as shown in the exemplary drawings , a first presently preferred embodiment of the present invention is embodied in a flexible , full face coverage mask for use by aircraft flight crews which includes a flexible lens sealingly molded in to the face seal . the mask also incorporates an inflatable harness which is inflated by the breathing oxygen regulated by a regulator incorporated into the face mask . the mask also provides for purging of the interior of the flexible lens by gas from the regulator in order to retard fogging and other obscuration of the view out of the lens by the wearer . the entire assembly is capable of being rolled up into a relatively small package , which facilitates its installation within the limited available space readily at hand to the seated crewmember on the flight deck . in a second presently preferred embodiment , the entire flexible mask portion , including the lens , can be formed of a single unit , either through use of an insert molded into the balance of the mask or by use of an elastomeric transparent material for the entire face mask portion of the assembly . fig1 illustrates a general arrangement of a first preferred embodiment of the present invention . the mask assembly 10 includes a face seal molding 12 formed to fit around the periphery of the face of the wearer and receive a flexible lens 14 which is bonded or inserted into the elasmeric face seal 12 . the lower forward portion of the face seal 12 incorporates a portion which includes an oxygen supply regulator assembly 16 removably attached to the lower forward portion of the mask . the regulator 16 supplies breathing oxygen to the mask wearer through ports internal to the lower forward portion of the face seal 12 , and also supplies oxygen or other breathing gas mixtures to an inflatable harness 18 connected to the breathing gas regulator and the face seal 12 via suitable gas passages and connectors in the mask . connecting straps 20 and 22 are then similarly connected at their extremities to a connector 24 which may also be adjustable to provide means to adjust for the size and comfort of the mask once inflated . a further connector 26 connects strap 20 to the inflatable portion 18 of the harness assembly . in a presently preferred embodiment , a clear flexible elastomeric lens 14 is either bonded or inserted into a receptacle in the elastomeric face seal 12 . the use of the flexible lens in concert with the elastomeric face seal of the invention serves to improve the ability of the mask to seal out toxic or vision impairing gases . these improved face sealing characteristics also improve the oxygen consumption performance of the mask , as there is less leakage over a wider variety of face configurations . the oxygen supply for the mask is provided by oxygen supply tube 28 connected to regulator 16 . in order to facilitate communication , the mask may also incorporate a microphone 17 which is connected to the aircraft communication system by electrical wiring 30 , which may be concurrently routed with oxygen supply tube 28 . certain benefits of the present invention may be better understood by reference to fig2 which illustrates the difference in size and configuration of the present invention as compared to prior art aircraft emergency crew masks incorporating rigid lens assemblies . as illustrated in the prior art , fig2 a , a mask 32 incorporating a rigid lens assembly 34 of necessity requires a fairly large enclosure 36 into which the mask must fit to account for the inflexibility of the lens , regardless of the flexibility of the balance of the mask assembly . in contrast , by use of the flexible lens , flexible face seal and inflatable harness of the present invention , as illustrated in fig2 b , the mask may be rolled so that lens 14 and face seal 12 consume a substantially smaller volume 38 as compared to prior art masks . this feature of the invention allows the mask to be mounted in a considerably smaller space within the aircraft and possibly be placed more conveniently to hand of the crewmember during times of emergency . in light of the increased complexity and sophistication of modern aircraft , and the use of fewer crewmembers compared to previous equally complex aircraft , flight deck volume has been in short supply and thus the smaller envelope of the stowed mask of the present invention represents a substantial advantage over prior art emergency crew masks . referring to fig3 fig3 a illustrates how the present invention readily adapts to faces of various sizes more easily than prior art masks . more specifically , referring to fig3 a , which illustrates both large 40 and small 42 heads which may be required to be accommodated by emergency flight crew masks assemblies , it may be seen that a conventional rigid mask lens assembly 34 incorporated into conventional mask face seal 44 cannot accommodate this range of head sizes without highly compliant seals provided at the edges of the lens and at the edges of the face seal . comparing the flexibility of the present lens assembly and the face seal illustrated in phantom as 46 shows the relatively small amount of flexibility available in a prior art lens assembly to accommodate the range of head sizes desired . referring to fig3 b , it may be seen that the same head sizes 40 and 42 may be more readily accommodated by the present invention . more specifically , it can be seen that the flexible integrated