| 摘要 |
PURPOSE:To perform high-precision position detection through relatively simple constitution by providing a detection part which detects magnetic bubbles propagated through a shift part and an erasing means which erases at least one magnetic bubble at a desired position on the shift part. CONSTITUTION:A control circuit 5 drives a bubble generator 1 firstly to generate magnetic bubbles successively. When a two-phase current of a sequence is flowed at right angles to a propagation path, a rotating magnetic field is produced by an uneven current flowing around holes 24 and 25 to move the bubbles 28 successively. When the magnetic bubbles spread over the whole of the bubble shift part 2, bubble shifting is stopped. Then, a specific position is irradiated with a laser light spot to erase at least one magnetic bubble. Then, the bubble shift part 2 is driven again to count cycles, i.e. magnetic bubbles until the erased part is detected. Then, the counted number of cycles is multiplied by a proper constant and a proper constant is added to the product to calculate the measured distance from a reference point. |
