Rotary character-carrying member and selector device therefor for a

Abstract

A print unit for an electronic typewriter comprising a removable character-carrying disc with flexible spokes which is operated by a selector motor which in turn is controlled by a control circuit. The character-carrying disc is provided with a plurality of reflective identification plates and a recognition circuit detects the pattern of the reflective plates present in selected ones of a series of predetermined angular sectors of the disc to identify some characteristics of the disc, e.g. typing pitch and character set. The angular position of the disc is detected by a position transducer which generates a position signal for the control circuit having a period which is double the angular distance between two contiguous character-carrying spokes discriminating the spokes at even positions from those at odd positions. In an initialization phase, a zeroing circuit coarsely positions the character-carrying disc in a zero area defined by a synchronization plate adjacent a plate-free gap and activates the control circuit to stop the character-carrying disc in a zero position in respect of a spoke having a predetermined parity. The print unit is provided with phase regulation elements for the position transducer and for the circuit for recognition of the reflective plates on the character-carrying disc.