In a web-fed rotary printing press, a method of printing elongate images on a continous web of material, which method comprises:
- (a) providing a first printing unit having a first printing cylinder and a first impression cylinder, the first printing cylinder coacting with the first impression cylinder for printing on a web a first image portion having a first dimension, in the longitudinal direction of the web, that is not more than the circumference of the first printing cylinder;
- (b) providing a second printing unit having a second printing cylinder and a second impression cylinder, the second printing cylinder coacting with the second impression cylinder for printing on the web a second portion having a second dimension, in the longitudinal direction of the web, that is not more than the circumferene of the second printing cylinder;
- (c) running a web at a prescribed speed through the first and the second printing unit;
- (d) holding the first impression cylinder against the first printing cylinder via the web for causing the first image portion to be printed thereon;
- (e) holding the first impression cylinder away from the first printing cylinder for causing the first image portion to be not printed on the web while the wb is traveling a first predetermined distance, which is equal to the second dimension, after each time the first image portion has been printed thereon;
- (f) rotating, if necessary, the first printing cylinder through an angle necessary for again printing the first image portion on the web immediately after the web has traveled the first predetermined distance;
- (g) again holding the first impression cylinder against the first printing cylinder via the web after the web has traveled the first predetermined distance, for causing the first image portion to be printed thereon, with the consequent creation of a blank between every two neighboring first image portion on the web, the blank being of the second dimension in the longitudinal direction of the web;
- (h) holding the second impression cylinder against the second printing cylinder via the web for causing the second image portion to be printed on one of the blanks of the web left by the first printing unit;
- (i) holding the second impression cylinder away from the second printing cylinder for causing the second image portion to be not printed on the web while the web is traveling a second predetermined distance, which is equal to the first dimension, after each time the second image portion has been printed thereon;
- (j) rotating, if necessary, the second printing cyliinder through an angle necessary for printing the second image portion on the next blank on the web;
- and
- (k) again holding the second impression cylinder against the second printing cylinder via the web after the web has traveled the second predetermined distance, for causing the second image portion to be printed on the next blank on the web;
- (l) whereby images can be printed on the web without intervening blanks, each printed image, if composed of the first and the second image portion, having a dimension in the longitudinal direction of the web up to the sum of the circumferences of the first and the second printing cylinder.