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PrintFlat™ removes banding from inkjet printing

The problem of non-uniformity from inkjet printheads

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If you’re developing an inkjet press you’ll know that the problem of non-uniformity or banding is a particularly difficult one to resolve. It’s especially acute on areas of flat tints with the result that printed output is unacceptable to you and to your customers.

Left unresolved, it could prevent you from going to market with a new press. Out in the field this problem has a severe impact on your customers who can either not run certain jobs on their inkjet press or, in some sectors of the market, are forced to sell their output at a discount.

The good news is that with PrintFlat you and your users have a solution that is quick to deploy and cost-effective, and it can be applied to any workflow with or without a RIP.

ScreenPro with PrintFlat technology reduces non-uniformity, commonly known as the inkjet smile.

PrintFlat reduces non-uniformity, commonly known as the inkjet smile.

What causes banding or stripes?

Banding is often referred to as the inkjet smile or frown and is due to variations in inkjet printheads. It is often caused by:

  1. variation of ink pressure or voltage changes within a head, which typically results in a smile or frown shape.
  2. manufacturing variation between heads, so that one may print lighter or darker than the head next to it in a print bar.
  3. some types of heads can wear in use, resulting in less regular banding which can change over time.

All three of these causes apply to single-pass and multi-pass inkjet presses. In the case of multi-pass presses the overlapping swathes of the print head add extra potential for problems. The typical method of correcting these effects is by tweaking head voltages, but that’s a very manual, time-consuming task which can’t always achieve the desired results.

Before PrintFlat

After PrintFlat

Before PrintFlat

After PrintFlat

Mitigate banding in software the PrintFlat way

PrintFlat creates a customized calibration based on measurements from the press. It corrects tonality to hide banding.

Your calibrations are installed into the ScreenPro™ screening engine which applies the correction to the press. ScreenPro can be applied to any workflow with any combination of printheads, inks, electronics, or other software choices that may have been made.

PrintFlat adjusts the density within ScreenPro to produce uniformity across a print bar. The process can be automated for closed-loop correction and, unlike correction by adjustment of voltages, there is no effect on jetting stability or head lifetime, nor ink pressure and timing/drop speed variation. It greatly reduces the time and cost both of building a press and of maintaining it.

Before PrintFlat

After PrintFlat

The benefits of using PrintFlat

  • You can achieve very fine granularity
    • address every nozzle separately
    • on any head/electronics
  • Results are almost instant once output is measured
    • can be automated for closed-loop correction
  • PrintFlat doesn’t affect
    • jetting stability or head lifetime
    • warranty compliance
    • ink pressure and timing/drop speed variation
    • ink coalescence on the substrate
    • halftoning

The disadvantages of trying hardware fixes

  • Not all heads have sufficient adjustment points to correct the smile
  • It’s often time-consuming work for an expert
    • Increases time and cost of installation or head replacement
  • Not readily automated for closed-loop correction
  • Difficult in head overlap/stitching regions
  • Reduces jetting stability and (anecdotally) head lifetime
    • especially risky to tweak heads beyond warranty limits
  • Causes ink pressure and timing/drop speed variation
    • which increase ink coalescence on the substrate …
    • Which causes texture artifacts …!