AU665003B2 - Viewing window protector - Google Patents

Description

ii OPI DATE 30/12/92 AOJP DATE 11/02/93 APPLN. ID 20084/92ll 11 11111 PCT NUMBER PCT/US92/04102 I ill AU9220084 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 92/20405 A62B 17/04, 18/00 Al (43) International Pub!ication Date: 26 November 1992 (26.11.92) (21) International Application Number: (22) International Filing Date: Priority data: 702,656 17 May 1 PCT/US92/04102 15 May 1992 (15.05.92) 991 (17.05.91) (71) Applicant: CABOT SAFETY CORPORATION [US/US]; Mechanic Street, Southbridge, MA 01550 (US).

(72) Inventors: SALCE, John, E. 166 Central Street, Auburn, MA 01501 JOHNSTON, Scott 196 Spring Street, Shrewsbury, MA 01545 (US).

(74) Agents: LANDO, Michelle, B. et al.; Cabot Corporation, 157 Concord Road, Billerica, MA 01821 (US).

(54) Title: VIEWING WINDOW PROTECTOR (81) Designated States: AT (European patent), AU, BB, BE (European patent), BG, BR, CA, CH (European patent), CS, DE (European patent), DK (European patent), ES (European patent), FI, FR (European patent), GB (European patent), GR (European patent), HU, IT (European patent), JP, KR, LK, LU (European patent), MC (European patent), MG, MN, MW, NL (European patent), NO, PL, RO, RU, SD, SE (European patent).

Published With international search report.

665003 (57) Abstract A full face respirator having an optically transparent lens (40) panel which includes a sh.!d (50) for protecting the exterior surface of the lens 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.

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WO 92/20405 PCT/US92/04102 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 an:d 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 WO 92/20405 PCT/US92/04102 2 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 disclos-is 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 fresh piece of film in its place.

U. 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 ir; pulled across the panel and torn off thereby leaving a fresh I 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 reusable and must be replaced on an on-going basis. Each layer in a stack w.ll. also provide su-,ace 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 peeloff lens covers are not resistant to abrasion and scratching, nor is cleaning possible.

I I WO 92/20405 PCT/US92/04102 -3- SUMIARY 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 o:f 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.

WO 92/20405 PCT/US92/04102 -4- 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 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 sufficient strength to withstand heavy impact without breaking, bending, cracking or shattering.

In addition, it is often necessary that the protective lens 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 Sof 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 velding operations. Lastly, the optical quality of the lens is reduced by deposition of opaque materials thereon, as typically associated with spray painting operations.

X I- i WO 92/20405 PCT/US92/04102 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 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 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 cov i: 6Cr su.. eat 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 j 'i aa=e4m a has been found suitable for cover 60 in achieving the aforementioned qualities and a-'.nM CO)t 'a 5 6 V\v objective, and a thickness of about 5t.etou-- 10 ml.. is t.iR, preferred. Especially preferred is a thickness of about k& l s uj WO 92/20405 PCT/US92/04102 -6- 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 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 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 andabout 5.05mm about M 1=.is while a preferred thickness is about9=m r_ 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, diecutting, dinking, and grinding. For example, a flat piece of t glass, cut to the desired length and width, may be slowly heated iY\ Fr WO 92/20405 PCT/US_. 102 -7in 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. Similar,-, 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 inportant 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 In the alternative, cover 60, with or without the aid of an adhesive, can be buckled, clipped, snapped or the like onto lens 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 using conventional techniques, e.g. in a clean room atmosphere.

Typically, a space (not shown) will exist between the cover and the lens 40 once attached. The space, will generally correspond to the thickness of the means when an adhesaive 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 WO 92/20405 PCT/US92/04102 8 cover 60 and lens 40. If the space is too great however, optical distortion may exist. In addition, the strength and integrity of cover 60 will diminish. In other words, if cover is located too far away from lens 40, it will appear more 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

I

I has been found to be appropriate.

A

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 115 quality and vision to a wearer. Especially preferred is a space between cover 60 and lens 40 of about 1/8 of an inch1.

B An extra seal (not shown), although not necessary, may be I desired to prevent migration of dust and other particles, or i 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 f (one half on the holder of lens 40 and one half on shield The full facepiece respirator 10 with shield 50 of the present invention may be then used in traditicoal 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 I 30 adhesive type means is used, cover 60 may be pried off lens with a slight force. Otherwise cover 60 may simply be unbuckled, unclipped, or unsnapped, etc. depending on the particular type of fastening means. Once the adhesive means loses its tackiness, a new layer should be applied to cover or lens

II

WO 92/20405 PC/US92/04102 -9- Depending on the nature of the material deposited on thc cover, any known chemical or mechanical cleaning technique may be employed. For example, tqe 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 may be cleaned with the use of a commercially available solvent.

Lastly, because of the hard, abrasion-resistant material of cover 60, pitting, burnipa end 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 0 C for minutes for each Pf .he sequentiPl 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 cLt.in tile finished curvature.

