Abstract: On manufacturing a low voltage electron beam excitation phosphor display apparatus (10) which includes an anode (6) having a principal surface and enclosed in a vacuum chamber (1, 2, and 3), a phosphor film (7) formed on the principal surface, and a cathode (9) enclosed in the vacuum chamber opposite to the phosphor film, a phosphor is prepared which consists essentially of an oxisulfide and an oxide which is inevitably formed on a surface of the oxisulfide on preparing the phosphor. The oxisulfide is represented by Ln.sub.2 O.sub.2 S:R, where Ln is at least one selected from a group consisting of Gd, La, Y, and Lu and where R is a rare-earth element. The oxide is removed from the phosphor to produce an oxide-removed phosphor. A pasts comprising a mixture of the oxide-removed phosphor, a conductive material, and an autolytic type binder is coated on the principal surface of the anode which is formed on an insulating substrate (1) constituting the vacuum chamber.

Abstract: An unmanned vehicle guide system has guide routes made of a magnetic material and an unmanned vehicle guided to travel on the guide route. The unmanned vehicle has an exciting coil for emitting a magnetic field, a pair of detection coils, arranged in a direction perpendicular to the travel direction of the unmanned vehicle, for detecting a magnetic field change, a comparator for measuring an output-difference between the detection coils, and a steering device for steering the unmanned vehicle such that the output-difference becomes a predetermined value. At an intersection where a plurality of guide routes intersect and in the vicinity thereof, at least one guide route lacks a magnetic material. Alternatively, an extra marker is added to each of the guide routes that intersect at the intersection.

Abstract: An improved magnetic object detecting system having high sensitivity and noise immunity is disclosed.The detection system is of the type having a stimulation coil for generating a magnetic field and a pair of magnetic field detection coils, and the stimulation coil is of a magnetic core type employing a magnetic core.

Abstract: An acoustooptic device using a single crystal as its acoustooptic medium consisting essentially of lead monoxide (PbO) and niobium pentoxide (Nb.sub.2 O.sub.5) in the composition ratio x by mol as 1.5 .ltoreq. x .ltoreq. 3.1 for PbO .multidot. x Nb.sub.2 O.sub.5.