Abstract: A stencil printer includes a plurality of ink drums spaced from each other in the direction of paper conveyance and each having a respective master wrapped therearound. An upstream ink drum and pressing means movable into and out of contact with the upstream ink drum define an upstream print position. A downstream ink drum and pressing means movable into and out of contact with the downstream ink drum define a downstream print position. An intermediate conveyor is located between the upstream print position and the downstream print position for conveying a paper carrying an image printed at the upstream print position toward the downstream print position. A distance which the paper moves from the upstream print position to the downstream print position is longer than a distance between the upstream print position and the downstream print position. Defective printing is reduced even when the peripheral speed of the upstream ink drum and that of the downstream ink drum are different from each other.

Abstract: A water-in-oil type emulsion ink for stencil printing, including 10-90% by weight of an oil phase and 90-10% by weight of an aqueous phase, the oil phase containing a mineral oil having a viscosity of at least 8 cSt at 40.degree. C. and such a carbon content distribution that a paraffinic carbon content C.sub.P is at least 55%, a naphthenic carbon content C.sub.N is at least 25% and an aromatic carbon content C.sub.A is not greater than 10%.

Abstract: A water-in-oil type emulsion ink for stencil printing, including 10-90% by weight of an oil phase and 90-10% by weight of an aqueous phase, the oil phase containing a mineral oil having a viscosity of greater than 10.0 mm.sup.2 /s at 40.degree. C. and such a carbon content distribution that a naphthenic carbon content C.sub.N is at least 34% and an aromatic carbon content C.sub.

Abstract: Provided are a stencil printing method and an apparatus therefor, in which a master having a low stiffness such as a single film may be transferred, in which a complicated mechanism for fitting and removing a plate is not needed and in which a degree of avoiding movement of a pressing roller to be in contact with the master can be minimized.

Abstract: A stencil printer of the present invention includes at least one ink drum for wrapping a master around its outer periphery. An ink feed device feeds ink to the master wrapped around the ink drum. A pressing member is movable into and out of contact with the ink drum at a position where it faces the ink feed device. An image is printed on a paper fed from a paper feed section at a print section where the ink drum and pressing member face each other. A belt conveyor includes a belt extending between the paper feed section located upstream of the print section in the direction of paper conveyance and a paper discharge section located downstream of the print section in the same direction through the print section. The belt conveys the paper fed from the paper feed section while causing it to electrostatically adhere thereto. The paper is sufficiently electrostatically adhered to the belt before it reaches the print section, so that air suction, an air knife, a separator or the like is not necessary.

Abstract: A thermal master making device includes a thermal head having a plurality of heating elements arranged in an array in the main scanning direction. The thermal head is caused to contact a stencil including a thermoplastic resin film. While the master is fed at a preselected feed pitch in the subscanning direction perpendicular to the main scanning direction, the heating elements selectively heat and perforate the film of the stencil in accordance with image data to thereby form an image in the stencil in the form of a dot pattern. A pitch at which the heating elements are arranged and the feed pitch are substantially equal to each other. The heating elements each have a length in the subscanning direction smaller than one-half of the feed pitch inclusive and have a length in the main scanning direction greater than the length in the subscanning direction. The device is capable of stably forming desired perforations in the stencil and extending the life of the heating element and therefore the life of the head.

Abstract: A paper feeder for feeding papers to an image forming apparatus and a paper tray elevation device therefore are disclosed. A first tray is movable up and down with a plurality of papers stacked thereon. A paper feed member feeds the papers from the first tray in a preselected direction of paper feed. A second tray is positioned beside the first tray in substantially the horizontal direction and movable up and down with a plurality of papers stacked thereon. A shifting device shifts the entire paper stack from the second tray to the first tray. A horizontal elevating mechanism elevates the first tray while maintaining it in substantially the horizontal position. An interlocking mechanism at least elevates, when papers of greater in size than the papers to be stacked on the first or second tray are stacked over the first and second trays in a single stack, the second tray in interlocked relation to the elevation of the first tray while maintaining the second tray in substantially the horizontal position.

Abstract: A press roller for a stencil printer of the present invention is rotatable while pressing a recording medium against an ink drum which is rotatable with a master wrapped therearound. The press drum includes a hollow cylinder and an elastic layer formed on the outer periphery of the hollow cylinder. The elastic layer has a higher compressibility than a recording medium and performs, when compressed, elastic deformation in place of bulk movement. With this configuration, the press drum protects the master from damage ascribable to the localization of a pressing force. In addition, the press drum prevents a recording medium from creasing due to a difference in linear velocity otherwise occurring between the press drum and the recording medium at a pressing position.

Abstract: A printer of the type wrapping a master around a print drum and pressing a sheet against the master with the print drum or a press drum is disclosed. A sheet clamper is arranged on the press drum. A timing sensing device for allowing the leading edge of the sheet to be fed toward the sheet clamper at a preselecting timing is arranged on the press drum or a member associated therewith. With this configuration, the printer causes the sheet clamper to surely clamp the leading edge of the sheet and prevents the sheet from rolling up. In addition, the printer feeds the sheet at a preselected timing with stability and reliability and thereby enhances accurate registration.

Abstract: A stencil printer or similar printer and an ink viscosity sensing device therefor are disclosed. The viscosity of ink which is the root cause of the degradation of image equality ascribable to, e.g., temperature and down time is directly sensed. The viscosity is combined with other information including a set print speed and the kind of the ink in order to effect delicate print pressure control matching the actual conditions of the printer. Stable image quality with a minimum of fluctuation is achievable against the varying environment and without resorting to complicated control pattern tables or a number of sensors.

