VIEWING WINDOW PROTECTOR

Abstract: A full face respirator having an optically transparent lens (40) panel which includes a shield (50) for protecting the exterior surface of the lens (40). The shield (50) includes an outer cover (60) adapted for attachment to the exterior surface of the respirator lens (40) and a means (70) for securely attaching the same. The outer cover (60) is made of durable, abrasion-resistant, optically transparent material capable of easy cleaning.

Description: _ i _ VIEWING WINDOW PROTECTOR BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to full facepiece respirators and the like and more particularly, to the lens or viewing window of the same. 2. Description of the Prior Art Safety and health regulations require that personnel working in any type of potentially hazardous environment be protected from that environment by wearing appropriate safety equipment. Of particular concern is protection for the eye and face area and, as a result, face shields and full facepiece respirators are typically used to minimize any serious injury. Such equipment typically includes a curved optical transparent or translucent lens panel to permit the wearer to visually monitor the work in progress and surroundings environment. The transparent lens panels serving as viewing windows must be made of materials strong enough and with a thickness dimension large enough to withstand heavy impacts without breaking or giving way. In some instances, these panels must also be capable of filtering out undesired incident light. In use, the viewing window is exposed to forces which tend to scratch or scrape the exterior surface. In addition, localized pitting or burning and the deposition of materials of the window is problematic. In any event, over a period of time, the optical quality of the viewing window or panel will be impaired to an extent sufficient to produce, in itself, a safety hazard. Known in the prior art are several arrangements that provide for removal and replacement of the viewing window. However, these windows are typically expensive and tend to require appropriate storage when not attached to the faceshield or respirator. In addition, because of the time associated with removal and replacement, the windows are typically not replaced as often as they should be, and as mentioned above, seriously interfere with the ability of the wearer to visually observe the work in progress. Also known are protective films of a peel-off nature for preserving the lens of a face mask or respirator. For example, U. S. Patent No. 4,076,373 discloses a means for shielding the exterior surface of the protective lens of a face mask by using a plurality of thin flexible sheets of material which is at least translucent. Each sheet includes an elongated flexible tab projecting from its edge. The sheets in turn are arranged in a mutually aligned stack with the tab of each sheet bent to extend along the surface in order for the top sheet of the stack to be individually removed from the stack by grasping the tab of the top sheet and peeling such top sheet away from the stack and protective lens. When soiled or impaired, the film is pulled across the panel and torn off thereby leaving a fresh piece of film in its place. ϋ. S. Patent No. 4,542,538 teaches a protective film accessory that includes an elongated sheet of thin, flexible, transparent film having a length many times the length of the lens panel and a width of substantial portion of the width of the lens panel. The protective film is tightly rolled about an axis in a housing located on one side of the lens panel. The film is pulled out of its housing and is extended across the exterior surface of the lens panel where it is held by a tensioning bar member. When soiled or impaired, the film is pulled across the panel and torn off thereby leaving a fresh piece of film in its place. Although the above means are available, problems still exist in the art. For example, the peel-off film is not re- usable and must be replaced on an on-going basis. Each layer in a stack will also provide surface reflection to the lens and distortion to the viewer. In addition to a limited shelf life, due to the nature of the flexible material employed, the peel- off lens covers are not resistant to abrasion and scratching, nor is cleaning possible. SUMMARY OF THE INVENTION It is therefore an object of this invention to provide an accessory for full facepiece respirators and the like which is simple and inexpensive while maintaining the integrity of the facepiece. Another object is to provide a durable and reusable accessory which can be easily cleaned with a solvent, scraper or other known technique. Still another object is to provide a cover to protect the exterior surface of a lens or viewing window which is resistant to pitting, burning and scratching forces. According to the teaching of the present invention, a full facepiece respirator having an optically transparent lens panel is provided with a shield for protecting the exterior surface of the respirator lens or viewing window. The shield includes an outer cover adapted for attachment to the exterior surface of the respirator lens and a means for securely attaching the same. The outer cover is made of a durable, abrasion-resistant optically transparent material capable of easy cleaning and is of a compatible shape to the respirator lens. The attaching means may be a pressure sensitive adhesive or any suitable fastener. The outer cover is attached over and against the effective view area of the respirator lens. The shield for protecting the exterior surface of a lens affects neither form, fit nor function of any commercially available full facepiece respirator. