Patents by Inventor Tetsumasa Itoh

Tetsumasa Itoh 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: 5426299
    Abstract: An object of the present invention is to provide a detection system wherein ion counting is performed by varying the quantity of the ions incident on a detector 13 of an inductive plasma mass spectrometer depending on the concentration of the impurities to be measured, thereby extending the life of the detector 13, expanding the range for measurement of impurities in high concentrations, and reducing costs. An assist electrode 30 having a hole for leading the ions which have passed through a mass filter 10 to a detector 30 is disposed between the axis of the mass filter 10 and the detector 13, and a means for applying voltage to a repeller electrode 12 and the assist electrode 30 is provided to vary the difference in voltage between the electrodes 12 and 30 depending on the concentration of impurities to be measured.
    Type: Grant
    Filed: March 9, 1994
    Date of Patent: June 20, 1995
    Assignee: Seiko Instruments Inc.
    Inventors: Yoshitomo Nakagawa, Tetsumasa Itoh