| 摘要 |
PURPOSE:To improve the detecting accuracy of an end point, with regard to an end point detecting device for a tridimensional body, by receiving a transient state from bright to dark or from dark to bright when the laser beams is cut by the objective body, comparing the level of the output signal with a plurality of threshold values, and extracting the position signal of the objective body corresponding to a timing pulse. CONSTITUTION:A light detector 17 receives the laser beam 16 whose brightness state is changed in a tansient mode, and sends out an output signal OP having the level corresponding to luminance. A comparator 21 compares the level of the output signal OP with each threhold value when the brightness of the laser beam 16 is changed. The signal representing the coincidence is sent to a register file 22 as the timing pulse TP. The position data accompained by the rotation of a rotary table 18 is continuously imparted to a register file 22. Therefore the position data is loaded to a register file 22 every time the timing pulse is received. The four position data stored in the register file 22 is processed and interpolated by a microcomputer 23, and the true end point position is obtained. |
