Patents by Inventor Ralph E. Marquardt

Ralph E. Marquardt 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: 4335376
    Abstract: A security device for protecting premises having three separate variable time delays. A first time delays allows a legitimate user of the device to enter the premises and de-activate the device before the alarm sounds. The second time delay permits a legitimate user to exit from the premises without sounding the alarm. The third time delay ensures that the alarm will sound for a minimum period once the loop has been opened by an intruder. The device has an integrated circuit and each of the time delays are achieved through the use of a resistor in combination with a capacitor. The device also has a supervisory loop and the alarm becomes activated when the loop has been opened.
    Type: Grant
    Filed: April 12, 1979
    Date of Patent: June 15, 1982
    Inventor: Ralph E. Marquardt