System for reducing setting-up time in printing machines having register adjustment devices

An automatic control system for reducing the setting-up times in the printing process by adjusting the axial, peripheral, and diagonal register in a multi-color printing machine before printing occurs, the printing machine having a plurality of plate cylinders with associated printing plates mounted thereon, the printing plates having register marks incorporated thereon, the printing machine having remotely-controllable devices for adjusting peripheral, axial and diagonal register associated with each of the plate cylinders, the control system comprising, in combination,

• a computer for performing numerical calculations and operating the register adjustment devices,
• an angular resolver for indicating to the computer the phase of the machine drive,
• optical scanning means associated with each plate cylinder for sensing the relative axial and peripheral positions of respective register marks on the associated printing plates with respect to the positions of the scanning means, the scanning means being mounted for traversing, generally axial movement with respect to the associated plate cylinder,
• computer controllable means for driving the scanning means for each plate cylinder to desired predetermined axial locations with respect to the machine frame,
• means for generating a gating signal to enable the optical scanning means to sense the register marks only during a predetermined range of plate cylinder phase, the predetermined range being specified by the computer,
• detector means for processing the output of the optical scanning means when enabled by the gating signal and generating a signal for input to the computer responsive to the times when the respective scanning means are precisely aligned with their respective register marks, thereby indicating the axial and peripheral coordinates of the register marks,
• the computer being programmed to provide means for
• commanding the means for driving to move the scanning means to at least one predetermined axial coordinate and for outputting to the means for gating at least one predetermined peripheral coordinate, the coordinates specifying the general locations of the register marks on the printing plates,
• thereafter, in response to the phase angle from the angular resolver, commanding the means for driving the scanners to traversably reciprocate the scanners in synchronism with the rotation of the plate cylinder so that the scanning means traverse across the respective register marks,
• obtaining axial and peripheral coordinates of the register marks from the signal received from the detector means,
• comparing the axial and peripheral coordinates of the register marks and computing axial, peripheral, and diagonal register errors in response to the comparisons, and
• controlling the register adjustment devices in response to the computed register errors so that the register errors are reduced.

An automatic control method performed by a computer for adjusting the axial, peripheral, and diagonal register in a multi-color printing machine before printing occurs, the printing machine having a plurality of plate cylinders and associated printing plates mounted thereon, each of the printing plates having register marks incorporated thereon, the printing machine having computer controllable devices for adjusting peripheral, axial and diagonal register associated with the plate cylinders and having scanning means for sensing the axial and peripheral positions of the register marks on the printing plates, the scanners being mounted to the machine frame for computer controllable generally axial movement with respect to the respective plate cylinders to axial coordinates with respect to the machine frame specified by the computer, the printing machine having gating means associated with the scanning means for enabling the sensing of the register marks when the marks have peripheral coordinates within a predetermined range of peripheral coordinates about at least one peripheral coordinate specified by the computer, the control method comprising the steps of:

• receiving from the machine operator axial and peripheral reference coordinates specifying the approximate locations of the register marks incorporated on the printing plates,
• commanding the scanning means to axially move to approximately the axial reference coordinates,
• specifying at least one of the peripheral reference coordinates to the gating means associated with the scanning means so that the scanning means are enabled to sense the axial and peripheral positions of the register marks,
• obtaining the axial and peripheral coordinates of the register marks from the output signal of the scanning means,
• computing axial, peripheral and diagonal register errors from the axial and peripheral coordinates of the register marks, and
• adjusting the axial, peripheral and diagonal register adjusting devices in response to the respective register error.