Patent Publication Number: US-2022225705-A1

Title: Optical Face Protection Shield, Heated Optical Face Protection Apparatus, and Method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 63/140,157 filed on Jan. 21, 2021 entitled Face Shield Heater and Eyeglass Heater, the entirety of which is incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     This disclosure pertains to heaters for eye and face protection. More particularly, this disclosure relates to heaters for face shields, eyeglasses, and goggles to remove condensation from optical shields used by manufacturing workers, construction workers, healthcare workers and anyone in need of face protection requiring optical clarity and visibility through the face shield. 
     BACKGROUND OF THE DISCLOSURE 
     Techniques are known for heating one or more lenses in a face mask, such as a scuba mask, eyeglasses, face shields or goggles. However, improvements are needed to enhance operation, aesthetic configuration layout, power supply interchangeability, airflow contamination, efficient heat delivery, and air flow convection and conveyance pathways on a face shield, mask, goggles, and/or eyeglasses. 
     SUMMARY OF THE INVENTION 
     A heater is provided for a mask or eyeglasses, such as a face shield or eyeglasses rendering an optically transmissive portion of a lens capable of removing or mitigating condensate, moisture, ice, snow and frost buildup that can interfere with a user having visibility while working in challenging conditions such as healthcare workers or manufacturing workers using such face shields to mitigate droplet transmissions during a viral pandemic, or for manufacturing workers needing protection from flying debris. 
     According to one aspect, an optical face protection shield is provided having a support body, an optic lens, and an elongate heater. The support body has a user interface. The optic lens is carried by the support body over a user&#39;s face configured to protect a user. The elongate heater is carried by the optic lens so as to traverse an expansive surface area of the optic lens. The elongate heater has an elongate resistive heating element and an outer thermally transmissive, peak temperature mitigating, and an electrically insulative cover material encompassing the resistive heating element. 
     According to another aspect, a heated optical face protection apparatus is provided having a support body, at least one lens, an elongate heating element, and a source of airflow. The support body is configured to be supported on a user. The at least one lens is carried by the support body and is configured to hold the at least one lens over an eye facial region of a user. The elongate heating element has an elongate tube and a heat source provided in the tube. The elongate heating element is carried by the body and is configured to traverse an expansive surface area of the at least one lens. The source of airflow communicates with the elongate heating element and is configured to drive airflow through the elongate heating element to heat the flow of air. 
     According to yet another aspect, a method is provided for heating an optical face protection apparatus. The method includes: providing a support body having a user interface, an optic lens carried by the support body, and an elongate heater spanning a portion of the optic lens; mating the user interface with a user to present the optic lens over a user&#39;s face; generating heat with the elongate heater; and distributing the generated heat to the optic lens to mitigate condensate occlusion on the lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the various disclosures are described below with reference to the following accompanying drawings. The drawings may be considered to represent scale. 
         FIG. 1  is a front perspective view from above of a heated face shield having an elongate heater carried in spaced apart relation along a bottom edge of the face shield lens. 
         FIG. 2  is a rear perspective view from below of the heated face shield of  FIG. 1 . 
         FIG. 3  is a front view of the face shield of  FIGS. 1-2 . 
         FIG. 4  is a right-side view of the face shield of  FIG. 3 . 
         FIG. 5  is a vertical sectional view of the face shield taken along line  5 - 5  of  FIG. 3 . 
         FIG. 6  is an enlarged view of the heater assembly and lens taken from the encircled region  6  of  FIG. 5 . 
         FIG. 7  is an exploded front perspective view from above of the heater assembly corresponding with the view taken in  FIG. 1 . 
         FIG. 8  is a front exploded perspective view from above of the heated face shield of  FIGS. 1-6 . 
         FIG. 9  is a perspective view of the battery pack and battery pack receiver for the heated face shield of  FIGS. 1-6 . 
         FIG. 10  is a right-side view of the battery pack and battery pack receiver of  FIG. 9 . 
         FIG. 11  is a front vertical view of the battery pack and battery pack receiver of  FIG. 10 . 
         FIG. 12  is an enlarged view of the battery latch spring of  FIG. 11  taken from the encircled region  12  of  FIG. 11 . 
         FIG. 13  is an exploded perspective view of the battery pack and battery pack receiver of  FIGS. 1-6 and 9-12 . 
         FIG. 14  is an exploded perspective view of the battery pack receiver of  FIGS. 1-6 and 9-13 . 
         FIG. 15  is a front perspective view from above of an alternate heated face shield with a heater and a portable filtered forced air source. 
         FIG. 16  is a rear perspective view from behind of the heated face shield of  FIG. 15 . 
         FIG. 17  is a front view of the face shield of  FIGS. 15-16 . 
         FIG. 18  is a right-side view of the face shield of  FIG. 17 . 
         FIG. 19  is a vertical sectional view of the face shield taken along line  19 - 19  of  FIG. 17 . 
