Sheet end indicating unit esp. for typewriter - uses photodiode and light source beneath platen with connection to warning device

In order to help a typist determine when the sheet end is approaching a detector and warning unit are incorporated in the machine. A sensor in the form of a photodiode is positioned beneath and to the rear of the platen and is connected to an optically or acoustically indicating warning device. A light source is provided near to the sensor and is directed together with the sensor towards the surface of the platen. Several sensors are arranged along the platen and are connected via AND-gates to the warning device. A delay circuit is interposed between the sensors and warning device, a lamp, so that a warning is not given until a predetermined number of line feeds has been effected.