Printing – Multicolor – Rotary machines
Reexamination Certificate
2001-10-09
2004-04-06
Hirshfeld, Andrew H. (Department: 2854)
Printing
Multicolor
Rotary machines
C101S180000, C101S170000, C101S211000
Reexamination Certificate
active
06715417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing press for doing printing such as offset printing in which inks are applied to printing plates to form ink images, which are then transferred onto printing paper. And especially, the present invention relates to a printing press equipped with a color chart measuring apparatus for reading a color chart printed on printing paper to acquire color chart information.
2. Description of the Background Art
Recently, printing presses which install therein a plate making machine (printing plate recording apparatus) for forming an image on a printing plate on the basis of digital image data, known as a CTP (computer-to-plate) machine, have been developed for commercial use. Such printing presses are called digital printing presses and are suitable for short-time print jobs such as multi-kinds, small-circulation printing, since they can produce printed matter directly from image data. Those digital printing presses have automatized a prepress process for ease of handling by even inexperienced operators, but still further automation of a printing process, such as ink feed control, is desired.
For the control of ink feed, conventional printing presses have generally used a separate type color measurement table for measuring a picked-up printed sample placed thereon. This, however, requires an operator to pick up an appropriate printed sample for color measurements of printed matter.
To solve this problem, printing presses comprising means for capturing an image of printing matter have been proposed. According to this conventional technique, the printing press obtains image data through imaging of printing matter on its impression cylinder and compares this image data with previously-obtained reference image data about reference printing matter for ink feed control. In this conventional technique, an image of printing matter is captured within the printing press, which brings the advantage of avoiding operator involvement which would be required when using the color measurement table.
The above conventional technique, however, has a problem that reading and comparing a whole image of printing matter with a reference image requires handling of a large amount of image data and requires much time for image data processing. In addition, the preparation of a reference image is not suitable for print jobs which require immediacy, such as multi-kinds, small-circulation printing.
SUMMARY OF THE INVENTION
The present invention is intended to solve the aforementioned conventional problems, and an object thereof is to provide a printing press equipped with a color chart measuring apparatus for providing a color chart on printing matter, instead of reading a whole image of the printing matter, and then reading and measuring only an area relating to the color chart on printing paper being transported. In this case, the amount of image data to be handled can be reduced and the use of the color chart avoids the necessity of preparing a reference image.
The present invention is especially suitable for a printing press equipped with a printing plate recording apparatus for recording an image on a printing plate, such as digital printing presses as above described. It provides a printing press capable of setting an area to read a color chart according to the recording position of the color chart in image recording.
Another object of the present invention is to provide a color chart that allows precise measurement and to provide a color chart measuring method and apparatus capable of measuring a color chart on printing paper being transported with high accuracy even if flapping or the like of the printing paper being transported causes variations in the imaging level in different parts of the printing paper.
A first aspect of the present invention is directed to a printing press for printing a color chart including a plurality of color chart fields in a margin of printing paper, said printing press equipped with a color chart measuring apparatus for reading each of the color chart fields on the printing paper to measure color chart information. The printing press comprises: a transport section for transporting the printing paper; an imaging section for capturing an image on the printing paper transported by the transport section; a reading time setting section for determining, in accordance with a transport operation of the printing paper, a reading time during which the imaging section reads an image of the color chart; an image data storage section for storing image data on an area read by the imaging section during the reading time, as readout image data; a color chart actual position calculation section for calculating an actual position in which each of the color chart fields was actually printed, on the basis of the readout image data; and a color chart information determination section for determining color chart information about each of the color chart fields from the readout image data corresponding to the actual position.
In the first aspect, the imaging section can read only an area including the color chart, which reduces the amount of image data to be handled. Further, the use of a preset color chart avoids the necessity of preparing a reference image for comparison.
According to a second aspect of the present invention, the printing press of the first aspect further comprises: a printing plate recording section for positioning and recording the color chart on a printing plate, wherein the reading time setting section determines the reading time on the basis of a position in which the color chart was recorded.
In the second aspect, the reading time to read the color chart can appropriately be determined according to the recording position of the color chart in image recording.
According to a third aspect of the present invention, the printing press of the second aspect further comprises: a color chart data adding section for adding color chart data representing the color chart to print image data representing printing matter; and a color chart position computation section for computing a position to which the color chart data was added, on the basis of an image size given by the print image data, wherein the reading time setting section determines the reading time on the basis of the position to which the color chart data was added.
In the third aspect, the position of the color chart is computed in response to an image size given by the image data, which allows proper setting of the reading time responsive to variations in the image size.
According to a fourth aspect of the present invention, the printing press of the first aspect further comprises: a plate cylinder for holding a printing plate; a blanket cylinder with a blanket surface for receiving an ink image from the plate cylinder; an impression cylinder for holding printing paper and receiving an ink image from the blanket cylinder; and an encoder for detecting a rotational position of at least any one of the impression cylinder, the plate cylinder, and the blanket cylinder, wherein the reading time setting section determines the reading time on the basis of a detection signal from the encoder.
In the fourth aspect, the reading time is determined by the encoder for detecting the rotational positions of the cylinders, which eliminates the need for additional means for detecting the position of printing paper.
According to a fifth aspect of the present invention, in the printing press of the fourth aspect, the plate cylinder and the blanket cylinder are double-diameter cylinders each having two print areas, and the impression cylinder is an n-fold diameter cylinder having a n/2-fold diameter of the plate cylinder (where n is a natural number). The printing press feeds and delivers the printing paper for every two turns of the impression cylinder, and further comprises: a paper feed/delivery signal setting section for setting a paper feed/delivery signal that indicates whether or not to feed/deliver the printing paper for each rotation of the im
Chau Minh
Dainippon Screen Mfg. Co,. Ltd.
Hirshfeld Andrew H.
McDermott & Will & Emery
LandOfFree
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