Abstract:
A diving mask includes a nose cover and a valve seat of a drainage mechanism having a check valve formed in the vicinity of the nose cover. The nose cover and the value seat are formed from an elastic material which is integral with a soft elastic material forming the nose cover. In the vicinity of the valve seat, an annular member formed from a plastic material plastics having a hardness and deformation-resistance both higher than those of the elastic material forming the valve seat is embedded in a bottom of the nose cover so as to extend along the valve seat.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a diving mask and more particularly to a diving mask having a drainage mechanism provided with a check valve. 
   Diving masks are well known which have a drainage mechanism provided with a check valve. For example, U.S. Pat. No. 5,890,234 (Reference 1) and U.S. Pat. No. 5,979,441 (Reference 2) disclose a diving mask comprising a nose cover formed integrally with a skirt member and an annular member attached to a bottom of the nose cover. The annular member includes a plurality of drain holes and a check valve adapted to be opened outward with respect to these drain holes. The check valve is normally held in close contact with a valve seat formed on the annular member. The annular member is previously formed using material different from material for the skirt member and set in a die when the skirt member is molded in this die so that the annular member may be integrated with the skirt member. 
   Conventionally, the annular member including the valve seat is formed using a plastic or metallic material is a relatively hard and deformation-resistant while the skirt member is formed using a soft and elastic rubber-like material. The annular member is provided with an annular projection having a height in a range of about 0.3 to about 0.5 mm serving as the valve seat. Generally, such annular member is set in the die used to mold the skirt member at a predetermined position of the die. Molten plastic material is injected at a high pressure into the closed die to obtain the skirt member including the nose cover integrated with the annular member. However, such a process of molding the skirt member may be often accompanied with a problem such that the molten plastic material flows to the annular member and partially covers the valve seat. Obviously, the valve seat should not be covered with the plastic material. The amount of the plastic material partially covering the valve seat in this manner refers to as flash and it is impossible to ensure that the check valve is normally held in close contact with the valve seat so far as such flash is not removed. 
   SUMMARY OF THE INVENTION 
   In view of the problem as has been described above, it is an object of the present invention to improve the conventional diving mask having the drain holes provided with the check valve so that the close contact between the check valve and the valve seat may be easily and reliably obtained. 
   The object set forth above is achieved, according to the present invention, by an improvement in a diving mask having a back-and-forth direction, a transverse direction and a vertical direction being orthogonal one to another, and comprising: a lens unit including one or more lenses formed from a soft and transparent material and located ahead in the back-and-forth direction; a skirt member formed from a soft elastic material and extending rearward from the lens unit and a head-strap member adapted to hold a peripheral edge of the skirt member in close contact with the face of a wearer, the skirt member being formed in a region corresponding to a middle region of the lens unit as viewed in the transverse direction with a nose cover; and a drainage mechanism including a check valve adapted to be opened toward an outside of the skirt member being formed in a bottom of the nose cover or in a vicinity of the nose cover. 
   The improvement according to the present invention is as follows: The drainage mechanism comprises an inner annulation defining a through-hole adapted to receive a mounting shaft of the check valve, a plurality of drain holes defined around the inner annulation by a plurality of spokes radially extending from the inner annulation and a valve seat extending in a circumferential direction of the inner annulation outside an array of the drain holes and projecting toward the check valve. The valve seat is formed from an elastic material integrated with the soft elastic material forming the skirt member. An annular member formed from one of a plastic material and a metallic material having a hardness and deformation-resistance both higher than those of the elastic material forming the valve seat is embedded in the bottom of the nose cover in a vicinity of the valve seat so as to extending along the valve seat. 
   According to one preferred embodiment of the present invention, the inner annulation of the drainage mechanism has the through-hole formed from the same hard material as the material forming the annular member so that the hard material constituting the inner annulation is connected with the annular member by means of the hard material extending along the spokes. 
