New development of the hottest offset ink color me

2022-09-27
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The new development of offset ink color measurement and adjustment technology

in recent years, the printing industry has applied colorimetry to evaluate printed matter, especially when it is related to standardization and color management of all processes in the digital production chain. In spot color printing, the final color effect can be accurately evaluated by colorimetric measurement and analysis

for this reason, Manroland developed col  or-Pi  Lot's new measurement system is used to integrate density and chromaticity measurement and adjustment

for more than 20 years, in order to achieve the effect required by the original and keep it stable, all printing plants have used measurement and adjustment technology. In this process, density measurement (measuring ink density) plays an important role. The inking density strip on the substrate is measured optically. As a result of the measurement, the system determines whether more or less ink is needed in the measured ink area. The complex adjustment algorithm eventually leads to the accurate opening/closing of the ink quantitative elements that control these ink areas. In this range, a little more or less ink is printed on the paper, which plays a role in controlling the amount of ink

the first ink adjusting device appeared in 1977

MAN Roland showed the first generation of rolandcci ink adjusting device in 1977 when the required parameters were set by full LCD numerical control. Since then, such devices have been continuously improved in terms of speed, measurement accuracy and reliability. In the late 1980s, with the adoption of the third generation of adjustment devices, the measurement time was greatly reduced: the measurement and control strip with a length of 1020mm can be completed in 14 seconds, and there are more measurement blocks on the measurement and control strip with a width of only 3mm, so more information can be obtained on the whole print (there are 340 measurement blocks on the medium-sized print)

1990, with the application of the ink adjusting device in the Roland 700 offset press, the time for controlling the quantitative sliding plate in the ink bucket was greatly shortened by Vertu and haoya. If a six color machine used to take 6 seconds, now it is less than this time. When the fourth generation rolandcci was launched in 1998, the measuring head can be used to measure the printing measurement and control strip with a width of only 3mm

color pilot integrated density measurement and chromaticity measurement

in 2002, color pilot integrated the density adjustment of chromaticity measurement into the measurement system, thus taking the most important step

in order to measure and adjust according to the ink density, [[color pilot]] at the same time, only 3mm from each of the printing measurement and control strips × The chromaticity value is measured on a small 4mm measuring block, which does not need additional time. A rated color space position can be input for each printing unit and each ink bucket sliding plate area

record color difference

color measurement results are displayed visually as color difference records of graphics and numbers (△ e - record), so that the tolerance range (allowable color difference) and the exceeded tolerance range can be seen immediately

each printing unit can select the so-called zoom display. A single ink control element in each ink area can be displayed. The color difference between the rated value and the actual value is displayed with numbers, graphics and a square control block, so as to visually check the authenticity of the color

statistics of color difference

the "statistical record" function of the color pilot system makes statistics from all recorded measurements of a live part, and makes a rectangular chart according to △ E. In the "Statistics" function, for each ink bucket skateboard area (each skateboard has a measurement block), the minimum, large and medium color differences can be calculated from all measurements, and displayed in numbers and graphics

"rectangular chart" function can also calculate the minimum, large and medium color difference from the ink bucket skateboard area of the company, which is one of the few large manufacturers of bridge parts in the United States, for each measured print sheet, and display it in graphics and numbers. Graphics and digital records can be printed as reports

advantages of density adjustment

density measurement method is a technology suitable for measuring ink volume. This density is directly related to the thickness of the ink layer on the printing sheet: generally, there is an almost linear relationship between the density and the thickness of the ink layer of the color code ink (up to 1/1000mm), so that the density is suitable for measuring and adjusting the thickness of the ink layer on the printing sheet. The measured value is directly affected by the adjustment of the ink bucket sliding plate, so that the measured value becomes the thickness of the ink layer

the diffuse gloss effect caused by ink drying can be eliminated by using the front polarization filter for density measurement. This almost eliminates the density difference between dry and wet ink. However, the use of polarization filters in colorimetry is problematic

the automatic adjustment of the position of the ink bucket sliding plate reduces the burden of the printer: he only needs to pull out a page of the printing sheet regularly, measure and put forward adjustment suggestions. In this way, in the formal printing, he can hand over the work of adjusting the ink volume to the computer control algorithm. The quality of the whole batch of prints is calculated through statistical analysis and provided to customers as quality evidence together with the prints to confirm the printing quality

its advantage is to adjust the important process parameters, that is, the thickness of the ink layer, through the density, which brings stability to the printing process and keeps the printing effect stable

for commercial printing plants that only use four-color dot images, the pure density measurement and adjustment system is completely sufficient in most cases, because they rarely use spot color printing. The standardization process in prepress and printing can improve the productivity and economic benefits of the whole printing system

colorimetric determination supplementary density determination

packaging and printing plants need additional auxiliary methods because of the high requirements for the color perception of packaging and printing products. They often evaluate spot color field ink, whose color should be the same as that of the manufacturer or the product. In order to evaluate print objectively, people need a measurement and evaluation system that can imitate the visual impression of the eyes. This system is called colorimetry. If only the density value is measured, it cannot accurately identify whether the tone of an ink is accurate. In this case, even changing the position of the ink bucket skateboard will not help

the same inking will also produce different visual impressions on the printing sheets at the same density according to the different substrates used (thickness, absorption, paper, carbon fiber products for pressure vessels with great market potential, etc.). The color of the substrate (that is, the different whiteness of the paper) plays a major role as the cause of different color vision

in the formal printing process, due to the failure, it is necessary to reconfirm the print sample to change the rated density. In this case, it is a suitable solution to supplement the density measurement with the chromaticity measurement provided by the color pilot system. (end)

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