Minebea Company, Limited

Yukio Suzuki

Osamu Kobayashi

Kiyoshi Ito

Osamu Yamada

Mayuka Shirai

A bead type noise filter according to the present invention is constituted by a magnetic coreformed of Mn&#x2014;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 coreconstituting the bead type noise filter is formed of a high resistivity soft magnetic material, is shaped cylindrical, and has at least one through-holeso as to form a closed magnetic path, and the bead type noise filter is attached on a signal linesuch that the signal lineis inserted through the through-hole. 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 &#x3a9;m or higher.

Bead type noise filter

A Mn&#x2014;Zn ferrite and a coil component are provided which obtains a low core loss in a frequency band above 1 MHz and even above 5 MHz and which can duly function in such a high frequency band. The Mn&#x2014;Zn contains as basic components 44.00 to 50.0 mol % Fe2O3 (50 mol % excluded), 4.0 to 26.5 mol % ZnO, and remainder MnO, and has a dielectric loss tan &#x3b4; of 0.3 or less at 1 kHz, and a complex relative permittivity &#x3b5; of 1,000 or less at 1 MHz, whereby a core loss decreases in the high frequency band.

Mn-Zn ferrite and coil component with magnetic core made of same

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.

Inductor

The Mn&mdash;Zn ferrite of the present invention contains basic components of 44.0 to 50.0 mol % (50.0 mol % is excluded) Fe O , 4.0 to 26.5 mol % ZnO and the remainder MnO, and has a real part &egr;&prime; of complex relative permittivity of 20,000 or less at 1 kHz and 50 or less at 1 MHz, thereby maintaining initial permeability in a wide frequency band, showing a low stray capacitance with a coil provided, and ensuring an excellent impedance in a wide frequency band. And a coil using the Mn&mdash;Zn ferrite as a magnetic core is also provided.

Mn-Zn ferrite and coil component using same

A common mode choke coil is described that is capable of providing improved characteristics at high frequencies. A bobbin having a toroidal core is mounted on a base. One coil is wound around one half of the bobbin and another coil is wound around the other half thereof. Both ends of each of the coils are connected to corresponding terminals provided on the base. The one coil has its one end connected to one of the terminals, is wound around one half of the bobbin from one side of the bobbin, finishes above the bobbin, that is, at the inner circumference of a core, leads out toward the other terminal provided on the base travelling along the outer face of a plate vertically mounted on the other side of the bobbin, and is connected to the terminal. The same applies to the other coil.

Growing community of inventors

Iwata-gun, Japan

Yukio Suzuki