PURPOSE: To measure an accurate back lash by operating a power transmission mechanism by the same driving source as that in a use state, and detecting the rotational quantitits of the input and output shafts of the transmission mechanism from the output of a detector.
CONSTITUTION: A control part 7 drives a motor 4 forward with a drive signal DS to rotate the input shaft 1a of a speed reduction gear 1. This rotation turns the output shaft 1b. A back lash, on the other hand, is caused when the speed reduction gear 1 reverses, so the rotation of the input shaft 1a is stopped after the motor 1 turns forward, and then the motor 1 is reversed to turn the input shaft 1a backward and then stop it. Detection pulses EP and TP detected in those forward and backward turns are counted up (forward rotation) and down (backward rotation) by counters 5 and 6, and a control part 7 obtains the rotational quantities from the values of both counters 5 and 6 after the reverse turn, thereby calculating the back lash from an arithmetic expression.
TABATA FUMIO
SHIRAISHI MITSURU
