Patents by Inventor David William Hagelbarger

David William Hagelbarger 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: 4007459
    Abstract: In a multitone pushbutton dial array each switch in the array has a variable impedance coupling between a fixedly mounted conductive plate and a movable conductive plate spaced apart from the fixedly mounted plate. Digitally synthesized signals having a predetermined phase and frequency are sequentially and recurrently used to scan interconnected columns of movable plates in the pushbutton dial array. Signals having an opposite phase from the scanning signals are continuously applied to the fixedly mounted plates. When a pushbutton is depressed variable impedance coupled summation signals are produced and these signals have a phase which is opposite to that of signals coupled to the detector from an unoperated switch. The detected digital signals are used to generate digital multitone row and column frequency signals. These digital row and column signals are converted to analog form and are transmitted to a telephone central office as a dialed digit code.
    Type: Grant
    Filed: July 10, 1975
    Date of Patent: February 8, 1977
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventor: David William Hagelbarger