Patents by Inventor David L. Stephens

David L. Stephens 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).

  • Patent number: 7104403
    Abstract: A two-stage static air classifier has a feed duct through which particles of a granular mixture fall. A classifying louver plate having fins forming upwardly inclined classifying channels is fitted into a side opening in the feed duct. Particles of a set size are drawn by air suction through the classifying channels in the first stage. A separator box having an inlet connected to the outlet of the classifying channels collects the separated particles in a second stage as the entrained particles fall by gravity to the bottom of the separator box while the air streams drawing the particles through the classifying channels pass out the top end of the box. Adjustable baffle plates transversely extending through the box permit control of the quantity of fines collected with the particles at the separator box bottom. Size of the collected particles is determined by the speed of a fan at the top outlet of the separator box.
    Type: Grant
    Filed: August 29, 2002
    Date of Patent: September 12, 2006
    Assignee: The Unimin Corporation
    Inventors: David L. Stephens, Gerald G. Verret, Richard U. Lalancette
  • Patent number: 6942103
    Abstract: A two-stage static air classifier has a feed duct through which particles of a granular mixture fall. A classifying louver plate having fins forming upwardly inclined classifying channels is fitted into a side opening in the feed duct. Particles of a set size are drawn by air suction through the classifying channels in the first stage. A separator box having an inlet connected to the outlet of the classifying channels collects the separated particles in a second stage as the entrained particles fall by gravity to the bottom of the separator box while the air streams drawing the particles through the classifying channels pass out the top end of the box. Adjustable baffle plates transversely extending through the box permit control of the quantity of fines collected with the particles at the separator box bottom. Size of the collected particles is determined by the speed of a fan at the top outlet of the separator box.
    Type: Grant
    Filed: August 29, 2002
    Date of Patent: September 13, 2005
    Assignee: The Unimin Corporation
    Inventors: David L. Stephens, Gerald G. Verret, Richard U. Lalancette
  • Patent number: 5454376
    Abstract: A breathing monitor article of wearing apparel, adapted for child users in order to monitor breathing conditions of a child user. The apparatus and the method of the invention are particularly adaptable for infant child users in order to prevent conditions such as Sudden Infant Death Syndrome and similar conditions arising from apnea. The article of wearing apparel comprises a shirt or like garment adapted to extend around the chest and/or abdomen portion of the child user and which contains a pocket having a monitor therein. An elastic belt extends about the chest and/or abdomen of the user and particularly, in the region of the user's lungs. A strain gauge is secured to the elastic belt and detects breathing movement through the expansion and contraction of the chest wall. The monitor is electronically operated and constructed so as to generate an alarm signal if there is a cessation of breathing for a minimum predetermined time period.
    Type: Grant
    Filed: August 16, 1993
    Date of Patent: October 3, 1995
    Inventors: David L. Stephens, David L. Stephens