Abstract:
Disclosed are designs and methods for integrating heating film onto surfaces and enclosures that are useful for preventing the infestation of pests. Specifically, designs to increase the effective heating area and location of said heating film within enclosures such as suitcases. Also, the use of heating films to create a thermal barrier to prevent pests from crawling across a surface. Heating films can be utilized that are inexpensive, low-profile, and lightweight.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present invention relates to killing bed bugs or other pests which may be located within a suitcase. This disclosure includes details which aid in the integration of heating elements into a piece of luggage to improve upon the functionality and manufacturability; and methods to manufacture heating film to suit various applications. Also disclosed is a system which may be used to establish an electrically heated, low-profile barrier to either contain or prevent infestation of an area. 
     The disclosure improves upon U.S. Patent Application 13/232,156, filed on Sep. 14, 2011, by Michael D. Lindsey, entitled “Heat Treatable Enclosure” and U.S. patent application Ser. No. 12/907,326, by David Levy, entitled “Inhibiting Pest Infestation”. 
     BACKGROUND 
     As people travel there is a growing incidence of pest or insect infestation of garments transported in luggage and materials shipped in containers. For example, bed bugs may be found in many hotels, motels, homes, or other accommodations, even in highly sanitary conditions. During the day, nocturnal insects, such as bedbugs, disappear in crevices associated with suitcases, garments, clothes, pillows, towels, or the like. Even when these materials are examined, it is common for these insects, or the eggs of these insects, to go undetected and packed with garments and transported in luggage. 
     Lethal conditions for bed bugs are a combination of time and temperature. While it is generally agreed that temperatures over 120 F will kill bed bugs and eggs instantly, lower temperatures require an increased exposure time. For example, in a 2011 paper by Dr. Stephan Kells, entitled “ Temperature and Time Requirements for Controlling Bed Bugs under Commercial Heat Treatment Conditions ”, cites that exposure to temperatures of 113 F may take an hour and a half to kill and adult and up to seven hours to destroy eggs. 
     The integration of surface heaters into a suitcase is discussed in prior art applications. This patent outlines manufacturing improvements and best practices for further integration. 
     SUMMARY OF THE INVENTION 
     The embodiment of the present invention comprises methods for integrating heating elements into luggage system for killing pests within which may reside in the interior or exterior of the luggage; the creation and manufacturing process to create these heating elements; and additional mechanical features which may aid in reducing the risk of pest contamination. 
     A significant challenge of heating an enclosure, such as a suitcase, lies in the fact that bed bugs, as well as other pests, are sensitive to heat and will move away from a heat source as the temperatures becomes lethal. Cool spots may be prevalent throughout the enclosure and provide a harborage for the pest during the heat treatment. For travel applications, such as suitcases, however, the uses of bulky insulation or convective passages are undesirable. 
     There are multiple requirements on the heating elements employed for this application. Heating elements must be strategically positioned to overcome the heat loss throughout the application. Heating elements should not impede the basic functionality of the luggage, ergo, they must be lightweight, consume a minimum volume within the enclosure, and resilient to the mechanical wear seen by luggage during transport. For safety and commercialization purposes, the overall system while the heating elements are active must be not exceed surface temperature standards enforced by UL, CSa, and CE. 
     Ideal candidates for this application are IR heating films which have been commonly used as under floor heating systems. Heating films consume a minimal amount of volume as the film thickness is roughly 0.25 mm. Heating films are moderately pliable and may be applied to any rigid surface, including surfaces which extend in multiple planes, to create a continuous heating surface. Heating films are mass produced via a screen printing process which deposits carbon-graphite elements between bus bars. This process allows for unique shapes and designs to be manufactured meeting the need of the application. Heating films are distributed world-wide and are recognized by various certification agencies. Advances in the heat film technology over the last two years include the use of positive temperature co-efficient materials in the carbon-graphite that can be employed to help to regulate temperatures. 
     Alternatively, heating elements may also be created using resistive heating elements such as ribbon wire or metal alloys such as NiChrome. These have been more traditionally accepted for use as heating pads, electric blankets, etc. These may have some advantages such as the ability to create unique designs, but the process to manufacturer is more costly. 
    
    
     
       A BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of heating film as it is currently produced. 
         FIG. 2  is a view of standard film when placed within an open suitcase. 
         FIG. 3  is a view of a film where the booth bar has been separated to enable differential voltage across. 
         FIG. 4  is a top view of heating film which may be die cut to form an application specific shape. 
         FIG. 5  is a view of a heating film created with a single booth bar. 
         FIG. 6  is a view of luggage with external features and corresponding heating film. 
         FIG. 7  is a view of a heating film which can form a three dimensional enclosure. 
         FIG. 8  is a view of luggage configured as a heating system. 
         FIG. 9  is a view of an alternate configuration of luggage as a heating system 
         FIG. 10  is a view of the heating film and zipper interface. 
