Method for tracking a registered pattern to a continuous web
A method of applying a registered pattern to a continuous web of material involves determining a position of a next pattern such that the next pattern is in registration with a previous pattern, adjusting the position to maintain a transverse location relative to the web, and adjusting a rotation of the pattern so that the pattern is substantially aligned with a longitudinal axis of the web. Registration features of the web and registration features of the next pattern are used to determine longitudinal, transverse, and rotational errors between the registered position of the next pattern and the path of the web. The registered position of the next pattern is adjusted along a transverse axis of the web according to a transverse error to maintain the transverse location. A rotation of the registered position is adjusted according to an angle that is determined using the transverse error and a distance from a registration feature to a center of the pattern along a longitudinal axis of the pattern.
1. A method of applying a registered pattern to a continuous web of material comprising the steps of:
(a) capturing an image of the web, wherein the image includes at least two registration features;
(b) computing registration corrections based on the registration features, wherein the registration corrections maintain registration between a next panel and a previous panel;
(c) computing a transverse path correction necessary to maintain the next panel at a same transverse location relative to the web as the previous panel;
(d) limiting the transverse path correction to a user-defined maximum if the transverse path correction exceeds the maximum;
(e) computing a rotational path correction to substantially align the next panel with a longitudinal axis of the web;
(f) limiting the rotational path correction to a user-defined maximum if the rotational correction exceeds the maximum;
(g) computing a composite set of corrections by combining the transverse path correction and the rotational path correction with the registration corrections
(h) computing a final set of corrections by adjusting the composite set of corrections according to a user-specified set of adjustments; and
(i) producing the next pattern on the web according to the final set of corrections.
2. The method as set forth in claim 1 , step (b) further comprising the step of:
(b1) computing the registration corrections by averaging longitudinal and transverse errors associated with each of the registration features and by determining an angle associated with the longitudinal and transverse errors.
3. The method as set forth in claim 1 , step (c) further comprising the step of:
(c1) computing the transverse path correction using a transverse error associated with one of the registration features.
4. The method as set forth in claim 1 , step (e) further comprising the step of:
(e1) computing the rotational path correction by determining an angle associated with a transverse error and a distance from a registration feature to a center of the pattern along a longitudinal axis of the pattern.