GB2035807A - Face visor for low temperature environments - Google Patents

Abstract

A face mask, to be worn by a wearer in dry cold weather, in which mask condensation and fogging are prevented, has a transparent visor overlying the eye and nasal areas of the wearer, and support means including a support harness. To inhibit condensation of moisture on the internal surface of the visor, a nasal cup is provided, being spaced from said visor and supported in a manner so as to form with the visor an air conducting channel. The nasal cup encloses a space in the nasal area. An inhalation valve in said nasal cup permits unidirectional air flow through the same upon inhalation by the wearer. Inhalation creates a pumping action to momentarily evacuate the enclosed space, such evacuation inducing a flow of dry cold air through the conducting channel and inhalation valve means. This flow of dry cold air inhibits the condensation of moisture on surfaces of the visor internally of the face mask. A supporting base member may also be provided, connected to both the visor and nasal cup so as to support the nasal cup. In a preferred configuration, the visor, supporting base member and nasal cup are integrally connected, being formed as a moulded, unitary structure. An exhalation valve means may also be provided, being operative upon exhalation by the wearer to permit the unidirectional flow of warm moist air from the enclosed space to the ambient environment. <IMAGE>

Description

SPECIFICATION Face visor for low temperature environments This invention relates generally to face protection as might be required by persons working in dry, cold atmospheric conditions such as those encountered in polar climates. More particularly, this invention relates to an imprved face mask adapted to be worn in such conditions, in which mask condensation and "fogging" are minimized.

Facial protection is often required by persons working outdoors in winter, or in other environments where cold dry atmospheric conditions are encountered such as high altitudes. This is especially important in the ambient winter conditions found in many parts of North America or Northern Europe and Asia, and particularly in Arctic and Antarctic regions. Indeed, such conditions of low humidity tend to be found in any region which is subject to continental weather conditions, as opposed to maritime conditions where ambient humidity levels tend to be much higher.

Protection for the eye and nasal areas is usually in the form of masks or goggles.

However, these are frequently subject to "fogging" or "frost-up" due to the condensation of moisture on the inner surfaces of the mask or goggles, due largely to the relatively low ambient humidity encountered. Such moisture is derived from exhaled air, or from perspiration from the face in the area covered by the mask or goggles. The presence of such moisture is inevitable, and aggravates the above-mentioned tendency for condensation.

According to the invention there is provided a face mask adapted to be worn by a wearer in dry cold atmospheric conditions, comprising a transparent visor to overlie eye and nasal areas of the wearer and support means including a support harness, and provided with a nasal cup spaced from the visor and supported in a manner so as to form with the visor an air conducting channel, said cup enclosing a space in the nasal area; and inhalation valve means provided in the nasal cup, the valve means permitting unidirectional air flow through the same upon inhalation by the wearer, so that said inhalation causes a momentary evacuation of the enclosed space, whereby the evacuation induces a flow of dry cold air through the conducting channel and inhalation valve means, such flow of dry cold air inhibiting condensation of moisture on surfaces of the visor internally of the face mask.

In a preferred form of the present face mask, a supporting base member is also provided, this base member being connected to both the transparent visor and nasal cup, with the nasal cup being supported by the base member.

In a more preferred form of face mask embodying the present invention, exhalation valve means are also provided in the base member, such exhalation valve means being in flow communication with the enclosed space and operative to permit unidirectional flow of warm moist air upon exhalation by the wearer from the space to the ambient environment. In this way the entry of moist exhaled air into the vicinity of the visor is prevented.

According to yet another preferred embodiment of this invention, the transparent visor, the supporting base member and nasal cup are intregrally connected, being formed as a unitary structure, preferably moulded, and formed with apertures therein for the unidirectional valve means.

The present invention, therefore, provides an improved face mask which minimizes problems of fogging or "frost-up" of prior art masks or goggles. The invention will now be illustrated by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates in side elevation one preferred embodiment encompassed by this invention; and Figure 2 is a front elevation view of the face mask illustrated in Fig. 1.

Fig. 1 shows overall one preferred form of face mask 10 according to this invention.

Thus, the face mask typically has a transparent visor 12 mounted on a supporting structure 14 that has a harness 16 adjustably connected to it. Adjustability of the harness 16 is by adjustment devices indicated at 18 typically being in the form of a buckle or hasp.

The transparent visor 12 overlies the eye and nasal areas of a wearer 20. This transparent visor is usually clear, although some colouring or tinting can be added if desired.

Further, the visor 12 is generally formed of sheet or planar material, curved to generally embrace or surround the eye and nasal area of the wearer 20. Moreover, the visor 12 is conventionally attached to the flexible support 14 by means of an adhesive or sealant well known to persons knowledgeable in this art.

The flexible support 14 extends peripherally of the transparent visor 12, and usually has a preformed edge adapted to follow fairly closely the contours of the face of the wearer 20.