         FIG. 11  is a view of mechanical barriers to protect wheels. 
         FIG. 12  is a view of mechanical barrier to protect handles. 
         FIG. 13  is a view of an enclosure with heat conductive elements. 
         FIG. 14  is a view of an unheated pocket for heat sensitive items. 
         FIG. 15  is a view of an electrical thermal barrier using resistive wiring. 
         FIG. 16  is a view of an electrical thermal barrier using heating film. 
         FIG. 17  is a view of an electrical thermal barrier around a bed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a view of heating film  100  as it is commonly produced. The heating film  100  is comprised of a base film  106  which carbon ink channels  102  are deposited between two bus bars, specifically bus bar neutral  104  and bus bar hot  108 . When a voltage differential is applied across the bus bar, the carbon ink produces heat via resistive heating and infrared radiation. 
       FIG. 2  is a view of the heating film  100  as commonly produced applied to an enclosure, in this case a suitcase lid  112 . The heating film  100  could also be applied to the suitcase base  110  and walls to create a heated enclosure that is capable killing pests within the enclosure. A deficiency in this design is the non-heated areas  116  which are outside of the heating area  114  and may not reach temperature sufficient to kill pests if the suitcase is loaded with materials. 
       FIG. 3  is a view of an improved heating film design for eliminating non-heated area  116  for the enclosure application. The improved design incorporates side heat channels  130  which extend the heat area  114  outside of the bus bar. To create a differential across the side heat channel  130 , the bus bar is severed at the bus bar cut line  128 . This heating element becomes active when bus bar B  126  and bus bar C  122  are connected to neutral and bus bar A  120  and bus bar D  124  are connected to hot. Additionally, the perimeter of the heating film is cut to mechanically fit along the shape cut outline  118 . 
       FIG. 4  illustrates how a mechanical punch could be employed to produce the improved element in a manufacturing environment. Registration marks  134  printed during the creation of the film could be used to accurately align a die cutting tool. In a single operation the die cutter would cut out the shape cut outline  118  and bus bar cut line(s)  128 . 
       FIG. 5  is another view of an improved heating film which uses a single bus bar. The bus bar cut line  128  separates the single bar into bus bar A  120  and bus bar B  126 . The side heat channel  132  would be designed as shown to have lower carbon deposits on the inner side heat channel  132  and greater carbon deposits on the outer side heat channel  132  to create a uniform heating element. 
       FIG. 6  is a view of an improved heating film design to accommodate features such as external pockets  136  which may exist in the application. To be effective, the heating elements must cover the entire design while accommodating an opening. Parallel resistive channels  138  may be designed into the film or u-shaped feature avoidance channels  140  are examples of solutions which address this challenge. 
       FIG. 7  is a view of a heating film design which may be used to create a three-dimensional object. The design includes side wall channels  144  which are printed on side all flaps. The side wall flaps  142  are installed into the application perpendicular to the base of the film. 
       FIG. 8  is view of a suitcase application where a single heating element is used. This approach is sufficient to eliminate pests within the suitcase when the suitcase is empty. A tilt sensor may be employed in the case where the optimum performance is dependent on the orientation of the enclosure. For this design, the heater element  210  is placed on base of the suitcase and on a wall opposite temperature monitors  204 . The heater element  210  temperature may be regulated by using a sensor element  212  feeding back to a controller  206 . The heater element  210  temperature may also be regulated by use of normally closed bi-metallic thermal switches. The heater element  210  may also be self-regulated using positive temperature coefficient materials within the element. Temperature monitors  204  may be monitored and report the lowest temperature to determine the end of a heating cycle or wired in series in the case of thermal switches. 
       FIG. 9  is a view of the heating element  210  when it is designed into the suitcase divider  204 . This design is an improvement to placing the element in the walls of the suitcase base  200  or suitcase lid  202  as it radiates equally to both sides of the container. The suitcase divider is common in the art of suitcase design to allow a user to close the suitcase lid  202 . The suitcase divider is commonly held in place by mating interface  216  such as zippers or latches. This design also illustrates using the wheels as standoffs to allows the majority of the enclosure to be surrounded by an ambient environment. Temperatures monitors are placed in the lower corners of the enclosure. 
       FIG. 10  is a close up view of a zipper and grommet which may be used to hold a suitcase in the closed position. This design allows the heating film  306  to be placed as close as possible to the zipper teeth  310  and zipper fabric  312 . Heat in these locations will cause most pests to move deeper into the enclosure rather than to attempt escape. The zipper grommet  308  is commonly used to secure the zipper fabric  312  to either the suitcase base shell  300  or the suitcase lid shell  302 . 
