Abstract:
The present invention relates to a sheet like resistance heating element for a battery powered lighter. The heating element includes a first terminal for connecting the heating element to a first contact of an electrical circuit and a second terminal for connecting the heating element to a second contact of the electrical circuit. The heating element further includes a heat generating body arranged between the first terminal and the second terminal, the heat generating body providing an electrical current path between the first terminal and the second terminal, wherein the heat generating body comprises a planar contact surface along the path, whereby a width of said contact surface in the plane is substantially greater then a thickness of the heat generating body.

Description:
RELATED APPLICATION 
       [0001]    The application claims the benefit of 35 USC 119(e) to U.S. Provisional Application Ser. No. 61/363,651 filed 13 Jul. 2010 (Dec. 7, 2010). 
     
    
     SCOPE OF THE INVENTION 
       [0002]    The present invention relates to a portable lighter, and more particularly to a battery powered flameless lighter. More specifically, the present invention relates to a rechargeable battery powered cigar lighter which includes a resistance heating element having a planar contact surface. 
       BACKGROUND OF THE INVENTION 
       [0003]    Most conventional battery powered portable lighters are designed for lighting cigarettes and mainly use double A or triple A batteries as their power source. Typically, the batteries are housed in an enclosure and are connected in series in an electrical circuit to pass current through a resistance wire heating element to generate heat. The wire heating element has a predetermined length dependent on the power source, and typically is wound into a tight spiral coil having an effective diameter sized to contact an abutting end of a cigarette. 
         [0004]    For example,  FIG. 1  illustrates a conventional wire heating element  500  having a first terminal connecting end  501 , a second terminal connecting end  502 , and an effective diameter D. In use, electrical current is passed through the wire heating element  500  from the first terminal connecting end  501  to the second terminal connecting end  502  to generate heat, and an abutting end of a cigarette is brought into contact with the heating element  500 , which serves as an ignition source. 
         [0005]    U.S. Pat. No. 5,235,157 published Aug. 10, 1993 discloses a typical battery powered cigarette lighter known in the art. The lighter includes two AA penlight batteries housed in a hollow plastic housing. The batteries are connected to one another in series to provide current to a spirally-wound Nichrome wire heating element. The lighter includes a pivotally mounted switch actuator to open and close a switch means to allow current to pass through the wire heating element to generate heat. The heating element is positioned within a cavity formed in a sidewall of the housing in recessed relation to the sidewall to provide access to the wire heating element. 
         [0006]    Battery powered lighters generally have not found widespread use or acceptance in the market place. This is because in comparison with gas lighters, in which fuel gas is ignited to generate a high temperature flame, the amount of energy at the resistance wire heating element is low, resulting in difficulties in igniting cigarettes and the like. Difficulties in ignition are further compounded due to the fact that the abutting end of the cigarette or the like only make contact with a portion of the outer circumferential surface of the wire heating element, which results in a majority of the heat generated in the wire heating element being dissipated radially outwardly to the surrounding atmosphere. Additionally, due to the current and voltage requirements of the batteries to generate sufficient heat in the wire heating element, conventional battery powered lighters are larger, heavier and more expensive to manufacture then conventional gas based lighters. 
         [0007]    Accordingly, there remains a need for a battery powered lighter which is inexpensive, light weight and which provides sufficient heat ignition properties. 
       SUMMARY OF INVENTION 
       [0008]    The present invention has been developed in view of the difficulties in the art noted and described above. To at least partially overcome these disadvantages, in a first aspect, the present invention provides a resistance heating element for a battery powered lighter, the heating element comprising: a first terminal for connecting the heating element to a first contact of an electrical circuit; a second terminal for connecting the heating element to a second contact of the electrical circuit; a heat generating body arranged between the first terminal and the second terminal, the heat generating body comprises an electrical resistance current path located between the first terminal and the second terminal for generating heat when current is applied between the first terminal and the second terminal, wherein the heat generating body comprises a planar contact surface along said path, whereby a width of said contact surface in said plane is substantially greater then a thickness of the heat generating body. 
