Product

Lotem^® 800 FH, version 3.60.09 and higher

Background

Staccato FM screening combines the benefits of both stochastic and conventional screening. It produces high-fidelity, artifact-free images that exhibit fine detail, without halftone rosettes, screening moire, gray level limitations or abrupt jumps in tone—with no impact on RIPing or rendering time.

Staccato FM screening also improves color and halftone stability on press, making it a perfect complement to consistent "by-the-numbers' printing. Imaging Staccato FM screening delivers unmatched quality to proof and plate, making FM screening a practical tool for today's pressroom, and an effective competitive edge for today's printers.

Requirements

The following prerequisites must be met prior to performing the procedure:

Brisque

• Version 4.0.97_23, FM_Screening License
• Version 4.1.76, Staccato 25 update

Lotem Application (min)

• Lotem S (24 beams): Version 2.30.01 (and all relevant updates)
• Lotem F (48 beams): Version 3.60.09 and higher (The software automatically reduces the number of beams to 24 in order to expose Staccato.)
• Laser Box: Check for sorted head (recommended)
• Sorted diode groups and part numbers

Lotem Hardware

• TSP
• LDD 2
• DDB-1-N Comp Level M and above
• Laser Box PM
• L-Box PM procedure for mother and daughter board replacement

Qualified Plates

Procedure

• Calibrating the Lotem
• Evaluating Image Quality
• Exposing Positive or Negative Plates

Calibrating the Lotem

Before starting the Lotem calibration, ensure the following:

• The Lotem exposes using Staccato, and the screen set is available (in order to eliminate Brisque problems).
• The light detector and head lenses are clean.
• The carriage beam is clean and lubricated.
• The head lenses are secure. In case they are loose, tighten them by implementing the Cleaning the optical v-groove assembly procedure.
• The drum and vacuum holes are clean.
  Note: Make sure the processor (developing line) is maintained, and that the condition of the chemicals is fresh to mid-life (1 or 2 days in production).

Perform fine calibrations on the head using Chapter 2, Configuration and Calibration of the Connectivity User Guide, according to the Brisque platform connected to the Lotem:

• Focus
• Intensity
• Uniformity: Expose 3 strips within the range of +/- 15% to verify Bagel diodes and linear response to power increase. Do not compensate for non-uniformities at this stage.
• Resolution Motor
• Delay
• ExCurve: Check for plate linearity; create a look-up table, if necessary.
• Color Managements: Check tone representation (dot gain), cutback curves, and ISO/ANSI standards.
• Image Quality: Check banding, edges, background, and so on.

Evaluating Image Quality

Note: Only image quality will be tested. Process control will be measured, but will not be a criterion for determining whether a site is ready.

Evaluate the processing latitude:

1. The banding latitude is assessed visually with a loupe according to the following test areas:
   • 2x2 pixel element (Ugra) for Staccato 25.
   • 3x3 pixel element for Staccato 35.
     Note: If a quality conflict occurs between the 2x2 element and the 4x4 element, artifacts will be introduced to AM screening. When this happens, use a microscope to assess the Resolution motor settings.
     The 2x2 element provides a banding free area, which is good for testing up to 300 LPI, while the 4x4 element produces banding that is good for testing AM screening up to 175 LPI.
2. Focus latitude: After the Lotem is set for optimum resolution motor, intensity and delay (hot spot), run a focus test and check the following:
   • Count the number of banding free strips and ensure your optimum setting.
   • Ensure a reasonable focus latitude of +/-15 microns.
   • Monitor the daily performance, consistency and stability of the processing line recorders.
3. Processor: Check the chemistry performance.
   Note: It is recommended to measure the dot % consistency on plates every morning/shift for 2 weeks after installation.
4. Expose a thick HS file with Staccato, as well as with the most useful AM screening, to verify exposure quality.

Exposing Positive or Negative Plates

Note: Consider different criteria for optimum intensity setting while exposing positive or negative plates.

Exposing positive plates

This procedure should provide a clear background with some latitude to consider developer exhaustion, as well as minimum highlight dot loss.

1. Evaluate the intensity value that clears the background.
2. Evaluate the intensity value that produces the minimum amount of dot loss (use the octagon element on the Ugra file).
3. Increase the intensity value by 20 mw increments.

Exposing negative plates

1. Evaluate the intensity value that produces equal lines in the positive/negative octagon element.
2. Check the star element to evaluate thickness differences between horizontal and vertical lines. A substantial difference indicates the need for software update.
3. Staccato 25 will be qualified only on 24-beam machines.
4. The Lotem 800 F setting for Staccato may affect the 48-beam output. Therefore, after completing the Lotem setting for staccato, expose an ATP file via a customer's home screen set(s) to evaluate quality.

Lotem family entry level releases:

• CEU - Release: May 2003
• Web V Sheet-fed press
• Press and Printing problems: Press Problems and Terminology
  Note: Ensure uniform ink solid density across the print.
• VIP services
• Customer training

For more information on Staccato, visit the following sites and refer to the documents:

• Staccato Implementation Guidelines and Best Practices
• SIP - Sales Information Portal
• Staccato FM Screening FAQ

Tools:

• X-rite or any similar densitometer
• Loup x8/10
• Microscope x50/60
• ATP and Staccato test file
• TechPlanet
• Troubleshooting; Basic Image Quality TS is applied

See also

Staccato Power Point presentation

Technical contact(s)

Itai Peperovich
See the Escalation page for escalation contacts.

Date submitted

08 Jun 2003