Patents by Inventor Donald A. Mitchell

Donald A. Mitchell 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: 4455517
    Abstract: An improvement in door activating control apparatus including a short delay between the time the door is stopped during its closing direction of travel and starts moving in the opening direction when any one of any switch or button for opening the door is activated, prevents the stress incurred when the door is required to instantly reverse its direction of travel while closing, demonstrates a distinct advantage especially when controlling large heavy doors, or for door openings that require a high volume of traffic and in emergency situations, includes a means to by-pass the delayed reversing when the door is in the closed position. Features a novel means of using a single pole double throw switch which will serve to defeat a safety edge device and by-pass the delayed reversing, embodied in a single enclosure along with the door closing limit switch, all actuated by a single mechanical actuating device at the door closed position, demonstrates distinct advantages in door operator design.
    Type: Grant
    Filed: September 27, 1982
    Date of Patent: June 19, 1984
    Inventor: Donald A. Mitchell