         FIG. 20  is an enlarged view of the forced air heater assembly and lens taken from the encircled region  20  of  FIG. 19 . 
         FIG. 21  is an exploded perspective view of the portable filtered forced air source of  FIGS. 15-20 . 
         FIG. 21A  is a transverse sectional view of the air filter element taken along section  21 A- 21 A of  FIG. 21 . 
         FIG. 22  is a rear perspective view of a further alternate heated and air ventilated face shield with an external clean air source, such as a hospital air source or a biologic research lab air source in the form of an external forced air source regulator assembly over that shown in  FIG. 15 , but having an external filtered air source, such as a wall-mounted building filtered air source found in a hospital or laboratory environment. 
         FIG. 23  is an exploded perspective view of the portable heated and filtered external forced air source regulator assembly of  FIG. 22 . 
         FIG. 24  is an enlarged view of an optional construction forced air lens cleaner for the mask of  FIGS. 22-23  taken from an encircled region corresponding with the encircled region  20  of  FIG. 19 , but for the face shield of  FIGS. 22-23 . 
         FIG. 25  is an enlarged view of a second optional construction forced air heater assembly and lens for the mask of  FIGS. 22-23  taken from an encircled region corresponding with the encircled region  20  of  FIG. 19 , but for the face shield of  FIGS. 22-23 . 
         FIG. 26  is an enlarged sectional view of the forced air heater assembly of  FIG. 25  taken from encircled region  26  of  FIG. 25 . 
         FIG. 27  is a third optional construction forced air heater assembly and lens for the mask of  FIGS. 22-23  taken from an encircled region corresponding with the encircled region  20  of  FIG. 19 , but for the face shield of  FIGS. 22-23 . 
         FIG. 28  is perspective view from in front and above of a pair of heated eyeglasses. 
         FIG. 29  is a perspective view from behind and below of the heated eyeglasses of  FIG. 28 . 
         FIG. 30  is a plan view from above of the heated eyeglasses of  FIGS. 28-29 . 
         FIG. 31  is a vertical sectional view of the eyeglasses taken through line  31 - 31  of  FIG. 30 . 
         FIG. 32  is an exploded perspective view of the eyeglasses of  FIG. 28 . 
         FIG. 33  is an enlarged perspective view from the encircled region  33  of  FIG. 32   
         FIG. 34  is an exploded perspective view of the temple for the eyeglasses of  FIGS. 28-32 . 
         FIG. 35  is a perspective view of heated safety glasses. 
         FIG. 36  is an exploded perspective view of the heated safety glasses of  FIG. 35 . 
         FIG. 37  is a vertical sectional view of one heated lens taken along line  37 - 37  of  FIG. 36 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     Eye and face protection can limit user visibility under certain conditions of temperature, humidity, especially when used in combination with masks during threat of a viral pandemic. During the recent outbreak of COVID-19, healthcare workers. manufacturing plant workers, restaurant workers, and business employees found themselves wearing masks and face shields to mitigate transmission of virus. However, constant use oftentimes leads to fogging of the lens on face shields and eyeglasses. This problem was further exacerbated when users wore face masks in combination with face shields. This resulted in risks to users as well as patients especially when used in a hospital setting. The addition of a portable heater source to face shields and eyeglasses has been found to mitigate such risks. 
       FIG. 1  illustrates one suitable construction for a heated face shield  10  having an elongate heater assembly  12  configured to mitigate condensate buildup on a lens  18  on face shield  10 . Face shield  10  has a visor, or top hood  24  affixed atop lens  18  which downward extends in a semi-circular configuration. A pair of frictionable pivot fastener assemblies  32  and  34  is provided along opposed top edges of visor  24  to secure visor  24  and lens  18  in pivotable relationship relative to a user headband assembly  26  that is received atop a user&#39;s head. Such configuration enables raising and lowering of visor  24  and lens  18  while a user is wearing heated face shield  10 . A plurality of adhesive backed mounting brackets  36 ,  38  and  40  are spaced apart along a bottom edge of lens  18  on an inner surface along with individual Nylon zip cable ties  52  (see  FIG. 2 ). Mounting brackets  36 ,  38  and  40  support elongate heater assembly  12  in radially inwardly spaced apart relation from an inner surface of lens  18 . Additionally, a battery support tray, or housing  28  is affixed onto a rear portion of headband assembly  26  configured to removably receive a battery pack  30 . 
       FIG. 2  illustrates in greater detail features of heated face shield  10 . More particularly, mounting brackets  36 ,  38  and  40  are adhesively affixed onto an inner surface of lens  18  and individual cable ties  52  affix heater tube assembly  12  at discrete, spaced-apart locations along lens  18  so as to provide arcuate air flow gaps  42  and  44  between lens  18  and heater assembly  12 . Visor  24  and lens  18  are pivotally affixed onto head band frame  26  via a pair of friction lock threaded bolt and nut fastener assemblies  32  and  34 . 