         [0009]    In a further aspect of the invention, there is provided a resistance heating element for a battery powered lighter, the heating element comprising: a first terminal for connecting the heating element to a first contact of an electrical circuit; a second terminal for connecting the heating element to a second contact of the electrical circuit; and a heat generating body arranged between the first terminal and the second terminal, the heat generating body providing an electrical current path between the first terminal and the second terminal, wherein the heat generating body comprises a planar contact surface along said path, whereby a width of said contact surface in said plane is substantially greater then a thickness of the heat generating body. 
         [0010]    In a further aspect of the invention, the resistance current path comprises a spiral winding. 
         [0011]    In yet a further aspect of the invention, the first terminal and the second terminal are longitudinally aligned in the plane at opposing sides of the heat generating body. 
         [0012]    In yet a further aspect of the invention, the first terminal, the second terminal and the heat generating body are integrally made. 
         [0013]    In yet a further aspect of the invention, the resistance heating element is formed from a single piece of sheet metal. 
         [0014]    In yet a further aspect of the invention, the sheet metal is selected from the group consisting of a nickel chromium based alloy and a tungsten based alloy. 
         [0015]    In yet another aspect, the present invention provides a battery powered lighter comprising a battery, switch actuating means, and a switch to open and close the electric circuit, wherein the improvement resides in the lighter comprising a planar sheet-like resistance heating element, the heating element comprising: a first terminal for connecting the heating element to a first contact of an electrical circuit; a second terminal for connecting the heating element to a second contact of the electrical circuit; and a heat generating body arranged between the first terminal and the second terminal, the heat generating body providing an electrical current path between the first terminal and the second terminal, wherein the heat generating body comprises a planar contact surface along said path, whereby a width of said contact surface in said plane is substantially greater then a thickness of the heat generating body 
         [0016]    Further aspects of the invention will become apparent upon reading the following detailed description and drawings, which illustrate exemplary embodiments of this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Reference may now be had to the following detailed description taken together with the accompanying drawings in which: 
           [0018]      FIG. 1  shows a conventional wire heating element known in the art. 
           [0019]      FIG. 2  shows a front perspective view of an exemplary embodiment of a lighter in accordance with the present invention. 
           [0020]      FIG. 3  shows a front elevation view of the lighter shown in  FIG. 1 . 
           [0021]      FIG. 4  shows a back elevation view of the lighter shown in  FIG. 1 . 
           [0022]      FIG. 5  shows a side elevation view of the lighter shown in  FIG. 1 . 
           [0023]      FIG. 6  shows a front perspective view of a lighter cover in accordance with the present invention. 
           [0024]      FIG. 7  shows a schematic illustration of the internal electronic circuitry of the lighter shown in  FIG. 1 . 
           [0025]      FIG. 8  shows a front elevated view of the heating element of the lighter shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Reference may now be made to  FIG. 2  which illustrates a preferred embodiment of the lighter  10  of the present invention. The lighter  10  includes a rectangular shaped enclosure  12  which houses the electrical circuitry of the lighter  10 . The enclosure  12  is made from two mating enclosure halves  11 ,  13 , as indicated by parting line  15  in  FIG. 2 . 
         [0027]    The enclosure  12  includes a front wall  14 , a back wall  16 , side walls  18  and  20 , top wall  22  and a bottom wall  24 . The front wall  14  includes an actuating button  32  which is positioned in an opening  30  in the front wall  14 . Preferably, to avoid accidental activation of the lighter, the button  32  is recessed from the surface of the front wall  14  for added safety. 
         [0028]    To activate the lighter, the actuating button  32  is pressed into contact with a tactile switch  400  to close the electrical circuit of the lighter so that current flows from the battery  100  through the resistance heating element  80  to generate heat, as more fully detailed below. When the lighter  10  is not being used, the actuating button  32  is biased away from the tactile switch  400  so that the electrical circuit is normally open so no current may flow from the battery  100  through the heating element  80 . 
