Office calculator printout unit - recording strip features several layers allowing data erasure and re-use

摘要

The design provides simple means for controlling the operations performed by the calculator with the visual display of results and at the same time ensures easy cancellation of the indicated data on the medium A. The latter includes a transparent layer, translucent intermediate layer and a base layer with a wax coating. The data are printed by type wheel 5 while feed of the recording medium is controlled by pawl 7 and ratchet wheel 6. Two-colour printout is achieved when the wax coating features strips with black and red particles, so that positive and negative values are shown. Erasure is obtained by the relative displacement of the intermittent layer and the wax-coated backing.