Abstract: Firming folds for increasing the firmness of the stencil itself are generated at a leading end of the stencil to be mounted to a cylindrical printing drum of a rotary stencil printer or a trailing end of the stencil mounted to the printing or both. To do so, a pair of rollers one of which has projections to form the folds at the stencil are provided to feed the stencil therebetween toward a stencil leading end mounting means of the printing drum positioned at a standby position.

Abstract: A stencil printer having a printing drum which is inked from the inside thereof. In order to prevent leaking out of ink from the perforated portion over the non-perforated stencil sheet leading end mounting portion of the stencil printing drum, in a construction wherein a printing drum cooperates with a back press roller or a transfer roller with a transverse bar portion of the printing drum is received in a transfer groove of the back press roller or the transfer roller, the outer circumferential length of the perforated portion of the printing drum and the traverse groove of the back press roller or the transfer roller and the relative rotation phase therebetween are so determined that the perforated portion is not laid one over the other with the transfer groove.

Abstract: A process for perforating a stencil sheet comprising a thermoplastic resin film is disclosed which process comprises melting predetermined portions of the thermoplastic resin film with the heat from heat-generating elements to form perforations while applying a pressure to the film and under such a condition that the film is spaced away from the heat-generating elements by a close distance. According to the process of the invention, perforations through which ink passes smoothly can be formed in a stencil sheet using a thermal head and thus clear images can be obtained.

Abstract: A printing drum for a rotary stencil printer having a sidewall in the form of a flexible perforated sheet. In order to allow for a bulging out deformation of the sidewall by an internal press roller to be easier and more uniform over the entire width of the printing, the flexible cylindrical body of the printing drum has its opposite side edge portions seated around the outer circumferential surfaces of a pair of annular portions (10a, 10b). The drum is constructed to have an inner circumferential length greater than the circumferential length of the outer circumferential surface of the annular portions by a predetermined amount which allows for a predetermined bulging out deformation of the flexible cylindrical body.

Abstract: In order to make the bulging out deformation of the printing drum of a rotary stencil printer having a flexible cylindrical body by the internal press roller to be more easy and more uniform over the entire width of the printing, a flexible perforated sheet (20) forming the flexible cylindrical body of the printing drum is beforehand constructed to be a cylindrical body with its opposite annular edge portions being laid over a pair of annular portions (10a, 10b) connected with one another by a transverse bar portion (12), wherein the internal circumferential length of the cylindrical body made of the flexible perforated sheet is larger than the outer circumferential length of the annular portions by a determinate amount for allowing a part of the flexible cylindrical body to bulge radially outwardly, and the flexible cylindrical body is latched at a portion thereof laid one over the other with the transverse bar portion against relative circumferential movement while relatively movable in the radial direction

Abstract: A mimeographic transfer printing machine includes a stencil support drum for supporting a stencil, an ink supply device for forcing ink through the stencil supported on the stencil support drum, an ink receiving transfer drum to which the ink forced out from the stencil is to be transferred, and a sheet support device for supporting a printing sheet to which the ink on the ink receiving transfer drum is to be transferred. The stencil support drum has a slightly larger diameter than the transfer drum so that the circumferential speed of the stencil support drum is greater than that of the transfer drum to provide to the stencil a tension acting in a direction opposite to the rotation of the stencil support drum.

Abstract: A mimeographic printing apparatus having a printing drum wound with a stencil and a clamping plate for fastening one end of the stencil on the drum. An elastic holding device is provided over a clamping position with a gap from the drum enough to receive one end of the supplied stencil. The holding device is, at the clamping state, pressed by the clamping plate to fasten one end of the stencil on the printing drum. At the non-clamping position, the holding device returns to the original position and here restrains the external curling of the stencil. The result is that the stencil thereafter reliably introduced to the removing device, thereby realizing a normal stencil-removing operation.