Riso Kagaku Corporation

Noboru Hayama

Yoshiharu Ohinata

Kazuo Sakamoto

Toshio Tanaka

Takanori Hasegawa

Satoru Komata

Masakazu Kera

Yoshio Tsuji

Kiyoshi Takehara

In a stencil printing including the steps of supplying ink in the form of a layer on one side of a perforated stencil sheet, contacting another side of the stencil sheet to a surface for printing, applying a pressure to the ink layer by a pressing means so as to transfer the ink of the ink layer through perforations of the stencil sheet from the one side to the other side of the stencil sheet and to attach the ink thus transferred onto the surface for printing, and detaching the surface for printing from the other side of the stencil sheet, the improvement is which the surface for printing is detached from the other side of the stencil sheet at a portion thereof where a movement of the ink layer relative to the stencil sheet is substantially impeded by the pressing means so that a drawing out of the ink from the ink layer onto the surface for printing due to the adhesiveness and viscosity of the ink does not occur when the surface for printing is detached from the stencil sheet, thus also allowing the extrusion of the ink through the stencil perforations to be expedited before the stencil sheet tightly contacts the printing surface, so as to avoid blank shadows of fibers of the stencil sheet, while avoiding the problem of back contamination.

Stencil printing with no back contamination

In a rotary stencil printer having a printing drum made of two annular members connected by a transverse bar member and a net member of woven, non-woven or knitted fibers of a rectangular shape in development wound around the two annular members with opposite side edge belt portions thereof being slidably laid on outer circumferential surfaces of the annular members so as to form a porous cylindrical body for mounting a stencil sheet as wound therearound, a back press roller of a diameter common with the printing drum disposed to face an outside surface of the printing drum so as to define a print sheet nip region with the printing drum therebetween and having a groove in an outside surface portion thereof adapted to receive the transverse bar member therein in meeting therewith in synchronized rotations of the printing drum and the back press roller in opposite directions, and an inner press roller disposed in an inside space of the printing drum so as to contact with an inside surface of the porous cylindrical body along a generatrix thereof, the transverse bar member is spaced radially outwardly from a cylindrical outer configuration of the porous cylindrical body at a portion thereof facing the porous cylindrical body so that the inner press roller can traverse a portion facing the transverse bar member with no collision therewith.

Rotary stencil printer with printing drum of net cylindrical body

A thermal stencil sheet assembly of the type having an annular frame made of a cardboard and a thermal stencil sheet attached to one face of the frame as fixed thereto along an entire peripheral portion thereof with or without an ink pressing sheet made of an ink impermeable sheet attached to another face of the frame, wherein the frame is assembled of a first frame element made of a relatively thin sheet material and a second frame element made of a cardboard, the two frame elements being detachably and reattachably bound together by a slippery surface provided on the first frame element being attached to a layer of a sticky binding material provided on the second frame element.

Thermal stencil sheet assembly with stencil sheet temporarily detachable

In a rotary stencil printer having a printing drum supported to be rotatable about a central axis thereof and having a cylindrical outer surface adapted to bear a perforated stencil sheet as attached therearound and formed with openings for supplying ink to an inside surface of the perforated stencil sheet, and a back press roller supported to be rotatable about a central axis thereof extending in parallel with the central axis of the printing drum and having a cylindrical outer surface which defines a nip area with the cylindrical outer surface of the printing drum therebetween for nipping and transferring a printing sheet therethrough. The printing drum has an outer peripheral wall portion substantially made of only a net material constructed by weaving or knitting filaments to provide the cylindrical outer surface thereof formed with the openings, and an internal press roller is provided so as to engage the outer peripheral wall portion at a radially inside surface thereof and to press the outer peripheral wall portion radially outwardly toward the back press roller, thereby locally elastically deforming the net material to traverse a nip area clearance when a printing sheet is supplied in the nip area.

Rotary stencil printer having printing drum having outer peripheral wall

An exposure device for a thermal stencil sheet having a linear electronic flash discharge tube and an enclosure made of a plate member curved around the tube in a substantially cylindrical shape coaxial with the tube while defining a slit opening parallel to the tube, wherein a thermal stencil sheet is loaded into the enclosure through the slit opening and is supported in a substantially cylindrical shape coaxially around the tube for receiving direct infrared radiation from the tube with no interposition of a glass layer or the like.

Exposure device for a thermal stencil sheet

A stencil paper assembly comprising a stencil paper sheet and an ink-impermeable sheet laid one over the other, said assembly being adapted to maintain a layer of ink between said stencil sheet and said ink-impermeable sheet so that numerous printed sheets may be obtained with one charge of ink and without causing smearing of ink.

Growing community of inventors

Tokyo, Japan

Noboru Hayama