| 摘要 |
PURPOSE:To provide a rotation detecting device for a small DC motor, which is able to detect motor rotation by shortening the total length of the motor, has a simple construction with good waterproofing ability and permits the use of common motors regardless of the presence or absence of the rotation detecting device. CONSTITUTION:Magnetic flux is created by a magnet installed inside of a casing 32 and by an armature rotating inside this magnet, and any magnetic flux leaked to the outside of the casing is detected. An inductor 53 for converting the change in the leaked magnetic flux into electric signals and a capacitor 55 forming a resonance circuit connected to said inductor 53 are attached to the outer surface of the casing. Then, the resonance frequency of the resonance circuit is set to a value corresponding to a certain signal frequency generated during the rotation of said armature, and the electric signal is output as a signal waveform. |
