| 摘要 |
A system and method are provided to calibrate a sheet velocity measurement derived from a drive nip system incorporating idler encoders. Testing has found that the velocity from an idler encoder system is subject to systematic errors, for example, errors that occur when the system is running media of different thicknesses. The system uses one or more nips with encoders mounted on the idlers and a number of point sensors that are spaced apart in the process direction. The point sensors are used to measure the transmit time of the sheet (lead edge or trail edge) between two sensor positions. The transit time is used to calculate the average sheet velocity. The average sheet velocity is compared with the velocity derived from the idler encoders to derive a correction factor. The velocity sensor are used to calibrate the idler-encoder velocity sensors, providing a worthwhile improvement to idler-encoder technology for media handling (e.g., feeding, transport, and finishing) in direct marking systems.
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