Indication of correct setting of projector for film cassette - uses coded contacts in projector completing circuit via cassette when switches are correctly set

摘要

The projector can be set to the requirements of a variety of cassettes. When the setting is incorrectly done, coded elements on the cassette either cause an indicative signal to be given, or switch off the projector's drive. Contacts on the cassette can be arranged to complete a circuit only when the projector's switches are correctly set; alternatively, the contacts can be inside the projector, and operated by cogs on the cassette.