Trash Mark
Definition
An extraneous mark appearing at a consistent position or periodic interval in photocopied documents, arising from platen glass contamination (fixed position) or drum surface defect (periodic, at the drum circumference interval).
- Appearance
- Extraneous mark at consistent position or periodic interval
- Fixed-position cause
- Platen glass contamination
- Periodic cause
- Drum surface defect, repeating at drum circumference
- Field
- Photocopier and toner examination
Common questions
How does a trash mark help link a document to a specific photocopier?+
A fixed-position mark from a scratched or dirty platen, or a periodic mark repeating at the drum's circumference, forms a defect signature unique to that machine, which examiners can match against test copies made on a suspect device.
How can an examiner tell whether a trash mark comes from the platen or the drum?+
A platen defect appears at the same position on every copy regardless of the original document, while a drum defect repeats at a fixed interval down the page corresponding to the drum's circumference, so the two produce different spacing patterns.
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- Platen Glass
- The flat transparent surface on which original documents are placed for scanning in a photocopier or flatbed scanner; contamination or scratches on...
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