| 摘要 |
<p>Lifeting device for a rotor (8) by means of a threaded spindle (6) driven by a servomotor (M2). Processes are known to detect the location within a lifting range by means of position sensors. This kind of detection is not tolerance-free and inaccurate. The present invention allows the location within a lifting range, for example a magnetic track within a magnetic tape width, to be accurately defined. Sensors (S1, S2) are linked to the rotor (8) and to the driving threaded spindle (6). Neither sensor has an ajusted position and both emit an impulse with each rotation. For a fixed predetermined measurement path (H) within a lifting displacement, the time difference Δt between the impulses emitted by the sensors (S1, S2) is determined by counting circuits. Given a known pitch (s) of the threaded spindle (6), the location of a magnetic track can be detected, thus allowing the location within a lifting range to be adjusted.</p> |
