| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a physical quantity measuring apparatus capable of making both compatible in securing detection resolution and measurement accuracy in a state that the main shaft of a machine tool rotates at a high speed and in securing responsibility in a state that the main shaft rotates at a low speed. <P>SOLUTION: A computing unit obtains an axial direction displacement amount of the main shaft of a machine tool, on the basis of the pulse period ratio δ/L which is the ratio of a partial period δ to a whole period L, the partial period δ being a period between a pair of pulses generated based on a pair of concave grooves 10a, 10b adjacent circumferentially, the whole period L being a period between a pair of pulses corresponding to a pair of mutually different characteristic change combination parts 3a, 3a to be detected. When the rotational speed of the main shaft is lower than a predetermined value, a value L<SB POS="POST">a</SB>relative to a pair of characteristic change combination parts 3a, 3a adjacent circumferentially to be detected is adopted as the whole period L as shown in (A). On the other hand, when the rotational speed is equal to or more than the predetermined value, a value L<SB POS="POST">b</SB>relative to a pair of characteristic change combination parts 3a, 3a to be detected, present by skipping one part therebetween, is adopted as the whole period L as shown in (B). <P>COPYRIGHT: (C)2012,JPO&INPIT |