     Head band assembly  26 , shown in  FIG. 2 , includes a front, or forehead band  46 , a top head band  48 , and a rear head band  50 . A battery pack holster, or case  28  is affixed onto a rear portion of rear head band  50  and a rechargeable battery pack  30  is affixed onto case  28 . One suitable battery pack is a lithium polymer battery. Another suitable battery pack is a Nickel metal hydride battery. Other types of batteries can also be used. 
     As shown in  FIGS. 3 and 4 , heated face shield  10  orients lens  18  in a vertical semi-cylindrical orientation when in use supporting shield  18  in front of a user&#39;s face, while heater assembly  12  is provided along a lowermost edge of shield  18  to mitigate condensate on an inner (and outer) surface of lens  18 . Head band assembly  26  supports heated face mask  10  atop a user&#39;s head while in use. 
       FIG. 5  illustrates support of heater assembly  12  along a bottom edge of lens  18  of face shield  10  in spaced apart relation so as to provide convection air gaps, such as arcuate gap  44 . While mounted on a user&#39;s head via head band assembly  26 , lens  18  is oriented vertically when lowered in use and heat from heater assembly  12  rises along an inner surface drawing a vertical upward flow of air through gap  44  along an inner surface of lens  18  to impart upward convection airflow that exits from a top portion of face shield  10 . 
       FIG. 6  illustrates the provision of a convective upward air flow gap  44  provided between an inner surface of lens  18  and heater assembly  12 . More particularly, heater assembly  12  is affixed in spaced-apart relation from an inner surface of lens  18 . Heat from heater assembly  12  rises, imparting upward convective air flow along an inner surface of lens  18  through air gaps, such as gap  44 . Heater assembly  12  comprises a polytetrafluoroethylene (PTFE) inner tube  56 , a polytetrafluoroethylene (PTFE) outer tube  58 , a central, or coaxial inner resistive heating wire, or Nichrome wire  60  and an insulated return ground wire  62 . 
       FIG. 7  illustrates in exploded perspective view components of heater assembly  12  of  FIGS. 1-6 . A U-shaped segment of Nichrome resistance heating wire  60  is inserted within inner PTFE tube  56  which is further inserted into a bottom curved portion of outer tube  58 . A distal end of Nichrome wire  60  is electrically coupled with a solder bead  70  to a distal end of an insulated copper ground wire  62  that follows an outer surface of inner tube  56 . An insulated copper power supply wire  68  is electrically affixed with a solder bead  66  onto a proximal end of Nichrome resistance heating wire  60 . A heat-resistant PTFE end plug  64  electrically isolates a distal end of outer tube  58 . 
     According to one construction, wire  66  is a coaxial inner Nichrome, or nickel chromium wire segment commercially available as Nichrome 60, available from MOR ELECTRIC HEATING ASSOC., INC, 5880 Alpine Ave. NW, Comstock Park, Mich. 49321 United States. 
     According to one construction, inner tube  56  is a PTFE extruded tube having an outer diameter and an inner diameter available from Zeus Inc. Headquarters., 620 Magnolia Street, Orangeburg, S.C. 29115 United States. 
     According to one construction, outer tube  58  is a PTFE extruded tube having an 0.35″ outer diameter and an 5/16″ inner diameter available from Zeus Inc. Headquarters., 620 Magnolia Street, Orangeburg, S.C. 29115 United States. Other high temperature plastics, composites, and/or metals can also be used for outer tube  58  in the various embodiments disclosed herein. 
       FIG. 8  illustrates details in exploded view of heated face shield  10 . Heater assembly  12  is affixed along a bottom edge of face shield lens  18  with three spaced apart adhesive tape mounting brackets  36 ,  38  and  40 . Additionally, adhesive tape mounting brackets  37  and  41 , and pivot bracket  63  affix an upper portion of heater assembly  12  onto head band frame  26 . One suitable mounting bracket  36 ,  37 ,  38 ,  39 ,  40  and  41  is a Panduit adhesive backed cable tie mount, Part No. ABM1M-A-C, available from Panduit Corp., Panduit Worldwide Headquarters, Tinley Park, 18900 Panduit Drive, Tinley Park, Ill. 60487. Individual Nylon or plastic Panduit Corp. cable ties  52  pass through holes in brackets  36 ,  37 ,  38 ,  39 ,  40  and  41  to secure heater assembly  12  onto heated face mask  10 . Other similar suitable adhesive or fastener affixed mounting brackets and retainers, or ties can also be used. 
     Wing nut friction fastener assemblies  32  and  34  of  FIG. 8  are provided on opposite side edges of lens  18  and crown  24  to pivotally affix crown  24  and lens  18  onto cylindrical apertures  33  and  35  in head band frame  26  for retention at desirable rotated positions. Fastener assembly  34  also includes an inserted heater mounting bracket  63  pivotally carried about an inner concentric pivot washer  69  that is sandwiched between stacked components of fastener assembly  34  and which can be tightened by tightening fastener assembly  34 . 
