Abstract:
A protective sole of an item of footwear for electric and electrostatic charges comprises a sole unit comprising at least a midsole portion and an outsole portion. The midsole portion is connected on top of the outsole, with the midsole portion oriented toward the wearer while the outsole portion is against the ground when the item of footwear is worn. An electronic device is inserted in the sole unit, and comprises circuitry with a first contact end exposed on a top surface of the midsole portion to be electrically connected with the wearer, and a second contact end to be electrically connected with the ground via the outsole portion. A substrate supports the circuitry and is adapted to be mounted in the sole unit. Electronic components are between the first and the second contact ends, on the circuitry, and concurrently performing a ground of electrostatic charges and insulation against electric discharges. A body made of an electrically insulated molding compound or conformal coating is accommodated in the sole unit, the body being sized to completely cover the at least one electronic component.

Description:
FIELD OF THE APPLICATION 
       [0001]    The present application relates to safety footwear and, more particularly, to footwear equipped with an electronic device for electro-hazard and/or electro-static protection. 
       BACKGROUND OF THE ART 
       [0002]    Work shoes incorporating resistors or electronic circuits have been disclosed to offer a way to dissipate static charges from the human body. Work shoes provide very difficult conditions to electronic devices incorporated within them. Work shoes are submitted to continuous flexions, walking impact and shocks, changing weight compressions, hydrolysis, varying temperatures, etc. Long term reliability of the electronic devices integrated in these shoes is essential since these shoes are worn on jobsites where static dissipative performance and electro-hazard protection are crucial. 
         [0003]    Protective footwear certification organizations (for example, the Canadian Standard Association) are concerned about static-dissipative work footwear that use electronic components like resistors. Certain organizations require flexion and compression tests of specimens to make sure they can live up to real-world conditions. Prior art shoes often fail to provide a stable and constant level of static-dissipative performance or electro-hazard protection under such conditions. 
         [0004]    The hydrolysis problem (i.e.: humidity penetrating into the sole of a shoe) has a particularly negative effect on the permanent functioning of electronic components. Work footwear constructed according to the prior art fail to supply a consistent static-dissipative performance and electro-hazard protection when affected by hydrolysis. The same can be said with regards to varying temperatures. 
         [0005]    More importantly, the protection of wearers against the risk of electrocution in conventional industrial settings requires particular attention to the integration of electronic components and electronic devices into footwear. For example, in North America, industrial manufacturers frequently use 600 volts alternative current power (600V A.C., 50-60 hertz) and thus, work footwear must be able to protect wearers against the grounding of such power. Electronic components have shown to be fragile when submitted to alternative current. High voltage is destructive to the components and impairs their proper functioning. Research (lab tests and real-world tests) points out that the use of carbon-powder enriched elastomers (plastics, rubbers or the like) near electronic components increases the risk of destruction of such electronic components. A 600 Volts A.C. “phase-to-neutral” electrical tension applied for 10 seconds to work footwear constructed according to the prior art destroys the electronic devices: the conductive elastomer is carbonized and the shoes set on fire. 
         [0006]    Furthermore, it is a difficult task for shoe manufacturers to integrate small electronic devices into footwear. The connection between the electronic device and the wearer interface (i.e.: insole) or the ground interface (i.e.: outsole) requires particular attention. Prior art shoe design has not entirely taken into consideration the particularities of the shoe industry in the integration of electronic components: shoe manufacturers require an easier way to integrate electronic devices into their goods. 
       SUMMARY OF THE APPLICATION 
       [0007]    It is therefore an aim of the present disclosure to provide a novel electronic device that addresses issues associated with the prior art. 
         [0008]    It is a further aim of the present disclosure to provide a novel method for assembling electronic devices into footwear items that addresses issues associated with the prior art. 
         [0009]    Therefore, in accordance with the present application, there is provided an electronic device to be inserted in the sole of a footwear item, comprising: circuitry with at least a first contact end to be electrically connected with the wearer and a second contact end to be electrically connected with the ground; a substrate supporting at least part of the circuitry and adapted to be mounted to the sole; at least one electronic component between the first and the second contact ends, on circuitry, the at least one electronic component concurrently performing a ground of electrostatic charges and insulation against electric discharges; a body made of an electrically insulated molding compound or of conformal coating, the body being sized to completely cover the at least one electronic component. 
