Product

• ThermoFlex^® Mid
• ThermoFlex Narrow

Background

The objective of the resolution test is to calibrate the optical head so that the distance between two adjacent laser dots corresponds with the file resolution. The test is performed for a resolution of 100 dpm, and is repeated for other resolutions that the customer intends to use.

The resolution test results do not depend on plate type, size or thickness. Therefore, this test can be performed on any plate that the customer uses.

Requirements

• Densitometer
• Microscope
• Flexo plate(s)
• Offset plate(s) if the configuration includes offset option
• Focus tested and adjusted, as described in the Focus Calibration Test
• Elevation tested and adjusted, as described in the Elevation Calibration Test
• Laser uniformity tested, as described in the Laser Uniformity Calibration Test.

Procedure

This procedure contains two stages, which should be repeated for each resolution that the customer uses:

• Testing resolution
• Selecting the correct resolution

Testing resolution

1. Load a test plate.
2. In TIFF FE, from the Launch Pad, select Utilities > Calibrate.
   
3. In the Calibration Type box, select Resolution.
   TIFF FE dialog box:
   
   
   
4. In the Current Plate list, select the Plate that you are using.
5. Select the relevant test file according to the type of plate:
   • Flexo—select machineCalibTest.lw
   • Offset—select CalibTest100AM.K.TIF
   • Offset Staccato—select CalibTest100FM.K.TIF

6. Define the Image offset values:
   
   • Horizontal offset—The value around the drum in mm
   • Vertical offset—The value along the drum in mm
   If you use the same plate for several tests, define different offset values for each test.
   Note: The (0,0) offset coordinate is located at the upper-left corner of the plate.
7. In the Test Resolution list, select the resolution value.
   Note: If the customer plans to expose in several different resolutions, it is recommended to repeat the test for all values in the Test Resolution list.

Note: The resolution calibration is performed four times, during which steps 8 and 9 are adjusted each time to fine-tune the resolution, according to the table in step 8.

8. In the Test Motor Values (steps) area, in the From and To boxes, define the motor values' range according to the table.
   
   Note: The recommended range for the first test is:
   • Flexo (lens 1:2)—between 700 and 1200
   • Offset (lens 1:3)—between 1400 and 1900

   	From/To range	Number of steps
   1st test (coarse)	Lens 1:2: 700–1200 Lens 1:3: 1400–1900	11
   2nd test (coarse)	results of 1st test ±100	11
   3rd test (fine)	results of 2st test ±50	11
   4th test (fine)	results of 3st test ±20	5

   
   Optional: To calculate the results for a resolution of 94.488, add the following value to the results of the 4^th test:
   • Flexo (lens 1:2)—Add 115
   • Offset (lens 1:3)—Add 170
   
   
9. In the Number of Steps list, type the required number of exposures according to the table in step 8.
10. Click Test. The application performs several exposures according to the settings.
11. Visually examine the results. The best coarse resolution (for 1st and 2nd tests) is the one without artifacts (such as slashes) in the 50% dot area.
    
    
12. To fine-tune the resolution perform the 3rd and 4th tests using the values in the table in step 8.
    Note: For flexo plates only, during the 3rd and 4th tests, in the Test File list, select the Moire test file. Note that the Moire test file is available only for resolutions of 2400 or 2540.
    

Selecting the correct resolution

1. Visually examine the results and select the value for the results that have no vertical lines, slashes, or other artifacts.
2. For offset plates only, using a microscope, examine the vertical 2P section of the test file. Look for the solid (100%) strips that are most identical, with equal widths of 2 pixels.
   
   
   • Differences in line spacing indicate incorrect resolution.
   • Even line spacing indicates correct resolution.
3. In the ThermoFlex Controller hardware tree, browse to Database and right-click Res Motor.
4. In the Res Motor dialog box, type the value of the stepper motor for the optimal results of the resolution test.
5. Repeat the test for other resolutions that the customer plans to use.

Technical contact(s)

Content owner: Viki Arviv
See the Escalation page for escalation contacts.

Date submitted

22 June 2004