Document Type and Number:
Japanese Patent JPS5250721
Kind Code:
Y2
Application Number:
JP9000372U
Publication Date:
November 17, 1977
Filing Date:
July 31, 1972
Export Citation:
International Classes:
G03B31/04; G03B31/00; G03B31/06; G11B31/00; (IPC1-7): G11B31/00