Lu Lizhe: 30 factors that affect printing color

The first person to discover that grey balance was a determinant of print quality was Mr. Bruner, who founded System Brunner as the most efficient system for automatic ink control on rotary presses. Even Bruneau's technology can be used in sheet-fed printing machines today, and the efficiency of ink control is rapidly increasing.

Humans have found that it is possible to copy a small grayscale at different resolutions of the material and copy the whole image; if the grayscale of the yellow, green, and black colors is arranged in the same small dot, it can even duplicate the entire color. image. Printing did not deviate from this principle from manual to automatic, from offset to digital; the continuous improvement of craftsmanship to fineness was the result of many thoughtful efforts.

Some people improve the printing equipment from the front to improve the efficiency and quality, and some people go back from the quality management side to improve the quality of printing.

In 1968, Mr. Brunner in Winterthur, Canton, Switzerland, invented the world's first print quality control bar. A bar of film is lined with a solid block of color across each ink zone. Let the printing factory stick to the big version of the film when it is printed, and print it together with the contents of the print. Both the color blocks and the printed content are printed using the same environment. Therefore, the quality management is based on the color blocks on the control strip, which is simpler and more effective than the use of landscapes or characters' photographs on the printed materials as the target. This is the earliest offset control strip. In 1969, Bruner improved the control strips with tone-graded color patches to detect dot gains; later, color patch specifications were defined for different paper characteristics. For decades, the Brunner control strip was mentioned in the textbooks of the School of Printing.

In 1975, Mr. Bruner prepared thousands of different prints and provided scores to thousands of printing professionals in Switzerland. He hoped to find out the basic factors of printing quality from the perspective of the printing experts. Most of them were considered to be "good. Of the hundreds of prints, Mr. Bruner discovered that these prints share a common factor: the "balance of the gray" is balanced.

This is the first printing industry to discover the impact of gray balance on print quality. Today, the printing industry is increasingly paying attention to the balance of the gray matter. This is mainly because GRACol, which was established in 1996, has repeatedly shown that its task is to help print through communication and education. Industrial application of new technologies to improve the quality of printing, one of which is the "gray balance" control.

Bruner launched the Instrument Flight online ink control system in 1991. It reads the color information of printed sheets from the printing process, uses gray balance as the main factor of ink control, and feeds back to the ink control system in time to correct the misaligned amount of ink. This is the first technology in the printing industry to supervise the printing quality. In 1998, cooperation with precision machinery control professional QuadTech began, marking the beginning of a new era of “on-board ink control system” for printing machines. While printing, the color information of printed sheets was read on the paper in real time, and the ink key correction information was analyzed after analysis. , passed back to the ink control station. Later, QuadTech installed a control system for many rotary machines. Some of the rotary machines calibrated the ink in a shorter time. The color information that QuadTech reads is measured in the most effective analytical technology capabilities of Instrument Flight in 6 to 7 seconds. In a short time, the amount of ink can be corrected to control the stable quality of the high-speed rotary press. Users of Gaussian rotary machines using Instrument Flight believe that Bruner's analysis can make a printing machine's printing color from head to tail impossible to run. Drop it.

How can Bruner complete the analysis of the color of each ink zone in such a short period of time to obtain a reasonable correction scale for ink keys?

In fact, there are many variables (factors) affecting the quality of the offset marking color, not just the concentration of the field, different tone and superimposition, and the Lab value. In the midtones, grayscales, skin tones, and halftone shades, as long as there is a little bit of change in the print, the colors will be immediately felt by the eye. Think about any color of any four colors. Just adding a little ink will cause color cast. This is a change that every printer will face every day. Only measuring the concentration difference calculated by the full-plate color patch, or the requirement of color stability, it is more important to measure the Lab value of the unique or overlapping printing of different shades of Huangpinqing black.

The general dead-cycle ink control is only a comparison of the concentration of solid color patches, too strong to drop a scale, too light to raise a scale, so that is not enough to reflect the efficiency of offset ink change, not to mention nearly one million hours an hour The rotary machine?

Instrument Flight uses solid color blocks (gray balance) to track the contrast of the full color gamut - paper white to full version, using color patches of different gradations (color balance) to track the color shift, and then using the Bruner control strip to find Out of 30 factors that affect print quality, cross-analysis quickly finds the value of the ink key correction.

The latest ink control technology, Instrument Flight, has been used successfully in rotary machines because QuadTech helps transfer ink key data to the ink control station's computer. If a sheet-fed press wants quick feedback on ink control technology, InkZone's technology can help transfer Instrument Flight's ink control data to various branded sheetfed presses.

With the CTP installed in the printing plant, you can enjoy the benefits of prepress digitalization. If the benefits of pre-inking are not enough to cope with the printing competition, Bruner Instrument Flight, which has the ability to analyze the 30 conditions that affect print quality, should be the best. chosen.

Beginning in 2013, Bruner cooperated with InkZone. Today, sheetfed presses can also be equipped with the Instrument Flight rapid analysis ink control system.