Web tracking system

Abstract

A web tracking system for a continuous web of material which is transported from a supply to a takeup means along a predetermined path via one or more processing stations and comprises aligned tracking indicia along at least one edge of the web. Means are provided to observe the tracking indica as the web is transported along the system path and produce information either indicative of dimensional changes in the length and width of the web due to web shrinkage or expansion or indicative of a particular point along the length of the web useful at one or more of the processing stations in the system.

What is claimed is: 
     
       1. Web tracking system for a continuous web of material which is transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat said web comprising aligned tracking indicia comprising a line of registration marks of substantially uniform spacing and width along each edge of said web,   means mounted relative to the passage of said web to optically observe said tracking indicia along each of said web edges as said web is transported along said path and produce informational tracking signals based upon the passage of said tracking indicia relative to said observation means,   circuit means responsive to said informational signals to produce control signals indicative of changes in the lateral and longitudinal dimensions of said web,   means to provide relative translation between said processing stations and said web along said path,   said translation means responsive to said control signals to translate said processing stations according to changes in the lateral and longitudinal dimensions of said web.   
     
     
       2. The system of claim 1 wherein said translation means comprises web guide servo control to laterally translate a web supply roll at said supply means relative to said processing station. 
     
     
       3. The system of claim 1 wherein said translation means includes a processing station lateral position control to laterally postion said processing station relative to said web in said path. 
     
     
       4. The system of claim 1 wherein said translation means includes a processing station rotational position control to rotate said processing station relative to said web in said path. 
     
     
       5. The system of claim 1 wherein said tracking marks comprise registration marks of equal spacing and width. 
     
     
       6. The system of claim 5 wherein said registration marks are .[.preceeded.]. .Iadd.preceded .Iaddend.by a plurality .Iadd.of .Iaddend.aligned initializing marks at the beginning of said web, said initializing marks having a different geometric shape compared to said registration marks. 
     
     
       7. The system of claim 6 wherein said different geometric shape comprises a different mark width. 
     
     
       8. The system of claim 6 wherein the change from said initializing marks to said registration marks is indicative of a starting point for determining a particular location further along said web. 
     
     
       9. The system of claim 1 wherein determination of dimensional changes by said circuit means via said observation means is accomplished by monitoring the spacing between registration marks along at least one edge of said web indicative of changes in web length and monitoring lateral shift of said lines of registration marks relative to its respective observation means at both edges of said web indicative of either a change in web width or a lateral shift of said web relative to said observation means. 
     
     
       10. The system of claim 1 wherein said aligned tracking indicia comprises a line of registration marks of substantially uniform spacing and width along each edge of said web for purposes of monitoring dimensional changes in the length of said web and   a solid line along each edge of said web ajacent to said line of registration marks for purposes of monitoring dimensional changes in the width of said web.   
     
     
       11. The system of claim 10 wherein determination of dimensional changes by said circuit means via said observation means is accomplished by monitoring the spacing between registration marks along at least one edge of said web indicative of changes in web length and monitoring lateral shift of said solid lines relative to its respective observation means at both edges of said web indicative of either a change in web width or a lateral shift of said web relative to said observation means. 
     
     
       12. Web tracking system for a continuous web of material which is transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat said web comprising aligned tracking indicia along at least one edge of said web,   said tracking indicia comprising a plurality of aligned of registration marks of substantially uniform spacing and width and a plurality of aligned initializing marks preceding said registration marks and having a different geometric shape compared to said registration marks,   means mounted relative to the passage of said web to optically observe said tracking indicia as said web is transported along said path and produce .[.an.]. informational .[.signal .]. .Iadd.signals .Iaddend.indicative of .[.distant.]. .Iadd.predetermined .Iaddend.lengths along said .[.medium.]. .Iadd.web .Iaddend.useful at one or more of said processing stations,   circuit means responsive to said informational .[.signal.]. .Iadd.signals .Iaddend.indicative of the recognition of said initalizing marks and determinative of the point of transition from the last of said initializing marks to the first of said registration marks, said circuit means further determinative of the distance between said transition point and a predetermined point further along said registration marks wherein the treatment of said web is desired to be initiated relative to any one of said stations.   
     