Abstract: A heat-sensitive stencil having a thermoplastic resin film, and a porous resin layer formed thereon. The stencil has an air permeability in the range of 1.0 cm.sup.3 /cm.sup.2 .multidot.sec to 157 cm.sup.3 /cm.sup.2 .multidot.sec in a portion thereof when the thermoplastic resin film of the portion is perforated to form perforations providing an open ratio S.sub.O /S.sub.P of at least 0.2, wherein S.sub.O represents a total area of the perforations and S.sub.P represents the area of the portion. The heat-sensitive stencil is prepared by applying a coating liquid containing the resin of the porous resin layer to the thermoplastic resin film and drying the coating. The coating liquid contains a mixture of a good solvent and a poor solvent less vaporizable than the good solvent so that the porous resin layer is formed after drying.

Abstract: A heat-sensitive stencil including a porous support, and a thermoplastic resin film laminated on the support and having a surface smoothness of at least 10,000 seconds. The stencil is fabricated by bonding a thermoplastic resin film to a porous support with an adhesive having a specific viscosity and a specific volatile matter content, while maintaining each of the support and the film under a specific tension. The stencil may also be fabricated by applying a coating composition containing a resin and first and second solvents having a specific solubility and specific evaporation rates, and drying the applied composition to form a porous support. A printing master is produced by heating the above stencil imagewise by a thermal head with a heating energy of not greater than 0.05 mJ/dot.

Abstract: A master making device of the present invention includes a support member supporting a stencil roll such that a stencil can be paid out from the roll. A thermal head perforates the stencil paid out from the roll while a platen roller rotates while pressing the stencil against the head. The support member, thermal head and platen are constructed into a master making unit. The master making unit is removably mounted to the body of a printer via rails. A broader space than is conventional is available for the stencil to be set or replaced or for a jam to be dealt with without a document reading section being displaced relative to the printer body.

Abstract: A stencil perforating device including a stencil roll holding unit (11) for rotatably holding a stencil roll (16). The stencil roll holding unit has at least one identification mark (11A10, 11A11) which corresponds to at least one identification mark (P1, P2) of the stencil roll (16).

Abstract: A pair of paper delivery side fences is provided within a paper delivery unit so as to approach each other and move away from each other. A drive unit drives the pair of paper delivery side fences so as to change an opposite interval defined therebetween. At this time, the size of a sheet of transfer paper discharged to the paper delivery unit is recognized and the interval defined between the pair of paper delivery side fences is set to an interval corresponding to the size of the transfer paper. Thus, the interval defined between the opposed paper delivery side fences can be automatically set according to the size of the transfer paper delivered to the paper delivery unit and hence workability can be improved.

Abstract: A stencil printer capable of printing a multicolor image on a sheet of the present invention includes a plurality of drums arranged side by side in an intended direction of sheet transport at a preselected interval. Ink of particular color is fed to the inner periphery of each drum carrying a respective master around its outer periphery. An intermediate transport device transports a sheet from an upstream drum to a downstream drum. A controller controls the sheet conveyance speed of the intermediate transport device and/or the print conveyance speed of the downstream drum in accordance with the size and/or the position of the sheet. The printer allows a minimum of double printing and misregister to occur by making up for a delay of transport of the sheet to the downstream drum.

Abstract: A device for collecting waste or used masters and applicable to a stencil printer or similar printer is disclosed. The device includes a waste master box accommodating a compression plate therein. The compression plate is rotatable at least more than 90 degrees about a shaft on which it is mounted. Every time a waste master peeled off a print drum is introduced into the box, the compression plate rotates over the above angular range in order to compress the waste master. The box prevents consecutive waste masters sequentially compressed by the compression plate from being localized.

Abstract: A stencil printer capable of conveying a paper by clamping the leading edge portion of the paper and printing an image on the paper is disclosed. Even when an envelope or similar relatively thick paper is used, the printer protects a master wrapped around an ink drum from ripping which would bring about various troubles including the contamination of printings due to ink.

Abstract: A thermal master making device and a thermal recording device each including a thermal head and a platen roller. The master making device thermally perforates, or cuts, a thermosensitive stencil for making a master while the recording device thermally records an image on a thermosensitive recording medium. The devices each reduce the corrosion of an expensive thermal head in any environmental conditions while guaranteeing the conveyance of the stencil or the recording medium. The stencil and recording medium each contain a corrosive substance in an antistatic agent or adhesive or an overcoat layer thereof. The corrosion of the head would directly translate into defective images. With the above devices, it is possible to reduce a burden on the user and to extend the life of the head. Extending the life of the head is desirable from the environmental standpoint also.

Abstract: A stencil printer of the present invention includes an ink drum and a press drum rotatable with a paper or similar recording means wrapped therearound while pressing the paper against the ink drum. A moving mechanism selectively moves the press drum into or out of contact with the ink drum in synchronism with the feed of the paper order to prevent the press drum from contacting the ink drum when the paper is absent therebetween. Even when the moving mechanism angularly moves the press drum, the press drum is free from a change in peripheral speed and can surely catch the leading edge of the paper. Drive transmission to the press drum is implemented by an Oldham coupling or a universal coupling.