Manroland Chocolate Boxes With PET Window Color-Pilot Offset Ink Color Measurement And Adjustment Technology Introduction

Manroland Chocolate Boxes With PET Window Color-Pilot offset ink color measurement and adjustment technology introduction

 

In recent years, the printing industry has applied colorimetry to the evaluation of printed matter, especially in relation to the color management of all processes in the standardized and digital production chain. In spot color printing, the final color effect can be accurately evaluated through chroma measurement and analysis.

 

For this reason, Manroland has developed a new measurement system, the Color-Pilot, for the integration of density and chrominance measurement and adjustment.

 

For more than 20 years, in order to achieve the desired effect of the original manuscript and keep it stable, various printing houses have used measurement and adjustment technology. In this process, the densitometry (determination of ink density) plays an important role.

 

The inking density strip on the substrate is optically determined. As a result, the system determines whether more or less ink is needed in the measured ink area. Complex adjustment algorithms ultimately result in the precise opening/closing of the ink quantification elements that control these ink zones. 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

Manroland presented the first generation of the RolandCCI ink conditioning unit in 1977. Since then, such devices have been continuously improved in terms of speed, measurement accuracy and reliability. At the end of the 1980s, with the introduction of the third generation of adjustment devices, the measurement time was greatly reduced: the measurement strip with a length of 1020mm could be measured in 14 seconds, and there were more measurement blocks on the strip with a width of only 3mm, so more information could be obtained on the entire sheet (340 measurement blocks on the medium size sheet).

 

In 1990, with the ink adjustment device used in the Roland 700 offset press, the time to control the quantitative slide in the ink tank was greatly reduced: if it used to take 6 seconds for a six-color machine, it is now less than this time. When the fourth generation of RolandCCI was introduced in 1998, it was possible to use the measuring head to determine printed control strips only 3mm wide.

 

Color-Pilot integrates density determination and colorimetry

In 2002, Color-Pilot took the most important step by integrating the density adjustment of chrominance measurement into the measurement system.

 

In order to measure and adjust according to ink density, Color-Pilot simultaneously determines chrominance values from each small measuring block of only 3mm x 4mm on the printed measuring strip, without the need for additional time. A rated color space position can be entered for each printing unit and each ink slide area.

 

Recording color difference

The color measurement results are visually displayed as graphic and digital color difference records (△ e-records), so that the tolerance range (allowed color difference) and the tolerance range beyond can be immediately seen.

 

Each printing unit has the option of a so-called zoom display. Individual ink control elements 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 to visually check the authenticity of the color.

 

Color difference statistics

The "Statistical recording" function of the Color-Pilot system makes statistics from all recorded measurements of a live part and creates a rectangular graph based on △E. In the "Statistics" function, the minimum, large and medium color difference can be calculated from all the measurements for each ink slide area (each slide has a measurement block) and displayed in numbers and graphs.

 

The "Rectangle Chart" function also calculates the minimum, large and medium color difference from all ink slide areas for each measured sheet and displays it in graphs and figures, which can be printed as reports.

 

Advantages of density regulation

Densitometry is a suitable technique for measuring the amount of ink. This density is directly related to the thickness of the ink layer on the printed sheet: usually in the range of color marking ink layer thickness (up to 1/1000mm), there is an almost linear relationship between the density and the ink layer thickness, making the density suitable for measuring and adjusting the ink layer thickness on the printed sheet. The measured value is directly affected by the adjustment of the ink slide, so that the measured value becomes the ink layer thickness.

 

The diffusion gloss effect caused by ink drying can be eliminated by using a front-mounted polarization filter for density determination. This almost eliminates the density difference between dry and wet ink, however, the use of polarizing filters in colorimetry is problematic.

The automatic adjustment of the position of the ink slide relieves the printer's burden: he only has to periodically pull out a sheet, measure and suggest adjustments. In this way, in the formal printing, he can adjust the ink amount of work to the computer control algorithm to do. The quality of the whole batch of printed parts is calculated by statistical analysis and provided to customers as quality evidence to confirm the printing quality.

 

Its advantage is that by adjusting the density of an important process parameter, the thickness of the ink layer, it brings stability to the printing process and maintains the stability of the printing effect achieved.

 

For commercial printers that only use four colors to print dot images, pure densitometry and conditioning systems are perfectly adequate in most cases, as they rarely print with spot colors. The standardization process in prepress and printing increases the productivity and economic efficiency of the entire printing system.

 

Chrominance measurement complements density measurement

Packaging printing plants need additional auxiliary methods because of the high requirements for the color perception of packaging prints. They often evaluate spot color field ink, whose color should be the same shade as the manufacturer or with the product.

 

In order to evaluate printing sheets objectively, people need a measurement and evaluation system that can imitate the visual impression of the eye. This system is called colorimetry. If only the density value is measured, it can not accurately identify whether the hue of an ink is accurate. In this case, even changing the position of the ink slide will not help.

 

The same inking, depending on the different substrate used (thickness, absorption, paper color), will also produce different visual impressions on the printed sheet at the same density. Substrate color (that is, the different whiteness of the paper) plays a major role as the cause of the different color perception.

 

In the official printing process, due to the failure, it is necessary to reconfirm the printing sample to change the rated density. In this case, supplementing density determination with chrominance determination provided by the Color-Pilot system is a suitable solution.