OmniDTF Printhead Alignment

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You will occasionally want to adjust the printhead alignment of your OmniDTF printer, to maintain ideal horizontal & vertical registration between the color and white layers of your prints. This adjustment does not involve manually repositioning the printheads. Instead, it is done using the OmniDTF UI software.

Print Speeds

There are three Print Speed settings for the OmniDTF: Production, Normal, and High Quality. All printhead alignment adjustments are made for a given Print Speed, so alignments should be made with the Print Speed being used when printing selected as the Print Speed for the alignment. The Print Speed currently selected for printing is shown (and may be changed) on the Settings tab.

OmniDTF UI: Production Print Speed setting
Without getting into details of the relationship between the Print Speed settings and the print resolutions & ink densities available in the RIP software (we’ll save that for another article), suffice it to say that the use of Production speed is recommended as it delivers the fastest output at any resolution & ink density selected from the RIP software’s Environment options.

Alignment Types

There are four types of alignments that can be done. We’ll explain and detail the process for each following the list of types below:

  1. Head Vertical Distance Adjustment
  2. Head Horizontal Distance – Left Adjustment
  3. Head Horizontal Distance – Right Adjustment
  4. Bidirectional Adjustment

To get started, all printhead alignment adjustment types are found under the Align tab of OmniDTF UI program.

Align tab of OmniDTF UI program

Head Vertical Distance

This adjustment, labeled Head Vert Distance Adjust in the software, aligns the white printhead with the CMYK printhead as the film moves forward while printing. (This “vertical” movement of the film is considered the Y axis, while the carriage’s left & right motion is considered the X axis.)

If you know that your printer’s vertical registration is off, be sure to first check the tension of the feed roller knobs on the back of the printer and make sure the left and right sides are at their minimum tension/friction settings before making a vertical printhead alignment adjustment. This mechanical adjustment is critical and may cause random vertical registration issues that cannot be resolved by this software alignment of the printheads.
  1. Select your Print Speed to match that on your Settings tab (or the speed you want to now align for if you’re running alignments for multiple speeds.)
  2. Select the Head Distance option on the left side of the Align screen.

    OmniDTF UI - Align Heads, Vertical Distance
  3. Click the N Check button under the Head Vert Distance Adjust heading when you’re ready to print the test pattern.

The test pattern prints a series of black & white horizontal line segments above numbered labels. The numbers range from -14 to +14, in increments of 2 and with zero in the center position.

Vertical alignment test print example
Vertical Alignment test print example (partial)

Yes, it’s a bit of an eye test, but our task is to identify the column number whose line segments show the black & white portions in best alignment with each other, resulting in a single straight horizontal line. In the above example, the best column is ‘+4’.

In the ‘+2’ column the white segments are slightly below the black segments, and in the ‘+6’ column the white segments are slightly above the black segments. As you look to the left of the ‘+2’ column you can see that the white segments keep getting further below the black segments and to the right of the ‘+6’ column the white segments keep getting further above the black segments.

So, our takeaway from the evaluation of the test print is that the column with the best alignment is ‘+4’.

  1. Now let’s return to the OmniDTF UI software’s Head Vert Distance Adjust section and note the current value of H2. In our screenshot from step #2 above, the value of H2 is “1453” and the number we got from evaluating the test print in step #3 was ‘+4’, so we add ‘4’ to ‘1453’ and enter the result of 1457 into the H2 field.

    If the column number from step #3 had been a negative number (‘-4’, for example), we would have subtracted ‘4’ from ‘1453’ and entered ‘1449’ into H2.
  2. Click the Save button in the top right corner of the OmniDTF UI window to make the alignment adjustment.

    OmniDTF UI: Save button
  3. Repeat step #3 above to print another test pattern. This should result in the best-aligned column sitting in the ‘0’ position. If this is the case, the vertical distance adjustment is now completed. If not, repeat steps 3 – 5 to ensure that the best alignment is in the ‘0’ position

Left Horizontal Distance

There are two horizontal distance adjustments under the Head Horz Distance Adjust heading. This is because your OmniDTF prints bidirectionally, so the white and CMYK printheads need to be aligned in both printing directions. The Left Adjust is used for the horizontal alignment when the carriage is moving from right to left, and the Right Adjust for when the carriage moves from left to right.

