Patents by Inventor Adrianus J. Sprenkels

Adrianus J. Sprenkels 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).

  • Electroacoustic transducer of the so-called "electret" type, and a method of making such a transducer
    Patent number: 4910840
    Abstract: This invention provides an electroacoustic transducer and a method of making it. The transducer according to the invention comprises a substrate of a semiconductor material with a recessed portion. A membrane is stretched across the recessed portion, which membrane is set in vibration in response to an input signal comprising audio and/or ultrasonorous frequencies. A pair of electrodes is provided, which form a capacitor, and between which an electric field is present. The electrodes are so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals. A layer of an electrically insulating material functions as a carrier for an electric charge to provide an auxiliary electric field between the electrodes.
    Type: Grant
    Filed: July 26, 1989
    Date of Patent: March 27, 1990
    Assignee: Microtel, B.V.
    Inventors: Adrianus J. Sprenkels, Piet Bergveld
  • Electroacoustic transducer of the so-called "electret" type, and a method of making such a transducer
    Patent number: 4908805
    Abstract: This invention provides an electroacoustic transducer and a method of making it. The transducer according to the invention comprises a substrate of a semiconductor material with a recessed portion. A membrane is stretched across the recessed portion, which membrane is set in vibration in response to an input signal comprising audio and/or ultrasonorous frequencies. A pair of electrodes is provided, which form a capacitor, and between which an electric field is present. The electrodes are so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals. A layer of an electrically insulating material functions as a carrier for an electric charge to provide an auxiliary electric field between the electrodes.
    Type: Grant
    Filed: October 27, 1988
    Date of Patent: March 13, 1990
    Assignee: Microtel B.V.
    Inventors: Adrianus J. Sprenkels, Piet Bergveld