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Title:
SPEED DETECTOR FOR BRUSHLESS MOTOR
Document Type and Number:
Japanese Patent JP3293324
Kind Code:
B2
Abstract:

PURPOSE: To reduce the lowest operating voltage of a motor by adding or subtracting the base potentials of first and second transistors in response to the variation of the base potential of a detecting transistor, and holding the base potentials of both transistors at the same potential.
CONSTITUTION: When the base potential of a detecting transistor Q29, for example, rise and the base potential of the one (second) transistor Q25 of differential paired transistors 41 tends to become higher than that of the other (first) transistor Q24, the collector current of the transistor Q25 decreases, and it is observed that the collector currents of the transistor Q24 and transistors Q26, Q27 for constituting a current mirror circuit 42 increase. Thus, the base and emitter currents of an output transistor Q32 increase, the base potential of the transistor Q29 is reduced, and the base potential of the transistor Q25 is also lowered. Accordingly, the base potential of the transistor Q25 is held substantially the same as the base potential of the transistor Q24.


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JP3240789BRUSHLESS MOTOR
Inventors:
Tsuchiya, Tomonori
Terada, Yukihiro
Application Number:
JP11725894A
Publication Date:
June 17, 2002
Filing Date:
May 30, 1994
Export Citation:
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Assignee:
MITSUMI ELECTRIC CO LTD
International Classes:
H02P6/06; G01P3/489; H02P6/08; H02P6/16; H02P6/182; (IPC1-7): H02P6/16
Attorney, Agent or Firm:
伊東 忠彦