Bunkyō-ku, Japan
Bunkyō-ku, Japan

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Patent
Kokusai Display Kogyo Co. | Date: 2015-12-16

To provide a brushless DC motor drive circuit operating with low electric power without a hall element, etc., and to provide a drive circuit for brushless DC motor which may be generally started regardless of an amount of load or size of inertia moment. The drive circuit comprises a two-stage amplifying circuit comprised of transistors 13 and 14 for switching and amplifying a drive current to drive coils 11; a detecting coil 15 disposed together with the drive coils in a magnetic field of permanent magnets in a rotor, and connected to a base of the transistor 14 at one end; and a diode connected in series with the other end of the detecting coil 15 and provided between the base and an emitter of the transistor 14, wherein the diode controls and adjusts a base current of the transistor 14 such that the transistor 14 is turned on when induced electromotive force generated in the detecting coil 15 is a reverse voltage, and such that the transistor 14 is turned off when the induced electromotive force of the detecting coil 15 is a forward voltage.


Patent
Kokusai Display Kogyo Co. | Date: 2014-04-15

To provide a brushless DC motor drive circuit operating with low electric power without a hall element, etc., and to provide a drive circuit for brushless DC motor which may be generally started regardless of an amount of load or size of inertia moment. The drive circuit comprises a two-stage amplifying circuit comprised of transistors 13 and 14 for switching and amplifying a drive current to drive coils 11; a detecting coil 15 disposed together with the drive coils in a magnetic field of permanent magnets in a rotor, and connected to a base of the transistor 14 at one end; and a diode connected in series with the other end of the detecting coil 15 and provided between the base and an emitter of the transistor 14, wherein the diode controls and adjusts a base current of the transistor 14 such that the transistor 14 is turned on when induced electromotive force generated in the detecting coil 15 is a reverse voltage, and such that the transistor 14 is turned off when the induced electromotive force of the detecting coil 15 is a forward voltage.

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