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic partially exploded perspective view of a full facepiece respirator with a shield adapted for attachment in accordance with one embodiment of the present invention. Figure 2 is a schematic partially exploded perspective view of a full facepiece respirator with a shield adapted for attachment in accordance with a second embodiment of the present invention. PREFERRED EMBODIMENTS OF THE INVENTION Referring now to Figure 1, shown in one embodiment is a conventional full facepiece respirator assembly 10 with respiration accessories. The respirator 10 broadly comprises a harness 15 for attaching the respirator against the face of a wearer, a face member or portion 20 and respiratory portion 30 which may include at least one removably attached filtration element capable of removing hazardous fumes and gases from inhaled air. The face portion 20 includes a transparent or translucent protective viewing window lens 40 which is located opposite the eyes and face of the wearer. Typically this protective lens 40 is of a rectangular nature to facilitate full field vision. In addition, lens 40 is typically curved along the length portion thereof to provide a convex exterior surface and a concave interior surface. In order to prevent wearer injury, the thickness of the protective lens 40 and the material of which it is made must be of suf icient strength to withstand heavy impact without breaking, bending, cracking or shattering. In addition, it is often necessary that the protective lens 40 be colored or tinted or otherwise adapted to filter out certain wavelengths of undesirable light in order to protect the eyes of the wearer. As a result, the protective lens 40 is typically expensive and, in addition, is expensive and time consuming to replace. After a period of use in normal applications, the optical quality of the protective lens 40 will be impaired. The impairment may result from the abrasion of the exterior surface of the protective lens 40 by impact of objects which scratch or scrape the surface. Similarly the optical quality may be diminished due to pitting or burning of the surface by small, high velocity or high temperature particles of material, as in sandblasting, burning and welding operations. Lastly, the optical quality of the lens is reduced by deposition of opaque materials thereon, as typically associated with spray painting operations. According to the teaching of the present invention, a shield 50 is utilized in order to protect and preserve the integrity of the protective lens 40 and the respirator 10 itself. The shield 50 comprises a cover 60 adapted for attachment to the protective lens 40 and a means 70 for securely attaching the cover 60 against the exterior surface of the lens 40. In view of the foregoing, the cover is composed of any durable abrasion resistant, easily cleaned material with good optical clarity. Typically, a transparent ceramic type material will meet the above requirements and a preferred material is glass, such as that used in windows and the like. For example, VYCOR® brand glass (Corning Glass Works, Corning NY) and standard soda lime glass have been found suitable for the cover 60. Other materials known to those in the art which meet the above characteristics are also contemplated. The cover is formed to a compatible shape of the protective lens by any commercial technique. Compatible shape does not mean that the shape of the cover 60 has to be identical or form fit to the lens 40. Compatible shape simply means that the cover 60 is such that it can be attached to lens 40 of the underlying respirator 10. Practically speaking, however, if the lens 40 is cylindrically curved, cover 60 will also be of a cylindrically curved nature to facilitate attachment. The length and width dimensions of cover 60 is sufficient to cover the usable, i.e. effective optical viewing area of the exterior surface of lens 40. Similarly, cover 60 should be of sufficient thickness to facilitate the manufacturing process yet maintain the optical qualities of the material. In other words, cover 60 can not be too thin so that it is brittle and too delicate to handle. Likewise, cover 60 should not be too thick so as to distort the wearer's view or create wear discomfort of the respirator due to additional heaviness. A thickness in the range between about 10 mils and 500 mils has been found suitable for cover 60 in achieving the aforementioned qualities and objective, and a thickness of about 50 to about 140 mils is preferred. Especially preferred is a thickness of about 100 mils. Generally, the cover 60 will be of a cylindrically curved rectangular shape, as shown in the drawings, with common side and end dimensions. However, circular, ovular, square