Patents by Inventor Hirohisa Umezaki

Hirohisa Umezaki has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Filter unit and dust-proof mask therewith
    Patent number: 6309438
    Abstract: The present invention provides a filter containing a filter material folded into a chrysanthemum shape. While such a filter can be made of an electret fiber nonwoven fabric or a fiberglass nonwoven fabric, preferably it is made of a polytetrafluoroethylene porous film that is extended lengthwise and widthwise such that the overall area is extended by more than fifty-fold.
    Type: Grant
    Filed: November 15, 1999
    Date of Patent: October 30, 2001
    Assignee: Mine Safety Appliances Company
    Inventors: Tomoaki Kanno, Kunio Yamada, Hirohisa Umezaki