Murata Manufacturing Co., Ltd.

Kenji Naito

Hisashi Takiguchi

Tadao Nagai

Masahiko Kitamoto

Tsuyoshi Umemoto

Yusuke Suzuki

Takaaki Ooi

Yoshihiro Sako

Masaru Omura

Minoru Sunahara

A coil antenna having a capacitor that is not separated from a metal terminal or an electrode of a mounting substrate even when a root portion of a bobbin around which a coil is wound is bent by an external force. The coil antenna includes a bobbin; a coil wound around the bobbin; a capacitor connected to the coil; a base made of an insulating material formed integrally with the bobbin; and a mounting substrate having a plate shape with a pair of electrodes formed on a surface of the mounting substrate extended from the base for mounting the capacitor, such that the mounting substrate is held in a cantilevered manner in a winding direction of the coil.

Coil antenna

An antenna coil includes a wound body including a magnetic core, a bobbin surrounding the magnetic core, and a coil wound around the bobbin, a case in which the wound body is placed, and a foam disposed in a gap between the wound body and the case. The foam is compressed at a rate of about 45% to about 65% on the basis of a thickness of the foam in a non-load state. The antenna coil prevents breakage of the magnetic core and is suitable for use in a short-distance communication system in an LF-band.

Antenna coil

A flyback transformer has a winding portion. The winding portion includes a low-voltage bobbin, a high-voltage bobbin, low-voltage winding, and high-voltage winding, each of which having a flattened substantially circular cross-section. The high-voltage winding is wound so as to have a film-layer winding structure. Diodes are provided such that each diode is coupled between two corresponding winding elements provided in the layers. A high-voltage capacitor and a high-voltage resistance substrate are connected to the output of the high-voltage winding. The diodes, the high-voltage capacitor, and the high-voltage resistance substrate are arranged in the longitudinal direction of the flattened substantially circular cross-section of the winding portion.

Flyback transformer

The number of layers of a secondary winding of a flyback transformer for use in a PWM controlled high-tension voltage generator is increased to six or higher. The distributed capacitance of the flyback transformer is thus decreased, the frequency of ringing is increased, and the pulse width of a flyback pulse is narrowed. The timing of the on-operation of a control FET is expedited, and the input current to the flyback transformer is lowered. A compact and power-saving flyback transformer thus results.

A high voltage generation circuit including a transformer, the transformer having a primary winding having a primary inductance; a power supply for supplying a voltage to the primary winding of the transformer; a switching element for controlling current flowing through the primary winding of the transformer from the power supply; and a resonance capacitor which resonates with the primary winding of the transformer when the switching element is off, so that a flyback pulse is generated. The circuit has a distributed inductance and a resonance capacitance. The switching element is controlled so as to be switched on nearly at the bottom of a quiescent ringing pulse which is produced by a resonance of the primary inductance of the transformer with a capacitance included in a circuit connected to the primary winding of the transformer, after the flyback pulse is generated.

Growing community of inventors

Shiga-ken, Japan

Kenji Naito