     Nylon turn buttons  43 ,  45 ,  47  and  49  in  FIG. 8  each have a keyway post that is received in respective keyway slots in the front edge of crown  24  used to affix lens  18  onto a front edge of crown by rotating and locking each button into each keyway slot. Such feature allows for removal and replacement of lens  18  and heater assembly  12 . 
     A headband rachet rotary driver  54  is affixed on a central back portion of head band frame  26 , as shown in  FIG. 8 . A pair of plastic mounting blocks  55  and  57  are adhesively affixed onto opposed sides of rotary driver  54 . Each mounting block has a vertical threaded bore positioned to receive a respective threaded fastener, or machine screw  59  and  61  to mount battery pack receiver, or mount  28  onto blocks  55  and  57  on head band frame  26 . A rechargeable battery pack  30  is removably affixed atop mount  28  where an electrical connection is also made to supply power from battery pack  30  to heater assembly  12 . 
       FIG. 9  is a perspective view from above of battery pack receiver  28  and battery pack  30  assembly together in both mechanical and electrically connected relationship. Battery pack  30  includes an outer plastic battery case  86  and a sealed end cap  88  affixed to an open end of battery case  86  with adhesive or ultrasonically welded. A receiving slot  74  on case  86  interlocks electrically and mechanically with a receiving T-rail  72  that engages in complementary interlocking relation with slot  74 , as shown in  FIGS. 9 and 10 . With end cap  88  shown in end view, housing  30  is shown in  FIG. 10  axially received in supported and interlocked relation onto receiver  28  with T-shaped rail  72  mated in axial relation within complementary T-shaped receiver slot  74 . 
       FIG. 11  shows battery pack  30  physically affixed onto receiver  28  in electrically conductive relation. More particularly, a three cell battery pack  84  is encased between case  86  and end cap  88  and electrically coupled with conductive U-shaped contacts, such as contact  92 . As shown, conductive U-shaped clip  92  is mated in electrically conductive contact with a complementary electrically conductive spring steel contact member  76 . 
       FIG. 12  illustrates in enlarged view electrical contact details showing engagement of electrical contact member  76  with conductive clip  92  while battery pack  28  is fully received in mated engagement with receiver  28 . An electrically conductive steel fastener, or machine screw  77  mounts electrical contact member  76  within a complementary receptacle in receiver  28 . Internal insulated conductive wires affix to each contact member  76  and  80  (see  FIG. 14 ) and run through passages in receiver  28  to deliver a supply of power provided within case  86 . 
       FIG. 13  is an exploded perspective view from above of receiver  28  and battery pack  30 . A shrink-wrapped array  84  of battery cells are encased in a plastic housing formed from case  86  and end cap  88 . Conductive wire clips  90  and  92  are passed through pairs of bores  91  and  93  in a bottom portion of case  86  and the ends are bent to entrap each clip  90  and  92 . Cells of battery array  84  are electrically connected via a connector or solder (not shown) to each clip  90  and  92 . Clips  90  and  92  extend downward outboard of receiver slot  74  to engage with contacts  80  and  76  outboard of rail  72  on battery pack receiver  28 . 
       FIG. 14  is an enlarged perspective view of battery pack receiver  28  showing assembly of each electrical contact  76  and  80  into in individual recesses, such as recess  82  in receiver  28 , using threaded fasteners  77  and  81 , respectively, that engaged with threaded bores in the bottom of each recess, such as recess  82  in receiver  28 . According to one construction, receiver  28  is made from a non-electrically conductive material, such as a plastic or filled plastic. A pair of mounting bores  65  and  67  are provided one at each end of rail  72 , configured to enable securement of receiver  28  onto blocks  55  and  57  (see  FIG. 8 ) with a pair of threaded fasteners, or bolts (not shown). 
       FIG. 15  is a front perspective view from above of an alternate heated face shield  110  with a heated and forced air heater assembly  112  including a portable filtered forced air source comprising a centrifugal fan  131  and a pre-filter  133 . Heater assembly  112  includes an arcuate heated segment of PTFE tube  158  extending along a bottom edge of lens  118  and having an array of spaced-apart air flow ports  129  that deliver a source of air from fan  131  to impinge on an inner surface of lens  118 . Visor, or crown  124  is affixed to a front end of head band frame  126 , while battery  130  is affixed to a rear end of frame  126 . An air flow bottom edge baffle, or skirt  135  is provided along a bottom edge of lens  118  beneath a heated elongate portion of heater assembly  112  in order to prevent or reduce convective air flow from beneath a bottom edge of lens  118  which might otherwise draw air from in front of lens  118 . Such mitigation of air flow is desirable particularly when face mask shield  110  is being used in an environment where there exists a risk of virus transmission or contaminant delivery to a user. 