   In the diving mask according to the present invention, the valve seat cooperating with the check valve is formed from the elastic material which is integrated with the elastic material used for the skirt member. This unique arrangement reliably eliminates the possibility that the elastic material used to form the skirt member might cover the valve seat in the form of flash. Furthermore, the through-hole and the annular member of the drainage mechanism can be formed at once from the hard material by connecting such hard material constituting the inner annulation with the annular member formed from the hard material extending along the spokes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing a diving mask as an embodiment of the invention; 
       FIG. 2  is a partially cutaway side view showing the diving mask; 
       FIG. 3  is a scale-enlarged sectional view taken along the line III-III in  FIG. 2 ; 
       FIG. 4  is a perspective view showing an annular member; 
       FIG. 5  is a view similar to  FIG. 3 , showing one preferred embodiment of the invention; and 
       FIG. 6  is a perspective view showing a drainage mechanism as partially broken away. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Details of a diving mask according to the present invention will be more fully understood from the description given hereunder with reference to the accompanying drawings. 
   A diving mask  1  shown in  FIG. 1  in a perspective view has a back-and-forth direction, a transverse direction and a vertical direction as indicated by double-headed arrows A, B and C, respectively, which are orthogonal one to another. The mask  1  comprises a lens unit  4  including a pair of lenses  2  and a lens frame  3  serving to hold peripheral edges of these lenses  2 , a skirt member  6  extending rearward from the lens unit  4 , and a head-strap member  7  extending rearward from transversely opposite side edges of the lens unit  4 . The skirt member  6  is formed with a nose cover  8  extending forward from a transverse middle of the lens unit  4 . The nose cover  8  is formed with a drainage mechanism  11  indicated by chain lines. Of such mask  1 , the lenses  2  are formed from a transparent hard material, for example, plastics such as a polycarbonate resin or inorganic glass, the lens frame  3  is formed from plastics such as a polypropylene resin, nylon resin, polycarbonate resin and ABS resin. The skirt member  6  and the head-strap member  7  are formed, for example, by an elastomer such as a silicon rubber or natural rubber. 
     FIG. 2  is a partially cutaway side view showing the diving mask  1  of  FIG. 1  and  FIG. 3  is a scale-enlarged sectional view taken along the line III-III in  FIG. 2 . The nose cover  8  has transversely opposite side walls  12  and a bottom  13  formed with the drainage mechanism  11 . The drainage mechanism  11  comprises, in addition to a check valve  16  for drainage formed separately from the bottom  13 , a through-hole  17  extending through the bottom  13  to be used for mounting of the check valve  16 , a plurality of drain holes  18  arranged around the through-hole  17 , spokes  25  radially extending from the through-hole  17 , and a valve seat  19  circularly extending outside the drain holes  18  around the through-hole  17 . Of these constituents, the through-hole  17 , the drain holes  18  and the spokes  25  are indicated by chain lines in  FIG. 1 . The check valve  16  comprises a disco-lamina  21  and a shaft  22  standing upright from a central zone of the disco-lamina  21  and press-fitted into the through-hole  17  for mounting of the check valve  16 . The check valve  16  is formed from a soft and elastically deformable elastomer such as a silicon rubber. In this bottom  13  comprising the through-hole  17 , the drain holes  18  and the valve seat  19 , the annular member  23  formed from a relatively hard and deformation-resistant material, for example, plastics such as a polycarbonate resin or metallic material is covered with the elastomer forming the skirt  6 . 
     FIG. 4  is a partially cutaway perspective view showing the annular member  23 . The annular member  23  comprises an inner annulation  24 , an outer annulation  26  and a plurality of spokes  27  connecting these two annulations with each other. The inner annulation  24  surrounds a central through-hole  28  and the spokes  27  circumferentially divide a space defined between the inner annulation  24  and the outer annulation  26  into a plurality of outside through-holes  29 . Such annular member  23  is previously set in the die at a predetermined position when the skirt member  6  is injection molded in this die. Upon completion of this molding process, the annular member  23  is fixed to the bottom  13  of the nose cover  8  as illustrated by  FIGS. 2 and 3 . However, a peripheral edge of a central through-hole  28  surrounded by an inner annulation  24  is not covered with the elastomer and thereby defines the through-hole  17  of the drainage mechanism  11 . The outside through-holes  29  respectively have peripheral edges covered with the elastomer and respectively define the drain holes  18  of the drainage mechanism  11 . The spokes  27  are covered with the elastomer and respectively define the spokes  25  of  FIG. 1 . The elastomer forming the nose cover  8  entirely covers the outer annulation  26  of the annular member  23  and, as will be apparent from  FIG. 3 , the valve seat  19  is formed in the vicinity of the annular member  23 . 
