INDUSTRIAL SCREEN PRINTING PART 1 – THE DPI MYTH

In the world of industrial screen printing, a trend has established itself in recent years that is often misunderstood – the ‘resolution race’. Manufacturers are outdoing each other with ever-higher dots-per-inch (dpi) values, now far exceeding the 10,000 mark. With this ‘reality check’, Grünig-SignTronic wants to focus on the technical fundamentals rather than theoretical numbers. Many users are wondering whether this progress actually leads to higher print quality. However, a look behind the scenes of prepress, reveals that a high number on a data sheet is worthless if the system lacks the corresponding optical discipline to transfer that data onto the mesh with physical stability.

“Many print shops consider quality to be a strictly linear function of resolution”

In the industry, there is intensive debate regarding various processes for effective image output. These include interpolation, stitching or interlacing. These techniques are proven tools for structural preparation in modern high-end production. However, they are only as effective as the hardware foundation upon which they operate. 

The decisive difference does not lie in the chosen strategy for data processing, but in the physical stability of the light transmission. Grünig-SignTronic’s system spectrum works with proven LED_Q4 technology and powerful light modulation. Resolutions range from 1,270dpi in the standard, to 3,040dpi in the HR3 specification (with 8.35µm pixel size). This guarantees an exact, mechanically stable reproduction of the physical pixel. If systems advertise values beyond 10,000dpi, the problem is not the value itself, but the integrity of the hardware. Without optics capable of transferring this data density onto the mesh without stray light, focus drift or thermal instability, a high dpi number remains merely a theoretical calculation.

A system that can process 10,000dpi but does not physically focus the energy precisely, delivers no gain in sharpness. 
It simply delivers a higher data load with persistently blurred contours. The company defines quality by the ability to translate high-resolution data into a stable, physical image where the smallest pixel remains undistorted.

 

“Grünig-SignTronic offers the entire process chain for ‘the perfect screen’”

Many print shops consider quality to be a strictly linear function of resolution. Yet, in industrial practice, this logic often fails. Grünig-SignTronic regularly observes users making enormous efforts to compensate for hardware deficiencies by chasing unresisting dpi values. These include insufficient focus, vibrations or poor light management. 

If the fundamental components – mesh, emulsion, resolution and exposure time – are not perfectly matched, no amount of high dpi will compensate for the deficit. A perfectly tuned system delivers results that a theoretical ‘high-dpi system’ with inferior optics can never achieve. Grünig-SignTronic’s LED_Q4 technology harmonises exactly with the spectral sensitivity of the emulsion and the mesh count.

Grünig-SignTronic’s experience shows that resolution is far more than just a software parameter. In reality, the optical precision of the exposure head is what determines the success of an application. Even at theoretically extreme dpi values, the result often remains blurred if the focus of the exposure optics does not work with absolute mechanical precision. Systems that advertise extreme numerical values must face the valid question of how this value is transferred to the screen in a physically stable manner. 

Grünig-SignTronic believes that to achieve top-level quality, decisive levers must be considered. This comprises the quality of the entire optical system and the precise control of the internal light modulation. Additionally, the exact adjustment of mechanical axis movements to the chosen resolution. As well as, in particular, the company’s unique autofocus solution. An exposure system that merely delivers a high dpi number on paper, but cannot reproduce it with physical stability, ultimately only produces more sharply imaged waste. The company’s excellence in detail reproduction results directly from the ability to guarantee a perfect and constant focal plane with every exposure through its autofocus and mechanical precision.

The pursuit of ‘more’ often ignores the economic reality of a productive print shop. True expertise lies in building a system that fulfils the requirements of the printed image. This comes about through a balanced combination of hardware power and optical precision. In this context, the choice of the correct mesh and professional coating technology is often more decisive for the result than the mere resolution specification. A perfectly homogeneously coated stencil – as made possible by Grünig’s coating machines – is the fundamental foundation upon which high-resolution exposure can unfold its full potential. Those who save here are vainly compensating for inadequate preparation with software resolution.

Grünig-SignTronic offers the entire process chain for ‘the perfect screen’. 

To perform the ‘reality check’ it is necessary to compare marketing numbers with actual, stable transferability. Behind the numbers it is important to analyse the sharpness of the edges and the stability of the half-tones. Quality is not a value on a piece of paper, but the result of technological discipline throughout the entire prepress process.