LOW SPEED ELECTRON BEAM EXCITING FLUORESCENT CHARACTER DISPLAY DEVICE AND MANUFACTURE THEREOF

PROBLEM TO BE SOLVED: To provide a phosphor for low speed electron beams containing no harmful cadmium, and a low speed electron beam exciting fluorescent character display device capable of emitting light at low voltage, having high brightness and a long life, and its manufacturing process. SOLUTION: A low speed electron beam exciting fluorescent character display device is constituted with a fluorescent character display tube 10 formed by arranging a filament cathode 9 faced to anode conductors 6, 6 and a light emitting member in a vacuum container comprising a base glass 1, a side plate 2, and a cover glass 3. The light emitting member is made of a phosphor film 7 containing an oxysulfide phosphor formed on the base glass 1. The oxysulfide phosphor is represented by a general formula, Ln2 O2 S:R (Ln is at least one of Gd, La, Y, and Yu, and R is a rare earth element.), and an oxide is removed by oxide removing treatment. The phosphor film 7 is formed by conducting oxide retarding treatment to the mixture paste of a phosphor from which oxides are removed, a conductive material, and a self-decomposing type binder formed on the base glass 1. In the oxide removing treatment, the oxide in the phosphor mainly comprising the oxysulfide compound is removed by acid washing and reduction treatment. In the oxide retarding treatment, in order to retard the oxidation in a display device manufacturing process, the baking of the phosphor film is conducted in the non-oxidizing atmosphere by using a low decomposition type or volatile binder requiring no oxygen.