Magnetic-tape apparatus having a disc with two control surfaces

Claim 1

A magnetic-tape apparatus comprising: at least two manually-operable push-butons for selecting modes of operation of the apparatus, a respective stop associated with each button for defining the mode of operation selected by actuation of the respective button, at least one apparatus part arranged to be positioned in conformity with the selected mode, and a servo mechanism which operates responsive to actuation of a button for positioning the apparatus part, said servo mechanism comprising a motor, a servo disc arranged to be driven by the motor for rotation upon actuation of a button, and having a first eccentric means arranged on the disc, a drive member arranged to be movable by said eccentric means, an actuating member arranged to position the apparatus part, said actuating member being movable by the drive member to different positions defined by said stops, and a control device comprising a second eccentric means arranged to be driven by said motor; at least one scanning element for scanning said stops, said scanning element arranged to cooperate with the second eccentric means and the actuating member, and to be released by said second eccentric means to scan the stops; and a spring arranged to bias said scanning element against a stop corresponding to the selected mode so as to scan said stop, said servo mechanism being so arranged that actuation of a button first causes the second eccentric means to release the scanning element in order to scan the stops, said spring moving the actuating member to the position defined by the stop corresponding to the selected mode, and urging the scanning element against that stop; and said first eccentric means then moves said drive member so as to cause said drive member to move the actuating member, and the actuating member to position the apparatus part, characterized in that said servo disc has a radial surface carrying a disc-shaped axially projecting portion having an endless groove formed in one side of said disc, and having a circumferential cam; and in that said endless groove constitutes the first eccentric means, and the circumferential cam constitutes the second eccentric means.