In recent years, the printing industry has applied colorimetry to evaluate printed materials, especially when it is related to standardization and color management of all processes in the digital production chain. While in the spot color printing, the color effect can be better accurately evaluated by the color measurement analysis.
To this end, Manroland has developed a new color-pilot measurement system for integrated density and color measurement and adjustment.
For more than 20 years, in order to achieve the effect required by the original and keep it stable, various printing plants have used measurement and adjustment techniques. In this process, the density measurement method (determination of ink density) plays an important role. The ink density bar on the substrate is measured optically. As a result of the determination, the system determines whether more or less ink is needed in the measured ink zone. Complex adjustment algorithms ultimately lead to the precise opening / closing of the ink metering elements that control these ink areas. Within this range, more or less ink is printed on the Paper, which plays a role in controlling the amount of ink.
The first ink adjustment device appeared in 1977
Manroland demonstrated the first generation Roland CCI ink adjustment device in 1977. 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 adjustment device, the measurement time was greatly reduced: the measurement and control strip with a length of 1020mm can be measured within 14 seconds, and there are more measurement blocks on the measurement and control strip, whose width is only 3mm , So more information is available on the entire press sheet (340 measurement blocks on medium-sized press sheets).
In 1990, with the ink adjustment device used in the Roland 700 offset press, the time to control the quantitative slide in the ink fountain was greatly shortened: if a six-color machine used to take 6 seconds, it is now less than this time. When the fourth-generation Roland CCI was launched in 1998, it was already possible to use a measuring head to measure a printed measurement and control strip that was only 3mm wide.
Color-Pilot integrates density and colorimetry
In 2002, Color-Pilot took the most important step by integrating the density adjustment of color measurement into the measurement system.
In order to measure and adjust according to the ink density, Color-Pilot simultaneously measures the chromaticity value from each small measuring block of only 3 mm × 4 mm in the printed measurement and control strip without additional time. A rated color space position can be entered for each printing unit and each ink fountain slide area.
Record color difference
The color measurement result is displayed graphically as a color difference record of figures and numbers (â–³ E-record), so that the tolerance range (allowable color difference) and the excess tolerance range can be seen immediately.
Each printing unit can choose the so-called zoom display. A single ink control element in each ink zone 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 colors.
Color difference statistics
The "statistical record" function of the Color-Pilot system makes statistics from all recorded measurements of a job, and makes a rectangular graph according to â–³ E. In the "statistics" function, for each ink fountain skateboard area (each skateboard has a measurement block), the smallest, large and medium color difference can be calculated from all the measurements and displayed in numbers and graphs.
The "rectangle" function can also calculate the minimum, large and medium color difference from all the ink fountain skateboard areas for each measured printed sheet, and display it with graphics and numbers. The graphics and digital records can be printed as reports.
Advantages of density adjustment
Density measurement is a technique suitable for measuring the amount of ink. This density is directly related to the thickness of the ink layer on the printed sheet: usually within the range of the thickness of the ink layer (up to 1 / 1000mm) of the color mark ink, there is an almost linear relationship between the density and the thickness of the ink layer, making the density suitable for the printed sheet Measure and adjust the thickness of the ink layer. The measured value is directly affected by the adjustment of the ink fountain slide, so that the measured value becomes the thickness of the ink layer.
The density measurement using a pre-polarized filter can eliminate the diffused gloss effect caused by ink drying. This almost eliminates the difference in density between the dry and wet inks, however, the use of polarizing filters in chromaticity measurement has problems.
The automatic adjustment of the position of the ink fountain slide reduces the burden on the printer: he only needs to pull out a printed sheet at regular intervals, measure and make adjustment suggestions. In this way, in formal printing, he can leave the job of adjusting the amount of ink to the computer's control algorithm. The quality of the entire batch of prints is evaluated through statistical analysis and used as quality evidence to provide customers with the prints to confirm the print quality.
Its advantage is to adjust the important process parameter, namely the thickness of the ink layer, by density, which brings stability to the printing process and keeps the achieved printing effect stable and unchanged.
For commercial printing plants that only use four-color printing 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 increase the productivity and economic benefits of the entire printing system.
Colorimetric Determination Supplementary Density Determination
Packaging and printing plants need additional auxiliary methods because they place high demands on the color vision of packaging and printing products. They often evaluate the spot color solid ink color, and the color should be the same color as the manufacturer or the product. In order to evaluate printed sheets objectively, people need a measurement and evaluation system that can mimic the visual impression of the eye. This system is called colorimetry. If only the density value is used for measurement, it is impossible to accurately recognize whether the color tone of an ink is accurate. In this case, even changing the position of the ink fountain skateboard will not help.
The same inking, according to the different substrates used (thickness, absorbency, paper color), will produce different visual impressions on the printed sheet at the same density. The color of the substrate (that is, the different whiteness of the paper) plays a major role as the cause of different color vision.
During the formal printing process, due to a malfunction, it is necessary to re-confirm that the printed sample changes the rated density. In this case, supplementing the density measurement with the colorimetric measurement provided by the Color-Pilot system is a suitable solution.
Soft Paper,Soft Tissue Paper,Softest Toilet Paper,Ultra Soft Toilet Paper
ShanDong YongFang Sanitary Products Co.,Ltd , https://www.sdyongfang.com