       FIG. 16  is a rear perspective view from behind of the heated face shield  110  of  FIG. 15  further illustrating the crown  124 , battery  130 , fan  131  and filter  133  affixed onto head band frame  126 . PTFE tube  158  is configured to deliver heated air via forced air heater assembly  112  along a bottom edge of lens  118  above skirt  135  from an electrical heater source provided by battery  130 , an air flow source provided by fan  131 , and a filtered source of air provided by filter  133 , such as a pleated HEPA or ULPA air filter. Tube  158  can have an inner Nichrome heating wire provided in a smaller PTFE tube, similar to the construction shown in version depicted in  FIGS. 1-14 , as shown in greater detail in  FIG. 20  below. Furthermore, a heater control switch, or circuit can be provided on heater system  112  including a bimetallic switch, a thermistor, or some other power control device that operates off of detected temperature thresholds to turn off a power to the heater, or Nichrome wire when a threshold temperature is reached. 
       FIG. 17  is a front view of the forced air heated face shield  110  of  FIGS. 15-16 . A plurality of equally spaced-apart air holes, or vents  129  deliver a flow of heated air to an inner lower surface of lens  118 . 
       FIG. 18  is a right-side view of the face shield  110  of  FIG. 17  illustrating details of heater assembly  112  with PTFE tube  158 , battery pack  130 , fan  131  and filter  133 . 
       FIG. 19  is a vertical sectional view of the face shield  110  taken along line  19 - 19  of  FIG. 17  showing lens  118  in centerline section. 
       FIG. 20  is an enlarged view of the heater assembly  112  and lens  118  taken from the encircled region  20  of  FIG. 19 . PTFE tube  158  has an inner bore  171  in fluid communication with a plurality of outlet ports, or bores  129  and is provided between lens  118  and skirt  135  which has an upturned end flange. A Nichrome heater wire  160  is provided in a smaller PTFE tube  161  inside of bore  171 . A return insulated ground wire  162  is also provided in bore  171 . A remaining open portion of bore  171  provides an airflow path for clean air that exits via ports  129  to impinge on an inner surface of lens  118 . 
       FIG. 21  is an exploded perspective view of the portable filtered forced air source of  FIGS. 15-20  comprising battery pack  130 , fan/filter carrier  151 , centrifugal fan  131 , and filter assembly  133 . Carrier  151  and receiver  128  are integrally formed from a single piece of plastic material. Optionally, carrier  151  is affixed with threaded fasteners to threaded complementary bores provided in battery pack receiver  128 . 
     Threaded fasteners, or bolts  102  of  FIG. 21  are used to secure receiver  128  to mounting blocks  155  and  157  within complementary threaded bores  107 . Mounting blocks  155  and  157  are affixed to the head band frame (not shown) with adhesive or fasteners (not shown). Spring latch electrical contacts  176  and  180  are affixed with threaded fasteners  177  and  181  to receiver  128 . A tapering or narrowing plenum, or collector  153  is affixed to an outlet end of centrifugal fan  131  and has an outlet tube configured to mate with tube  158  (see  FIG. 16 ). Filter assembly  133  and fan  131  are affixed to a back surface of bracket  151  with a pair of threaded fasteners, or bolts  175  that each pass through clearance through-bores  101  and  109  and into threaded bores  105 . Bores  101  are provided in housing frame  185  of filter assembly  131 . Accordingly, fan  131  and filter assembly  133  are affixed to and carried by housing frame  185  sealed around an outer periphery with housing frame  185 . 
     According to one construction, one suitable form of centrifugal fan  131  is a Model No. B5015M fan, or DC blower available from Mechatronics, Inc., 8152-304th Ave. SE, PO Box 5012, Preston, Wash. 98050-5012. USA. However, other pressurized air sources are also possible, such as compressed air sources or other forms of fans and forced clean air sources. 
       FIG. 21A  is a transverse sectional view of the air filter assembly  179  taken along section  21 A- 21 A of  FIG. 21  and showing the folded, or pleated HEPA or ULPA air filter  183 . Other suitable filters can also be used. According to one construction, filter  183  is encased along an outer periphery with a soft rubber or silicon outer edge frame that seats and seals with an inner periphery of housing frame  185 . 
