of aperture 2 as depicted in Fig. 2 is circular in shape, the edges having a chamfer to assist in a smooth motion of the cup. Other opening shapes are possible provided that the opening is sufficiently large for cup 1 to pass through and sufficient tray 3 material is left to support the cut film piece so that platen 5, slightly larger than aperture 2, will hold the cut film piece in place around the circumference of aperture 2. This ensures that the cut film piece is held firmly and will not shift when the cut film piece and platen 5 are engaged by upwardly travelling cup 1 as shown in Fig. 1. Fig. 1 also depicts sealing chamber 31, suspended from support plate 56 and larger in diameter than platen 5 in position to guide cup, film and platen 5 towards the radiant energy sources 23. Those with ordinary skill in the art will realize that various alternatives that have similar results are possible. For example, in one embodiment sealing chamber 31 also moves up and down.

The preferred embodiment of platen 5 depicted in Fig.1 and Fig.14 is a circular disc of a smooth and polished stainless steel or other food contact approved material that is able to conduct and resist heat and is reflective to radiant energy.

Centrally located and fastened to the top surface of platen 5 is solenoid plunger 7.

Plunger 7, at least partially consisting of a magnetically receptive material, serves as a guide to the upward motion of platen 5 and cup 1 when cup 1 travels beyond guide rails 23. When fusion is complete, plunger 7 in conjunction with an energized solenoid 25 will hold platen 5 in an upward position in order not to interfere with the advancement of film 4 into tray 3. Another function of platen 5 is to provide a flat, stable and horizontal surface for the upwardly moving cup, and cut film piece 4 to press against. This prevents leakage of beverage and presents cup rim 6 and cut film piece 4 evenly to the radiant energy sources 23.

Fig. 14 also depicts 3 round openings 38 equally spaced around the centre of platen 5. These openings serve two functions. One function is to prevent a rush of air caused by platen 5 as it drops on cut film piece 4 resting in tray 3. A rush of air may depress the central portion of cut film 4 into aperture 2 and negatively affect the final product.

The other function of openings 38 is to provide 3 finger holes to permit platen 5 to be grasped, rotated and removed. As depicted in Fig. 14, indentations 37 are positioned at the rim of platen 5 the same distance apart as guide rails 22 and with allowances for the adjustment of guide rails 22.

The mechanism as described detail the preferred embodiment of the invention, those of ordinary skill in the art will appreciate that modifications are possible to achieve similar results.

After removal of tray 3 indentations 37 are positioned above guide rails 22 by means of openings 38. Platen 5 can now be lowered from solenoid 33 and sealing chamber 31. Sealing chamber 31 can now be removed to provide access to the radiant energy sources 23 and an opportunity to clean platen 5 and sealing chamber 3.

Turn now to sealing chamber 31 as depicted in Fig.1. In the preferred embodiment of the present invention, former 9 is a clear, circular borosilicate glass sleeve such as Pyrex ®. At 3 mm thick it is transparent to 92% of the available radiant energy from radiant energy sources 23. Those of ordinary skill in the art will recognize that other transparent material such as special heat resistant plastics will function. Glass is preferred due to its superior surface hardness useful for abrasion resistance in cleaning. Certain safety regulations will have a bearing on the construction and materials used. For example, Canadian Standards Association (CSA) standard C22.2 NO 250.0.24 and Underwriters Laboratories Inc. (UL) standard 1598 have specific requirements on glass thickness, mounting and position of bulbs and the like.

Former 9 is attached to cover 40 made of a material similar to platen 5. Cover 40 provides a means of locating and suspending former 9 and an aperture for proximity switch 36. When platen 5 reaches the limit of its upward travel, switch 36 initiates the beginning of the sealing cycle that starts with the timed activation of radiant energy sources 23.

Figs. 2, 3, 4 and 5 depict the sequence of events that constitute the fusion cycle. Fig. 2 depicts cup 1 moving in an upwardly direction with film piece 4 captured between cup rim 6 and platen 5. Platen 5 prevents the film from slipping, tends to square the cup and prevents leakage. The assembly enters sealing chamber 31 and glass former 9 drapes the rectangular cut piece 4 around the cup. When the assembly reaches proximity switch 36 it can go no further and is now optimally positioned for the radiant energy sources 23 to be activated by proximity switch 36. Fig. 3 depicts radiant energy sources 23 activated and fusing film 4 to the cup rim. Fig. 4 depicts the new lidded cup being lowered from sealing chamber 31 and removed through aperture 2 in tray 3. Platen 5 remains in the upward position held in place by solenoid 33. Fig. 5 depicts film 4 being pushed horizontally through guillotine 1 1 by corrugating rollers 12 and 19, suspended above tray 3 and below platen 5 just before being cut by guillotine 11. As depicted in Fig. 11, the primary purpose of former 9, in addition to acting as a safety barrier to radiant energy sources 23, is to shape the periphery of cut film 4 extending from platen 5 to a downwardly draped position, parallel and in close proximity to the cup 1 sidewall. This allows the radiant energy to impinge on the energy absorbent portion of the film at the optimum angle for absorption and urges the film to shrink in the direction of the wall of cup 1 and cup rim 6. Since the present invention employs a standard cup diameter, the cut film periphery is presented to the focused radiant energy sources in the same pre-determined optimum position. In the preferred embodiment of the invention, former glass 9 inside diameter is approximately ¼" larger than the outside diameter of cup 1.

