Pad printing technology in the pad printer

In pad printing technology, the correct reproduction of colors plays an important role in print quality. In color matching, the problem of color matching related to color measurement equipment is an objective scientific problem, which can be expressed in data. The problem of device-independent color matching is a subjective problem, subject to limitations of artistic accomplishment and observation level. How to establish the relationship of ink color in printing can correctly express the color, which is related to subjectivity and objectivity. Sometimes, although the color is matched according to the correct method, it is rejected because of the customer's own visual defects (such as color blindness or eye fatigue). . Therefore, in order to meet the needs of customers, both the impact of objective data and the desired artistic effect must be considered when printing.

Ingredients in the ink component also affect the color of the ink. Diluents, catalysts, flow agents, etc. are generally colorless, and therefore, the hiding power of the ink is reduced. For example, adding a certain catalyst (such as hardener) to the ink in a ratio of 2:1 will reduce the hiding power by 50%, which is almost as obvious as the difference between single printing and multiple printing. Therefore, it is important for the operator performing the color matching to understand the additive required and the specific ratio at the time of addition so that the correct addition can be completed prior to the coloration.

Observing the environment

Light is generated by electromagnetic radiation, so light is expressed from a portion of the electromagnetic spectrum. The spectral range that can be observed by human eyes is called visible light, from the long wavelength red light to the shorter wavelength blue-violet light. Since the light color seen by the human eye is only a certain wavelength of light in the visible light wave range, the light conditions in the observation environment have a great influence on the observation result. If the colors to be matched are observed during the day and the colors are obtained under fluorescent conditions, then this match is not a true match.

In addition, the environment in which the target turnover is observed also has an effect on the color of the observed image. For example, in the dark background, the color perception obtained by observing the same image with a bright background is different. This is even more important when presenting samples to customers for comments. It is important to ensure that the customer's observation conditions are consistent with the environmental conditions during the printing process, or that the light conditions during production are the same as the customer's observation conditions.

The observer can be a human observer, or it can be a color measuring device (such as a spectrophotometer)

Neither the producer nor the equipment can see the same image at different times. Why is this?

Start with humans themselves. Human vision can distinguish 10 million colors, and the individual's psychological condition influences his or her feelings about color. When a person is in a healthy state, the observed color is not the same as the color he feels when he is tired, sick, or depressed; adults feel differently from children. Moreover, certain types of people are less sensitive to color changes in a certain wavelength range, and some are even color blind patients. Therefore, judging whether a color is correct or not is based on the visual characteristics of many people.

Color measuring equipment such as spectrophotometers are measured by measuring the reflected light from an object in a simulated three-dimensional color model, also known as the color space, in the form of a set of color stimulus matches. During the measurement process, each device is calibrated to the color of the color sample after being calibrated under certain given conditions. These given conditions include lighting conditions or light source types, viewing angles, consideration of the influence of gloss, and the like.

In theory, the results of different device measurements under the same environmental conditions will have the same color matching performance in the color space. But in fact, there are differences between different devices, and the results are different. Even if the same device itself, the results of two consecutive measurements may be different without changing any conditions. In most cases, these subtle differences do not affect the results too much, but problems arise when the different devices under different conditions or the specified color tolerance is too small. Although the printing department and the customer may use the same equipment, since we cannot guarantee that these equipments are calibrated to observe the colors in the same way and complete the measurement, differences often occur. For example, for a person who specifies or sets the color, the gloss factor is taken into consideration when making the color sample, and the printer observes the color matching condition and does not consider the gloss factor when measuring the color sample. Then, although the naked eye observes The matching result is acceptable, but it will be unacceptable from the instrument measurement results. Therefore, it is important to ensure that the measuring equipment and the equipment used to set the colors are observed in the same environment when matching the colors within a specific tolerance range generated by the computer.

Color measurement plays an important role in color matching. The measurement results can produce a large amount of useful information, which can directly indicate the location of the matched color in the color space, and provide help for reliable matching. However, in other cases, although the matching effect is good from the measurement results, it is not ideal from the visual or artistic effects. This is because human vision still occupies a major position in the evaluation of color matching, so it is necessary not only to consider the role of measurement tools in color matching, but also to consider the influence of human subjectivity on subjective perception.

After comprehensively considering the factors involved in observing the target and observing the effects of the environment and observing the role of the subject (measurement equipment and humans), color management becomes simple, and with the understanding and implementation of effective control of the variables, it makes Headache color matching work becomes easy and efficient. I believe that in the near future, the control of color will be more powerful.