Riso Kagaku Corporation

Masakazu Miyata

Yoshikazu Hara

Hiroshi Hanzawa

Tomoko Nagano

Hitoshi Watanabe

Masahiro Nishihata

Kosai Adachi

Katsuro Motoe

Yoshihiro Noguchi

Toshihiro Bansyo

Koji Nakayama

Kaoru Kimura

Mitsuru Takeno

Tetsuya Hashimoto

Mashiro Nishihata

A stencil printing machine includes an image reading section, an image processing section for processing to convert image data into perforating data which is used for perforating a stencil sheet, an image perforating section for perforating the stencil sheet in accordance with the perforating data, a printing section for applying ink to a print sheet by using the perforated stencil sheet, and a data holding section for holding perforating data in stencil making operation as re-perforating data. When the number of print sheets comes to a predetermined number, the re-perforating data held in the data holding section is used to re-perforate another stencil sheet to exchange with the previous stencil sheet. The printing is again performed.

Stencil printing machine and stencil printing method

In the multi-drum type rotary stencil printer adapted to drive a plurality of printing drums altogether in synchronization with one another by a common drive mechanism, when one of the printing drums is placed out of engagement with a printing, a degradation of ink is anticipated in the temporarily rested printing drum due to its excessive stirring during an idling rotation. In order to avoid such an ink degradation, a clutch is incorporated in a route of transmitting a driving force from the common drive mechanism to each of the printing drums, so that the transmission of the driving force through each of the route can be selectively interrupted.

Multi-drum rotary stencil printer with each selected printing drum isolatable from rotation

According to the stencil making and attaching method of a printing device of the present invention, independent of variations in the detection of the stencil sheet set position detection sensor and variations in the clamped state due to curled stencil sheet, etc., it is possible to always set the image-formation start position of the stencil sheet at a regular position with respect to the drum rotation position, and consequently to improve the positional precision of the printing operation.

Stencil making and attaching method of printing device

A stencil printer has a rotary printing drum removably supported in a printer body. A lamp is provided inside the printer body, and a control circuit permits, in response to an action necessary for maintenance of the printer body, the lamp means to be turned on.

Stencil printer

Overlapped paper feed can be detected easily and promptly. Along a paper feeding path, a light emitting element 1 and a light receiving sensor 2 are placed face to face and a detection signal corresponding to the light transmissivity of paper is output. The detection signal is not amplified by one system and amplified at a predetermined amplification ratio via an amplifying circuit 3 in the other system. An A/D converter 5a or 5b is set in each system and outputs the detection signal to a CPU 6 after sampling the detection signal. The CPU 6 detects overlapped feed by selecting the system whose detection signal value is within the effective range which is not effected by noise and not at a saturation level.

Overlapped feed detecting device

A multiple feed detecting system is provided with a sheet thickness sensor which outputs thickness signals representing the thickness of a sheet to be conveyed, and a sheet size sensor which detects the size of the sheet to be conveyed as measured in the direction of conveyance. A detecting area is set according to the size of the sheet detected and whether multiple feed occurs is determined on the basis of sampling data obtained by the sheet thickness detecting sensor over the detecting area set.

Multiple feed detecting system

In stencil printing, a printing matrix is thermally made in a printing matrix area on a stencil material on the basis of image information representing an image on an original. The printing matrix area is determined according to the sheet size of printing paper sheet. The stencil thus obtained is wrapped around a printing drum and a printing paper sheet fed toward the printing drum is pressed against the printing drum by a pressure member. A memory which is provided on the printing drum side stores information on the area of the printing matrix. The sheet size is compared with the area of the printing matrix based on information extracted from the memory. When the former is smaller than the latter, printing is inhibited and an error signal which advises against printing is output.

