Iwatsu Electric Company Ltd.

Haruo Abe

Takefumi Kato

A method for ready and thorough erasure of information in a scan converter storage tube of the class including an electron gun of an electrostatic focus and deflection variety and a storage target having a substrate made from sapphire or like monocrystalline insulator. The storage surface of the substrate is first primed by a scanning electron beam from the electron gun while the potential of a collector electrode on the storage surface is set higher than the value which is lower than the potential of the field mesh electrode of the electron gun by up to about 100 volts. Then the storage surface is again scanned after setting the collector electrode potential higher than the potential of the cathode included in the electron gun and at such a value that the storage surface potential with respect to the cathode potential becomes less than a potential at which the secondary emission ratio of the monocrystalline substrate first becomes unity. Thus, as the storage surface acquires the cathode potential as a result of the scanning, a prewrite potential difference is established between storage surface and collector electrode.

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Hino, Japan

Haruo Abe