The face mask 10 also includes a base member 22 which is generally planar in form.

In the face mask 10 shown in Figs. 1 and 2, this base member 22 is formed integrally with the transparent visor 12 and a nasal cup 24.

This nasal cup 24 is spaced from the visor 12 and supported on the base member 22 in a manner so as to form with that visor an air conducting channel or passageway.

Of particular importance to the present invention is the nasal cup 24 which encloses a space 28 of preselected volume around the nasal area of the wearer 20. The volume of space 28 should be less, preferably considerably less, than the volume of air normally inhaled by wearer 20 at rest. Thus, the volume of air inhaled by wearer 20 while working or exerting some effort, say, while walking fast, will greatly exceed the volume of space 28. Inhalation by wearer 20 will, therefore, develop a pumping action tending to evacuate the space 28 momentarily, and induce a purging flow of cold, dry ambient air into the face mask, across the inside surface of the transparent visor 12. Typically, a wearer 20 may inhale 25-30 litres/minute of air while resting, and say 110 litres/minute while working.

The volume of space 28 is much less, typically in the order of 50 to 100 milliliters.

In the preferred form of face mask 10 illustrated herein, the base member 22 is provided with apertures containing at least one inhalation valve 30. In the face mask illustrated, the inhalation valve 30 is a unidirectional valve and is in flow communication from the ambient environment to the air conducting passageway 26. The nasal cup 24 is also provided with one or more unidirectional inhalation valves 32. Thus, inhalation by the wearer 20 initially causes a momentary evacuation of the space 28, which then induces an in-flow of dry cold air from the ambient environment via inhalation valve 30, air conducting passageway 26 and inhalation valves 32 into the previously evacuated space 28. Thus, the flow of cold dry air which normally is also of low humidity, passes over the inner surface of the transparent visor 12.This purging flow of air tends to flush any moisture derived, for example, from facial perspiration under the visor into the space 28 from which it is initially inhaled and then subsequently exhaled by the wearer 20. As clearly seen from Figs. 1 and 2, exhalation orally will be directly into the ambient environment.

Normally, however, exhalation and inhalation occurs via the nose. Thus, the face mask 10 of Figs. 1 and 2 is also provided with at least one unidirectional exhalation valve 34.

The exhalation valve 34 interconnects the space 28 with the ambient environment outside of the face mask.

The exact structure and configuration of the inhalation valves 30 and 32, and exhalation valves 34 are well known in this art. The exact structure of such valves does not form part of the present invention and need not be described any further herein.

As a modification to the face mask 10 shown in Figs. 1 and 2, louvers or slots may optionally be provided peripherally of the visor 12. Such peripheral slots would further promote the purging movement of cold dry air from the exterior of the mask across the internal surface of the visor 12. As mentioned previously that purging movement inhibits the condensation or "frost-up" of moisture on that interior surface.

The foregoing has described one preferred form of face mask envisaged by this invention. Some modifications have been suggested, and others will be evident to persons knowledgeable in this art. It is intended to encompass all such modifications as fall within the scope of the invention defined in the claims below.

Claims (7)

1. A face mask adapted to be worn by a wearer in dry cold atmospheric conditions, comprising a transparent visor to overlie eye and nasal areas of the wearer, and support means including a support harness, and provided with a nasal cup spaced from said visor and supported in a manner so as to form with said visor an air conducting channel, said cup enclosing a space in said nasal area; and inhalation valve means provided in said nasal cup, said valve means permitting unidirectional air flow through the same upon inhalation by the wearer, so that said inhalation causes a momentary evacuation of said enclosed space whereby said evacuation induces a flow of dry cold air inhibiting condensation of moisture on surfaces of said visor internally of the face mask.

2. A face mask according to claim 1, wherein a supporting base member is provided, said base member being connected to both said visor and nasal cup, the nasal cup being supported by said base member.

3. A face mask according to claim 2, wherein exhalation valve means is provided in said base member, said exhalation valve means being in flow communication with said enclosed space and operative to permit unidirectional flow of warm moist air upon exhalation by the wearer from said space to the embient environment.

4. A face mask according to claim 1, 2 or 3 3 wherein air channel means are formed in said visor peripherally thereof, thereby to facilitate ducting of the incoming cold dry ambient air across the visor over the eye and nasal areas of the wearer upon inhalation by the wearer.

5. A face'mask according to claim 2, 3 or 4 wherein the visor, supporting base member, and nasal cup are integrally connected, being formed as a unitary structure, and formed with apertures therein for said valve means.

6. A face mask according to any one of claims 1 to 4 wherein said support means also includes a flexible sealing element adapted to conform to the facial contours of the wearer.

7. A face mask according to any of the preceding claims, substantially as herein described with reference to the accompanying drawings.