shapes and the like are also contemplated. Means 70 are provided for attaching or mounting the cover 60 against the exterior surface of the lens 40. Typically the attaching means 70 will be comprised of a commercially available tacky or gummy material, such as a pressure sensitive adhesive, putty, tape, and the like. In addition, the material should be resilient enough to deform to any irregularities between the cover 60 and lens 40 and retain its tackiness when exposed to air. For example, silicone based pressure sensitive adhesives sold by Manco Inc. (Westlake, Ohio) and Walco Corp. (Glenshaw, Pennsylvania) have been found to be useful in the application of the present invention. The means 70 can be located substantially about the periphery of the cover or localized at designated points, as shown in Figure 1. In any event, means 70 should not affect the effective viewing area of the wearer. In addition, the means should be sufficient to allow for regular functional use, i.e. hold the cover 60 against the exterior surface of the lens 40 without falling off, in traditional facepiece applications. Although it will be recognized by one in the art that the thickness and quantity of adhesive will be dictated by the nature of the cover 60 and lens 40, a suitable thickness for an adhesive type means 70 is found to be about 50 mils and about 120 mils, while a preferred thickness is about 90 mils. Although a pressure sensitive adhesive is suitable for most applications, other commercially available attaching or fastening means may also be used. For example, clip-on type means 75, as illustrated in Figure 2, shows another embodiment of the present invention. Similarly, buckle or snap-on type means may be preferred by a particular user. Cover 60 of the present invention is fabricated using conventional methods such as slumping, pressing, forming, die- cutting, dinking, and grinding. For example, a flat piece of glass, cut to the desired length and width, may be slowly heated in an oven to a point where it softens. The piece of glass which is placed over a pre-shaped mold form will then collapse down and contour to the form. Similarly, the glass could be heated and pressed into a pre-shaped mold form. The glass piece will then be cooled down at a slow controlled rate. If the material is not a ceramic material, such as glass, cover 60 may be molded or casted, as required. Whatever technique is employed, it is important to maintain the desired optical quality of cover 60. For example, a piece of finished polished glass (sometimes referred to as "float glass") is typically used as the starting material, and as a result, maintenance of this surface quality is desirable. Means 70, if a pressure sensitive adhesive, can be applied to the cover 60 or directly to the lens 40. Typically, attachment of means 70 will be no more than applying with a thumb, small putty knife, and the like. Likewise, application may be with a machine or dispenser type apparatus like a syringe. The cover 60 and applied means 70 are placed over the effective viewing area of lens 40 and pressed with a small force, e.g. by hand, to securely attach the cover 60 to the lens 40. In the alternative, cover 60, with or without the aid of an adhesive, can be buckled, clipped, snapped or the like onto lens 40 with a means which corresponds to the particular fastener utilized. Although a lay-over type cover as described above is preferred because of its adaptability to existing products, a laminated type bond between cover 60 and lens 40 is also contemplated. For example, a transparent adhesive layer may be applied to provide a permanent bond between cover 60 and lens 40 using conventional techniques, e.g. in a clean room atmosphere. Typically, a space (not shown) will exist between the cover 60 and the lens 40 once attached. The space, will generally correspond to the thickness of the means when an adhesive type means is employed. If a clip-on, etc. type means is more preferred, a small gasket may be used to provide a space between cover 60 and lens 40. A space is preferred to allow for any irregularities or discrepancies that may exist in fit between cover 60 and lens 40. If the space is too great however, optical distortion may exist. In addition, the strength an integrity of cover 60 will diminish. In other words, if cove 60 is located too far away from lens 40, it will appear mor like an add-on attachment, provide additional weight to respirator 10 and ultimately, more discomfort to the wearer. On the other hand, if the space is too small, dust particles may get trapped between cover 60 and lens 40 during usage and create structural weaknesses in both the cover and lens. As such, a space between cover 60 and lens 40 within the range of about 1/300 of an inch and 1 inch has been found to be appropriate. A space between 1/100th of an inch and about 1/2 inch is preferred because such a space has been found to provide structural support to cover 60 while maintaining good optical quality and vision to a wearer. Especially preferred is a space between cover 60 and lens 40 of about 1/8 of an inch. An extra seal (not shown) , although not necessary, may be desired to prevent migration of dust and other particles, or simply