       FIG. 11  is a view of a mechanical barrier which may be used to prevent pests from climbing up the wheel and taking harborage or from egressing from a heated suitcase to a cooler point. During heated operation, the suitcase base shell  300  is designed to reach a temperature that would cause the bug to egress from the outer surfaces. The escape instinct threshold for pests such as bed bugs is reported as 108 F. If the wheel barrier  318  is designed to be sufficiently smooth, the pest would unable to escape by crawling down the wheel pivot rod  320  and taking harborage on the wheel assembly  316 . The wheel pivot rod may also be made from a material which would conduct heat further making harborage on the wheel assembly  316  undesirable. The convex shape of the wheel barrier  318  would prevent pests from crawling up the wheel assembly to take harborage on the suitcase when the elements are inactive. 
       FIG. 12  is a view of a mechanical barrier which may be used to prevent pests from aking harborage on the handle  322 . The handle barrier may take a convex shape as shown or simply be made of materials that are sufficiently non-porous to prevent traction by the pests. 
       FIG. 13  is a view of an enclosure which comprises an enclosure base  326  and an enclosure lid  328 . While the enclosure is shown as a suitcase, it is used here to demonstrate a method to employ heat conductive elements  330  to locally raise the temperature of cool spots previously identified as non-heated area  116 . The heat conductive elements  330  are arranged such that they transfer heat from the heating area  334  which is created by active elements of the heating film  332 . The heat conductive elements  330  can be coupled proximate or adjacent to the heating area  334 . The heat conductive element  330  can comprise a number of materials with a high thermal conductivity such as any of a heavy aluminum, copper, or alloy metal foil, biaxially-oriented polyethylene terephthalate, or the like. The heat conductive elements  330  can have several functions including: increased uniform distribution of heat generated by the heating film  332  within the heating area  334 , heat transfer from the heating area  334  to other areas within the inside space of the enclosure body, additional structural support for the heating film  332 , electrical isolation of the heating film  332  and associated circuitry, and contact protection of the heating film  332 . 
     There are numerous items used during travel which may be sensitive to heat which may include medicines, deodorants, and such.  FIG. 14  is a view of a non-heated pocket  400  which may be used to hold such materials during the heat treatment. The pocket may be on the enclosure wall  406  as shown or embedded in such that the outer flap is flush with the enclosure wall  406 . An insulation layer  404  may be used to prevent heat from the heating layer  402  to permeate the contents of the non-heated pocket. Mechanical barriers may be used to prevent pests from easily accessing the pocket. 
       FIG. 15  and  FIG. 16  are the detailed design of a heating tape  520  which may provide an electrical heat based barrier which may prevent pests from traversing across the barrier. The barrier is designed to have an extremely low profile thus avoiding a trip hazard and allowing easy access for devices such as hospital gurneys or wheeled medical equipment. The surface temperature should be sufficiently high to deter pests from going across, but low enough not to cause burns or be a health risk to humans. Because the width of the barrier is significantly small, the voltage across bus bar A  504  and bus bar B  506  may be low voltage thus reducing electrical hazard. The barrier layer  502  is a heat conductive material that is held at temperatures of 120 to 178 degrees Fahrenheit. The barrier layer is designed to incorporate several functions including: thermal transfer from the resistive elements  508  or IR carbon elements  510 , electrical isolation, and physical protection of the active elements. The width of the barrier layer  502  may vary depending on the environment and type of pest, but is designed such that a pest crawling across the surface would instantly be exterminated. The base layer  500  should have sufficient insulation such that it may be applied to cement or tile floors. As shown in  FIG. 15 , the heating elements may comprise resistive elements  508  such as NiChrome wire or similar alloy, carbon based. As shown in  FIG. 16 , the heating elements may comprise of IR carbon elements  510  such as those used in IR film. The IR carbon elements may be printed directly on the base layer  500  or barrier layer  502 . An adhesive may be applied to the base layer for ease of installation. For an alternative embodiment, the adhesive may be applied to the top of the barrier layer to heat items. The resistive elements  508  or IR Carbon Elements  510  may be regulated through the use of positive temperature coefficient materials. The power sent through the resistive elements  508  may be adjusted in manufacturing by increasing or decreasing the gap between the teeth of bus bar A and bus bar B. Because the elements in this design are parallel circuits, the overall length of the tape may be sufficiently long without affecting performance. 
       FIG. 17  is an example of how the heating tape  520  may be applied to the floor to create a protected area  522 . A splice connector  512  may be used at the corners to form angles or from the incoming power supply. The installation in  FIG. 17  shows a power cord  516  and step down transformer  518  to reduce the voltage. The low voltage line  514  which provides power to the heat tape  520  may be either AC or DC. While this figure illustrates the use of the heat barrier on the floor, it can equally be employed around doorways, on walls, or any surface to create a thermal barrier. 
     A temperature monitor  522 , such as a thermistor, may be used to locally read the temperature of the thermal barrier. Said temperature monitor may be coupled to a microprocessor  524  to provide a closed loop control of the heat tape  520 . The microprocessor  524  would limit power to the heat tape through a TRIAC or other common electrical power control circuit. Alternatively, a mechanical rheostat or other power limiting device may be used to set temperatures during installation or ongoing by the user.