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Patent Searching and Data


Title:
STOPPAGE DETECTOR FOR FAN MOTOR
Document Type and Number:
Japanese Patent JPH01198294
Kind Code:
A
Abstract:

PURPOSE: To reduce manufacturing cost, by detecting stoppage of a fan motor based on the variation of drive current and alarming abnormal stoppage thereof.

CONSTITUTION: Variation of current flowing through a fan motor is converted through a small resistor R1 into the variation of voltage waveform, which is compared with a reference voltage and shaped into the waveform of signal level then the shaped waveform is fed to a retrigger monostable multivibrator IC2. The IC2 feeds the shaped waveform, as a fan sensor timing pulse, to a judging means(CPU)1. Since the width of the voltage signal varies in proportion to the rotary speed of the fan motor, the IC2 retriggers if the width of the signal is narrower than a predetermined level but the IC2 does not trigger if the width of the signal is wider than the predetermined level and fixed a high level. The CPU1 confirms the condition of the fan motor based on the pulse and the level thereof.


Inventors:
OCHI MASATO
Application Number:
JP1988000019329
Publication Date:
April 09, 1999
Filing Date:
January 29, 1988
Export Citation:
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Assignee:
NIKON CORP
International Classes:
G03B27/72; H04N1/00; H04N1/04; (IPC1-7): H04N1/00; G03B27/72; H04N1/04