mask and lens assembly 48 can deflect over a substantially greater range as illustrated in phantom by dotted lines 50 to more easily accommodate the required range of head sizes . furthermore , such accommodation is accomplished without the requirements for high compliance seals at the edges of the lens assembly in order to bridge the difference in rigidity between a rigid lens and a soft face seal , and the stresses on the seal between the lens and the face seal are substantially reduced by the increased flexibility of the lens of the present invention . because of the lens flexibility in the present invention , the entire face seal can then flex more to varying head and face sizes . another benefit of the present invention is that since the soft lens is intentionally flexed with the face seal by the combination to the face of the user in response to the inflatable harness , less face seal frame structure is needed than in hard lens designs which must include an adequate structure to support the rigid lens . fig4 is a cross sectional view of the flexible mask and lens assembly of the present invention , illustrating the ease with which the mask both accommodates to the face of the user and provides a seal with the user &# 39 ; s face . referring to fig4 which illustrates a cross sectional view of the mask assembly of the present invention on the face of the user , it can be seen that the flexible face seal portion 12 conforms closely with the face of the wearer 52 , thereby providing an excellent seal for the mask for a variety of face configurations and surfaces . flexible lens 14 is sealingly attached to face seal 12 at positions 54 , 56 , allowing face seal 12 to conform closely to the wearer &# 39 ; s face by deflecting to accommodate any of a variety of facial configurations . a nose bridge seal portion 58 is molded into the face seal 12 in order to provide a particularly compliant configuration for sealing across the nose bridge of the wearer . fig5 is an illustration of a vertical aspect illustrating the field of view of a wearer , and showing the superior accommodation of fields of view of a wearer by the present invention . the wearer 60 , whose eyeballs 62 are capable of a field of view θ is ordinarily limited by the field of view of a rigid lens of the type utilized in the prior art 64 . such a rigid or semi - rigid lens , while providing good optical quality , does not allow for a broad field of view and this may have certain important limitations , particularly in the event of emergency circumstances for a flight crew in an aircraft . by contrast , the present invention lens 14 is capable of deflection over a far wider region of the wearer &# 39 ; s face while maintaining acceptable optical quality , thus allowing for a full view through the opt ion of the mask of the field of view θ of the user &# 39 ; s eyes 62 . this wide field of view is further enhanced by the ability to provide a closely fitting mask on the side portions of the face by use of the flexible lens 14 and flexible face seal 12 which can conform tightly with the forward side portions of the wearer &# 39 ; s face . fig6 through 9 illustrate a variety of configurations which may be used for the inflatable harness in order to provide close fitting and comfort for the wearer of the mask of the present invention . the inflatable portion of fig6 includes both a lateral wrap - around elastomeric tube 66 and a central circular elastomeric tube 68 which are connected to one another by a harness connection 70 and into the mask by adjustable straps 72 . a similar configuration is illustrated in fig7 in which a single inflatable tube 66 is configured to assume a similar shape to that of fig6 by connectors 74 , thereby gaining the benefit of a single continuous tube to be used for the inflatable harness assembly . similarly to fig6 the inflatable portion of the harness is then attached to the face seal by straps 72 . fig8 illustrates a further variation in which the inflatable assembly consists of both a top and bottom lateral tube 66 , 76 connected by a vertical tube 80 , all of which are supplied with air via the regulator in the forward portion of the mask . fig9 illustrates yet another configuration for the harness which may be advantageously used with the invention . in this embodiment elastomeric tubes 82 , 84 are attached to mask face seal 12 by connectors 86 and are held in place in the crossed position behind the wearer &# 39 ; s head by retainer 88 . a strap 90 also serves to preserve the shape of the harness during use . it is important that the lens of the present system have sufficient optical quality and resistance to abrasion and other damage to function similarly to the rigid and semi - rigid lenses of prior art masks . it is well known that a number of formulations of silicone exist that provide resistances to yellowing and other optical degradation sufficient for use in a mask which must be stored for long periods of time prior to use . one such material which should be suitable for this purpose as a lens material is general electric se6800 - d2 silicone in the &# 34 ; clear &# 34 ; peroxide cured molding grade . other clear , flexible plastic materials with optical transmittance in the 80 % range may also be suitable , depending on the detail design of the mask . there are also scratch resistant additives and coatings that are available for silicone formulations which enhance