초록 ▼

A method and apparatus for controlling the lateral position of a moving web in a dual control mode system. The control system ordinarily operates in a precise, highly-sensitive fine mode but is automatically switched into a less precise but rapidly responding coarse mode in response to loss of contr

A method and apparatus for controlling the lateral position of a moving web in a dual control mode system. The control system ordinarily operates in a precise, highly-sensitive fine mode but is automatically switched into a less precise but rapidly responding coarse mode in response to loss of control in the fine mode. After control is reestablished in the coarse mode, the coarse mode control is terminated and the fine mode control is resumed.

대표청구항 ▼

A control system for controlling the lateral position of a moving web of material comprising: (a) a first sensor means having a first relatively wide scan path extending transversely of the web for sensing the relative lateral position of preselected web lateral position indicating indicia associate

A control system for controlling the lateral position of a moving web of material comprising: (a) a first sensor means having a first relatively wide scan path extending transversely of the web for sensing the relative lateral position of preselected web lateral position indicating indicia associated with the first sensor means and generating a first sensor signal indicative of the relative lateral position of the web; (b) coarse mode control means for causing relatively rapid adjustment of the lateral position of the web in response to said first sensor signal for adjustably moving the web to a predetermined lateral position within a first set of tolerances during a coarse mode of control; (c) a second sensor means having a second relatively narrow transversely extending scan path for sensing the relative lateral position of preselected web lateral position indicating indicia associated with the second sensor means and generating a second sensor signal indicative of the relative lateral position of the web; (d) fine mode control means for causing adjustment of the lateral position of the web in response to said second sensor signal for maintaining the web in said predetermined lateral position within a second set of tolerances in a fine mode of control; (e) control mode switching means for switching from said fine control mode to said coarse control mode whenever said web position indicating indicia associated with said second sensor are not detected thereby for a predetermined period of time and for switching from said coarse control mode to said fine control mode whenever said second sensor continuously detects the presence of said web position indicating indicia associated therewith for a predetermined period of time.