       FIG. 22  is a rear perspective view of a further alternate heated and clean air ventilated face shield  210  with a heated wire and forced clean air source, or assembly  212  and a portable filtered external forced air source regulator assembly  231  over that shown in  FIG. 15 , but having an external filtered air source, such as a wall-mounted building filtered air source found in a hospital or laboratory environment delivered via a coiled, retractable pressure air-line  285  via a releasable pneumatic coupling  283  that releasably mates with a complementary male pneumatic coupling member  279 . PTFE tube  258  has a Nichrome heating wire, or heat source, and clears moisture from lens  218  using a flow of heated clean air from an external filter pressurized air source delivered via pneumatic line  285  to regulator  231  for delivery to tube  258  to apertures  229  (see  FIG. 24 ). Regulator  231  is affixed to a rear of bracket  251  on head band frame  226 . Optionally, a Nichrome (or nickel chromium) heating wire (such as wire  160  of  FIG. 20 ) can also be provided with outside air to deliver heat and airflow to clear an inner surface of lens  218 . Heated wire assembly  161  and insulated ground wire  262  are electrically coupled with battery pack  230  and enter metal tube  295  (see  FIG. 23 ) and extend into tube  258  where a segment of wire assembly  261  comprises a Nichrome wire section extending along a bottom edge of lens  218 . Optionally, battery pack  230  and wires  261  and  262  can be eliminated from assembly  212 , as shown in  FIG. 24  to provide a face shield that clears an inner surface of lens  218  with a flow of filtered outside air from hose  285  emanating from tube  258  along skirt  235 . Tube  258  forms a bend where crown  224  and lens  218  pivot on head band frame  226 . Optionally, tube  258  can be formed from smooth PTFE tubing with a medial portion formed from corrugated PTFE tubing  1258  in the region of the bend near the pivot point. 
       FIG. 23  is an exploded perspective view of the portable heated and filtered external forced air source regulator assembly  212  of  FIG. 22 . Regulator  231  is affixed to mounting plate  299  with threaded fasteners  203  that pass through bosses  207  and thread into corresponding bores (not shown) in the bottom of housing body  205  of regulator  231 . Clearance bores  215  are provided in battery bracket  251  to provide clearance for the heads on fasteners  203 . Threaded plugs, or set screws  297  and  298  are received in extra ports on body  205  and threaded elbow pneumatic pressure fitting, or push-to-connect 90 degree elbow adapter  296  having a tube-receiving port and a threaded inlet and directs regulated reduced pressure clean air into fitted metal pipe  295  where it is delivered into tube  258  (see  FIG. 22 ) and affixed with a tight and sealed insert fit within tube  258 . Regulator  231  is affixed to plate  299  via fasteners  204  which pass through bores  217  into threaded bores  213  in battery bracket  251 . 
     One suitable form of regulator  231  in  FIG. 23  is commercially available from ControlAir, Type 850 Series miniature air pressure regulator, available from ControlAir, International HQ, 8 Columbia Drive, Amherst, N.H. 03031. A rotary adjustment knob  206  enables adjustment of the outlet air pressure delivered by regulator  231  to line  295 . Other forms of regulators can also be used to reduce line pressure from the source. Typical medical air is delivered to rooms at 50-65 psi and needs to be reduced before delivery to the face mask shield. A hose coupling plug  279  is threaded into a bottom threaded bore (not shown) in body  205  to supply pressurized air to regulator  231  from complementary pneumatic coupling  283  (see  FIG. 22 ). 
     As shown in  FIG. 23 , battery bracket  251  is affixed to head band frame  226  (see  FIG. 22 ) using a pair of threaded fasteners  202  that pass through bores, such as bore  267  in receiver  228  and into threaded bores  207  provided in each block  255  and  257  which are affixed to such head band frame using foam adhesive pads (not shown). Wires  261  and  262  extend from tube  295  and into bores  295  and  297  in receiver  228  to electrically couple with electrical contacts  280  and  276  such as with solder joints (not shown). Contacts  276  and  280  are each affixed into complementary recesses in receiver  228  with threaded fasteners  277  and  281 . Battery pack  230  is then slid onto receiver  228 . 
       FIG. 24  is an enlarged view of an optional construction forced air lens cleaner assembly  1212  for the mask of  FIGS. 22-23  taken from an encircled region corresponding with a view of the encircled region  20  of  FIG. 19 , but for the face shield of  FIGS. 22-23  and omitting provision of any heating wire. More particularly, PTFE tube  1258  includes an inner bore  1271  that feeds filtered, clean air via a plurality of outlet ports, or bores  1229  configured to direct clearing air flow onto an inner surface of lens  1218  to clear and prevent accumulation of moisture on such surface. Optionally, any form of tube can be used for tube  1258  including lower temperature plastic tubes because there is no heat source on face shield  1210 . Upturned skirt  1235  isolates tube  1228  proximate lens  1218  and reduces induced air flow from in front of lens  1218  due to air flow from ports  1229 . 