the ability of the lens to maintain optical quality when subject to abrasion . one such scratch resistant coating involves the coating of the lens with urethane . in a presently preferred embodiment , the invention involves the use of a urethane coated silicone lens bonded to the silicone based face seal by use of the following process . the lens is premolded out of silicone and coated with an abrasion resistive coating , such as urethane . the lens is then placed in a mold which is designed to receive the lens and mold the liquid mask material around the lens and other inserts , if any , such as the harness mounting hardware and regulator mounting assembly . the lens perimeter and mask seal is cleaned with methyl ethyl ketone and the lens with hexane . an adhesive such as 34d manufactured by synthetic surfaces , scotch plains , new jersey is then used to adhere the lens to the face seal . the mask is then cured , depending upon the requirements of the particular silicone , and the completed mask is removed from the mold . an important aspect of the invention is the ability to combine the flexibility of the mask seal and lens with the inflatable harness in order to provide previously unavailable levels of lens field of view , storability , comfort , wearability and sealing in a mask that is also providing sufficient optical quality for use under high stress conditions by flight crews . while a variety of regulators may be used , in a presently preferred embodiment , one regulator suitable for use with the mask is the puritan - bennett oxygen pressure regulator previously utilized in the puritan - bennett sweep on 2000 crew mask , available without a lens but with an inflatable harness made of silicone tubing overlaid with nomexs braided material . this demand regulator also provide the ability to adjust the pressure in the inflatable harness , and thus the comfort of the harness , by access to a crew control knob or lever on the side of the demand regulator assembly . the demand regulator assembly also provides for a means to provide purging air to the inside of the lens assembly via suitably arranged passages in the mask . a second presently preferred embodiment addresses the desirable benefits , for cost , reliability and manufactureability reasons , to manufacture the mask as a single piece lens and face seal assembly out of transparent silicone of the type suitable for use as a flexible lens material . it has been found that such a configuration further simplifies the design of the mask by eliminating the manufacturing step of sealing the lens with the balance of the face seal , and avoiding irregularities in flexibility associated with dis - continuities between materials and the transition between the lens and the face seal . similarly to the previously described embodiments , the forward lower portion of the face seal is molded to accommodate the demand flow regulator and the attach points of the inflatable harness straps to provide a complete assembly . in this alternative method of construction , the area of the mold representing the lens is finished to a sufficiently high optical accuracy for the intended purpose and the mold is configured to provide appropriate thickness to the lens area in comparison to the balance of the mask . then , an optical quality clear silicone is used to mold the mask and to thus provide an integrally formed mask and lens assembly . in a presently preferred embodiment , a general electric silicone known as 454 - 3243 ultra tufel &# 34 ; water clear , fast cure can be used to mold such a mask and provide acceptable clarity , flexibility , strengths and damage resistance capabilities . from the forgoing , it will be appreciated that the crew emergency mask assembly of the present invention allows for a substantially improved field of view and stowability while still providing a comfortable and highly effective mask for use in hazardous circumstances in the flight deck of a high performance aircraft . while several forms of the invention have been illustrated and described , it will also be apparent that various modifications can be made without departing from the spirit and scope of the invention . accordingly , it is not intended that the invention be limited except as by the appended claims .
a mask and harness system for use in providing breathing oxygen and protection from pollutants for the eyes and respiratory system as might be encountered in high altitude aviation environments . in one preferred embodiment , the mask system has a face seal , a soft flexible lens , a pneumatically - actuated harness , and a regulator with microphone to control the flow of oxygen and to facilitate communications in aircraft flight decks and other aircraft compartments . the system is designed for required five - second donning with one hand and because of the flexible lens , is capable of storage in the relatively preferred on crowded flight decks . it is connected to an oxygen source and , optionally , with aircraft communications . the regulator controls the flow rate of oxygen to the wearer based on altitude and physiological requirements . the regulator includes a valve for purging the condensation - prone moist gases from the lens area and provides positive pressure in the mask . a second preferred embodiment molds the lens and mask seal of a single material having sufficient optical quality and flexibility to accomplish both purposes .