| 摘要 |
1,158,896. Automatic control. GENERAL ELECTRIC CO. Sept.19, 1966 [Nov.29, 1965], No.41750/66. Heading G3R. Deviations of a variable cause operation of a plurality of electrical switch means to produce step signals and signals which build up at different rates in a storage device, pairs of these signals being combined so that the deviation is corrected at a rate corresponding to the magnitude of the combination which is effective at any given time. As applied to a system for automatically maintaining constant tension in material being wound on a drum, a spring-loaded dancer roll, forming a loop in the material, moves a shutter so that if the loop has a length corresponding to the desired tension, photo-cells 1 and 2, Fig. 3, are screened from light. Then, if tension decreases and loop length increases, photo-cell 2 is uncovered and rendered conductive so that a voltage, which immediately appears across a resistor 32, is amplified by transistors 47-49 to influence a controller 20 so that the speed of D.C. winding motor 13 is increased to restore proper tension. The voltage across resistor 32 is enhanced initially by a differentiating circuit 39, 41 and is later increased gradually by a voltage which builds up across a condenser 31. The voltage across condenser 31 leaks through a resistor 46 when photo-cell 2 is covered again. If tension should fall abnormally, photocell 1 is uncovered and a greater correcting voltage produced across resistor 32 and built up across condenser 31. If, however, tension increases abnormally, photo-cell 3 is covered to decrease the voltage across resistor 32 and rapidly discharge condenser 31 to decrease the speed of the winding motor. The motor current produces a voltage across a resistor 57 which, if low, renders a transistor 55 non-conductive to prevent further discharge of condenser 31 and fall of motor current. Use of A.C., hydraulic or pneumatic winding motors and use of switches other than photo-cells are referred to. Application to the control of speed or voltage is also referred to.
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