| 摘要 |
PURPOSE:To eliminate the need to provide a mechanical speed detector, to easily make a pickup driving device small in size, and to always execute a stable control by converting a tracking error signal to a speed signal by a differentiating circuit, and a frequency - voltage transducer. CONSTITUTION:When a pickup element 2 is following a track, a DC linear motor 3 is being driven by a low frequency component of a tracking error signal. The low frequency component of this tracking error signal shows a position of the DC linear motor 3 in the vicinity of the track to be followed by the pickup element 2, therefore, a differentiating circuit 15 adds a differential characteristic to the tracking error signal and forms a speed signal. In this state, the tracking error signal at the time of jumping the track, namely, at the time of crossing the track continuously is fetched by a comparator 16, its frequency is converted to a voltage by a frequency - voltage converter 17, and the speed signal being a signal corresponding to a speed of the DC linear motor 3 is formed. |