In the preferred embodiment radiant energy sources 23 are halogen bulbs. Those with ordinary skill in the art will know that there are many available sources of radiant energy. Halogen bulbs have the advantage of being compact, instantly on and off, producing useful radiant energy in the 600 - 1400 nm wavelength range. They can be readily focused and with a small thermal mass will not retain significant amounts of heat.

In the present invention the preferred bulb is designated as a DRA bulb. These bulbs are available from a number of manufacturers such as; Sylvania, Philips and Ushio. The DRA is a compact, rugged, 110 volt, 300 watt bulb, and with a 2 pin terminal it is capable of being mounted in a vertical downward position facilitating replacement if required. Turning now to the compound configuration of reflector 8. Fig. 10 depicts a partial top cross sectional view that reveals the parabolic geometry of reflector 8 in the horizontal plane. Fig. 11 depicts a partial cross-sectional side view that reveals the elliptical geometry of reflector 8 in the vertical plane. The combination of these geometric shapes results in an oblong, cup shaped reflector. Reflector 8 may be constructed of a heat resistant material such as aluminum with an inner surface that is reflective.

Bulb 23 is positioned to act as a point source of light in the elliptical vertical plane. This directs the energy of the bulb from the central portion of reflector 8 primarily vertically towards the downwardly draped corner 45 of rectangular film piece 4 in a manner that can focus the energy exactly where it is required to heat the full vertical length of the corner.

The parabolic geometry of the horizontal portion of reflector 8 acts to spread energy in a more narrow horizontal direction to impinge on film periphery 44. The bulb socket 42 is positioned so that the length of filament 39 as depicted in Fig.10 and Fig.1 1 is in a horizontal position and thus mostly out of the focal point of the parabolic geometry of reflector 8. This disperses the radiant energy in the horizontal plane as depicted in Fig.10.

It can now be appreciated that the position and configuration of the cup, the draped position of the rectangular film piece 4 and combination of bulb position and compound geometric shape of reflector 8, is able to convey energy in a more effective and consistent manner to film 4 than prior art devices. These devices did not consider, for example, the out of focus situation introduced by different cup diameters.

Turning now to guillotine 11 as depicted in Fig. 1. It provides the function of severing a portion of film 4 from the film web. Those with ordinary skill in the art will recognize that various embodiments are available to cut the thin film 4. One such embodiment employs a hot wire, however this means has been regulated to industrial environments where the resultant nauseous fumes and odours generated can be properly contained and removed. Another embodiment employs steel knife blades of various configurations. These blades however are subject to wear and require ongoing maintenance that may be beyond the capability of a QSR operator. The preferred embodiment is a standard guillotine device extensively used for cutting receipts from paper rolls typically used in devices such as cash registers, bank machines and the like. Model ROG146KZ6 made by the Oyane Riki Manufacturer have been successfully used. These devices are self sharpening and have a proven record of performance and are typically guaranteed to function for several million cuts which is comparable to the expected life span of the lidding device. Guillotine 11 is activated to cut when forward motion of film 4 ceases when motor 16 stops.

Film entry guides 53 are useful in guiding the leading edge of film 4 into the guillotine upon initiation of a new film roll. In the preferred embodiment the initiation of a new film 4 from roll 10 is simplified to eliminate operator frustration common in devices that require paper to be threaded. Roller 19 is removed and the leading edge of film 4 is inserted under forming bar 21 and pulled through to be inserted into entry guides 53. Roller 19 is replaced. The edge of film 4 must slide through photo sensor 13.

Turning now to rollers 12 and 19 depicted in Fig. 1, Fig. 6 and Fig. 7. In the preferred embodiment these rollers are fluted so that they can mesh together to corrugate film 4 as depicted in Fig. 7. Shaft 51 of roller 19 can move freely in a vertical direction inside slotted bracket 52. This allows the weight of roller 19 to press down on film 4 and shape it into corrugations. The slot of bracket 52 is open at the top permitting complete removal of roller 19. This accommodates placement of the leading edge of film 4 into the entry guides 53 and provides ready access to this area if required. The bottom corrugating roller 12 is driven by belt 49 and sprocket 48. Film 4, pressed between rollers 12 and 1 , is now in a corrugated shape. When the device requires more film, rollers 12 and 19 are activated and film 4 is pushed through guillotine 11 in the corrugated shape and is suspended above tray 3 until cut by guillotine 11.

