The high quality of newspaper prints originates from online detection technology (I)

The most important thing in newspaper printing is the printing quality of newspapers. This is not only the basis for customer satisfaction, but also an important technical means for newspapers to succeed in commercial trade. In recent years, with the popularity of color newspaper printing, advertising editions have become an indispensable part of newspaper layout. The continuous expansion of the advertisement layout has brought about good economic benefits for the newspapers, but also put forward higher requirements for the printing quality of the entire newspaper. As a result, newspaper printers inevitably face increasing pressure and challenges, and they have to face up to the ever-increasing demands and demands for improving print quality, especially the print quality of advertisements. Therefore, in order to cope with this change, many newspaper printing centers have begun to turn their attention to the advanced printing equipment with the functions of automatic detection and control adjustment commonly used in magazine printing.

Based on the growing pressure from newspapers to improve the printing quality of newspapers, when newspapers invest in printing new equipment and new technologies in newspapers, they first think of using closed-loop printing quality control systems. In the existing printing equipment using a print quality closed-loop control system, not only the color control and adjustment in the printing process but also the quality control of the printing plate production process can be completed. However, for newspaper printing, the closed-loop control of print quality in newspapers is difficult to achieve due to the variety of paper paths and paper paths in newspaper printing.

In the past several years, on-machine detection systems like paper-path-side control and paper tension detection have been gradually implemented. The latest development in newspaper printing is the deployment of automatic detection and control systems on the printing production line to achieve detection and adjustment of printing colors. . The use of on-machine closed-loop control systems in newspaper printing is an important measure to improve the printing quality of newspapers. It can also bring predictable advantages in terms of reducing losses and reducing customer disputes. In this way, the printing company really has a quality assurance system, which can not only print high-quality prints that are consistent with the accuracy of the sample, but also greatly reduce the consumption of printing ink.

Image quality control through gray balance detection

In the short time, two kinds of image quality detection methods have been proved to be very effective and practical. One is to use the gray balance measurement and control strip for printing quality detection and control, and the other is to use a spectrophotometer or a CCD camera. Print images for direct spectral detection. The detection principle of these two methods is obviously different, in which the camera detects the distribution of printed colors in a specific area, rather than the density of the conventional detection, because the density cannot be directly measured on the printed image. When it comes to printing color deviations, spectral detection methods can provide the best detection results. However, CCD cameras can only provide RGB images, which must then be converted back to density values. The detection speed and results are somewhat different from the spectral detection methods.

Finnish manufacturers leading in the field of print on-line inspection technology have provided printing companies with the best printing and gray balance detection and control strip detection system. The system can print paper at speeds of up to 17 meters per second. Within a distance of 5 mm from the paper surface, image detection was carried out for a gray balance bar measuring approximately 1.7 mm wide on the cross section of the paper strip arranged in the newspaper layout. The method is to configure a series of diode detection heads for detecting RGB on the test cross section. The detection head device has no moving parts and is specially designed to detect newspaper printing under poor production conditions. Careful consideration must also be given when selecting LEDs. Detection LEDs need to perform better than conventional LEDs.

When designing a newspaper layout, the print quality control strips can be set horizontally or vertically. In addition to the yellow, cyan, and cyan test strips, the black strips must also be printed in a mesh to enable reliable color detection. However, even if such a detection value is not quite accurate, at least two measurement bars need to be arranged in this system. The test result is not immediately reflected on the printing equipment and printing paper tape, but is implemented on a printing console other than the printing equipment. Practice has confirmed that narrow-width control strips can achieve excellent cooperation with newspaper layouts.

Although newspaper printing companies initially doubted online print quality testing, they are now eager to adopt this new system, and newspapers and customers have gradually accepted the fine gray control strips that appear in newspaper layouts. The equipment cost for configuring a newspaper printing color detection system will increase by 1.7%. However, due to closed-loop control of gray balance control, the printing cost will also drop by 0.8% to 1.6%. It will also reduce printing losses and reduce disputes with customers.

Printing closed-loop quality control is actually sending a message to customers. They are also involved in the industrial production of newspaper printing. Their print production is based on a newspaper printing orientation system, while in another company it may be based on rotation. The production of gravure printing guidance system, and the quality of the products produced by different printing guidance systems are of course inconceivable. Experts believe that closed-loop control of printing quality is part of the customer-oriented concept. Since newspaper printing serves customers, of course, it also serves readers.

(to be continued)