Method for calculating a print medium pick time for an imaging apparatus that transports print media at variable speeds

A system for calculating a print medium pick time for an imaging apparatus that transports media at variable speeds along a media path, comprising:

• a media path sensor for sensing an arrival of a media sheet at a known location along said media path;
• an image transfer member for receiving an image;
• an image transfer nip defining an image transfer location adjacent said media path;
• staging means for executing a staging process for varying a transport velocity of said media sheet before transferring said image to said media sheet at said image transfer location, said staging process positioning a top writing line margin of said media sheet in relation to said image at said image transfer location;
• means for determining a time period t1 corresponding to a time when a pick motor is started to pick said media sheet to a time when said staging process is started;
• means for determining a derived time period t2 representative of a normalized time from when said staging process is started to a time when said media path sensor senses said media sheet;
• and
• means for summing said time period t1 with said time period t2 to determine a compensated calculated pick time for said media sheet.

A printer, comprising:

• a media tray for holding media sheets;
• a pick motor for picking a media sheet from said media tray;
• a staging system including a staging motor operating in accordance with a staging process effecting a staging algorithm for transporting said media sheet along a media path;
• a staging motor encoder coupled to said staging system for determining a distance traveled by said media sheet;
• a sensor for sensing an arrival of said media sheet at a known location along said media path;
• and
• a microcontroller for executing computer instructions to determine a compensated calculated pick time (CPTcomx) for said media sheet, said computer instructions effecting the equation:
• CPTcomx=Staging13 Encoders13 From13 Staging13 Algorithm_Start_To_S2_Make/Staging13 Encoders13 Per_Second_At_Normal_Process13 Speed+Staging13 Start13 TimeStamp−Pick_Start_TimeStamp
• wherein:
• Staging13 Encoders13 From_Staging13 Algorithm13 Start_To_S2_Make is a number of staging motor encoder pulses counted from when said staging algorithm starts until said sensor detects said media sheet;
• Staging13 Encoders13 Per_Second_At_Normal_Process13 Speed is set to a number of encoder pulses per second that should occur if said staging motor was rotating at a known process speed;
• Staging13 Start13 TimeStamp is a system time of said printer when said staging algorithm is started;
• and
• Pick_Start_TimeStamp is a system time of said printer when said pick motor is started.