| abstract |
In synchronizing the movement of first and second articles, such as an elongated strand (jacketed cable) and a rotatable printing wheel mechanism for printing markings on the strand at accurately spaced intervals, the printing wheel mechanism is rotatably driven by a variable speed drive mechanism. The variable speed drive mechanism. The variable speed drive mechanism and a strand advancing mechanism drive respective signal generating devices, the signals of which are compared to produce a coarse analogue control signal representative of any difference therebetween. Similarly, the variable speed drive mechanism and a rotatable control member which is rotatably driven through frictional engagement with the advancing strand, drive digital signal generating devices, the signals of which are compared and used to produce an overriding fine analogue control signal representative of any difference between them. The coarse and fine analogue control signals then are combined to produce a signal for controlling the speed of the variable speed drive mechanism, and thus of the printing wheel mechanism. |