Registration control device for use in a rotary printing machine
AssigneeBobst SA
InventorPatrick Monney
Life of this patent
Estimating the term…
Abstract
A register control device has a head which scans registration marks printed on a web, the scanning head having a row of discrete photosensitive elements arranged crosswise to the traveling direction of the web and in a plane situated above and parallel to the web. The scanning head has in the same plane a linear video bar situated parallel to the row of photosensitive elements. The device includes a microprocessor which selects the photosensitive element to be used according to the temporary sideways displacement of the web and controls the scanning operations of the linear video bar. The scanning head may also include a second row of discrete photosensitive elements arranged parallel between the first row of discrete photosensitive elements and the linear video bar.
Claims13
An apparatus, for use in a rotary printing machine having a traveling web with registration marks disposed thereon, for determining misregistration of said web, said apparatus comprising:
- a scanning head having a row of individually selectable discrete photosensitive elements and a video bar, both disposed in a plane parallel to said web and both extending parallel to the cross-machine direction for scanning said registration marks as they pass beneath said scanning head, and each of said row of discrete photosensitive elements and said video bar generating respective electrical signals upon scanning said registration marks;
- microprocessor means connected to said row of discrete photosensitive elements for selecting, dependent on a current amount of cross-machine displacement of said web, at least one photosensitive element in said row to be used to detect misregistration of said web, and to said video bar for controlling scanning of said web by said video bar;
- first processing means, connected to said row of discrete photosensitive elements and to said microprocessor means, for generating a signal corresponding to machine-direction misregistration of said web from said electrical signal from said row of photosensitive elements;
- and
- second processing means, connected to said video bar and to said microprocessor means, for generating a signal corresponding to cross-machine misregistration of said web from said electrical signals from said video bar quasi-simultaneously with the generation of said signal corresponding to machine-direction misregistration by said first processing means.
A method for determining misregistration of a traveling web in a rotary printing machine, said web having side-by-side registration marks thereon extending in a cross-machine direction, said method comprising the steps of:
- scanning said registration marks with a single row of discrete photosensitive elements and a video bar, both disposed in a plane parallel to said web and both extending parallel to the cross-machine direction;
- during scanning of said registration marks, selecting one photosensitive element in a right half of said row and selecting another, different photosensitive element in a left side of said row;
- generating respective, spaced pulses from said selected photosensitive elements in said left and right halves of said row corresponding to the passage of said registration marks beneath said row;
- identifying a midpoint between said pulses from said selected photosensitive elements and generating a signal corresponding to machine-direction misregistration of said web based on the identification of said midpoint between said pulses from said selected photosensitive elements in said left and right halves of said row;
- generating two spaced pulses from said video bar corresponding to the passage of said registration marks beneath said video bar;
- and
- identifying a midpoint between said pulses from said video bar, and generating a signal corresponding to cross-machine misregistration of said web based on the identification of said midpoint between said pulses from said video bar.
A method for determining misregistration of a traveling web in a rotary printing machine, said web having successive registration marks thereon extending in a machine-direction, said method comprising the steps of:
- scanning said registration marks with a two row of discrete photosensitive elements and a video bar, all disposed in a plane parallel to said web and all extending parallel to the cross-machine direction;
- during scanning of said registration marks, selecting one photosensitive element in each of said rows;
- generating respective, spaced pulses from said selected photosensitive elements in said rows, corresponding to the passage of said registration marks beneath said rows;
- identifying a midpoint between said pulses from said selected photosensitive elements in said row and generating a signal corresponding to machine-direction misregistration of said web based on the identification of said midpoint between said pulses from said selected photosensitive elements in said rows,
- generating two spaced pulses from said video bar corresponding to the passage of said registration marks beneath said video bar;
- and
- identifying a midpoint between said pulses from said video bar, and generating a signal corresponding to cross-machine misregistration of said web based on the identification of said midpoint between said pulses from said video bar.
Dependencies are inferred from the claim text.