       FIG. 25  is an enlarged view of a second optional construction heated and forced air heater assembly  312  and lens  318  for the mask of  FIGS. 22-23  taken from an encircled region corresponding with a view of the encircled region  20 , but for the face shield of  FIGS. 22-23 . More particularly, PTFE tube  358  comprises a D-shaped cross section tube having a recessed flat face configured to receive an indium tin oxide layer  360  deposited, such as by vapor deposition, on an outer surface of a strip of printed circuit board substrate that is inserted within the recessed flat face of tube  358 . Layer  360  generates heat when electricity is delivered across layer  360 . A plurality of ports, or bores  329  further deliver forced clean air from interior bore  371  of tube  358  which further directs heat generated from layer  360  onto an inner surface of lens  318 . An insulated ground wire, or copper ground wire  362  is also carried inside of interior bore  371  of tube  358 . Upturned skirt  335  isolates tube  358  proximate lens  318  and mitigates induced convective air flow from in front of lens  318  that might otherwise draw contaminants and/or viral components behind lens  318 . 
       FIG. 26  is an enlarged sectional view of the forced air heater assembly  312  of  FIG. 25  taken from encircled region  26  of  FIG. 25 . More particularly, indium tine oxide layer, or coating  360  is retained in a slot, or recess in tube  358 . Filtered, clean air is delivered under pressure via bore  371  for delivery to a plurality of spaced-apart flow apertures  329  to further impart condensate mitigation or removal in combination with heat from layer  329 . Insulated ground wire  362  is carried inside of bore  371  to complete an electrical power supply circuit with a battery pack on a face shield, as previously taught above to provide heated and force air heater assembly  312 . 
       FIG. 27  is a third optional construction forced air heater assembly  412  and lens for the mask of  FIGS. 22-23  taken from an encircled region corresponding with the encircled region  20  of  FIG. 19 , but for the face shield of  FIGS. 22-23 . More particularly, a layer, or coating of indium tin oxide is deposited onto an inner surface of lens  418  of a face shield, such as a shield shown in prior disclosed versions above. In one case, lens  418  is a glass or high temperature plastic lens. PTFE tube  458  includes bore  471  configured to deliver filtered, clean air flow via plurality of bores  429  over and upward to an inner surface of lens  418  to enhance condensate mitigation and removal in combination with heat generated by layer  460 . Upturned lip  435  further functions to isolate heat and airflow from tube  458  and layer  460  to minimize or eliminate convective airflow from occurring under a bottom edge of lens  418  that might otherwise draw contaminants from in front of lens  418  to a backside of lens  418  where a user might inhale such contaminants. 
       FIG. 28  is perspective view from in front and above of a pair of heated eyeglasses  510 . Eyeglasses  510  include a heater assembly  512  that is integrally formed as a portion of a frame holding together eyeglasses  510 . Bridge assembly  520  extends between lenses  518  and  519  and heater assembly  512  extends along a lower semi-cylindrical portion of each lens  518  and  519 . Temple pieces, or temples  522  and  524  extend from hinges  534  and  536 , respectively, affixed to end pieces  526  and  528 . Temple tips  526  and  528  on each temple  522  and  524 , respectively, each support a battery pack  529  and  531  configured to supply power to heater tubes along each lens  518  and  519 , such as PTFE nichrome wire heater tube  559  on lens  519 . Microswitch  533  is configured to turn on and off power from battery pack  531  to power heater  512  at heating portions  558  and  559 . 
       FIG. 29  is a perspective view from behind and below of the heated eyeglasses  510  of  FIG. 28  further illustrating the position of heater assembly  512  along each lower eye glass  518  and  519 . Nose pad arms  538  and  540  are mounted to nose bridge assembly  520  and internal components of heater assembly  512  extend through a hollow tube of nose bridge assembly  520 . Remaining portions of wiring for heater assembly  512  extend internally within a hollow portion of each bridge  522  and  524  and electrically connect with switches  532  (see  FIG. 30 ) and  533  and battery packs  529  and  531  in temple end pieces  528  and  530 . One suitable source of microswitch  533  is E-Switch Model No. TL3305 tactile switch available from DigiKey Electronics, 701 Brooks Ave. South, Thief River Falls, Minn. 56701. 
       FIG. 30  is a plan view from above of the heated eyeglasses  510  of  FIGS. 28-29 . Switch  533  is shown on temple end piece  528  of temple  524  adjacent to and electrically coupled with battery pack  531 . The resulting selectively activated electrical circuit is used to power heater assembly  512  on each side to mitigate condensate accumulation on lenses  518  and  519 . Optionally, a timer can be provided with switch  533  that triggers operation of heat delivery for a predefined period of time. Further optionally, a switch can be provided on each temple end piece  526  and  528 . 
       FIG. 31  is a vertical sectional view of the eyeglasses  510  taken through line  31 - 31  of  FIG. 30 . PTFE heater tube  559  of heater assembly  512  is shown configured to apply heat to a lower portion of lens  519  adjacent nose arm pad  540 . Lens  519  can be either glass or plastic or some other suitable optically transmissive material. 
