Abstract: A method for preparing three types of benzidine compounds in a specific ratio, the method uses two types of diphenylamine compounds and one type of biphenyldihalide compound in a specific ratio as reactants to mix with an organic solvent and an additive to synthesize benzidine compounds in one step. The synthesized three types of benzidine compounds specially perform in a designated mixturing ratio having excellent photoelectric characteristics for a charge transporting layer in an organic photo-conductive drum.

Abstract: A method for preparing three types of benzidine compounds in a specific ratio, the method uses two types of diphenylamine compounds and one type of biphenyldihalide compound in a specific ratio as reactants to mix with an organic solvent and an additive to synthesize benzidine compounds in one step. The synthesized three types of benzidine compounds specially perform in a designated mixturing ratio having excellent photoelectric characteristics for a charge transporting layer in an organic photo-conductive drum.

Abstract: A sound illustrated book comprises a plurality of sheets bearing printed matter, a page indicator circuit, and an audio sound reproducing circuit. The page indicator circuit comprises a code generator, and a decoder. An unique code is generated by said code generator, when the book is opened to any one of said sheet. Said unique code is transmitted to said decoder, and a pre-recorded message related to the matter printed on said any one of said sheets is played by said audio sound reproducing circuit according to a decoded signal from said decoder.