     
       13. In the web tracking system of claim 12 wherein said initializing marks are identical to said registration marks but are of a different dimensional width. 
     
     
       14. In the web tracking system of claim 13 wherein said initializing marks are smaller dimensional width than said registration marks. .Iadd.15. The system of claim 1 wherein said circuit means comprises means for comparing said informational signals with a known value to produce said control signals representing a dimensional change in the lateral and longitudinal direction of the web, means for averaging a plurality of said control signals together to produce a composite error signal representative of a running average in the lateral and longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the relative positional relationship of said web relative to one or more of said processing stations to compensate for any changes that have occurred in web lateral and longitudinal dimension. .Iaddend. .Iadd.16. The system of claim 1 wherein said circuit means comprises means to correct for misalignment between the lateral positional relationship of said web   
     
     
        relative to at least one of said processing stations. .Iaddend. .Iadd.17. The system of claim 12 wherein said circuit means comprises means for comparing said informational signals with a known value to produce control signals representing a dimensional change in the lateral and longitudinal direction of the web, means for averaging a plurality of said control signals together to produce a composite error signal representative of a running average in the longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the relative positional relationship of said web relative to one or more of said processing stations to compensate for any changes that have occurred in web longitudinal dimension. .Iaddend. .Iadd.18. The system of claim 17 wherein said utilizing means comprises means to correct for lateral misalignment between the lateral positional relationship of said web   
     
     
        relative to at least one of said processing stations. .Iaddend. .Iadd.19. The system of claim 12 wherein there are aligned along at least two edges of said web, means to correct for lateral misalignment between (a) the lateral positional relationship of said web relative to one or more of said processing stations and (b) the lateral dimensional relationship of said web due to changes in the lateral shrinkage or expansion of said web 
     
     
        relative to at least one of said processing stations. .Iaddend. .Iadd.20. The system of claim 12 wherein there is means to translation between at least one of said processing stations and said web along said path. .Iaddend. .Iadd.21. The system of claim 20 wherein said translation means comprises web guide servo control to laterally translate said supply roll means relative to one or more of said processing stations. .Iaddend. .Iadd.22. The system of claim 20 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web in said path. .Iaddend. .Iadd.23. The system of claim 20 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web in said path. .Iaddend. .Iadd.24. The system of claim 12 wherein said tracking indicia comprise registration marks of substantially equal spacing and width. .Iaddend. .Iadd.25. The system of claim 12 wherein said different geometric shape comprises a different dimensional width. .Iaddend. .Iadd.26. A system for controlling the track or position of a continuous web of material traveling from a supply roll to a takeup roll along a predetermined path via one or more sequentially positioned processing stations for selectively treating a portion of the web comprising aligned tracking indicia along at least one region of said web portion,   means mounted relative to the passage of said web to observe said tracking indicia as said web is transported along said path and produce informational tracking signals based upon the passage of said tracking indicia relative to said observations means,   circuit means for comparing said signals with a known value to produce error signals representing a dimensional change in the longitudinal direction of the web,   means for averaging a plurality of said error signals together to produce a composite error signal representative of a running average in longitudinal shrinkage or expansion of said web portion, and   means for utilizing said composite error signal to adjust the relative positional relationship of said web portion relative to one or more of said processing stations to compensate for any changes that have occurred in web longitudinal dimension. .Iaddend. .Iadd.27. The system of claim 26 wherein said utilizing means includes means to correct for lateral misalignment between the lateral positional relationship of said web portion relative to one or more of said processing stations. .Iaddend. .Iadd.28. The system of claim 26 wherein there are aligned tracking indicia along at least two regions of said web portion, said utilizing means including means to correct for lateral misalignment between (a) the lateral positional relationship of said web portion relative to one or more of said processing stations or (b) the lateral dimensional relationship of said web portion due to changes in the lateral shrinkage or expansion of said web portion relative to one or more of said processing stations. .Iaddend. .Iadd.29. The system of claim 26 wherein said utilizing means includes means to provide relative translation between at least one of said processing stations and said web portion along said path. .Iaddend. .Iadd.30. The system of claim 29 wherein said translation means comprises web guide servo control to laterally translate said supply roll relative to said processing station. .Iaddend. .Iadd.31. The system of claim 29 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web portion in said path.   
     