         [0010]    Further in accordance with the present application, there is provided a protective sole of an item of footwear for electric and electrostatic charges, the protective sole comprising: a sole unit comprising at least a midsole portion and an outsole portion, the midsole portion connected on top of the outsole, with the midsole portion oriented toward the wearer while the outsole portion is against the ground when the item of footwear is worn; and an electronic device to be inserted in the sole unit, and comprising: circuitry with at least a first contact end exposed on a top surface of the midsole portion to be electrically connected with the wearer, and a second contact end to be electrically connected with the ground via the outsole portion; a substrate supporting at least part of the circuitry and adapted to be mounted in the sole unit; at least one electronic component between the first and the second contact ends, on the circuitry, the at least one electronic component concurrently performing a ground of electrostatic charges and insulation against electric discharges; and a body made of an electrically insulated molding compound or of conformal coating accommodated in the sole unit, the body being sized to completely cover the at least one electronic component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a top perspective view of an electronic device constructed in accordance with a first embodiment of the present disclosure; 
           [0012]      FIG. 2  is a bottom perspective view of the electronic device of  FIG. 1 ; 
           [0013]      FIG. 3  is a top view of the electronic device of  FIG. 1 ; 
           [0014]      FIG. 4  is a bottom view of the electronic device of  FIG. 1 ; 
           [0015]      FIG. 5  is a side view of the electronic device of  FIG. 1 ; 
           [0016]      FIG. 6  is a cross-sectional view A-A of  FIG. 5 ; 
           [0017]      FIG. 7  is a top assembly view of the electronic device of  FIG. 1 ; 
           [0018]      FIG. 8  is a bottom assembly view of the electronic device of  FIG. 1 ; 
           [0019]      FIG. 9  is a top perspective view of a footwear sole incorporating the electronic device of  FIG. 1 ; 
           [0020]      FIG. 10  is a top assembly view of the footwear sole of  FIG. 9 ; 
           [0021]      FIG. 11  is a bottom assembly view of the footwear sole of  FIG. 9 ; 
           [0022]      FIG. 12  is a top perspective view of an electronic device constructed in accordance with a second embodiment of the present disclosure; 
           [0023]      FIG. 13  is a top view of the electronic device of  FIG. 12 ; 
           [0024]      FIG. 14  is a perspective view of a an electronic device constructed in accordance with a third embodiment of the present disclosure; 
           [0025]      FIG. 15  is a top view of the electronic device of  FIG. 14 ; 
           [0026]      FIG. 16  is a top assembly view of the electronic device of  FIG. 14 ; 
           [0027]      FIG. 17  is a bottom assembly view of the electronic device of  FIG. 14 ; 
           [0028]      FIG. 18  is a schematic view of a top of a printed circuit of the electronic device of  FIGS. 1 ,  11  and  13 ; 
           [0029]      FIG. 19  is a schematic view of the bottom of the printed circuit of the electronic device of  FIGS. 1 ,  11  and  13 ; 
           [0030]      FIG. 20  is a top plan view of an electronic device constructed in accordance with a fourth embodiment of the present disclosure; 
           [0031]      FIG. 21  is a top plan view of the electronic device of  FIG. 20 , with an insulated molding body removed from a printed circuit; 
           [0032]      FIG. 22  is a bottom plan view of the electronic device of  FIG. 21 ; 
           [0033]      FIG. 23  is a top perspective view of a footwear sole incorporating the electronic device  FIG. 20 ; and 
           [0034]      FIG. 24  is an assembly view of a footwear midsole and outsole incorporating the electronic device of  FIG. 20 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Description of the First Embodiment of the Electronic Device 
       [0035]    Referring to  FIGS. 1 to 8 , an electronic device in accordance with a first embodiment is generally shown at  1 . The electronic device  1  is used as part of a shoe to dissipate electric charges and to protect the wearer of the shoe from electro hazards, and therefore defines a conductive path via a circuitry. The electronic device  1  has a top interface  2  exposed in its top surface. A body  3  of the electronic device  1  is shaped as a disc, or in any other suitable shape. The body  3  is made of an insulated molding material, such as thermoplastic hot melt, of a conformal coating, or of any other appropriate polymeric material or the like providing protection from moisture. The conformal coating may be acrylic, epoxy, polurethane, silicone, poly-para-xylylene (parylene) or amorphous fluoropolymer, among other possibilities. 
