Drum Period
Definition
The repeat interval of a drum-surface defect in the printed output, equal to the drum's circumference; measured in millimetres to identify the component and, combined with defect morphology, to identify a specific printer unit.
- Field
- Printer identification, laser printers
- Definition
- Repeat interval of a drum-surface defect
- Equals
- Drum circumference
- Measured in
- Millimetres
Common questions
How does measuring drum period help identify a specific printer?+
Each physical drum has microscopic surface imperfections that mark the printed page at a fixed spacing equal to its circumference. Measuring that spacing on a questioned document and matching it to the defect pattern of a suspect printer's drum links the page to that specific unit rather than just to a printer model.
Can drum period identification distinguish two printers of the identical make and model?+
Yes. While the nominal drum circumference is a model-level specification shared by identical printers, the exact defect pattern and its position within that repeat interval are individual to a given drum's wear, which is what allows examiners to individualise a print to one specific machine rather than only a model.
Related terms
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- Fourier Banding Analysis
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