Apparel – Guard or protector – For wearer's head
Reexamination Certificate
1999-12-10
2001-08-14
Nerbun, Peter (Department: 3741)
Apparel
Guard or protector
For wearer's head
Reexamination Certificate
active
06272693
ABSTRACT:
DESCRIPTION
1. Field of the Invention
The present invention relates to the field of diving equipment, and in particular to a dive mask model.
2. Description of the Prior Art
As it is known, a dive mask comprises a rigid frame supporting a pair of plane glasses. A flexible seal extends from the contour of the frame and is fit to be positioned onto the diver's face to make the space in front of the eyes watertight. More specifically, the seal is positioned over a forehead portion, at the temples, the cheekbones and below the diver's nose, without covering the mouth. Sometimes a single moulded glass, letting at least partially protrude the nose enclosure of the seal, is provided in place of the pair of glasses. The glasses (or the single glass) of the mask lie on a plane perpendicular to the front axis of the face, i.e. to the diver's visual axis.
The frame supporting the glasses is provided with a ledge onto which the glasses themselves abut with the interposition of the edge of the flexible seal in order to support it. Locking means of the glasses are further provided, usually formed by thin rings, moulded according to the frame contour and apt to engage therewith to lock the glasses against the above-mentioned ledge.
The above-described structure entails a certain frame thickness; therefore, although the glasses have suitable dimensions for allowing a wide visual angle, the frame constitutes a hindrance for the view. In particular, the lower portion of the visual field is the one most affected by the frame thickness. In fact, even leaning forward the head as much as possible, until touching the chest, the frame screens altogether the view of the upper portion of the diver chest.
This entails no significant inconvenience in skin-diving. However, in case of a diving carried out with the complex apparatus required by the use of bottles, some important components thereof, in particular the control instruments located just at the upper chest portion, are left out of the diver's field of view. Hence, unless tiring and awkward twisting is performed, such instruments have to be laboriously operated by groping only.
A first solution of this problem, tested in the past yet readily discarded, foresees the mere downward inclination of the glasses. This did not achieve the desired effect, in view of the fact that, at the high angles required to provide the diver's chest sight, a considerable distortion of the perceived images occurs.
As a further solution, a dive mask provided with ancillary glasses inclined with respect to the main ones and located at the lower portion of the mask, and possibly also at both sides thereof, was proposed. This solution, disclosed in Italian patent application GE/91/A/000002, increases the diver's angle of view, but exhibits several drawbacks.
Firstly, the mask is bulkier and more expensive, and its design is subject to additional constraints, unavoidably making it unappealing. However, the most serious drawback lies in the fact that the ancillary glasses, which are substantially orthogonal to the main glasses, “fragment” the overall image perception, due to the presence of intermediate blind parts, corresponding to the angles between the main and the ancillary glasses. The resulting visual effect is extremely irksome, in light of the further magnification of the aforementioned blind parts due to the water refraction. In particular, due to the impermanency of the visualised item, the diver experiments queasiness and confusion.
Likewise solutions having analogous drawbacks, for instance the one disclosed in Italian patent No. 1284748, foresee the adoption of glasses having an at least partially curved development, therefore capable of increasing the angle of view below the mask and possibly at the sides thereof. In this instance as well, the problems of the image distortion and of the consequent discomfort to the diver are extremely relevant.
Surprisingly, by re-examining and thoroughly studying the most banal solution, i.e. that of the mere downward inclination of the glass, it has been found a novel structure of an inclined glass dive mask combining simplicity of design and attainment of an optimum chest visibility by the diver with no sensible image distortion.
SUMMARY OF THE INVENTION
Therefore it is an object of the present invention to provide a dive mask having a rigid frame for supporting at least one transparent glass, a flexible seal extending from the frame contour and apt to be secured on the diver's face by means of an adjustable strap. The at least one glass is supported by the frame so as to have a downward inclination with respect to the plane orthogonal to the diver's visual axis when the mask is put on, thereby facilitating the view of the upper chest portion of the diver. According to the invention, the ratio between the height of the at least one glass, measured orthogonally to the visual axis of view when the mask is put on, and the maximum distance between the axis of symmetry of the frame and the edge of the at least one glass is higher than or equal to 0.75.
Thus, the angle of view can remarkably be increased at the bottom side of the visual field, allowing the diver a chest view, although with a reduced angle of the glass plane of the mask, entailing no sensible distortion. The concept is explained in the annexed
FIG. 1
, schematically showing the variation of the visual angle as a function of the downward inclination of the plane of the mask glasses. It has to be noted that the planes defined below are represented by their respective traces on the plane of FIG.
1
.
In the above figure, the diver's eye position is indicated at O and the front axis or visual axis of view thereof is indicated with X. A known vertical glass mask, the section plane of which is indicated by A
o
B, allows a visual angle &bgr;
o
defined by a plane b, passing through point O as well as point B, corresponding to the top edge of the glasses, and by a plane a
o
, passing through point O and a point A
o
, belonging to the bottom edge of the same glasses.
Starting from this solution, in order to avoid the screening action of the bottom edge of the mask frame, it is necessary to downwardly incline the glass plane at an angle &agr;
1
by rotation around the top edge thereof, represented by point B, to displace the bottom edge of the glasses from A
0
to A
1
. The point A
1
indicates the maximum allowable setback, corresponding to a positioning of such bottom edge at the diver's cheekbones. Thus, the angle of view is increased from &bgr;
0
to &bgr;
1
, the latter angle being defined by the plane b and by a plane a
1
, passing through points O and A
1
. However, with the prior art mask geometry the angle &bgr;
1
entails an unacceptable image distortion, and this is the reason why it was found unsatisfactory, as explained in the introductory part of the description.
According to the invention, if the glasses have a longer relative height with respect to the known masks, the plane at the glasses can be inclined of an angle of &agr;
2
, represented by the trace between B and A
2
, which is sensibly less than &agr;
1
, and therefore does not entail a considerable distortion, but yields an angle of view &bgr;
2
even greater than &bgr;
1
and defined by the plane a
2
passing through points O and A
2
. This is possible because, as it is evident in the figure, point A
2
lies below point A
1
, and therefore below the level of the diver's cheekbone. Hence the bottom edge of the frame does not hinder a suitable chest view.
REFERENCES:
patent: 3944345 (1976-03-01), Decorato
patent: 5345615 (1994-09-01), Garofalo
patent: 5420649 (1995-05-01), Lewis
patent: 5819321 (1998-10-01), Wang
patent: GE91A0002 (1991-01-01), None
patent: 01284748 (1996-08-01), None
Browdy and Neimark
Cressi-Sub S.p.A.
Nerbun Peter
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