Patents by Inventor Mayuka Shirai

Mayuka Shirai 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: 7148767
    Abstract: A bead type noise filter according to the present invention is constituted by a magnetic core 1 formed of Mn—Zn ferrite having its resistivity increased so as to improve a high frequency characteristic, and having its permittivity lowered, and thereby can successfully suppress radiation noises without distorting the waveform of transmission signals. The magnetic core 1 constituting the bead type noise filter is formed of a high resistivity soft magnetic material, is shaped cylindrical, and has at least one through-hole 1a so as to form a closed magnetic path, and the bead type noise filter is attached on a signal line 2 such that the signal line 2 is inserted through the through-hole 1a. The soft magnetic material has a real part of complex relative permittivity ranging from 1,000 up to 20,000 at 1 kHz and 50 or lower at 1 MHz, and has a resistivity of 150 ?m or higher.
    Type: Grant
    Filed: September 22, 2003
    Date of Patent: December 12, 2006
    Assignee: Minebea Co., Ltd.
    Inventors: Osamu Kobayashi, Osamu Yamada, Yukio Suzuki, Kiyoshi Ito, Mayuka Shirai
  • Publication number: 20060055487
    Abstract: A bead type noise filter according to the present invention is constituted by a magnetic core 1 formed of Mn—Zn ferrite having its resistivity increased so as to improve a high frequency characteristic, and having its permittivity lowered, and thereby can successfully suppress radiation noises without distorting the waveform of transmission signals. The magnetic core 1 constituting the bead type noise filter is formed of a high resistivity soft magnetic material, is shaped cylindrical, and has at least one through-hole 1a so as to form a closed magnetic path, and the bead type noise filter is attached on a signal line 2 such that the signal line 2 is inserted through the through-hole 1a. The soft magnetic material has a real part of complex relative permittivity ranging from 1,000 up to 20,000 at 1 kHz and 50 or lower at 1 MHz, and has a resistivity of 150 ?m or higher.
    Type: Application
    Filed: September 22, 2003
    Publication date: March 16, 2006
    Applicant: MINEBEA CO., LTD.
    Inventors: Osamu Kobayashi, Osamu Yamada, Yukio Suzuki, Kiyoshi Ito, Mayuka Shirai
  • Publication number: 20050162234
    Abstract: A signal discriminator is provided which leverages variation of permittivity of Mn—Zn-based ferrite. The signal discriminator comprises a soft magnetic material which has a capacitive reactance C, and which has its complex relative permittivity varying with frequency such that the real part ?? of the complex relative permittivity is large in a low frequency domain and small in a high frequency domain. In the reactance component X2, the capacitive reactance C is not negligible with respect to the inductive reactance L in a low frequency domain, in consequence of which the value of the reactance component X2 as a parallel circuit of the capacitive reactance C and the inductive reactance L is caused to decrease, and the influence of the capacitive reactance C is decreased in a high frequency domain.
    Type: Application
    Filed: September 22, 2003
    Publication date: July 28, 2005
    Inventors: Osamu Kobayashi, Osamu Yamada, Yukio Suzuki, Kiyoshi Ito, Mayuka Shirai
  • Patent number: 6798329
    Abstract: In an inductor comprising an open magnetic path formed by a soft magnetic material and a winding provided around the open magnetic path, the soft magnetic material has its relative complex dielectric constant varying according to a frequency. In the soft magnetic material, the imaginary part of the relative complex dielectric constant is greater than the real part thereof in a high-frequency band equal higher than the frequency of the electric signal flowing in the winding. Specifically, the soft magnetic material has a resistivity of 150 &OHgr;m, has a real part of the relative complex dielectric constant, ranging from 1,000 to 20,000 at 1 kHz and 50 or less at 1 MHz, and the imaginary part is greater than the real part at 1 MHz.
    Type: Grant
    Filed: April 23, 2003
    Date of Patent: September 28, 2004
    Assignee: Minebea Co., Ltd.
    Inventors: Osamu Kobayashi, Osamu Yamada, Yukio Suzuki, Kiyoshi Ito, Mayuka Shirai
  • Publication number: 20040004526
    Abstract: In an inductor comprising an open magnetic path formed by a soft magnetic material and a winding provided around the open magnetic path, the soft magnetic material has its relative complex dielectric constant varying according to a frequency. In the soft magnetic material, the imaginary part of the relative complex dielectric constant is greater than the real part thereof in a high-frequency band equal higher than the frequency of the electric signal flowing in the winding. Specifically, the soft magnetic material has a resistivity of 150 &OHgr;m, has a real part of the relative complex dielectric constant, ranging from 1,000 to 20,000 at 1 kHz and 50 or less at 1 MHz, and the imaginary part is greater than the real part at 1 MHz.
    Type: Application
    Filed: April 23, 2003
    Publication date: January 8, 2004
    Applicant: Minebea Co., Ltd.
    Inventors: Osamu Kobayashi, Osamu Yamada, Yukio Suzuki, Kiyoshi Ito, Mayuka Shirai