to reinforce shield 50 and lens 40. Typically, one-sided PVC adhesive tape or weather stripping, e.g. standard electrical tape, may be placed over the shield 50 and lens 40 interface (one half on the holder of lens 40 and one half on shield 50) . The full facepiece respirator 10 with shield 50 of the present invention may be then used in traditional applications. Once optical quality is impaired or diminished to the point where the wearer's vision is affected, and hence his/her safety and ability to perform, the cover 60 may be cleaned. Cleaning of cover 60 is easily accomplished while directly attached to lens 40 or cover 60 may be removed and then cleaned. If an adhesive type means is used, cover 60 may be pried off lens 40 with a slight force. Otherwise cover 60 may simply be unbuckled, undipped, or unsnapped, etc. depending on the particular type of fastening means. Once the adhesive means 70 loses its tackiness, a new layer should be applied to cover 60 or lens 40. Depending on the nature of the material deposited on the cover, any known chemical or mechanical cleaning technique may be employed. For example, the deposited material may be scraped with a razor blade, scrubbed or scoured with steel wool, soaked in a bath, or simply washed and wiped. In addition, cover 60 may be cleaned with the use of a commercially available solvent. Lastly, because of the hard, abrasion-resistant material of cover 60, pitting, burning and scratches are no longer problematic. The shield of the present invention affects neither form, fit or function of any full facepiece respirator. Unlike the flexible lens cover of the prior art, the shield is durable, simple and cost effective. In addition, the shield of the present invention may be used as a protector of face shields, goggles, or any face or head protective safety apparatus having a optically transparent viewing window or lens panel. Lastly, the cover may be colored or tinted or the shield otherwise adapted to filter out certain wavelengths of undesirable light. A non-limiting illustration of the shield of the present invention follows. EXAMPLE A shield in accordance with the present invention was produced by slumping a flat piece of glass, available from American Flat Glass Co. , over a series of preforms. The piece of glass, cut to the dimension shown below, was sequentially laid over the series of three concave cylindrically curved rectangular preforms and heated in an oven at 650°C for 60 minutes for each of the sequential slumping operations. Once slumping began, the glass naturally slumped or caved into each of the preform. A three step slumping operation, using successive stronger concave curves, was utilized to minimize the distortion and more accurately obtain the finished curvature. The glass piece, having been formed, was then slowly cooled in a four step process to minimize stress. The first cooling step was a 260°C drop in 4 minutes, followed by a 93°C drop in 10 minutes, then a 150°C drop in 5 minutes and, finally, the piec was allowed to air cool to ambient temperature. As an exampl of the above, the shield has a shape and design substantially i accordance with the principles and embodiment of the inventio shown in the drawings hereof. Means 70 is a commercially available adhesive, namely a tub and tile cocking sold by Manco Inc. (Model PN BCT-1) . Cover 60 was of compatible shape to an OMNI STAR™ Full Facepiece Respirator (available from Cabot Safety Corp., Southbridge, MA) and had the following dimensions (before and after the slumping process) : Four circular pieces of adhesive, having a thickness dimension 90 mils and a diameter of 750 mils were applied to the four corners of cover 60. Cover 60 was then placed over the effective viewing area on the OMNI STAR™ respirator lens. A slight force was applied by hand to securely hold the cover 60 to lens 40. An extra adhesive strip of black electrical tape was place over the shield and lens interface to provide extra reinforcement. Quantitative tests of the respirator were performed to determine the protection factor (defined as the concentration of particles in the ambient air divided by the concentration of particles inside of respirator 10) before and after shield 50 was mounted to the respirator. In particular a PORTA-COUNT (available from TSI Inc., St. Paul, Minnesota) particle counter was used to determine the protection factor. A protection factor of 8000 was recorded, both before shield 50 was mounted to the respirator and after shield 50 was mounted to the respirator, thus illustrating that the shield of the present invention affected neither form, fit nor function of the OMNI STAR™ respirator. As illustrated by the above example, the shield of the present invention provides for an efficient and reusable cover. The protective lens of a respiratory or face mask is shielded against pitting, burning, abrasion, scratching, and deposition of opaque materials. The cover may be simply removed and cleaned by any known technique. The need for peel-away flexible sheets is obviated. It is understood that the present invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the scope and spirit of the invention. What is claimed is:

