| 摘要 |
<p>PURPOSE: To accurately and rapidly index by receiving a display signal from a sensor by a control means, determining a present position of an aperture means to a reference position from the signal, rotating it, accurately aligning one of apertures of different sizes to a beam axis and disposing it. CONSTITUTION: When a switch 45 is energized by a pin 46, presence of a reference indicating line is displayed at a reference point formed by a position of the switch 45 on a frame 22. A control means rotates an aperture wheel 10 to start an indexing step, and relates the line to the switch 45. And, when the wheel 10 is rotated in either direction via a sensor 44, number of balance points generated by the sensor 44 is counted, and the control means calculates an angular displacement of the wheel 10 to the reference point relative to the wheel 10, aligns one of the apertures 36 of different point to the beam axis 14 and selectively orients it.</p> |
