A study was conducted in which the cause of flow pattern, a repetitive mottle-like defect, was investigated. Results obtained indicate that vacuum pressure fluctuations occur at the start of coating by the vacuum flow port that are 367% greater than at the center of coating. These fluctuations decay in time during the period of flow pattern occurrence, and range in frequency from 0 to .10 mm-1. These pressure fluctuations correlate to flow pattern density fluctuation frequencies of the same range. Additionally, it was seen that the decay rate of the ME side of the vacuum chamber was three times the rate of the UME side. No significant pressure fluctuation phenomena was observed by the end seals of the vacuum chamber.
Imaging Science (BS)
Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Fitzpatrick, Paul, "Correlation of silver halide emulsion bar-coater vacuum chamber pressure fluctuations with flow pattern occurrence" (1982). Thesis. Rochester Institute of Technology. Accessed from
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