   In the drainage mechanism  11  of the mask  1 , the disco-lamina  21  of the check valve  16  is normally held from the outside in close contact with the valve seat  19  of the nose cover  8 . To drain off an amount of water accumulated within the nose cover  8 , a mask wearer may breathe hard through his or her nose to open the check valve outward. In the drainage mechanism  11  functioning in this manner, the disco-lamina  21  as well as the valve seat  19  of the check valve  16  are formed from the soft elastomer. However, the annular member  23  lying in close proximity to the valve seat  19  is sufficiently hard and deformation-resistant to prevent the valve seat  19  from being significantly deformed and to hold the valve seat  19  in contact with the check valve  16  as closely as the conventional valve seat often formed from a hard material has been the case. In addition, the drainage mechanism  11  according to the present invention is advantageously free from the problem that the valve seat  19  as a part of the annular member  23  might be covered with flash of the elastomer destined to form the nose cover  8  during injection molding of the skirt member  6 . This is because that the present invention allows the nose cover  8  to be obtained without reliance upon the conventional process in which the annular member previously formed together with the valve seat by a relatively hard material is set in the die for molding the nose cover so that the annular member may be integrated with the nose cover. 
     FIG. 5  is a view similar to  FIG. 3 , showing another preferred embodiment of the invention and  FIG. 6  is a partially cutaway perspective view showing a drainage member  111  destined to form the drainage mechanism  11  of  FIG. 5 . The drainage mechanism  11  of  FIG. 5  is obtained by previously setting the drainage member  111  formed separately from the nose cover  8  in the die for molding of the skirt member  6  so that the drainage member  111  may be integrated with the elastomer for the nose cover  8  within the die. The drainage member  111  comprises the annular member  23  similar to that shown in  FIG. 2  and an elastomer  112  partially covering this annular member  23 . More specifically, an outer peripheral zone of the inner annulation  24 , an inner peripheral zone of the outer annulation  26  and the spokes  27  are covered with the elastomer  112 . Of the annular member  23 , an inner peripheral zone  113  of the inner annulation  24  and an outer peripheral zone  114  of the outer annulation  26  are exposed. In this drainage member  111 , a region to define the through-hole  17  of  FIG. 5  has already been formed from hard plastics and a region to define the valve seat  19  of  FIG. 5  has already been formed from the elastomer  112 . The elastomer  112  may be the same as the elastomer used for molding of the skirt member  6  or a relatively soft elastomer easily weldable to the aforementioned elastomer. When the drainage member  111  is set in the die in order to integrate the drainage member  111  with the nose cover  8 , portions of the elastomer  112  covering the outer annulation  26  of the annular member  23  from above and below as viewed in  FIG. 6 , i.e., the portions  116 ,  117  shown in  FIG. 6  are held tight to prevent the elastomer destined to form the nose cover from flowing inward beyond these portions  116 ,  117  in the form of flash. Outside these portions  116 ,  117 , on the other hand, the elastomer  112  is integrated with the elastomer forming the nose cover  8 . These portions  116 ,  117  formed from the elastomer  112  ensure that the die can be completely closed even if a thickness of the drainage member  111  more or less exceeds a depth of the die cavity at these portions  116 ,  117 . Furthermore, there is no anxiety that undesirable flash might be created and damage the previously formed valve seat  19 . 
   While description has been made above with respect to the diving mask  1  of twin-lens type, the present invention may be exploited also in the form of a single eyed diving mask. While the illustrated diving mask  1  has the drainage mechanism  11  in the bottom  13  of the nose cover  8 , the present invention may be exploited also in the form of a diving mask having the drainage mechanism  11  in any other region, for example, in the vicinity of the nose cover. 
   The present invention allows the diving mask ensuring the reliable close contact between the check valve and the valve seat for drainage to be easily produced.