| 摘要 |
<p>PURPOSE:To accurately discriminate a control position and to improve positioning accuracy by varying a driving current to be supplied to a light projection part stepwise and outputting an inversion signal correspondingly. CONSTITUTION:For example, an LED driving current is set to 7mA and the position where a movable piece 10 reaches a broken line L0 in a figure and the inversion signal is outputted is regarded as a target position 0 where a home position HP is accurately detected. In this state, a fine adjusting mechanism 32 is operated to move a photointerrupter PI 12 in a + direction and then the inversion signal is not sent out even when the driving current value is 5.0mA unless its control position becomes <=-40mum, so that none of LEDs 30a - 30f illuminate. Further, the PI 12 is moved in a + direction and the LED 30a is turned on only when the driving current value is 5.0mA, so that the control position of the PI 12 is discriminated, for example, as -30mum. Similarly, the PI 12 is moved in the + direction, the control based upon 7.0mA in actual use is carried out eventually, the when the LED 30e is turned on, the PI is positioned, so that the control position accuracy is suppressed <=+ or -10mum.</p> |
