The present invention is directed to a registration system for a printing press and to a method of registering the printing rollers of a printing press.
There are various types of conventional printing presses. One conventional printing press includes a first rotatable printing roller that prints ink of a first color on a web of material and causes a first registration mark to be periodically printed in the first color on the web, a second rotatable printing roller that prints ink of a second color on the web and causes a second registration mark to be periodically printed in the second color on the web, and a third rotatable printing roller that prints ink of a third color on the web and causes a third registration mark to be periodically printed in the third color on the web. The phase or registration of the printing rollers is controlled to cause a multicolor image to be printed on the web, the multicolor image being composed of the single-color images or image portions printed by each printing roller. To that end, the conventional printing press includes an imaging device positioned to detect the registration marks printed on the web by said printing rollers that generates image data representing the registration marks and a controller operatively coupled to the printing rollers and the imaging device that generates a control signal that adjusts the phase or registration of the printing rollers so that they are in proper phase or registration.
One example of a printing press with a registration system is disclosed in U.S. Pat. No. 5,056,430 to Bayerlein, et al. As shown in FIG. 1 of the patent, that printing press is shown to be provided with four printing rollers that include printing plates 12, 13, 14, 16 each of which prints in a different color and each of which periodically prints a registration mark having a different size, as shown in FIG. 3 of the patent. After the registration marks are printed on the web, they are detected by an imaging detecting device 22, as shown in FIG. 4, that is used to measure deviations in the positions of the registration marks relative to each other. Those deviations are used to generate correction signals for correcting the registration of the printing rollers so that the multicolor image is in proper registration.
In one aspect, the invention is directed to a printing press that may be provided with a first rotatable printing roller that prints ink of a first color on a web of material and causes a first pair of registration marks to be periodically printed in the first color on the web, a second rotatable printing roller that prints ink of a second color on the web of material and causes a second pair of registration marks to be periodically printed in the second color on the web, a third rotatable printing roller that prints ink of a third color on the web of material and causes a third pair of registration marks to be periodically printed in the third color on the web, an imaging device positioned to detect the registration marks printed on the web that generates image data representing the registration marks, and a controller operatively coupled to the printing rollers and the imaging device.
The controller may include a processor and a memory, and the controller may be programmed to identify the pairs of registration marks based on the image data and based on registration mark reference data for at least three registration mark pairs defined by a registration mark relationship table set forth below:
wherein the Offset X value for each of the registration mark pairs corresponds to an offset value in a first direction between the registration marks in the registration mark pair, and wherein the Offset Y value for each of the registration mark pairs corresponds to an offset value in a second direction between the registration marks in the registration mark pair, the second direction being perpendicular to the first direction.
In another aspect, the invention is directed to a controller for a printing press that may include a processor, a memory operatively coupled to the processor, and a computer program stored in the memory and executed by the processor. The computer program may cause the processor to identify a pair of printed registration marks based on image data generated from detection of the printed registration marks and based on registration mark reference data for at least three registration mark pairs defined by a registration mark relationship table set forth below:
wherein the Offset X value for each of the registration mark pairs corresponds to an offset value in a first direction between the registration marks in the registration mark pair, and wherein the Offset Y value for each of the registration mark pairs corresponds to an offset value in a second direction between the registration marks in the registration mark pair, the second direction being perpendicular to the first direction.
The invention is also directed to a method which may include printing a first pair of registration marks in a first color on a web of material with a first rotatable printing roller, printing a second pair of registration marks in a second color on the web of material with a second rotatable printing roller, printing a third pair of registration marks in a third color on the web of material with a third rotatable printing roller. The method may also include generating image data representing the registration marks printed on the web by the printing rollers and identifying the pairs of registration marks based on the image data and based on registration mark reference data for at least three registration mark pairs defined by a registration mark relationship table set forth below:
wherein the Offset X value for each of the registration mark pairs corresponds to an offset value in a first direction between the registration marks in the registration mark pair, and wherein the Offset Y value for each of the registration mark pairs corresponds to an offset value in a second direction between the registration marks in the registration mark pair, the second direction being perpendicular to the first direction.