         [0036]    The body  3  encapsulates electronic components that perform the electrostatic and/or electrical protective functions. More specifically, a printed circuit  4  (such as a printed circuit board or other type of circuitry  4 ) is inside the body  3 , and is connected to the top interface  2  and a bottom contact plate  5 . The bottom contact plate  5  may or may not be an integral part of the printed circuit  4 . The bottom contact plate  5  is exposed through a bottom hole  6  in the body  3 . 
         [0037]    Referring to  FIGS. 6 to 8 , an interior and an assembly of the electronic device  1  are illustrated. The top interface  2  is part of a substrate comprising a top conductive insert  7  that is in contact with the printed circuit  4 , through a rectangular prism  9 . The insert  7  is for instance made of a conductive elastomer, amongst other possibilities of substrate materials. The prism  9  may have various shapes, as long as it contacts the printed circuit  4 . The printed circuit  4  has electronic components  8  mounted thereto, such as resistors, transistors or the like. 
         [0038]    In order to be connected with the conductive insert  9 , the printed circuit  4  is part of the conductive circuitry, which may also comprise a top contact plate  10  ( FIG. 7 ), being in contact with the prism  9 . Accordingly, the printed circuit  4  is in contact with both the insert  7 , and the bottom contact plate  5 . 
         [0039]    In the embodiment of  FIGS. 1 to 8 , the body  3  may be overmolded onto the other components of the electronic device  1 , leaving at least the top interface  2  and the bottom contact plate  5  exposed. The hole  6  in the body  3  allows the electronic device  1  to be used in conjunction with cemented and direct-attach sole assembly processes. 
         [0040]    Referring to  FIG. 9 to 11 , the electronic device  1  is shown being inserted in a sole  11  of a shoe. The sole  11  has a midsole  12  that may be electrically insulated (to some extent), and features a hole  14 , for instance in the heel, to accommodate the electronic device  1 . The hole  14  is sized and shaped for snugly receiving the electronic device  1 . An outsole  13  is at a bottom of the midsole  12 , and is partly electrically insulated. 
         [0041]    Referring to  FIG. 10 , an interface is provided on a top surface of the outsole  13 , for contact with the electronic device  1 . In the illustrated embodiment, the interface has a large cylinder  15 , upon which is concentrically positioned a small cylinder  16 , projecting upwardly from the large cylinder  15 . Accordingly, the small cylinder  16  is mated into the bottom hole  6  of the electronic device  1 , and an annular bottom of the body  3  sits on the large cylinder  15 . The small cylinder  15  is made of a conductive material, and contacts conductive zones  17  on a bottom of the outsole  13 . The conductive zones  17  define a conductive path  18  in a bottom of the outsole  13 . The conductive path  18  may form only a part of the undersurface of the outsole  13 , with non-conductive zones  19  being made of a material with non-marking properties. The non-conductive zones  19  may be made of a material of lesser cost. 
       Description of the Second Embodiment of the Electronic Device 
       [0042]    Referring to  FIGS. 12 and 13 , an electronic device in accordance with a second embodiment is shown at  20 , and does not have a conductive elastomer material. The body  21  is made of an insulated molding material, such as a thermoplastic overmelt encapsulating the electronic components of the circuitry (not shown). A hole  22  is defined in the material of the body  21 , and is illustrated having a rectangular section, amongst other possibilities. Accordingly, a top contact plate of the circuitry is exposed through the hole  22 . The electronic components are in zone  24 , and are encapsulated in the material of the body  21 . 