It was found that to be useful for the present invention, corrugated film piece 4 needed to be sufficiently stiffened by the corrugations to create a cantilevered beam effect with a minimum deflection, yet resilient enough to quickly return to a flat state in tray 3 after being cut by guillotine 1 1. This required roller 19 to have an optimum combination of weight and pitch and depth of corrugations. In the preferred embodiment the weight of roller 19 was find useful in the range of 1 lb, the preferred pitch was ¼ inch and the corrugation depth was 1/8 inch. High Density Polyethylene (HDPE) was found to be a suitable material although those with common knowledge of the art will recognize that other materials are also suitable.

Turning now to film supply roll 10 as depicted in Fig. 1. In the preferred embodiment, roll 10 is in a standard format commonly used in the film and printing industry and wound on 3" diameter fibre cores. A roll containing 2 000 linear feet of 75 gauge shrink film will measure 6 inches in diameter and yield approximately 5 000 lids in the present invention. Roll 10 is lowered onto rollers 18 and 47. The unwinding of film 4 from roll 10 is necessary to supply film 4 for the lidding operation.

Those with common knowledge of the art will know that many arrangements are possible to unwind roll 10. In the preferred embodiment, roll 10 is not centrally mounted on a spindle. This would require roll 10 to be side loaded which would require space on the loading side that may not be available. Unwinding of film roll 10 is accomplished by rotation of roller 18 powered by motor 16. The rotation speed of roller 18 is linked to the desired recycle time between lidding operations and the capability of the other components in the film feed system. These include the speed of the motor, size of sprockets, rotational speed and size of corrugating rollers and response time of optical sensor 13. It was found that a linear speed of film 4 to 6 inches per second work well. The relatively slow speed minimizes the rotational momentum of roll 10. Unlike the prior art film feed systems, the preferred embodiment operates with a minimum film tension. In the present invention, only such film tension as required to move a small piece of thin film forward approximately 5 inches is required. Any force or tension beyond this requirement is redundant and requires additional components to control.

One such component is the brake and clutch system commonly used in prior art that controls rotational momentum of a supply roll. Instead the weight of roll 10 against roller 18 acts as a brake when roller 18 abruptly stops.

Yet another important aspect of film feeding is maintaining film tautness. Prior art typically employ a method that involves a dancer roller. The present invention eliminates the requirement for separate mechanisms to maintain tautness by means of corrugating rollers 12 and 19 pulling film 4 at a slightly faster rate than it is being released by roll 10. Since the nip pressure of the corrugating rolls is light, once tautness is achieved the rotating rollers simply slide on film 4.

Roll 10 is printed and unwound so that the ink side of film 4 is uppermost and presents the unprinted side to the contents of cup 1 . Essential for the film feed system is a means of registering each printed image on film 4 to the open top of cup 1. This is accomplished by photo sensor 13 that reads the registration mark 57 as depicted in Fig.8. In the preferred embodiment 57 is a clear, unprinted portion measuring ½ inch by ¼ inch and sufficient large photo sensor 13 to read as film 4 travels past. The space between the registration marks determines the cut length of film piece 4. The relative position of the photo sensor to guillotine 11 determines the position of the printing design to the cut film piece 4.

Adjacent to roll 10 as depicted in Fig. 1 is the piercing tool assembly consisting of solenoid 14, piercing tool 15 and forming bar 21. The primary purpose of the piercing tool is to provide a venting means to allow the escape of carbonation or steam. Typically the vent is a small pin prick 58 as depicted in Fig. 8. Another possible use of piercing tool 15 as depicted in Fig. 9 is to create a small cut 59 in film 4 approximately 1/8 inch long. This facilitates the entry of a non-slant cut straw. In both instances the piercing tool 15 penetrates film 4 and extends its' travel into a cavity of forming bar 21. This prevents any possible injury from the sharp piercing tool.

Turning now to Fig. 8 that depicts a cut portion of film 4 modified to be used as a lid according to the present invention with the extremity of one corner 60 not treated to absorb radiant energy to the same extent as portion 61. When exposed to radiant energy film piece 4 forms a lid as depicted in Fig. 9 with corner 60 not shrinking to the same extent or not at all as modified portion 61. This then provides a portion of the lid that can be grasped and used as a pull tab to remove the lid. As depicted in Fig. 9 a portion of the modified film 4 extends over rim 6. This assists in the information panel 63 being tightened as the radiant energy sources shrink the film at rim 6. This feature also ensures that if the film lid is placed askew relative to cup 1, there will be an effective seal.