A theory of contact printing

In anhysteretic contact printing, a high-frequency transfer field is used to promote the acquisition, by a low-coercivity slave tape, of information prerecorded on a high-coercivity master tape. The slave tape is thus magnetized anhysteretically in the fringing field of the master and its own demagnetizing field. The slave tape magnetization and output voltage may be obtained by solving an integral equation. For master tapes of normal output, the integral equation is linear, and an exact closed-form solution for the slave tape output voltage valid at all wavelengths is presented; the contact printing efficiency exhibits the - 6 dB/octave loss at long wavelengths known previously and, for the first time, the specific dependency of slave tape output on its anhysteretic susceptibility. With master tapes of substantially greater than normal output, nonlinearities become significant and-results of numerical solutions are given. Some of the factors governing the choice of transfer field direction, magnitude, and decrement are discussed. Finally, since anhysteresis and thermoremanence are known to be similar processes, the theory is shown to be adaptable immediately to thermoremanent contact printing.