| 摘要 |
PURPOSE:To attempt miniaturization as well as to detect the tilting of a detecting bar accurately by arranging a pluraity of emitters on the same circumference at certain interval with center at the axial center of a clyndrical body, and by arranging each receptor to each position corresponding coaxially to each emitter respectively whereby providing a shutter between the emitter and the receptor. CONSTITUTION:When a detecting bar 4 is conditioned to a tilted position, the position of its shaft center of a shutter 9 becomes off the axial center of a cylindrical body 2, for example, it is tilted to the side of a receptor 133 whereby a light path from an emitter 123 to the receptor 133 is much more interrupted as compared with a light path from an emitter 121 opposite to the aforementioned emitter to a receptor 131. And as for the amount of light received by each receptor 131 through 134 when the detecting bar 4 is tilted to the direction A, the amount of light received by the receptor 131 is increased, at the amount of light received by the receptor 133 opposite to said receptor is decreased. In this case, there causes no difference in the amount of light received between the receptors 132 and 133. And the tilting of the detecting bar to the direction A is judged by a control circuit based on the relative difference in the amount of light received between the receptors 131 and 133. Namely, the emitter is not arranged at the center of the lay-out of each receptor whereby the cylindrical body can be made small in outer diameter. |
