Print media transfer schedule setting unit and method for image forming apparatus

An image forming apparatus, comprising:

• a plurality of paper feed units configured to draw and feed, one by one, print media stacked on a paper feed table with sheet sizes different from one another;
• a printing unit configured to print a print medium fed by the paper feed units, based on a received print job including one of a first print job or a second print job, the first print job not including a double-sided printing request of a set of print media of a plurality of sheet sizes, the second print job including a double-sided printing request of a set of print media of a plurality of sheet sizes;
• a resist unit configured to transfer print medium fed from the plurality of paper feed units to the printing unit at a predetermined timing;
• a circulating path configured to transfer print medium printed by the printing unit at a transfer speed, the transfer speed in the first print job being determined for each sheet size;
• a reversal unit configured to reverse print medium transferred on the circulating path and then transfer the reversed print medium to the resist unit;
• a transfer schedule setting unit configured to set, when the received print job is the second print job, a transfer schedule for the set of the print media of the plurality of sheet sizes;
• and
• a control unit configured to start feeding or transfer from any one of the plurality of paper feed units or the reversal unit to the resist unit based on the set transfer schedule, wherein
• the transfer schedule is a first transfer schedule or a second transfer schedule,
• the first transfer schedule transfers the print media of the plurality of sheet sizes to the resist unit by transferring the print media on the circulating path at a transfer speed at which a print medium of the largest sheet size of the plurality of sheet sizes is transferred on the circulating path in the first print job, or
• the second transfer schedule transfers, before transferring a last print medium of a first sheet size reversed by the reversal unit to the resist unit, the print medium of a second sheet size different from the first sheet size that follows the print medium of the first sheet size from any one of the plurality of paper feed units to the resist unit for each set of the plurality of sheet sizes, and
• the transfer schedule setting unit is further configured to calculate a productivity of the first transfer schedule and a productivity of the second transfer schedule based on the second print job as received, and set the transfer schedule based on which transfer schedule requires shorter time to complete printing.

An image forming method in an image forming apparatus including:

• a plurality of paper feed units configured to draw and feed, one by one, print media stacked on a paper feed table with sheet sizes different from one another;
• a printing unit configured to print a print medium fed by the paper feed unit based on a received print job including one of a first print job or a second print job, the first print job not including a double-sided printing request of a set of print media of a plurality of sheet sizes, the second print job including a double-sided printing request of a set of print media of a plurality of sheet sizes;
• a resist unit configured to transfer a print medium fed from the plurality of paper feed units to the printing unit at a predetermined timing;
• a circulating path configured to transfer a print medium printed by the printing unit at a transfer speed, the transfer speed in the first print job being determined for each sheet size;
• a reversal unit configured to transfer a print medium transferred on the circulating path and then transfer the reversed print medium to the resist unit,
• the method comprising:
• setting a transfer schedule, when the received print job is the second print job, for the set of print media of the plurality of sheet sizes according to the sheet size of the print media, using a transfer schedule setting unit;
• and
• controlling a start of feeding or transfer from any one of the plurality of paper feed units or the reversal unit to the resist unit based on the set transfer schedule, using a control unit,
• wherein in setting the transfer schedule, the transfer schedule is set so that before a last print medium of a first sheet size reversed by the reversal unit is transferred to the resist unit, the print medium of a second sheet size different from the first sheet size that follows the print medium of the first sheet size is fed from any one of the plurality of paper feed units to the resist unit,
• and wherein in setting the transfer schedule, the transfer schedule is set so that:
• when the transfer schedule is switched from the print medium of a small sheet size to the print medium of a large sheet size larger than the small sheet size, the transfer schedule of the print medium on the circulating path is the transfer schedule for the print medium of the large sheet size, and further a start of transfer of the print medium of the small sheet size from the reversal unit to the resist unit is delayed by a predetermined time;
• and
• when the transfer schedule is switched from the print medium of the large sheet size to the print medium of the small sheet size, the transfer schedule of the print medium on the circulating path is the transfer schedule for the small sheet size, the transfer speed of the print medium of the large sheet size from the reversal unit to the resist unit is a transfer speed increased higher than a transfer speed in the transfer schedule of the small sheet size, and the print medium of the small sheet size is fed from any one of the plurality of paper feed units after a minimum paper feed interval elapses after the start of transfer of the print medium of the large sheet size from the reversal unit to the resist unit.

An image forming method in an image forming apparatus including:

• a plurality of paper feed units configured to draw and feed, one by one, print media stacked on a paper feed table with sheet sizes different from one another;
• a printing unit configured to print a print medium fed by the paper feed unit based on a received print job including one of a first print job or a second print job, the first print job not including a double-sided printing request of a set of print media of a plurality of sheet sizes, the second print job including a double-sided printing request of a set of print media of a plurality of sheet sizes;
• a resist unit configured to transfer a print medium fed from the plurality of paper feed units to the printing unit at a predetermined timing;
• a circulating path configured to transfer a print medium printed by the printing unit at a transfer speed, the transfer speed in the first print job being determined for each sheet size;
• a reversal unit configured to transfer a print medium transferred on the circulating path and then transfer the reversed print medium to the resist unit,
• the method comprising:
• setting a transfer schedule, when the received print job is the second print job, for the set of print media of the plurality of sheet sizes according to the sheet size of the print media, using a transfer schedule setting unit;
• and
• controlling a start of feeding or transfer from any one of the plurality of paper feed units or the reversal unit to the resist unit based on the set transfer schedule, using a control unit, wherein
• the transfer schedule is a first transfer schedule or a second transfer schedule
• the first transfer schedule transfers the print media of the plurality of sheet sizes to the resist unit by transferring the print media on the circulating path at a transfer speed at which a print medium of the largest sheet size of the plurality of sheet sizes is transferred on the circulating in the first print job, or
• the second transfer schedule transfers, before transferring a last print medium of a first sheet size reversed by the reversal unit to the resist unit, the print medium of a second sheet size different from the first sheet size that follows the print medium of the first sheet size from any one of the plurality of paper feed units to the resist unit for each set of the plurality of sheet sizes, and
• in setting the transfer schedule, a productivity of the first transfer schedule and a productivity of the second transfer schedule are calculated based on the second print job as received, and the transfer schedule is set based on which transfer schedule requires shorter time to complete printing.