Multi-drum stencil printer with duplex printing sections

A multi-drum stencil printer, comprising:

• a plurality of printing sections each including a respective print drum and a respective press roller configured to press a sheet against said print drum;
• an intermediate conveyor positioned between an upstream printing section of said plurality of printing sections and a downstream printing section of the plurality of printing sections to convey the sheet from the upstream printing section toward the downstream printing section in a direction of sheet conveyance;
• a dual master formed with a first image and a second image configured to be wrapped around a circumferential surface of the print drum in a most upstream one of the plurality of printing sections located at a most upstream position in the direction of sheet conveyance;
• and
• a controller configured to control the multi-drum stencil printer in response to a selected print mode, wherein
• the press roller in said most upstream one of the plurality of printing sections is rotated by a drive source,
• said most upstream one of the plurality of printing sections and at least one downstream one of the plurality of printing sections, located downstream of said most upstream one of the plurality of printing sections in the direction of sheet conveyance, includes a single-flow duplex printing section including a refeeding device for storing a sheet, the sheet carrying an image on one surface thereof, and then refeeding said sheet toward a gap between said respective print drum and said respective press roller, a path selector selectively movable to a first position for guiding the sheet toward said refeeding device or a second position for guiding said sheet toward said intermediate conveyor, and a switching device for causing said press roller to remain in contact with said print drum over any one of a first range corresponding to the first image, a second range corresponding to the second image and a third range covering both of said first image and said second image, and
• when a print mode is selected to produce a print carrying multicolor images on both surfaces thereof, the controller controls a positioning of the dual masters such that the dual master wrapped around said print drum of one of the single-flow duplex printing sections has the first image and the second image in opposite positions to the first image and the second image of the dual master used in an adjacent one of the single-flow duplex printing sections.

A multi-drum stencil printer, comprising:

• a plurality of printing sections, wherein each of the plurality of printing sections includes a print drum and a press roller configured to press a sheet against the print drum;
• at least one intermediate conveyor configured to convey the sheet from an upstream printing section toward a downstream printing section in a direction of sheet conveyance;
• a first single-flow duplex printing section including a first refeeding device, located at a most upstream position in the direction of sheet conveyance, the first single-flow duplex printing section is configured to store a sheet carrying an image on one surface thereof and then refeed the sheet toward a gap between a first print drum and a first press roller in the first single-flow duplex printing section;
• a first path selector, included in the first single-flow duplex printing section, configured to be selectively movable to a first position for guiding the sheet toward the first refeeding device or a second position for guiding the sheet toward a first intermediate conveyor located in a downstream direction from the first single-flow duplex printing section;
• a first switching device, included in the first single-flow duplex printing section, configured to cause the first press roller to remain in contact with the first print drum over any one of a first range corresponding to a first image, a second range corresponding to a second image and a third range covering both of the first image and the second image;
• a second printing section, located next to the first printing section in the direction of sheet conveyance, including a second single-flow duplex printing section configured to store the sheet and then refeed the sheet toward a gap between a second print drum and a second press roller included in the second printing section and conflaured to receive a second dual master formed with the third image and the fourth image around a circumferential surface of the second print drum;
• and
• a controller configured to control the multi-drum stencil printer in response to a selected print mode, wherein
• the first single-flow duplex printing section includes the first print drum configured to receive a first dual master formed with a first image and a second image around a circumferential surface of the upper most print drum, and
• when a print mode is selected to produce a print carrying multicolor images on both surfaces thereof, the controller controls a positioning of the dual masters such that the dual master wrapped around the first print drum has the first image and the second image in opposite positions to the third image and the fourth image of the dual master wrapped around the second print drum.