     
        .Iaddend. .Iadd.32.  The system of claim 29 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web portion in said path. .Iaddend. .Iadd.33. The system of claim 26 wherein said tracking indicia comprise registration marks of substantially equal spacing and width. .Iaddend. .Iadd.34. The system of claim 26 wherein said tracking indicia are preceded by initializing means indicative of a start point for processing of said web relative to any one of said processing stations and in conjunction with said utilizing means determinative of the distance between said start point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated relative to any one of said processing stations. .Iaddend. .Iadd.35. The system of claim 34 wherein said initializing means comprises 
     
     
        at least one tracking indicia. .Iaddend. .Iadd.36.  The system of claim 26 which includes increment means to translate longitudinally, laterally or rotationally one or more of said processing stations or a component part of one or more of said processing stations,   said observation means including paired sensing means positioned relative to said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals,   differences in magitude between said information signals indicative of the   
     
     
        changes in said positional relationship. .Iaddend. 37. Web tracking system for a continuous web of material which is transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat regional portions of said web and wherein a desired positional relationship is to be maintained between said web and one or more of said processing stations and comprising aligned tracking indicia continuous or closely spaced, intermittently continuous longitudinally along at least two regions of said web adjacent to said treated regional portions,   means mounted relative to the passage of said web to continuously observe said tracking indicia as said web is trasnported along said path and simultaneously produce on-the-fly informational signals based upon the passage of said tracking indicia relative to said observations means as said treated regional portions move into and through one or more of said processing stations,   means for utilizing said signals to correct on-the-fly for misalignment in the positional relationship of said web relative to at least one of said processing stations due to shrinkage or expansion changes in said web in either the lateral or longitudinal dimensions of said web or in both   
     
     
        dimensions thereof.  .Iadd.38.  The system of claim 37 wherein said circuit means comprises means for comparing said informational signals with a known value to produce said control signals representing a dimensional change in the longitudinal direction of the web, means for averaging a plurality of said control signals together to produce a composite error signal representative of a running average in the longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the positional relationship of said web relative to one or more of said processing stations to compensate for said changes that have occurred in web   
     
     
        longitudinal dimension. .Iaddend. .Iadd.39.  The system of claim 37 wherein said utilizing means includes means to provide relative translation between at least one of said processing stations and said web along said path. .Iaddend. .Iadd.40. The system of claim 39 wherein said translation means comprises web guide servo control to laterally translate said supply roll means relative to one or more of said processing stations. .Iaddend. .Iadd.41. The system of claim 39 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web in said path. .Iaddend. .Iadd.42. The system of claim 39 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web in said path. .Iaddend. .Iadd.43. The system of claim 37 wherein said tracking indicia are preceded by initializing means indicative of a start point for processing of said web relative to any one of said processing stations and in conjunction with said utilizing means determinative of the distance between said start point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated relative to any one of said processing stations. .Iaddend. .Iadd.44. The system of claim 43 wherein said initializing means comprises 
     
     
        at least one tracking indicia. .Iaddend. .Iadd.45.  The system of claim 37 which includes increment means to translate longitudinally, laterally or rotationally one or more of said processing stations or a component part of one or more of said processing stations,   said observation means including paired sensing means positioned relative to each of said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals,   differences in magnitude between said information signals indicative of the   
     