The process and test patterns for both the Left and Right printhead horizontal distance alignment adjustments are identical, so we will detail the process just once. The instructions will call out the Left Adjust button and H2 field, and you will follow these same steps modified for the Right Adjust button and H2 field for the Right Horizontal Distance Adjustment.
  1. Click the Left Adjust button to run a test print.
    OmniDTF UI: Horiz Left Adjust button

    The test pattern prints a series of black & white vertical bars above numbered labels. The numbers range from -12 to +12 with zero in the center position.

    OmniDTF UI: Horizontal alignment test print

    The goal is to have the best-aligned set of black & white bars in the 0 (zero) position. So, our takeaway from the evaluation of the test print is that the column with the best alignment is ‘-11’.
  2. Now let’s return to the OmniDTF UI software’s Head Horz Distance Adjust section and note the current value of H2. In our screenshot from step #1 above, the value of H2 (for the Left Adjust line) is “9”. The number we got from evaluating the test print was ‘-11’, so we sum together ‘9’ (or ‘+9’, to be exact) with ‘-11’ and enter the result of ‘-2’ into the H2 field…

    H2 field set to -2

    …then click the Save button.

    OmniDTF UI: Save button
  3. Repeat step #1 above to print another test pattern. This should result in the best-aligned column sitting in the ‘0’ position.

    OmniDTF UI: Horiz alignment test zeroed out

With the 0 (zero) position of the test print showing the black & white segments in perfect alignment, the Printhead Horizontal Distance Adjustment (for the leftward motion, in this example) is now complete.

Right Horizontal Distance

The exact same process as the Left Horizontal Distance Adjustment is used to check and adjust the rightward motion alignment.

Follow the instructions from the above Left Horizontal Distance Adjustment section, substituting the Right Adjust button to run test prints and the Right Adjust H2 field to enter updates to that value, as needed.

Bidirectional

Our final task is to align the printheads during bidirectional printing (both left and right.)

  1. Select Bidirec Adjust from the options on the left side of the OmniDTF UI program.

    OmniDTF UI: Bidirectional Adjustment

  2. Click on the N Check button to print a test pattern.

    OmniDTF UI: Bidirectional test print


    The Printhead Bidirectional Alignment Adjustment test pattern will print.

    OmniDTF UI: Bidirectional alignment test pattern example

    The vertical bar test pattern has top & bottom black segments and a grey middle segment.

    Our task now is to identify the number under the test bar where the middle segment is best aligned with the top & bottom segments, creating a straight vertical bar with the right & left edges of each of the three vertical segments perfectly aligned.

    In our example test print image above, the ‘+3’ column is vertically aligned.

    Bidirect test pattern aligned at +3

  3. Returning to the OmniDTF UI program, we take that value (‘+3’) and sum it with the number in the direct Value field (‘12.00’ in the above screenshot example.) 12+3=15, so we will replace the value of ‘12.00’ with ’15’.

    OmniDTF UI: Bidirect value set to 15


    …and then click the Save button in the upper right corner.

    OmniDTF UI: Save button

  4. Click the N Check button again to print another test pattern and confirm that the vertical segments are perfectly aligned at the 0 (zero) position.

    OmniDTF: Bidirect test print aligned at zero position


    With the 0 (zero) position of the test print showing the black & gray segments in perfect alignment, the Printhead Bidirectional Adjustment is now complete.

Wrap Up

Congratulations! If you’ve been following along on your OmniDTF printer while reading this article you have now completed all four printhead alignment processes: the Vertical Distance, Left Horizontal Distance, Right Horizontal Distance, and Bidirectional Adjustments.

Remember that these adjustments are each made with a specific Print Speed setting, so if you print using different speed selections at different times then you’ll need to repeat this process for each speed that you use.

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