Calculation of correction factors for lead edge sensor measurement in duplex registration

A print making device comprising:

• a conveying apparatus adapted to move a media sheet, the media sheet including a lead edge and a trail edge;
• the conveying apparatus including sensors, a velocity controller and a datum;
• the sensors including a leading edge sensor to record a time of arrival of the lead edge, a trailing edge sensor to record a time of arrival of the trail edge and a registration device sensor;
• the velocity controller being adapted to adjust the velocity of the media sheet based on a difference between the arrival time of the lead edge and the time of arrival of the trail edge;
• and
• a registration controller operatively connected to the conveying apparatus and to the sensors, the registration controller being adapted to calculate an edge arrival calculated time difference between the arrival of the trail edge using output from the trailing edge sensor and the arrival time of the lead edge using output from the leading edge sensor, calculate a correction factor based upon the calculated time difference minus a nominal time difference, and calculate a corrected time interval of the media sheet from the registration device sensor to the datum using the correction factor and a predetermined time of arrival of the media sheet to the datum to align items printed on the media sheet, and notify the velocity controller for adjusting the current velocity of the sheet based on the correction factor to deliver the media sheet to the datum at the predetermined time of arrival of the media sheet to the datum to provide accurate alignment of items to be printed on the media sheet.

A print making system comprising:

• a conveying apparatus adapted to move a media sheet, the media sheet including a lead edge and a trail edge;
• the conveying apparatus comprising a leading edge sensor, a trailing edge sensor, a registration device sensor, a velocity controller and a datum;
• the leading edge sensor being between the trailing edge sensor and the registration device sensor;
• the leading edge sensor records the time of arrival of the lead edge at the leading edge sensor, the trailing edge sensor records the time of arrival of the trail edge at the trailing edge sensor, the registration device sensor records the time of arrival of the lead edge at the registration device sensor;
• the velocity controller adjusts the velocity of the media sheet based on the difference between the arrival time of the lead edge at the leading edge sensor and the time of arrival of the trail edge at the trailing edge sensor;
• and
• a registration controller operatively connected to the conveying apparatus and to the sensors, the registration controller being adapted to calculate the difference between the arrival time of the trail edge using output from the trailing edge sensor and the arrival time of the lead edge using output from the leading edge sensor, calculate a correction factor based upon the time difference;
• and calculate a corrected time interval of the media sheet from the registration device sensor to the datum using the correction factor and a predetermined time of arrival of the media sheet to the datum to align items printed on the media sheet, and notify the velocity controller for adjusting the current velocity of the sheet based on the correction factor to deliver the media sheet to the datum at the predetermined time of arrival of the media sheet to the datum to provide accurate alignment of items to be printed on the media sheet.