GB1182860A - An Arrangement for Improving the Transient Response of a Register Control System. - Google Patents

Abstract

1,182,860. Automatic registration control systems. SIEMENS A.G. Sept.25, 1968 [Oct.11, 1967], No.45622/68. Heading G3R. In an arrangement for automatically maintaining register in a multi-colour printing press, register error and rate of error control signals are derived from marks imposed on the web by the individual printing cylinders and combined to control a register regulating servomotor of the press. As shown the two register mark signals X1, X2 to be compared are fed to an input stage 1, which produces a signal whose length is equivalent to the time difference between the register marks and whose amplitude is proportional to the paper speed. This signal is fed to a first expander 2, i.e. an integrator and snap-action amplifier which resets the integrator at a specific integrated voltage, which produces a signal, the amplitude of which is constant and the length of which is directly proportional to the register error. This error signal is fed to the input a of a further expander 3 and simultaneously to the input of an integrator 7. The signal fed to input a of expander 3 is summed with a rate error signal fed to input b from a P.D. amplifier stage 8 and the output is integrated in integrator 4. The integrator output drives a tri-stable switch 5 into one of its states to selectively energize relays 61, 62, controlling forward and reverse running of the register servomotor. The P.D. stage 8 comprises a proportional amplifier given P.D. characteristics by an integrating RC-network with a pair of opposed Zener diodes in the input to determine the threshold values and a smoothing RC-network and a pair of opposed Zener diodes in the output to determine the threshold values to input b of expander 3. The input threshold circuit includes a resistor which may be switched in or out to vary the threshold value. If the error signal from 2 is small the error voltage produced by integrator 7 which is proportional to the length of the error signal is below the input threshold of P.D. stage 8 so that the register motor is controlled solely through the expanders 2, 3, integrator 4 and tristable switch 5. If the error voltage from integrator 7 exceeds the threshold voltage the P.D. amplifier produces a series of voltage peaks whose amplitude is proportional to the rate of increase of error voltage until the saturation value of P.D. amplifier is reached. When the smoothed output of P.D. amplifier exceeds the output threshold, which occurs for example after three error signals. The P.D. output is added to the proportional control signal in expander 3 so that the register motor is controlled by a rate error and proportional error signal. When the rate of change of error voltage reverses, the sign of the smoothed output reverses after a few pulses and exceeds the reverse output threshold so that the register motor is reversed.