ContvHV.spt

When to run this script | Graphs | Data | Interpretation

This script measures the contrast ratio of the light valve (off-light over on-light) using the beam balance sensor, as the hvtrim is incremented from 65V to 80V. Your system must be properly configured before running this script. For more information, see Note 1 .

When to run this script

Use this script to diagnose beam balance failures, banding and as part of preventative maintenance.

Before you run ContvHV.spt, you must run Contrvbp.spt and the select the correct beamposition setting.

Graphs

All the graphs have the High Voltage as the x-axis.

• Sample 1: An example of a good Offvhv result. The LVD HVTrim should be adjusted to 72.5.
• Sample 2: An example of an OffvHV result where the HVTrim required is 80. Since 80 is the maximum setpoint for HVTrim any future aging of the LV will not be able to be tuned with HVTrim. If the thermal head is equipped with reverse hardware make sure that automatic beam correction is enabled. Initiating a manual beam correction (time permitting) will reduce the HVTrim requirement.

Interpretation

The LVD HVTrim parameter should be set for the minimum Off in the OffvHV graph.

Data

This script produces one data file, ContvHV_data.txt. This file has four columns:

1. High voltage
2. Contrast ratio, in percent
3. Write laser power, in Watts, with all pixels on.
4. Write laser power, in Watts, with all pixels off.