Claims: CLAIMS 1. A shield for protecting the exterior surface of optically transparent lens comprising: a cover adapted for attachment over said lens, said cover formed to a shape compatible to said lens; and a means for securely attaching said cover against said exterior surface of said lens; wherein said cover is attached over the effective viewing area of said lens. 2. The shield according to Claim 1 wherein said cover comprises a optically transparent, durable, abrasion-resistant material. 3. The shield according to Claim 2 wherein said material is glass. 4. The shield according to Claim 1 wherein said shape is a cylindrically curved rectangle. 5. The shield according to Claim 1 wherein said attaching means is a pressure sensitive adhesive. 6. The shield according to Claim 1 wherein said attaching means is located at the four corners of said cover. 7. The shield according to Claim 1 wherein said cover has a thickness between about 10 mils and about 500 mils. 8. The shield according to Claim 7 wherein said thickness is between 50 mils and 140 mils. 9. The shield according to Claim 1 wherein a space exists between said cover and said lens when attached of between about 1/300" and about 1" . 10. The shield according to Claim 9 wherein said space is between about 1/100" and about 1/2". 11. The shield according to Claim 1 wherein said shield is mounted to said lens of a respirator. 12. The shield according to Claim 11 wherein said respirator is a full facepiece respirator. 13. The shield according to Claim 1 wherein said shield is mounted to said lens of a faceshield. 14. The shield according to Claim 1 wherein said shield is mounted to said lens of a protective goggle. 15. A shield for protecting the exterior surface of the lens of a full facepiece respirator comprising: a cover adapted for attachment over said respirator lens, said cover formed to a shape compatible to said respirator lens; and a means for securely attaching said cover against said exterior surface of said respirator lens; wherein said cover is attached over the effective viewing area of said respirator lens. 16. The shield according to Claim 15 wherein said cover comprises an optically transparent, durable, abrasion-resistant material. 17. The shield according to Claim 16 wherein said material is glass. 18. The shield according to Claim 15 wherein said shape is a cylindrically curved rectangle. 19. The shield according to Claim 15 wherein said attaching means is a pressure sensitive adhesive. 20. The shield according to Claim 15 wherein said attaching means is located at the four corners of said cover. 21. The shield according to Claim 15 wherein said cover has a thickness between about 10 mils and about 500 mils. 22. The shield according to Claim 21 wherein said thickness is between about 50 and 140 mils. 23. The shield according to Claim 15 wherein a space exists between said cover and said respirator lens when attached of between about 1/300" and about 1". 24. The shield according to Claim 23 wherein said spacing is about 1/100" and about 1/2". 25. A full facepiece respirator adapted to cover at least the eyes, nose, and mouth of a wearer comprising a soft, conformable face sealing member having an optically transparent lens panel of a given width and length, an exhalation means, a harness assembly for attaching said face sealing member tightly against the face of a wearer wherein said improvement comprises a shield for protecting the exterior surface of said lens comprising: a cover adapted for attachment over said lens, said cover formed to a shape compatible to said lens; and a means for securely attaching said cover against said exterior surface of said lens; wherein said cover is attached over the effective viewing area of said lens. 26. The respirator according to Claim 25 wherein said cover is composed of an optically transparent, durable, abrasion-resistant material. 27. The respirator according to Claim 26 wherein said material is glass. 28. The respirator according to Claim 25 wherein said shape is a cylindrically curved rectangle. 29. The respirator according to Claim 25 wherein said attaching means is a pressure sensitive adhesive. 30. The respirator according to Claim 25 wherein said attaching means is located at the four corners of said cover. 31. The respirator according to Claim 25 wherein said cover has a thickness of between about 10 mils and 500 mils. 32. The respirator according to Claim 31 wherein said thickness is between about 50 mils and 140 mils. 33. The respirator according to Claim 25 wherein a space exists between said cover and said lens when attached of between about 1/300" and about 1". 34. The respirator according to Claim 33 wherein said space is between about 1/100" and about 1/2". 35. The respirator according to Claim 25 wherein said respirator further comprises an inhalation means. 36. The respirator according to Claim 35 wherein said respirator further comprises at least one removably attached filtration element capable of removing hazardous fumes and gases air inhaled through said inhalation means.

Inventors: JOHNSTON R SCOTT, SALCE JOHN E, JOHNSTON, R., SCOTT, SALCE, JOHN, E.
Applicants: CABOT SAFETY CORP, CABOT SAFETY CORPORATION
Application year: 1992
Main classification: A62B18
IPC codes: A62B18