         [0043]    The electronic device  20  as shown in the second embodiment presents a cost effective because of the absence of a conductive elastomer insert. However, it may be more difficult to integrate into footwear items, as the manufacturer must make sure the top contact plate  23  of the circuitry is in a permanent and reliable electric contact with the wearer. Consequently, a conductive filler may be used or may be required. The hole in the bottom (similar to hole  6  in  FIG. 6 ) allows the electronic device  20  to be used in conjunction with cemented and with direct-attach sole assembly processes. 
       Description of the Third Embodiment of the Electronic Device 
       [0044]    Referring to  FIGS. 14 to 17 , an electronic device in accordance with a third embodiment is generally shown at  25 , and has two conductive elastomer inserts, namely top conductive elastomer insert  28  and bottom conductive elastomer insert  30 . The body  26  is made of an insulated molding material, such as a thermoplastic hotmelt overmolding printed circuitry  29 . The conductive elastomer insert  28  has a top interface  27 , having a hexagonal shape, or any suitable shape, projecting from a bottom disc portion. Accordingly, the insert  28  is encapsulated in the body  26 , with the hexagonal top interface  27  being exposed for contact with a wearer. 
         [0045]    The printed circuitry  29  has a top contact plate  31  that is in contact with a rectangular projection  34  ( FIG. 17 ) of the top conductive elastomer insert  28 , and a bottom contact plate  33  in contact with the bottom conductive elastomer insert  30 . The insert  30  has a bottom interface  32  that is in contact with a conductive zone of the outsole, in similar fashion to the electronic device  1  ( FIGS. 1 to 11 ). 
         [0046]    The third embodiment is more expensive to produce than the other two embodiments, as the overmolding process is more complex. However, it provides a simple solution to integrate into cemented footwear items. 
       Description of the Fourth Embodiment of the Electronic Device 
       [0047]    Referring to  FIGS. 20 to 22 , there is illustrated an electronic device  42  in accordance with yet another embodiment of the present disclosure. The electronic device  42  has a substrate made from an elongated strip of a flexible material (or part flexible material, part rigid material). In an embodiment, the flexible material is a polymer, such as polyimide, polyester, PET, PEEK, or the like. In another embodiment, the flexible material forms flexible electronics with the circuitry thereon. In such a case, the circuitry may be installed on the flexible material in any appropriate way (e.g., screen printing, photolithographic technology, or the like). The elongated strip has a first flexible substrate portion  43  and a second flexible portion substrate  44 . The flexible substrate portions  43  and  44  are interconnected by an electronic component housed in body  45 . The body  45  is similar to the afore-mentioned bodies and is typically made of an insulated molding compound, a conformal coating or a material that will house electronic components and therefore protect same from temperature, humidity, compression, impacts, etc. The flexible substrates  43  and  44  have conductive elements thereon that will be in contact with the circuitry within the body  45 . 
         [0048]    More specifically, a first contact plate is generally illustrated at  46  and is on the first flexible substrate  43 . The first contact plate  46  is in contact with the foot of the wear or with a conductive sock liner that is in contact with the foot of the wearer. In the illustrated embodiment, the first contact plate  46  is in conductive relation with a conductive portion  47   a  on another side of the flexible substrate  43 . The conductive portion  47   a  is separated from a second contact plate  47   b  that is positioned on a bottom surface of the second flexible substrate  44 . The second contact plate  47   b  is therefore in conductive relation with parts of the outsole as will be shown hereinafter. 
         [0049]    Printed circuit  48  may either be flexible or rigid and is housed in the body  45 . The printed circuit  48  performs the electrostatic and electric protective functions. In the embodiment of  FIGS. 20 to 24 , the printed circuit  48  has a sequence of a small-signal transistor  49  (depletion mode, SIPMOS# 1 ), a first resistor  50 , another small-signal transistor  51  (depletion mode, SIPMOS# 2 ), a third small-signal transistor  52  (depletion mode, SIPMOS# 3 ), a second resistor  53 , and finally another small-signal transistor  54  (depletion mode, SIPMOS# 4 ). It is pointed out that the printed circuit  48  may have more than two resistors. Similarly, more than four depletion mode small-signal transistors may be used. The transistors are the gate threshold of the printed circuit  48 , ensuring that the voltage at the resistors is controlled. The resistor opposes a resistance to the voltage, so as to control the current passing through the printed circuit  48 . 
