In the past years there have been several improvements in the flexo printing plates manufacturing, such as better mounting devices, improved plate quality with higher resolution and high quality negatives.

The only thing which has not been greatly improved in the conventional plate manufacturing is the exposure process. In retrospect, bank exposure (tube exposure) has been used since the beginning of plate production in 1974. Initially, with very little UV-A output and in the course of time with a higher UV output; however, the system was not changed. This means a large number of tubes and a matt vacuum foil is still needed.

This also means in spite of the improvements of the flexo plate material an improvement of the quality can only be achieved to a certain extent. One of the reasons that no improvements have been achieved with tube exposure units is the irregular UV output.

Furthermore, the extreme scattered light caused by the close arrangement of tubes and the vacuum foil is also a disadvantage of the bank exposure units. In addition, the temperature variations during the exposure have had a negative impact on the quality. These limitations could not be eliminated, although modern tube technology, cooling and control systems have been applied.

Point light was introduced in the 90`s. Unfortunately, this kind of light source which originated from offset led into the wrong direction. Due to the three-dimensional plate structure, it was not possible to achieve a solid shoulder by use of a point light source. The further away the lines were from the exposing center, the more unstable they were, with the tendency to topple over.

Even the use of a diffusion sheet which is inserted before the exposure between the plate and light led to no improvements. A cooperation of the companies THEIMER, F-TH and InnoFlex has led to the new concept, QualyDOT Scan-Light-Source. A high-tech light source moves across the flexo plate. The great advantage of a scan light source is obvious: The complete plate format is evenly exposed. Because of the high UV output the exposure time is reduced. An efficient cooling system HEAT-EX prevents the flexo plate from receiving too much heat.

An even UV output allows a concentrated exposure, which means it is not necessary to over expose as a result of uneven amounts of UV delivered to the plate. Another important point is the drastic reduction of scattered light and therefore deep reverses, steep flank angles and exact transfer of the screen dots from the negative. The sensor-controlled even UV output leads to repeatable good results each time.

The construction of the QualyDOT has additional advantages over the bank exposure. A newly designed vacuum bed guaranties a rapid and excellent vacuum build-up. By means of a handle the semi-automatic vacuum foil dispenser is evenly rolled over the plate without creating bubbles and wrinkles. The dispenser can be arrested at various positions in order to remove dust or other particles. The working area is accessible from three sides at an operator-friendly height. The design of the QualyDOT is simple and safe, which rules out any operating errors. The change of the vacuum foil and the UV tubes can be carried out very easily, thus longer production interruptions can be avoided.

The following formats are available: 650 x 900 mm (25 x 35 in.), 950 x 1350 mm (37 x 53 in.), 1350 x 1600 mm (53 x 63 in.), 1350 x 2100 mm (53 x 82 in.).

With the technology of the QualyDOT the conventional plate exposure meets the high quality standards of the existing flexo plates. In summary, the QualyDOT Scan-Light-Source exposure sets new standards in analogous plate exposure, as well as in connection with CTP in an economical way.