Patents by Inventor David K. Long

David K. Long 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: 5377260
    Abstract: A telephone system includes a data modem that is coupled to a control microprocessor and a Data Access Arrangement (DAA) for detecting a Caller ID. The detected information is used to select a specific action dependent upon the specific Caller ID. Only one relay is needed with no other parts to connect the Caller ID to the data modem. A programmed Intelligent Work Station (IWS) determines whether to respond to the call and the type of response.
    Type: Grant
    Filed: December 5, 1991
    Date of Patent: December 27, 1994
    Assignee: Sierra Semiconductor Corporation
    Inventor: David K. Long
  • Patent number: 4191942
    Abstract: A converter circuit employs a capacitor coupled through a selector switch to an analog voltage so that the capacitor is charged to the analog level. When a conversion is commanded, the capacitor is disconnected from the analog voltage and discharged through a constant current load. This results in a linear voltage ramp. A comparator senses the capacitor voltage and compares it to a reference level that is slightly above ground. Upon starting the ramp an increment of voltage slightly larger than the reference is applied in series with the capacitor. When the ramp drops below the reference level the comparator output is used to terminate the conversion interval. Thus, the conversion interval is directly and linearly proportional to the magnitude of the analog voltage. If desired, the conversion interval can be used to operate a counter to provide a conventional digital readout.
    Type: Grant
    Filed: June 8, 1978
    Date of Patent: March 4, 1980
    Assignee: National Semiconductor Corporation
    Inventor: David K. Long
  • Patent number: 4051386
    Abstract: A frequency doubler circuit uses a single capacitor which is initially charged. A pair of switches is sequentially actuated so that each switch acts to first discharge the capacitor and then charge it in the opposite polarity. The switches are sequentially actuated from a differential input amplifier. Thus each input cycle will actuate both switches so as to discharge and charge the capacitor twice. Output logic senses the capacitor cycling and produces two output pulses for each input cycle.
    Type: Grant
    Filed: July 22, 1976
    Date of Patent: September 27, 1977
    Assignee: National Semiconductor Corporation
    Inventors: David K. Long, Robert W. Miller
  • Patent number: 3943376
    Abstract: Occupancy detector apparatus including a metallic electrode disposed to cooperate with the body of an automobile to form an occupant sensing capacitor, a reference capacitor, and an IC capacitance detecting and logic generating circuit. The IC includes a current source for continuously supplying charging current to the sensing capacitor and the reference capacitor, a first charge detecting circuit for detecting the charge on the sensing capacitor, a second charge detecting circuit for detecting the charge on the reference capacitor, and a comparator circuit for comparing the output signals developed by the first and second charge detecting circuits and for developing a logic output commensurate with the relationship between the capacitances of the sensing capacitor and the reference capacitor.
    Type: Grant
    Filed: January 27, 1975
    Date of Patent: March 9, 1976
    Assignee: Fairchild Camera and Instrument Corporation
    Inventor: David K. Long