Abstract: In a helical scan video recorder in which the magnetic heads are arranged on bimorph piezoelectric actuators it may be desirable, in order to counteract depolarization of the piezoelectric elements, to bias these elements. This is possible without the use of additional slip rings if the electrode to which the drive voltage is applied is connected, via a diode, to the electrode to which the bias is applied and the bias is applied, alternately with the drive voltage, at instants at which the associated magnetic head is not used. If the (lower) drive voltage is applied the diode is cut off and the bias is isolated from the drive.

Abstract: A method of recording information on a tape-like record carrier by means of a device provided with a rotary head disc on which a write head with controllable height is mounted for actively following the tracks. During recording tracking signals are written with the aid of a separate fixed head, which preferably also constitutes the erase head, and the write head follows the tracking signal recorded by the fixed head during the recording of information.

Abstract: A servo system for controlling the position of a magnetic reading head relative to the center of a selected information track. During writing, long-wave track sensing signals are written below the data signal in parts of the tracks and that in such manner that corresponding parts of successive tracks alternately contain or do not contain track sensing signals. During reading, the head reads not only the information of the selected track but as a result of crosstalk also reads the track sensing signals of the adjacent tracks. After filtering and processing the track sensing signals a control signal for controlling the head is obtained. Application in particular in helical and transversal scan video recorders.