     
        changes in said positional relationship. .Iaddend. .Iadd.46.  Web tracking system for a continuous web of material transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat said web wherein a desired positional relationship is to be maintained between said web and one or more of said stations and comprising aligned tracking indicia along at least two regions of said web,   means mounted relative to the passage of said web to observe said tracking indicia as said web is transported along said path and produce informational signals based upon the passage of said tracking indicia and a web edge relative to said observations means,   means for utilizing said signals to correct for misalignment in the positional relationship of said web relative to at least one of said processing stations due to changes in the lateral positional relationship of said web relative to said processing station or due to shrinkage or expansion changes in said web in either the lateral and longitudinal dimensions of said web or in both dimensions thereof. .Iaddend. .Iadd.47. The system of claim 46 wherein said circuit means comprises means for comparing said informational signals with a known value to produce said control signals representing a dimensional change in the longitudinal direction of the web, p1 means for averaging a plurality of said control signals produce a composite error signal representative of a running average in the longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the positional relationship of said web relative to one or more of said processing stations to compensate for said changes that have occurred in web longitudinal dimension. .Iaddend. .Iadd.48. The system of claim 46 wherein said utilizing means includes means to provide relative translation between at least one of said processing stations and said web along said path. .Iaddend. .Iadd.49. The system of claim 48 wherein said translation means comprises web guide servo control to laterally translate said supply roll means relative to one or more of said processing stations. .Iaddend. .Iadd.50. The system of claim 48 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web in said path. .Iaddend. .Iadd.51. The system of claim 48 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web in said path. .Iaddend. .Iadd.52. The system of claim 46 wherein said tracking indicia are preceded by initializing means indicative of a start point for processing of said web relative to any one of said processing stations and in conjunction with said utilizing means determinative of the distance between said start point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated relative to any one of said processing stations. .Iaddend. .Iadd.53. The system of claim 52 wherein said initializing means comprises at least one tracking indicia.   
     
     
        .Iaddend. .Iadd.54.  The system of claim 46 which includes increment means to translate longitudinally, laterally or rotationally one or more of said processing stations or a component part of one or more of said processing stations,   said observation means including paired sensing means positioned relative to each of said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals,   differences in magnitude between said information signals indicative of the changes in said positional relationship. .Iaddend. .Iadd.55. The system of claim 46 wherein said aligned tracking indicia are continuous or closely spaced, intermittently continuous indicia longitudinally along said at least two regions adjacent to regional portions of said web to be treated at said processing stations,   said mounted means to continuously observe said longitudinally continuous tracking indicia and simultaneously produce on-the-fly said information signals as said treated regional portions move into and thorugh one or   
     
     
        more of said processing stations. .Iadd.56.  Web tracking system for a continuous web of material which is transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat regional portions of said web and wherein a desired positional relationship is to be maintained between said web and one or more of said processing stations and comprising aligned tracking indicia continuous or closely spaced, intermittently continuous longitudinally along at least one region of said web adjacent to said treated regional portions,   means mounted relative to the passage of said web to continuously observe said tracking indicia as said web is transported along said path and simultaneously produce on-the-fly informational signals based upon the passage of said tracking indicia and a web edge relative to said observations means as said treated regional portions move into and through one or more of said processing stations,   means for utilizing said signals to correct on-the-fly for misalignment in the positional relationship of said web relative to at least one of said processing stations due to changes in the lateral positional relationship of said web relative to said processing station and due to shrinkage or expansion changes in said web in the longitudinal dimension of said web.   
     
     
        .Iaddend. .Iadd.57.  The system of claim 56 wherein said circuit means comprises means for comparing said informational signals with a known value to produce said control signals representing a dimensional change in the longitudinal direction of the web, means for averaging a plurality of said control signals together to produce a composite error signal representative of a running average in the longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the positional relationship of said web relative to one or more of said processing stations to compensate for said changes that have occurred in web longitudinal dimension. .Iaddend. .Iadd.58. The system of claim 56 wherein said utilizing means includes means to provide relative translation between at least one of said processing stations and said web along said path. .Iaddend. .Iadd.59. The system of claim 58 wherein said translation means comprises web guide servo control to laterally translate said supply roll means relative to one or more of said processing stations. .Iaddend.   
     
