Verfahren und Vorrichtung zum Lesen magnetisch gespeicherter Signale

摘要

The invention is based on a process for reading magnetically recorded signals from a photographic film provided with a transparent thin magnetic layer. The signals from a magnetic reading head applied to the moving film are pre-amplified and the pre-amplified signals are evaluated. Signals capable of being read from transparent magnetic layers are likely to be at least two hundred times weaker than those from standard layers used for recording audio signals or computer data. The object of the invention is therefore to design a procedure suitable for reading extremely weak magnetic signals. This involves operating the magnetic reading head (2) through the pre-amplifier in short-circuit. This means that the internal resistance Ri of the magnetic head is very high compared to the input resistance Re of the amplifier connected immediately downstream of the magnetic head coil.