The field of this invention relates to fabric face masks that are used by medical personnel, construction workers, dog groomers and others to filter contaminants.
Many fabric face masks use thin bands of metal called “nosepieces” or “nosewires” to provide rigidity to the fabric. The nosepieces generally extend for the entire width of the face mask. An example of such a face mask is U.S. Pat. No. 5,699,791 (Sukiennik et al).
In theory, nosepieces can readily be bent to conform to contours of a persons face and promote a better fit. However, upon reviewing results of leakage tests, the Applicant has reached the conclusion that conventional nosepieces actually contribute to leakage as the wearer breathes in and out, which has lead to the Applicant seeking a face mask construction with an alternative form of nosepiece.
There is provided a face mask that has a fabric body of folded filter material defining an expandable face pocket. For purposes of orientation, the body can be said to have an interior face, an exterior face, a top edge, a bottom edge and opposed side edges. A bendable strip of metal defines a nosepiece. The nosepiece is centrally positioned between the opposed side edges along the top edge. For reasons that will hereinafter be more fully explained, it has a length that is not less than 3.50 cm and not more than 6.00 cm, with a width that is not less than 0.30 cm and not more than 2.00 cm. Straps are used to secure the fabric body to a person's head.
The theory behind this face mask is that a stable anchor in the vicinity of the nose is the key to obtaining a fit with less leakage. As will hereinafter be further described, the masks generally come in small, medium and large sizes. Consistent with all sizes is a nosepiece that bends to fit the contours of the nose. It is to believed that the nosepiece is critical to maintaining a seal to prevent leakage as the wearer breathes in and out. When the length of the nosepiece is less than 3.50 cm, the nosepiece does not properly engage the nose and, therefore, does not provide the desired anchor. It also is prone to leakage. When the length of the nosepiece exceeds 6.00 cm, it extends beyond the natural creases along the nose and onto the cheeks. It has been found that although there may initially be a seal, as soon as the wearer talks or makes a facial expression, the seal is lost. A length of less than 6.00 cm engages the nose, without creating this leakage problem. The width of the nosepiece is equally important. When the width is less than 0.30 cm, there is insufficient rigidity to engage the nose and maintain a seal. When the width is greater than 2.00 cm, the nosepiece becomes too rigid and leakage occurs under the nosepiece.
Once the problem of anchoring to the nose was solved, different methods of securing the bottom edge and opposed side edges of the body were tried, Superior results were obtained when an elastomeric strip under tension was extended from a strap anchoring point one third of a distance down one of the opposed sides, along the bottom edge to an opposed strap anchoring point two thirds of a distance up another of the opposed sides. It is to be noted that the elastomeric strip is under tension. This exerts a biasing three upon the body to draw the expandable face pocket into a wearer's face along the bottom edge and the opposed side edges.
The preferred positions for attaching the straps to the body are at the strap anchoring point and the opposed strap anchoring point. It has been found to simplify the manufacturing process when a one piece construction is used, with the straps merely being extensions of the elastomeric strip.
These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein:
A face mask, generally identified by reference numeral 10, will now be described with reference to
Referring to
An elastomeric strip 34 under tension extends from a strap anchoring point 36 one third of the distance down one of opposed sides 24 and along bottom edge 22 to an opposed strap anchoring point 38 two thirds of the distance up another of opposed sides 24. Straps 30 are secured to strap anchoring point 36 and opposed strap anchoring point 38 and are integrally formed extensions of elastomeric strip 34. Referring to
Face mask 10 is worn over a face 40 of person's head 32 as illustrated in
As elastomeric strip 34 is under tension, it exerts a biasing force upon the body 12 to draw the expandable face pocket 14 into a wearer's face 40 along the bottom edge 22 and the opposed side edges 24. Referring to
A face can be categorized as small, medium or large. The length of a person's face is determined by the menton-sellion length, extending from the top of the bridge of the nose to the bottom of the chin. The width of a person's face is determined by the bi-zygomatic breadth, which is the distance between the zygomatic arches. Although the broad working range has been described above, best mode in small, medium and large is considered to be as follows:
Length 4 cm×Width 0.75 cm.
Length 5 cm×Width 1.00 cm
Length 6 cm×Width 1.5 cm
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
It will be apparent to One skilled in the art that modifications may be made to the illustrated embodiments without departing from scope of the Claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CA2009/001041 | 7/22/2009 | WO | 00 | 1/23/2012 |