         [0029]    The bottom wall  24  includes a charging interface  40  which is positioned within an opening  42  in the bottom wall  24 . Preferably, the charging interface  40  is a micro USB connector. This common connector will allow for charging from many different sources. For example, desktop computers, laptops, wall units, cell phone chargers and solar panel units are all power sources that often have USB ports available and could all be used as a charging means to connect to the charging interface  40 . 
         [0030]    It is to be noted that the shape, size and material selection of the enclosure is not particularly limiting, but preferably is selected to be slim and lightweight to fit comfortably in the pocket of a user. Preferably the enclosure  12  is made from aluminium, and is dimensioned to have a width preferably between 30 mm to 50 mm, a height preferably between 80 mm to 100 mm, a thickness preferably between 6 mm to 10 mm, and a weight preferably between 20 g to 25 g. Larger enclosures may be used, which would allow for larger battery capacity. Similarly, the enclosure may have a cylindrical shape, or any other physical shape. 
         [0031]    As shown in  FIG. 3  and  FIG. 4 , the front wall  14  and back wall  16  include axially aligned circular openings  34   a  and  34   b , respectively. The heating element  80  is axially aligned and positioned within the cavity formed by the openings  34   a  and  34   b  in recessed relation to the front wall  14  and back wall  16 , respectively. In this manner, a cigar or the like may be ignited by axially inserting a leading end of the cigar through either the front opening  34   a  or back opening  34   b  into abutting contact with the contact surface of the heating element  80 . 
         [0032]    As shown in  FIG. 6 , the lighter  10  is provided with a rectangular cover  600  sized to be slidably received about a top portion of the enclosure  12  and to cover the heating element  80  and the actuating button  32 . A bottom half of the enclosure  12  is provided with an outwardly extending flange  602  which abuts a bottom portion  604  of the cover  600  so that with the cover installed, the outer faces of the cover  600  lay flush with the bottom portion of the enclosure  12 . Preferably, the cover includes a thermally insulating material so that with the cover installed, the lighter may be placed in the pocket of a user after using the lighter  10 . 
         [0033]      FIG. 7  shows a simplified schematic of the internal electrical circuitry of the lighter  10  housed within the enclosure  12 . The circuitry includes a battery  100  having a positive battery terminal (B+) and a negative battery terminal (B−). A printed circuit board (“PCB”)  200  which includes the charging interface  40 ; a Mosfet  300  having a Mosfet drain (Md), a Mosfet source (Ms) and a Mosfet gate (Mg); and a tactile switch  400  having a tactile switch connection (Ta) and a tactile switch connection (Tb). 
         [0034]    The following details the component connections relevant to powering the heating element  80 . The positive battery terminal (B+) is connected directly to the second connecting terminal  84  of the heating element  80 . The battery terminal (B+) is also connected to one side of the tactile switch connection (Ta). The other side of the tactile switch connection (Tb) is connected to the Mosfet gate (Mg). This provides a switch controlled positive charge to the Mosfet gate (Mg). When the tactile switch  400  is activated, there will be a positive charge between the Mosfet gate (Mg) and the Mosfet source (Ms) which is connected directly to the negative battery terminal (B−). This positive charge to the Mosfet gate (Mg) allows the current to flow through the Mosfet source (Ms) to the Mosfet drain (Md) and then through the connection of the Mosfet drain (Md) to the first connecting terminal  82  of the heating element  80 . The current will then flow through the heating element  80 , back to the battery  100  through the positive battery terminal (B+). The selected Mosfet  300  preferably has low resistance at load voltage in order to maximize power to the heating element  80 . The Mosfet  300  also preferably has a high resistance at low voltage, so that the battery  100  does not over discharge. 
         [0035]    In an alternative embodiment, a simpler PCB may be designed without a MOSFET if a high current switch is used. Additionally, with a PCB mounted tactile switch, the user actuating button  32  can be designed as part of the enclosure  12  or cover  600 , with any material and any shape, so long as the actuating button  32  comes into contact with the tactile switch  400 . 
         [0036]    As a further alternative to the PCB herein described, a battery with simple recharge characteristics (such as standard AA NiCads) and a switch of high current capacity would allow for direct wire connections between all components. This would eliminate the need for a PCB altogether. However, this would result in a larger overall unit size, fewer uses per charge, and reduced element heat output depending on the number of batteries used. 
         [0037]    The battery  100  is the sole energy source for the resistance heating element  80  and therefore is required to drive sufficient current through the heating element  80  to overcome the element&#39;s resistance. In selecting the battery  100 , appropriate considerations has to be given to the requirements, including but not limited to the power of the battery to drive sufficient current at the required voltages; recharge capability and total number of useful charges over its lifetime; the physical size of the battery; and the energy storage capacity of the battery. Given that the heating element  80  must be of a certain length and cross section to provide ignition heating over a certain contact surface area, and that the heating element must be of a certain resistance to generate sufficient ignition heat at the contact surface of the heating element  80 , there is a minimum determinable requirement for power. 
         [0038]    Preferably, the selected battery  100  is a single lithium ion polymer cell. Lithium ion polymer batteries have a small volume and high power output. They are small physical size, reasonable voltage, and excellent current capacity. Lithium ion polymer batteries also have good recharging characteristics, but require a specific charging pattern. This charging logic may be provided by an integrated circuit on the PCB. Preferably, the cell can be discharged at twenty times its energy storage capacity (20 C) and measures 30 mm wide, 50 mm tall, and 6 mm in thickness and has a storage capacity of 600 mAh. 
         [0039]    Alternatively, rather than a single cell, multiple cells could be used to power the heating element  80 . This would allow for a larger heating surface and faster heat up time. It could also provide longer use between charges and higher overall heating capability. 
         [0040]    In addition to the above mentioned components required for powering the heating element  80 , the PCB  200  also includes an integrated circuit to provide the charging logic for the battery. The charging integrated circuit was selected for its small size, ease of assembly, and simple functionality. The additional supporting components included are more fully described in the documentation provided with the charging integrated circuit, which is incorporated herein by reference. 
         [0041]    Reference may now be had to  FIG. 8  which illustrates the heating element  80  of the invention. The heating element  80  includes a first terminal  82  for connecting the heating element  80  to the Mosfet  300  and a second terminal  84  for connecting the heating element  80  to the positive battery terminal (B+). Each terminal  82  and  84  are provided with an aperture  90 A and  90 B, respectively, to position and/or secure the heating element  80  within the enclosure  12  by the use of internal locating pins (not shown) protruding from the enclosure  12 . 
         [0042]    Arranged between the first terminal  82  and the second terminal  84  is a heat generating body  86  having an articulate shape, resembling a wound spiral coil configuration. The heat generating body  86  provides an electrical resistance current path (P), indicated by the solid arrows, between the first terminal  82  and the second terminal  84 . Due to the electrical resistance characteristics of the heat generating body  86 , as current flows through the body  86 , resistance heat is generated by the body  86 . 
         [0043]    The heat generating body  86  has a sheet like construction having planar contact surfaces on opposing top and bottom faces of the body  86  (only top face contact surface  88  shown). The in plane width (W) across the path (P) of the contact surface  88  is substantially greater then a thickness of the heat generating body  86  due to the sheet like planar construction of the body  86 . Accordingly, the effective heating area diameter (D) of the heating element  80  would be equivalent to the total width (W) of each of the spiral loops plus the spacing provided between each loop, which is preferably as small as possible. 
         [0044]    Preferably, the first terminal  82 , the second terminal  84  and the heat generating body  86  are integrally made. More preferably, the heating element  80  is cut from a flat sheet metal into its desired shape, as for example using laser cutting. Preferably the heating element  80  has an effective heating area diameter D between 20 mm to 30 mm, and more preferably 25 mm. 
         [0045]    The heating element  80  of the present invention provides a greater contact surface  88  area for an abutting end of a cigar when compared to similar constructions made from a standard round wire heating element  500  of similar length and cross-sectional area. The greater contact surface  88  area results in improved ignition properties of the heating element  80 . Furthermore, the planar contact surface  88  provides directional heating, dissipating a majority of the heat orthogonally away from the contact surface  88 . 