         [0050]    Referring to  FIGS. 23 and 24 , there is illustrated the electronic device  42  as positioned in a sole  55  of a footwear item. The sole  55  has a midsole  56  that is relatively insulated (e.g., an electrical resistance being over 35,000,000 ohms according to test method ASTM F2413-05 is well suited for the midsole  56 ). The outsole  57  is at a bottom of the midsole  56  and is relatively conductive or has parts that are relatively conductive (e.g., an electrical resistance being below 500,000 ohms according to test method ASTM F2413-05 is well suited for the outsole  57 ). A slot  58  is defined in the midsole  56  and allows a portion of the first flexible substrate portion  43  to pass therethrough so as to have a major portion of the electronic device  42  on a bottom side of the midsole  56 , and therefore in contact with the outsole  57 . As shown in  FIG. 24 , there may be defined a cavity in the midsole  56  so as to accommodate the body  45  of the electronic device  42 . Considering that the substrate portions  43  and  44  are flexible, they have a tendency to remain in contact with the foot of the wearer, thereby insuring that there remains a conductive path between the foot of the wearer and the electronic device  42 . 
       Description of an Embodiment of the Printed Circuit 
       [0051]    Referring to  FIGS. 18 and 19 , an example of suitable printed circuit is shown at  35  in the form of a printed circuit board, and has a top contact plate  36 , small signal transistor  37 , resistor  38 , small signal transistor  39 . A hole  40  in the printed circuit  35  allows electrical contact between the circuit and a bottom contact plate  41 . 
         [0052]    The small signal transistors  37  and  39  may operate in a depletion mode, and may be SIPMOS, by Infineon #BSS126, among other possibilities. The resistor  38  may be a SEI # RMCF 1/16 6K04 1% TR, among other possibilities. 
         [0053]    The electronic devices described herein improve the functioning and long-term reliability of safety footwear by protecting printed circuits and electronic components. The thermoplastic hotmelt molding material offers thermal stability and physical protection against impact shocks, weight compressions and flexions. It also offers a high level of electrical insulation, resisting in some cases a tension of 18,000 Volts with a 1 mm thickness. 
         [0054]    Moreover, the electronic devices described herein reduce problems due to hydrolysis by sealing the printed circuits and electronic components. The injection process of the thermoplastic hotmelt molding material assures that components stay dry and protected from humidity. 
         [0055]    The electronic devices described herein also provide a solution to reduce the risk of destruction of electronic components in situation of high voltage alternative current discharge. The thermoplastic hotmelt molding material electrically insulates all parts of the disclosed electronic device, significantly reducing the risk of electrical “short” or “arc” from one conductive part to an other (for example: from the top conductive elastomer insert  7  to the small cylinder  16  of the sole, as in  FIG. 10 ). High voltage alternative current may be highly hazardous to human. Consequently, footwear incorporating electrical devices must be designed to assure enhanced safety. 
         [0056]    The electronic devices described herein provides a reliable solution to comply with standards on protective footwear incorporating electronic components like resistors, and simplifies the integration of electrical devices into footwear by shoe manufacturers. The shape of the disclosed electronic device makes it easier for manufacturers of footwear to assure a good electrical contact from the top layers (insole, construction board) of the shoe to the top contact plate ( 10 ) of the electronic device and from the bottom contact plate ( 5 ) to the conductive zones ( 17 ) of the outsole. 
         [0057]    The novel method of assembly simplifies the integration of electrical devices into footwear by shoe manufacturers. The method ensures a reliable electrical connection between the top layers (insole, construction board) of the shoe and the top interface  2  of the electronic device. The method also ensures a reliable electrical connection between the bottom contact plate  5  of the electronic device and the conductive zones  17  of the outsole, and provides an efficient dissipative performance without sacrificing the “non-marking” and other important physical properties of the outsole.