Magnetic tape duplication by contact printing at short wavelengths

Magnetic tape duplication by the contact printing method was first developed in 1949, but there were still many difficulties in the way of successful duplication at short wavelength signals of a few micrometers. The bifilar tape winding system has been newly developed for successful duplication of signals as short as 2 μm. The optimum strength of the transfer field for maximum output of the duplicated slave tape is exactly the same value even at very short wavelengths. The optimum coercivity of the master tape is about two and half times that of the slave tape. The decrease of the recorded master tape at 2-μm wavelength is within 2 dB for the first duplication with no further decrease after more than hundreds duplications. This system is applied to a video tape duplicator and can transfer automatically a 1-hour program within 2 minutes. The duplicated picture quality is almost undiscernible from the master. This system is also adaptable to the duplication of audio, digital, and any other magnetic tapes or sheet information.