| 摘要 |
PROBLEM TO BE SOLVED: To provide inexpensively a small-sized rotary encoder capable of performing speed measurement with high resolution and high accuracy, even when the speed of a rotated measuring object is low. SOLUTION: This rotary encoder 15 includes a rotary disk 16 mounted rotatably in a body on a motor shaft 11 (rotated measuring object), a laser diode 17 for irradiating one side face of the rotary disk 16 with light, and a built-in photosensor PD on the back side of the laser diode 17. The photosensor PD receives emitted light from the rear end face of the laser diode 17 subjected to self-mixing modulation by return of a part of reflected scattered light from the rotary disk 16 to the laser diode 17. The rotational speed or rotation angle displacement of the motor shaft 11 is measured highly precisely by a beat signal detected by the photosensor PD. COPYRIGHT: (C)2007,JPO&INPIT
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