       FIG. 32  is an exploded perspective view of the eyeglasses  510  of  FIG. 28  but omitting each Eyeglass lens. Heater assembly  512  comprises a pair of insulated conductive wires  566 ,  567  and  568 ,  569  on each side that insert into PTFE tubes  558  and  559 . Wires  566  and  568  are conductive leads that are soldered to segments of Nichrome electrically resistive and heat dissipating wire in each tube  558  and  558 , such as Nichrome wire  564  in tube  559  (see  FIG. 33 ). Insulated wire  560  is soldered to each segment of Nichrome wire within heater tubes  558  and  559  in bridge  520 . Insulated wires  567  and  569  are ground wires that extend through tubes  558  and  559  and are coupled with insulated wire  562  in the region of bridge  520 . 
     According to one construction, bridge assembly  520  of  FIG. 32  includes a tubular metal body that receives wires from heater assembly  512  and affixed, such as by soldering to Eyeglass frame members  525  and  527 . Bridge assembly  520 , frame members  525  and  527 , hinges  534  and  536 , and arms  530  and  532  are constructed from metal, or steel according to one construction. Temples  522  and  524  are hollow and have an extra hole for receiving tubes  558  and  559  and wires  566 ,  567  and  568 ,  569  where they pass internally to battery packs  529  and  531  and switch  533  on tips  526  and  528 , respectively. 
       FIG. 33  is an enlarged perspective view from the encircled region  33  of  FIG. 32  showing one heater tube  558  receiving an insulated ground wire  562  and an insulated power wire  560  that is soldered in-line with a nichrome resistance heating wire  564 . Wire  564  passes through tube  558 , and while subjected to current flow, imparts heat via lens  558  to an Eyeglass lens. Wire  564  is soldered in-line at an opposite end to insulated power wire  566 . 
       FIG. 34  is an exploded perspective view of the temple  524  for the eyeglasses of  FIGS. 28-33 . More particularly, a portion of hinge  534  affixes to one end of hollow temple, or arm  524  through which corresponding wires (not shown) are fed to reach a printed circuit board  570  containing a microswitch  533 . PC board  570  is electrically coupled with contacts (not shown) that draw power from battery pack  531 , including a pair of button batteries  574  encased in a receiving socket  572  of temple tip  528  and affixed with a threaded battery retaining cover  576 . 
       FIG. 35  is an exploded perspective view of heated safety glasses  610 . Glasses  610  have a heating assembly  612  comprising a central nichrome wire and an outer PTFE tube as shown above in previous designs. An outer unitary lens  618  is sandwiched with an adhesive with a first PTFE tube and a second PTFE tube of heating assembly  612  and with inner lenses  658  and  659 , each tube having an internal nichrome heating wire driven by battery power and wiring (not shown) similar to that shown in the versions of  FIGS. 28-34 . Temples  622  and  624  are pivotally affixed via hinges to unitary lenses, or face shield  618 . Optionally, optical inner lenses  658  and  659  can have perpendicular edge flanges that affix with adhesive or ultrasonic welding to an inner surface of unitary outer lens  618 . 
       FIG. 36  is an exploded perspective view of the heated safety glasses  610  of  FIG. 36 . Outer unitary lens  618  and temples  622  and  624  are shown relative to the pair of PTFE and nichrome wire tube heaters forming heating assembly  612 . Inner lenses  658  and  659  are sandwiched in assembly so that heater assembly  612  imparts heat to an air gap provided between outer lens assembly  618  and inner lenses  658  and  659 , thereby reducing a volume of air or gas that needs to be heated in order to effectively heat lenses  618  and  658 ,  659 . 
       FIG. 37  is a vertical sectional view of one heated lens assembly taken along line  37 - 37  of  FIG. 36 . More particularly, outer lens  618  is affixed adhesively about an outer edge of heater assembly  612  to inner lens  619  to form a sealed and unitary sandwich heater construction for the lenses  618  and  619 . 
     Although the elongate resistive heating element of the elongate heater is shown in many forms in  FIGS. 1-37  as a resistive heating wire, or Nichrome wire, it is understood that the elongate resistive heating element can comprise a trace of resistive heat generating coating, placed down by vapor deposition or laid down as an ink, such as indium tin oxide, or a Positive Temperature Coefficient (PTC) ink trace, or layer. 
     According to one construction, an electrically conductive, yet partially resistive, PTC ink for generating a trace is available as Loctite brand ECI 8000 E &amp; C Series (including ECI 8120 PTC printable ink) from Henkel Corporation 14000 Jamboree Road, Irvine, Calif. 92606, United States. Optionally, a trace of indium tin oxide can be used. Further optionally, any other form of ink PTC traces can be used. 
     The terms “a”, “an”, and “the” as used in the claims herein are used in conformance with long-standing claim drafting practice and not in a limiting way. Unless specifically set forth herein, the terms “a”, “an”, and “the” are not limited to one of such elements, but instead mean “at least one”. 
     In compliance with the statute, the various embodiments have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the various embodiments are not limited to the specific features shown and described, since the means herein disclosed comprise disclosures of putting the various embodiments into effect. The various embodiments are, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.