| 摘要 |
1,156,839. Selective signalling. INTERNATIONAL BUSINESS MACHINES CORP. 13 Dec., 1966 [23 Dec., 1965], No. 55782/66. Heading G4H. [Also in Divisions G3, H1 and H3] Two systems are described for limiting the average paper-feed rate in a line printer. In the first the average speed of the paper feed roller 148, Fig. 8, is compared with a reference speed obtained from a motor M by two cams 142a, 142b which are so arranged that if the average speed of the roller 148 is at its nominal value then two cams both rotate with little relative movement and with the projections out of registration. If however, the average speed of the roller rises, cam 142b gains relative to cam 142a and eventually the projections come into registration, as shown, and contacts 140a, 140b open to interrupt the drive to the roller. In the second system, each pulse " carr. go ", Fig. 9, that should normally cause the paper to be advanced by one line, causes an increment of charge to be applied to a capacitor C1, having a leakage path via a transistor T3 to earth. If the average frequency of the " carr. go " pulses rises too high an emitter follower T4 conducts and produces an output pulse " gate print " which inhibits the application of the " carr. go " pulse to the paper feed drive. |
