The ThermoFlex Wide II device is capable of seamless imaging. This means that on a continuous photo polymer sleeve, a halftone screen can be imaged around the cylinder without any join being visible—all halftone dots meet and join precisely. This requires special screening, known as IS or (irrational) screening, to be used in Prinergy.
ThermoFlex Wide II with sleeve option
In seamless imaging, the top and bottom of an image meet around the cylinder, and the dots must mesh exactly to avoid any visible join. Seamless imaging cannot be done with normal Prinergy screening, which is known as threshold array screening. Threshold array screening works by building up an array, or tile, of dots and then repeating this tile over and over to fill the entire plate surface. The size of these tiles cannot be adjusted, and the positions of the edges of dots at the top and bottom of an image cannot be precisely controlled.
Threshold array tiles
Note: Screen is built up using discrete tiles
Once an image has been prepared for seamless imaging, it can be opened in the Sleeve Toolkit software (STK), and the join can be viewed for accuracy. If seamless imaging is done with threshold array screening and viewed in STK, you will see a visible join, because the halftone dots do not mesh precisely.
Threshold array screening imaged for seamless and viewed in Sleeve Toolkit
Note: Halftone dots do not mesh at seam.
Seamless imaging is a chargeable feature—you must be licensed to use it.
To do seamless imaging in Prinergy, you must use IS screening. IS screening is available to all Kodak flexo customers, but seamless imaging cannot be done without a license.
Prinergy IS screening uses irrational tangent algorithms to calculate the placement of halftone dots. IS screening calculates the placement of each halftone dot in an entire row of halftone dots in one calculation. This allows IS screening to adjust the placement of halftone dots very accurately, by slightly adjusting the angle or frequency of the halftone dot screen.
IS screening calculates angle and frequency of the entire row of dots in one instance
Note: The second screen has been adjusted in angle and height (frequency) to change the position of the top halftone dot.
By making angle and frequency microadjustments to the placement of the entire row of dots from top to bottom, IS screening ensures that dots will mesh where they meet at the join in the cylinder. This can be confirmed by viewing the join in STK.
Viewed in STK, screens generated by IS screening will merge seamlessly at the join
IS screening must be specified in process templates
The process for creating seamless output in Prinergy is very simple. Prepare the seamless artwork so that there is no image or marks outside the live area of the job. In the Layout section of the output process template, set the Max Height size for the exact repeat distance of the cylinder, for plating output without any margins.
At output, the Max Height must be specified to the exact repeat distance
You must use an IS screen, and the IS screen instance must have the Seamless flag set when you create it. You use a stand-alone application called the ScreenSet Editor to create and modify IS screen instances. ScreenSet Editor is located on the Prinergy or Prinergy Evo server. The Seamless flag is a check box that is available when you create the screen instance in ScreenSet Editor. If you do not set the Seamless flag, the halftone dots will not mesh properly at the join.