Automatic control system for offset printing machine

An improved automatically controllable offset printing machine having eight discrete states of operation in each cycle, the machine comprising a drive motor arranged to be energized during each but the first of the eight states of operation, an ink kneading device operatable during the second of said states of operation, a rotatable cylinder for supporting a removable master plate, a master plate feeder operable only during the third of said states to feed a master plate to said master cylinder, an etching device operable only during the third of said states and including a roller for applying an ink-repellent etching solution to a master plate when mounted on said master cylinder, an ink device operable only during the fourth of said states for applying ink to a master plate, a rotatable blanket cylinder operable only during the fifth of said states and arranged to engage said master cylinder to receive an ink image from a master when on said master cylinder, a sheet feeder operable during the sixth and eighth of said states for feeding copy sheets to said blanket cylinder, an impression cylinder for urging copy sheets against said blanket cylinder, cleaning means operable only during the seventh of said states for cleaning said blanket cylinder, master plate ejection means operable only during the seventh of said states for ejecting a used master plate from said master cylinder, a control shaft mechanism including a control shaft arranged to be located in a first position during the second, third, seventh and eighth states to create a mechanical condition such that at least the inking device is disengaged from a master plate when on said master cylinder, and arranged to be located in a second position during the fourth, fifth and sixth states to create a mechanical condition such that at least the inking device is in engagement with a master plate when on said master cylinder, a cam and linkage mechanism operable to switch the control shaft between the first and second positions, and drive means operable to actuate said cam and linkage mechanism to cause the control shaft to switch between the first and second positions, the improvement comprising (a) shaft position detecting means for detecting the actual position of the control shaft, (b) an instruction decoder having eight output terminals to decode a stop signal for said drive motor, an ink knead signal for controlling the operation of said ink kneading device, an etch signal for controlling the rotation of the roller in said etching device, an ink form signal for controlling the operation of said ink forming device, a transfer signal for effecting engagement of said master and said blanket cylinders, a print signal for controlling the operation of said sheet feeder, a clean signal for said cleaning means, and a final signal, (c) a shaft position judging circuit connected to the instruction decoder and the shaft position detecting means, said shaft position judging circuit including first gate means to designate a desired position for the control shaft in each of said states, second gate means responsive to the desired position and actual position of the control shaft to energize the drive means of the control shaft mechanism when the designated and actual positions are not the same, and third gate means to provide either a first position agreement signal or a second position agreement signal respectively when the control shaft is in the desired first or second position, (d) a synchronizing unit for generating a synchronizing pulse each time said master cylinder makes one complete revolution, (e) a binary counter arranged to be enabled by a respective one of etch, ink form, transfer and clean signals to count the synchronizing pulses, (f) a sequence counter arranged to be enabled by the etch and clean signals to count the synchronizing pulses, said sequence counter also producing a signal for making the master plate feeding operation and the master ejection operation effective during a period of corresponding to one complete revolution of the master cylinder during the presence of the etch signal, and subsequently, producing an end signal when the master cylinder has rotated through a predetermined number of revolutions, (g) a presettable copy number counter arranged to count the number copy sheets passing through the machine during the printing operation and to produce an output signal when the counted value coincides with the preset value, (h) operation duration setting means including four independent rotary switches each presettable to a value indicative of the desired period respectively for etching, ink forming, transferring and cleaning operations, and a coder responsive to the setting of each said rotary switch to produce a binary output signal corresponding thereto, (i) a coincidence circuit for comparing the instantaneous count of the binary counter with each output of said coder and to provide a coincidence signal when coincidence is detected, (j-1) signal conversion means having a diode matrix, (j-2) jump gate means having a first AND gate which permits the passage of the ink knead signal so as to produce an etching instruction of four-bit code in the diode matrix when the first position agreement signal is produced, a second AND gate which permits the passage of the etch signal to produce an inking instruction of four-bit code in the diode matrix when the coincidence signal is produced, a third AND gate which permits the passage of the ink form signal to produce a transfer instruction of four-bit code in the diode matrix when the coincidence signal is produced, a fourth AND gate which permits the passage of the transfer signal to produce a printing instruction of four-bit code in the diode matrix when the coincidence signal is produced, a fifth AND gate which permits the passage of the print signal to produce a cleaning instruction of four-bit code in the diode matrix when the output signal from the copy number counter is received, a sixth AND gate which permits the passage of the clean signal to produce a final instruction of four-bit code in the diode matrix when the coincidence signal is produced, and a seventh AND gate which permits the passage of the final signal from the instruction decoder to produce a stop instruction of four-bit code in the diode matrix when the end signal is produced at the sequence counter while a single mode signal is produced for single mode operation, and (j-3) a first detector to detect the presence of a signal at any one of the AND gates in the jump gate means, (k) a single pulse generator connected to the first detector to generate a clocked clock pulse synchronized with the synchronizing pulses from an oscillator in response to an output signal from the first detector, (1) a register arranged to store an instruction code from the diode matrix in response to the clocked clock pulses and arranged to apply the stored instruction to the instruction decoder for conversion of the instruction into a said signal corresponding to the code stored by the register, (m) an auto start switch and (n) start gate means responsive to actuation of the auto start switch when a stop signal is produced by the instruction decoder, to supply a signal indicative of the ink kneading state to the register, to supply a signal for generating a clocked clock pulse to the single pulse generator, and to produce a motor start signal, the binary counter and said sequence counter being reset by the clocked clock pule from the single pulse generator.