         [0046]    The material selection of the heating element  80  is not particularly limiting. However, consideration must be given to the melting point, temperature deformation, and corrosion properties of the selected material. In addition, internal resistance is a critical factor in selecting the appropriate material in consideration of power restrictions. Preferably, the heating element  80  is made from a Nickel and Chromium based alloy. These alloys have high resistance properties and excellent heating characteristics, do not change shape significantly when heated, resist corrosion very well, and are highly efficient in converting electrical current into heat. 
         [0047]    The shape of the heating element  80  is also not particularly limiting, so long as the overall resistance allows for a reasonable heat output. However, when investigating standard round wire, the manufacturability of a finely wound wire in a flat shape with no terminal ending in the centre of the shape was determined to be impossible or cost prohibitive. This difficulty is directly overcome with the heating element of the present invention in accordance with the preferred embodiment illustrated in  FIG. 8 . 
         [0048]    Various thicknesses for the heating element were also tested. In selecting the thickness, the heat output is optimized against the overall resistance. For the given power output of the battery, the highest resistance possible would reduce overall current use and allow for more uses per charge. However, a resistance that is too high would result in too little heat output given the limited power output of the battery. A compromise is required and this was determined experimentally. However, there is a wide range of thicknesses that would still allow for functionality of the unit recognizing the trade off in component lifespan, battery lifespan, uses per charge, heat dissipation into the enclosure, and useful element heat output. Preferably the overall length of the heating element is between 190 mm to 150 mm, and more preferably about 170 mm. T width (w) is preferably between 2 mm and 1 mm, and more preferably about 1.85 mm, and the thickness is preferably less then 0.3 mm, and more preferably about 0.2 mm. Heating elements having the preferred construction were tested to reach red hot temperature in less then ten seconds. 
         [0049]    Although this disclosure has described and illustrated certain preferred embodiments of the present invention, it is also to be understood that the invention is not restricted to these particular embodiments. For example, in an alternative embodiment, the back wall  16  of the enclosure  12  may be provided with a highly reflective surface positioned directly behind the heating element  80 . The reflective surface would reflect heat emanating from the back face surface  88  of the heating element  80  towards the front. This reflective surface may be flat, or curved to direct the generated heat to the center or edges of the heating plane. 
         [0050]    Additionally, the enclosure  12  may be provided with internal contact pressure protrusions arranged for mating the internal components of the electric circuit. For example, this would be an alternative to soldering or crimping for internal connections between the battery  100 , PCB  200 , and heating element  80 . In this case, rather than wire conductors, pre-cut sheet metal conductors in the required shapes could be used to join the components. The sheet metal conductors would be placed into grooves within the bottom enclosure half  13 , and pressure would be applied from the top enclosure half  11  to form a connection between sheet metal conductors. The enclosure halves  11 , 13  may be screwed together at several points so that pressure is maintained as required to keep the conducting metal nodes firmly mated to one another. 
         [0051]    To the extent that a patentee may act as its own lexicographer under applicable law, it is hereby further directed that all words appearing in the claims section, except for the above defined words, shall take on their ordinary, plain and accustomed meanings (as generally evidenced, inter alia, by dictionaries and/or technical lexicons), and shall not be considered to be specially defined in this specification. Notwithstanding this limitation on the inference of “special definitions,” the specification may be used to evidence the appropriate, ordinary, plain and accustomed meanings (as generally evidenced, inter alia, by dictionaries and/or technical lexicons), in the situation where a word or term used in the claims has more than one pre-established meaning and the specification is helpful in choosing between the alternatives. 
         [0052]    It will be understood that, although various features of the invention have been described with respect to one or another of the embodiments of the invention, the various features and embodiments of the invention may be combined or used in conjunction with other features and embodiments of the invention as described and illustrated herein. 
         [0053]    Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to these particular embodiments. Rather, the invention includes all embodiments, which are functional, electrical or mechanical equivalents of the specific embodiments and features that have been described and illustrated herein.