Riso Kagaku Corporation

Koji Nakayama

Yasuhiro Takahashi

Katsuro Motoe

Yoshikazu Hara

Masakazu Miyata

Hideharu Yoneoka

Hiroshi Hanzawa

Masaharu Ogata

A stencil printing machine is provided with a stencil drum and a opposite which are a pair of cylindrical parts located with their external peripheral surfaces being close to each other, a stencil sheet being detachably wound on the external peripheral surface of the stencil drum , and serves to perform stencil printing process by rotating the stencil drum and the opposite in order that the external peripheral surfaces thereof are located close to each other and moved in the same direction while the stencil sheet is pressed against the opposite , and by making the stencil sheet in contact under pressure with a sheet of paper passing between the stencil drum and the opposite by the pressing force of the stencil drum . The stencil drum is detachably mounted on the stencil printing machine and provided with storage units to for storing information about the pressing force of the stencil drum against the opposite

Stencil printing machine

According to the stencil printing machine of the present invention, ink that has entered the gap between a circumferential wall and a stencil sheet is allowed to escape to the outsides of an inner pressing roll in the axis direction. When it reaches the outer circumferential face of an ink free passage section of a screen, the escape ink is allowed to pass through the ink free passage section by a pressing force from the pressure drum, and directed to the inner circumferential side; therefore, it is possible to prevent the escape ink from reaching the right and left ends of the stencil sheet, and consequently to eliminate the limitation to the number of prints in endurance printing processes that is imposed due to ink leakage from the stencil. Moreover, since it is not necessary to form a raised portion along the circumferential face, the printing drum can be easily manufactured at low costs.

A stencil printer has a printing drum which has an ink-permeable peripheral wall around which a stencil master is wound and to the inner surface of which ink is supplied. The printing drum is rotated about its longitudinal axis. An internal press roller is disposed inside the printing drum and is rotated in contact with the inner surface of the peripheral wall of the printing drum. A paper pinch drum is disposed outside the printing drum and is pressed against the peripheral wall of the printing drum with a printing paper pinched between the pinching means and the stencil master wound around the peripheral wall. A retainer roller is disposed in a predetermined position near the internal press roller and the inner surface of the peripheral wall downstream of the contact line between the internal press roller and the inner surface of the peripheral wall in the direction of rotation of the printing drum.

Stencil printer having printing drum and retainer roller

A stencil printing machine includes a printing drum having a flexible ink-permeable circumferential wall adapted to receive a perforated stencil sheet around an outer circumferential surface thereof, the printing drum being driven to rotate around a central axis thereof; a pressing device situated inside the printing drum for supplying ink to an inner surface of the circumferential wall, the pressing device being movable between a pressing position for pressing the circumferential wall to be deformed radially outwardly and a standing position for releasing the circumferential wall from deformation; an opposing drum disposed adjacent to the printing drum and driven to rotate in a direction opposite to that of the printing drum, the opposing drum having a recess formed in an outer circumferential surface thereof; a clamp disposed on an outer circumferential surface of the opposing drum and operating in synchronization with rotation of the opposing drum to hold a leading edge of a printing sheet supplied between the printing drum and the opposing drum; a clamp cover disposed on the outer circumferential surface of the opposing drum adjacent to the clamp relative to the direction of rotation of the opposing drum and covering the recess formed in the opposing drum for allowing operation of the clamp, the clamp cover selectively opening and closing the recess in synchronization with operation of the clamp; and a driving mechanism for driving the clamp cover to move alternately in a circumferential direction of the opposing drum and in a radial direction of the opposing drum.

In a stencil printer, in order to definitely prevent an ink leakage even when the perforated portion 20c of the printing drum laps over the clamp 25 of the back press roller 14, the portions of a part of the outer circumferential surface of the back press roller positioned adjacent to the rear and opposite side edges of the clamp 25 is provided by a movable circumferential member 66 adapted to bias rearward relative to the clamp in synchronization with the opening operation of the clamp, so as thereby to cancel the clearance formed along the periphery of the clamp without obstructing the opening operation of the clamp.

Stencil printer having back press roller with clamp and movable wall

In the ink supply construction of a stencil printer, having an ink holding space 14 defined by an outer circumferential surface of an ink supply roller 4 and an ink supply control member 8, there is provided an ink interrupting member 30 as opposed to the ink supply control member across the ink holding space for restricting a side of the ink holding space opposite to the ink supply control member, in order to stabilize and highly uniformalize the cross sectional size of a rotating lump of ink L formed in the ink holding space along the length of the lump of ink. The lump of ink may be rotationally driven by an ink driving rod member 15 provided in the ink holding space. When the lump of ink is not rotationally driven by the ink driving rod member, the ink interrupting member may be constructed to rotationally drive the lump of ink.

Ink supply construction of printer having ink interrupting member

In a stencil printer having a printing drum 10 which has a circumferential wall portion for mounting a stencil sheet made of a flexible sheet member 20 and including a perforated portion 20c, an inking roller 12 provided inside of the printing drum for supplying ink to the printing drum from its inside, and a back press roller 14 for supporting a print sheet against the printing drum by holding a leading end of the print sheet by clamps 25, a strip of elastic sheet 52 is provided to prevent ink leakage from the perforated portion 20c of the printing drum due to insufficient support of the print sheet by the back press roller at the portion of the clamps 25.

Stencil printer having ink leakage preventing construction

A sheet receiving and stacking apparatus includes a base table with a stacking section for stacking a rectangular sheet, and a guide device for receiving the rectangular sheet and guiding the rectangular sheet to the stacking section of the base table. The guide device has a plurality of guide sections rotating in contact with the rectangular sheet above said stacking section.

Sheet receiving and stacking apparatus

In order to ensure that the leading end of a print sheet mounted to the back press means by a clamp member is engaged by a claw member for removing the print sheet from the back press means when the leading end has been released from the clamping by the clamp member, there is provided a means for lifting up the leading end of the print sheet above a supporting surface therefor of the back press means after the release of the leading end from the clamp member.

Print sheet leading end mounting device having means for lifting

A sheet receiving and stacking apparatus is formed of a base table with a stacking section for stacking a rectangular sheet, and a guide device for receiving the rectangular sheet and for guiding the rectangular sheet to the stacking section of the base table. The guide device has a rotatable curved guide surface, and guides the rectangular sheet to the stacking section while being rotated with the side edges of the rectangular sheet when the guide surface has received the side edges of the rectangular sheet which is floating downwardly.

A sheet receiving and stacking apparatus is formed of a base table with a stacking section for stacking a rectangular sheet, and guide members for receiving the rectangular sheet and for guiding the rectangular sheet to the stacking section of the base table. The guide members have at least one movable member which protrudes out on the stacking section side of the base table. The movable member receives the side edge of the rectangular sheet floating downwardly, retreats to the outside of the stacking section with the weight of the rectangular sheet, and is movable to protrude again towards the stacking section side when freed from the weight of the rectangular sheet.

In a rotary stencil printer in which a back press roller 12 is provided with a transverse groove 26 for receiving a transverse bar 16 of a printing drum 10 and a printing sheet applied with a printing at a nipping region 32 between the printing drum and the back press roller is transferred for a while as attached onto the cylindrical outer circumferential surface of the back press roller by a pinch roller or rollers 40 provided at an outlet side of the nipping region so as to press at a side edge portion or portions of the printing sheet against the outer circumferential surface of the back press roller, the position control of the pinch roller or rollers to conform to the sheet width is carried out in a condition that the pinch roller or rollers are aligned with the transverse groove of the back press roller.

Growing community of inventors

Ibaraki-ken, Japan

Koji Nakayama