| 摘要 |
PURPOSE:To perform speed detection with high accuracy and high resolution over a wide range by performing the speed detection while paying attention to the zero voltage of a sine wave encoder in a high speed state or to the phase angle of the sine wave encoder in a slow speed state. CONSTITUTION:Values of a microcomputer 14, a reversible counter 7, a register 8, a direction deciding circuit 11, and a memory 13 are inputted at every con stant period Tc. Then, the difference DELTAC in angle of rotation from the last value of the counter 7 is found. When the absolute value of this DELTAC is larger than a constant value C0, it is considered that the rotating speed of the encoder 1 is fast, and the difference Ta from the value of the register 8 is held every time a pulse AP, so that the accurate speed is obtained by using the distance ¦DELTAC¦ in Ta. When ¦DELTAC¦ is smaller than the value C0, on the other hand, that indicates that the speed of the encoder decreases, and the phase angle DELTAtheta vary ing in the Tc at the time of detection is expressed by a digital value while the phase angle 180 deg. of a sine wave signal A is denoted as 2N, thereby finding a speed detected value ND from the value proportional to ¦DELTAC¦.DELTAtheta.
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