Abstract: A detection system including a radiation source and a radiation detector wherein the output of the radiation detector is positively fed back to the radiation source through a variable voltage/current controlling unit thereby providing a rapid and reliable detection signal on the current path for supplying a current to the radiation source. The variable voltage/current controlling unit may be, for example a parallel connection of a Zener diode or resistor and a bipolar junction transistor or FET controlled by the current output from the radiation detector. The radiation source part and the radiation detector part can be electrically connected to reduce the number of lead wires.

Abstract: At the start of operation, a floating magnetic head is brought into contact with the surface of a magnetic disk and the magnetic disk is then rotated to float the magnetic head off the magnetic disk surface. At the end of operation, the floating magnetic head is drawn away from the magnetic disk surface of the rotating magnetic disk and, after the lapse of a certain period of time, the magnetic disk is stopped. This prevents the floating magnetic head from sticking to the magnetic disk owing to dew condensation, permits easy miniaturization of the floating space and provides for increased recording density.