     
         0. The system of claim 58 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web in said path.  .Iadd.61. The system of claim 58 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web in said path. .Iaddend. .Iadd.62. The system of claim 56 wherein said tracking indicia are preceded by initializing means indicative of a start point for processing of said web relative to any one of said processing stations and in conjunction with said utilizing means determinative of the distance between said start point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated relative to any one of said processing stations. .Iaddend. .Iadd.63. The system of claim 62 wherein said initializing means comprises at least one tracking indicia. .Iaddend. .Iadd.64. The system of claim 56 which includes increment means to translate longitudinally, laterally or rotationally one or more of said processing stations or a component part of one or more of said processing stations,   said observation means including paired sensing means positioned relative to said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals,   differences in magnitude between said information signals indicative of the changes in said positional relationship. .Iaddend. .Iadd.65. Web tracking system for a continuous web of material which is transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat said web wherein a desired positional relationship is to be maintained between said web and one or more of said stations and comprising aligned tracking indicia along at least two regions of said web,   means mounted relative to the passage of said web to observe said tracking indicia as said web is transported along said path and produce informational signals based upon the passage of said tracking indicia and a web edge relative to said observations means,   means for utilizing said signals to correct for misalignment in the positional relationship of said web relative to at least one of said processing stations due to changes in the lateral positional relationship of said web relative to said processing station or due to shrinkage or expansion changes in said web in the lateral dimension of said web or due to both of said changes. .Iaddend. .Iadd.66. The system of claim 65 wherein said circuit means comprises means for comparing said informational signals with a known value to produce said control signals representing a dimensional change in the longitudinal direction of the web,   means for averaging a plurality of said control signals together to produce a composite error signal representative of a running average in the longitudinal shrinkage or expansion of said web, and   means for utilizing said composite error signal to adjust the positional relationship of said web relative to one or more of said processing stations to compensate for said changes that have occurred in web longitudinal dimension. .Iaddend. .Iadd.67. The system of claim 65 wherein said utilizing means includes means to provide relative translation between at least one of said processing stations and said web along said path. .Iaddend. .Iadd.68. The system of claim 67 wherein said translation means comprises web guide servo control to laterally translate said supply roll means relative to one or more of said processing stations. .Iaddend. .Iadd.69. The system of claim 67 wherein said translation means comprises a processing station lateral position control means to laterally position said processing station relative to said web in said path. .Iaddend. .Iadd.70. The system of claim 67 wherein said translation means comprises a processing station rotational position control to rotate said processing station relative to said web in said path. .Iaddend. .Iadd.71. The system of claim 65 wherein said tracking indicia are preceded by initializing means indicative of a start point for processing of said web relative to any one of said processing stations and in conjunction with said utilizing means determinative of the distance between said start point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated relative to any one of   
     
     
        said processing stations. .Iaddend. .Iadd.72.  The system of claim 71 wherein said initializing at least one tracking indicia. .Iaddend. 
     
     
        .Iadd.  .  The system of claim 65 which includes increment means to translate longitudinally, laterally or rotationally one or more of said processing stations or a component part of of one or more of said processing stations,   said observation means including paired sensing means positioned relative to each of said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals, differences in magnitude between said information signals indicative of the changes in said positional relationship. .Iaddend. .Iadd.74. The system of claim 65 wherein said aligned tracking indicia are continuous or closely spaced, intermittently continuous indicia longitudinally along said at least two regions adjacent to regional portions of said web to be treated at said processing stations,   said mounted means to continuously observe said longitudinally continuous tracking indicia and simultaneously produce on-the-fly said informational signals as said treated regional portions move into and through one or   
     
     
        more of said processing stations. .Iaddend. .Iadd.75.  Web tracking system for a continuous web of material transported from a supply roll means to a takeup roll means along a predetermined path via one or more sequentially positioned processing stations to treat said web comprising aligned tracking indicia along at least one region of said web,   initializing means preceding said aligned tracking indicia,   means mounted relative to the passage of said web to optically observe said tracking indicia as said web is transported along said path and produce informational signals indicative of the longitudinal dimension along said web useful at one or more of said processing stations,   circuit means responsive to said informational signals indicative of the recognition of said initializing means and determinative of the point of transition from said initializing means to said tracking indicia, said circuit means further determinative of the distance between said transition point and a predetermined point further along said tracking indicia wherein the treatment of said web is desired to be initiated   
     
     
        relative to any one of said stations. .Iaddend. .Iadd.76.  The system of claim 75 wherein said initializing at least one registration mark on said 
     
     
        web. .Iaddend. .Iadd.77.  The system of claim 75 which includes paired sensing means positioned relative to said tracking indicia, the outputs of corresponding pairs of said paired sensing means coupled to produce separate summed outputs comprising said information signals,   differences in magnitude between said information signals indicative of said point of transition. .Iaddend.