In another aspect, the invention is directed to a printing press that may have a first rotatable printing roller that prints ink of a first color on a web of material and causes a first pair of registration marks to be periodically printed in the first color on the web, a second rotatable printing roller that prints ink of a second color on the web of material and causes a second pair of registration marks to be periodically printed in the second color on the web, a third rotatable printing roller that prints ink of a third color on the web of material and causes a third pair of registration marks to be periodically printed in the third color on the web, an imaging device positioned to detect the registration marks printed on the web that generates image data representing the registration marks, and a controller operatively coupled to the printing rollers and the imaging device.
The controller may include a processor and a memory, and the controller may be programmed to group the registration marks in pairs based on the image data by generating a list of possible registration mark pairs and by eliminating from the list at least one of the possible registration mark pairs. The controller may be programmed to determine a centerpoint for each of the pairs of registration marks, and the controller may also be programmed to generate a registration correction value for one of the printing rollers based on a plurality of the centerpoints.
The invention is also directed to a method that may include printing a first pair of registration marks in a first color on a web of material with a first rotatable printing roller, printing a second pair of registration marks in a second color on the web of material with a second rotatable printing roller, printing a third pair of registration marks in a third color on the web of material with a third rotatable printing roller, generating image data representing the registration marks printed on the web by the printing rollers, and grouping the registration marks in pairs based on the image data by generating a list of possible registration mark pairs and by eliminating from the list at least one of the possible registration mark pairs.
In a further aspect, the invention is directed to a printing press that may include a first rotatable printing roller that prints ink of a first color on a web of material and that causes a first pair of registration marks to be periodically printed in the first color on the web, a second rotatable printing roller that prints ink of a second color on the web of material and causes a second pair of registration marks to be periodically printed in the second color on the web, a third rotatable printing roller that prints ink of a third color on the web of material and causes a third pair of registration marks to be periodically printed in the third color on the web, an imaging device positioned to detect the registration marks printed on the web by the printing rollers that generates image data representing the registration marks, and a controller operatively coupled to the printing rollers and the imaging device. The controller may have a processor and a memory, and the controller may be programmed to determine an offset value between a first registration mark in one of the pairs of registration marks and a second registration mark in the one pair of registration marks, the offset value being determined based upon a dimension of one of the registration marks.
The invention is also directed to a method that may include printing a first pair of registration marks in a first color on a web of material with a first rotatable printing roller, printing a second pair of registration marks in a second color on the web of material with a second rotatable printing roller, printing a third pair of registration marks in a third color on the web of material with a third rotatable printing roller, generating image data representing the registration marks printed on the web by the printing rollers, and determining an offset value between a first registration mark in one of the pairs of registration marks and a second registration mark in the one pair of registration marks, the offset value being determined based upon a dimension of one of the registration marks.
In another aspect, the invention is directed to a printing press that may be provided with a first rotatable printing roller that prints ink of a first color on a web of material and causes a first registration mark to be periodically printed in the first color on the web, a second rotatable printing roller that prints ink of a second color on the web of material and causes a second registration mark to be periodically printed in the second color on the web, a third rotatable printing roller that prints ink of a third color on the web of material and causes a third registration mark to be periodically printed in the third color on the web, an imaging device positioned to detect the registration marks printed on the web by the printing rollers that generates image data representing the registration marks, and a controller operatively coupled to the printing rollers and the imaging device. The controller may include a processor and a memory, and the controller may be programmed to generate a registration correction value for one of the printing rollers based on data indicative of a spacing between a plurality of the registration marks and based on a dimension of at least one of the registration marks.
The invention is also directed to a method that may include printing a first registration mark in a first color on a web of material with a first rotatable printing roller, printing a second registration mark in a second color on the web of material with a second rotatable printing roller, printing a third registration mark in a third color on the web of material with a third rotatable printing roller, generating image data representing the registration marks printed on the web by the printing rollers, and generating a registration correction value for one of the printing rollers based on data indicative of a spacing between a plurality of the registration marks and based on a dimension of at least one of the registration marks so that the registration correction value may be generated regardless of the size of the registration marks.
The features and advantages of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided below.