The glass piece, having been form(d, was then slowly cooled in a four step process to minimize stres;. The first cooling step was a 2600C drop in 4 minutes, followed by a 930C drop in minutes, then a 1500C drop in 5 minutes and, finally, the piece was allowed to air cool to ambient temperature. As an example of the above, the shield has a shape and design substantially in accordance with the principles and embodiment of the invention 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 T Full Facepiece Respirator (available from Cabot Safety Corp., Southbridge, MA) and had the following dimensions (before and after the slumping process): Cover 60 Flat piece Length 209.55 mm Width 101.6 mm Thickness 2.3622 mm Curvature Flat Cover 60 Developed piece SLength 160.02 mm Width 101.6 mm Thickness 2.3622 mm Total arc 1450 Curvature inside 81.76 mm Curvature outside 84.15 mm Four circular pieces of adhesive, having a thickness dimension 2.29 mm and a diameter of 19.05 mm were applied to the four corners of cover 60. Cover S 60 was then placed over the effective viewing area on the OMNI STAR T M "o 25 respirator lens. A slight force was applied by hand to securely hold the cover V. to lens 40. An extra adhesive strip of black electrical tape was placed over the shield ,nd 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

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WO 92/20405 PCT/US92/04102 11 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 de-arting from the scope and spirit of the invention.

I What is claimed is: 1 LI C I

Claims (22)

1. A shield for protecting the exterior surface of an optically transparent viewing window lens attached to a respirator comprising: a reusable cover formed from an optically transparent, durable, abrasion- resistant, rigid material and having a shape compatible with said lens; and a means for securely attaching said cover agair st said exterior surface of said lens; wherein said cover is located over the effective viewing area of said lens and is spaced between 0.762 mm to 25.4 mm from said exterior surface of said lens.

2. The shield according to claim 1, wherein said material is glass.

3. The shield according to claim 1, wherein said shape is a cylindrically curved rectangle.

4. The shield according to claim 1, wherein said attaching means is a u pressure sensitive adhesive. 4 The shield according to claim 1, wherein said attaching means is located at the four corners of said cover.

6. The shield according to claim 1, wherein said cover has a thickness between 0.254 mm to 12.7 mm.

7. The shield according to claim 6, wherein said thickness is between 1.27 mm and 3.56 mm.

8. The shield according to claim 1, wherein a space existing between said cover and said lens is between .254 mm and 12.7 mm. 1 13

9. The shield according to claim 1, wherein said shield is mounted to said lens of a respirator. The shield according to claim 1, wherein said respirator is a full facepiece respirator.

11. The shield according to claim 1, wherein said shield is mounted to said lens of a faceshield.

12. The shield according to claim 1, wherein said shield is mounted to said lens of a protective goggle.

13. A shield for protecting the exterior surface of the iens of a full facepiece respirator comprising: a reusable cover formed from an optically transparent, durable, abrasion- resistant, rigid material and having a shape compatible with said respirator lens; and a means for securely attaching said cover against said exterior surface of said respirator lens; wherein said cover is located over the effective viewing area of said respirator lens, and is spaced between 0.762 mm and 25.4 mm (1/300" to 1") from said exterior surface of said lens. S14. The shield according to claim 13, wherein said material is glass. The shield according to claim 13, wherein said shape is a cylindrically curved rectangle.

16. The shield according to claim 13, wherein said attaching means is a pressure sensitive adhesive.

17. The shield according to claim 13, wherein said attaching means is located at the four corners of said cover. I II I I I 1 14

18. The shield according to claim 13, wherein said cover has a thickness between 0.254 mm and 12.7 mm.

19. The shield according to claim 18, wherein said thickness is between 1.27 mm and 3.56 mm. The shield according to claim 13, wherein a space exists between said cover and said respirator lens when attached of between 0.0762 mm and

25.4 mm. 21. The shield according to claim 20, wherein said spacing is 0.254 mm and 12.7 mm. 22. 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 the improvement of the full facepiece respirator comprises a shield for protecting the exterior surface of said lens comprising: a reusable cover formed from an optically transparent, durable, abrasion- resistant, rigid material and having a shape compatible with said lens; and a means for securely attaching said cover against said exterior surface of said lens; wherein said cover is located over the effective viewing area of said lens, and is spaced between 0.762 mm and 25.4 mm from said exterior surface of said lens. 23. The shield according to claim 22, wherein said material is glass. 24. The respirator according to claim 22, wherein said shape is a cylindric&;y curved rectangle. 1 The respirator according to claim 22, wherein said attaching means is a pressure sensitive adhesive.

26. The respirator according to claim 22, wherein said attaching means is located at the four corners of said cover.

27. The respirator according to claim 22, wherein said cover has a thickness of between 0.254 mm and 12.7 mm.

28. The respirator according to claim 27 wherein said thickness is betweci 1.27 mm and 3.56 mm.

29. The respirator according to claim 22, wherein a space exists between said cover and said lens when attached of between 0.0762 mm and 25.4 mm. The respirator according to claim 29, wherein said space is between 0.254 mm and 12.7 mm.

31. The respirator according to claim 22, wherein said respirator further comprises an inhalation means.

32. The respirator according to claim 31, wherein said respirator further comprises at least one removably attached filtration element capable of removing hazardous fumes and gases from air inhaled through said inhalation f means. DATED this lth day of October, 1995 CABOT SAFETY CORPORATION WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA