Hitachi, Ltd.

Hiromu Ishihara

Takashi Suga

Tsutomu Hara

Hitoshi Yokota

Hideo Sawada

Mariko Kasai

An electronic apparatus is comprised of a circuit apparatus; and an electromagnetic wave absorbing device arranged in the vicinity of the circuit apparatus in an insulating manner with respect to a circuit of the circuit apparatus, and having a metal loop, a portion of which is made of a high resistor. The metal loop contains a first member having a resistor having a resistance value smaller than, or equal to several ohms; and a second member having a resistor having a resistance value larger than, or equal to several ohms, and connected so as to form an electric loop in combination with the first member. The electromagnetic wave absorbing device containing a first member having a resistor having a resistance value smaller than, or equal to several ohms; and a second member having a resistor having a resistance value larger than, or equal to several ohms, and connected so as to form an electric loop in combination with the first member, is mounted on an adhesive tape and the like in order to be attached to an arbitrary electronic appliance. Also, this electromagnetic wave absorbing device is mounted on a circuit board, and an electronic component such as an IC and an LSI as a portion of this structure. As a result, this electromagnetic wave absorbing device realizes suppressions and reductions of electromagnetic noise such as EMI and higher harmonic waves thereof.

Electromagnetic noise reducing device, noise reducing electronic component and electronic appliance manufacturing method

In a circuit board having a multilayer structure comprising a ground pattern and a power-supply pattern both, for example, by forming a plurality of slits along each side of the ground pattern or the power-supply pattern, a long thin conduction path connecting a corner and a side center of the ground pattern is formed and resistive elements are placed in the middles of the conduction path to short, circuit the corner and a side center of the ground pattern. Therefore, portions corresponding to an antinode and a node or antinode and an antinode of a standing wave are short-circuited. The standing wave is generated when electric power is supplied to ICs and LSIs mounted on the circuit board. Thus, noise sources caused by the standing wave cancel each other. As a result, the occurrence of an antiresonance phenomenon and an increase in impedance of the power supplying system caused by the standing wave can be suppressed.

Reducing impedance of power supplying system in a circuit board by connecting two points in one of a power supply pattern and a ground pattern by a resistive member

Growing community of inventors

Hadano, Japan

Hiromu Ishihara