Abstract:
A system is disclosed for securing registration of a patterned embossing roll with a similarly patterned printed moving web. The purpose of the embossing roll is to indent the surface of the printed web in register with the printing in certain designated areas. In one embodiment, a series of randomly spaced register marks on the printed web selvage edge and identically spaced register marks on the embossing roll are viewed by appropriate scanners. Electrical signatures representing the two sets of register marks are generated by the sensors and fed to a signal correlator for comparison. The correlator determines the degree of statistical error between the two signatures and displays this error in the form of a time delay on a CRT (Cathode Ray Tube). If manual registration control is desired, an operator can manually adjust the speed or phase of the embossing roll by observing the peaked wave display on the CRT to bring the roll into a statistical best fit of the embossing pattern with the printed pattern. Automatic control of embossing roll speed and orientation to achieve registration is also possible if the correlator is interfaced with a digital computer and servo correction motors on the embosser drive system. The disclosed system is an improvement over conventional benchmark oriented registration sensing and control systems in that it is capable of continuous error determinations and asynchronous error corrections on demand rather than periodically at the end of pattern length intervals.
Abstract:
Digital inputs are fed to a programmed digital computer for a precise measurement and calculation of key line-speed parameters. The ratio of the web infeed speed measured at a point upstream of all processing actions relative to the embossing roll speed is the controlled variable. Digital speed recorders measure the web infeed speed and the embossing roll speed. The relationship between these two is automatically manipulated by the digital computer which reflect the process dynamics and describe the desired system response.