Stencil printer and method of stencil printing

In order to indicate more distinctly the results of transverse and longitudinal adjustments of a print image, in a printer image position indicating device, a standard print position indication mark showing a printing master being positioned at the standard position relative to a print sheet and a biased print position indication mark showing a biased position of the printing master in either or both of the transverse and longitudinal directions relative to the standard position are expressed as marks each including at least two straight lines perpendicular to one another, and the biased print position indication mark is biased in the transverse and/or longitudinal directions according to a corresponding biasing of the printing master relative to the print sheet. The standard print position mark and the biased print position mark are expressed by different kinds of lines so as to clearly contrast one against the other. In addition, the biased print position indication mark is biased at a greater rate than a ratio of a biasing amount of the printing master from the standard position to the site of the printing master.

Print image position indication device

In a stencil printer in which a printing drum is carried by a carrier mounted in a frame body of the printer to be transversely withdrawable from the frame body on its one side for maintenance, etc., the carrier is selectively engaged with a transverse position adjustment device at its operating position inside the frame body, wherein the transverse position adjustment device engages the carrier to adjust its transverse position for adjustment of transverse position of print image via a latching mechanism so that, when the carrier is to be disengaged from the transverse position adjustment device for the withdrawal, the transverse position adjustment device once shifts the carrier to its terminal biasing position toward the withdrawal direction and returns to its standard transverse position, while disengaging the latching mechanism at the moment of reversing its biasing movement.

Stencil printer equipped with print image transverse position adjustment

A cut sheet feeder for an image forming apparatus is basically formed of one sheet feed mechanism for picking up stacked cut sheets at a single sheet feed position, a sheet feed unit vertically movable relative to the sheet feed mechanism, a cassette detachably attached to the sheet feed unit and containing the cut sheets, and a sheet feed table vertically movably situated inside said sheet feed unit and carrying a large number of the cut sheets.. The feeder further includes a cassette presence detection device for detecting presence or absence of the cassette on the sheet feed unit, a cover detection device for indicating an opening status of a cover for the sheet feed unit, a mode establishment device for establishing a cassette feed mode or a table feed mode, and a mode control device for controlling the sheet feed unit. The mode control device lowers the sheet feed unit to a predetermined position in case the cassette feed mode is changed to the table feed mode by the mode establishment device while the cover detection device outputs a detection signal indicating a closed status of the cover and the cassette presence detection device outputs a signal indicating the presence of the cassette.

Cut sheet feeder for image forming apparatus

A cut sheet feeder for use with an image forming apparatus is formed of a sheet feed mechanism for picking up stacked cut sheets one at a time from a single sheet feed position and for feeding each sheet to an image recording portion; a sheet feed unit which is vertically movable relative to the sheet feed mechanism and to which a cassette containing cut sheets may be attached in a detachable manner; a sheet feed table which is vertically movable within the sheet feed unit and which carries a large number of cut sheets; a cassette presence detection device for detecting the presence and absence of a cassette on the sheet feed unit and for outputting a signal indicating either the presence or the absence of the cassette; a power switch for starting and stopping the cut sheet feeder; and a mode establishment device. A cassette feed mode involving the cassette for minority sheet feed is established if the detection signal from the cassette presence detection device indicates the presence of the cassette when the power switch is turned on, and a table feed mode involving the sheet feed table for majority sheet feed is established if the detection signal from the cassette presence detection device indicates the absence of the cassette.

A cut sheet feeder for use with an image forming apparatus, is formed of: a sheet feed mechanism for picking up stacked cut sheets one at a time from a single sheet feed position and for feeding each sheet to an image recording portion; a sheet feed unit which is vertically movable relative to the sheet feed mechanism and to which a cassette containing cut sheets may be attached in a detachable manner; a sheet feed table which is vertically movable within the sheet feed unit and which carries a large number of cut sheets; a plurality of detectors for detecting the positions of the sheet feed unit, the sheet feed table and the cut sheets relative to the sheet feed position; and a sheet overload detector. The overload is detected by the detectors with respect to the relative position between the sheet feed unit and the sheet feed table with reference to the sheet feed position. A mode controller controls the vertical movement of the sheet feed unit and the sheet feed table and stops the vertical movement when the detection signal from the sheet overload detector is admitted.

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.

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Ibaraki-ken, Japan

Masakazu Miyata