Stencil printing apparatus

Abstract: A stencil printing apparatus comprising a base (1) on which an original is set during a perforating operation and an item to be printed is set during a printing operation, a pressing member (2) pivotally attached to one end of the base (1) and having mounting means for mounting a stencil sheet (5) on a plane facing against the base, and supporting means arranged to be projected near the mounting means at the pressing member (2) and supporting a part of peripheral edges of the engaged stencil sheet (5).

Description: This invention relates to a stencil printing apparatus in which a heatsensitive perforating and a stencil printing are carried out by one unit of printing device, and more particularly a stencil printing apparatus capable of performing both making of a perforated plate and printing well. Fig. 10 is a perspective view showing a known stencil printing apparatus. This device is comprised of substantially a base 1, a pressing plate 2 which can be rotated against the base 1 and a light radiating device 3 which can be freely set to or removed from the pressing plate 2. The making of perforated plate is carried out such that the light radiating device 3 and a stencil sheet 5 are attached at the side of the pressing plate 2 and the pressing plate 2 is pushed against the base 1 while the original is being placed on the base seat 4 of the base 1. In addition, printing is carried out similarly by a method wherein the pressing plate 2 is pushed against the item to be placed on the base seat 4 while printing ink is included in the stencil sheet 5. The stencil sheet 5 has a frame member 5a of which circumference is formed by a hard sheet of paper or the like and in the case of performing the making of perforated plate and printing operation, the sheet is engaged with and held by guides 6a on the transparent plate 8 arranged at a plane of the pressing plate 2 oppositely facing against the base 1. However, when the stencil sheet 5 is set or removed, the stencil sheet 5 sometimes scratches the transparent plate 8 to make scar on it. The transparent plate 8 in the device disclosed in the gazette of Japanese Utility Model Laid-Open No.Sho 58-133455 was constructed such that light radiated from the light radiating device 3 passed through the transparent member to make a heatsensitive perforated plate of the stencil sheet 5, so that if the transparent plate 8 was scarred, this scar might cause a lack of radiation of light beam to be generated and a poor perforated part was sometimes generated at the same location in the stencil sheet 5. Upon application of the stencil sheet 5 having poor making of perforated plate, irregular printing such as blur may be produced at the same location also during the printing operation. The present invention has been completed in order to solve the aforesaid problem, wherein it is an object of the present invention to provide a stencil printing apparatus in which the transparent plate is not scarred when the stencil sheet is set to or removed from the device, a poor making of the perforated plate caused by this scar can be prevented and a printing quality can be improved. The present invention is as claimed in claim 1 or claim 2 with optional features as claimed in the dependent claims. In the case that the stencil sheet is set or removed along the mounting means, the outermost parts of the peripheral edges of the stencil sheet are pressed by the mounting means, portions slightly inside the outermost parts are slightly lifted up by the supporting members from the pressing plane. With such an arrangement as above, the stencil sheet is warped toward the base to generate a clearance between itself and the surface of the pressing plane. The sheet is not scratched with the pressing plane and does not scar the pressing plane. The perforating process can be performed well. In addition, during the printing operation, since the stencil sheet is curved by the supporting members toward the item to be printed, the stencil sheet is positively contacted with the item to be printed and the scar in an image can be prevented. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a top plan view for showing a transparent plate to be used in a stencil printing device; Fig. 2 is a sectional view taken along a line A-A of Fig. 1; Fig. 3 is a partial sectional view for showing a side guide; Fig. 4 is a sectional view for showing a setting state of a stencil sheet; Fig. 5 is a partial sectional view for showing a modification of a rib; Fig. 6 is a perspective view showing a setting or a removing configuration of a light radiating device; Fig. 7 is a front elevation view partly broken away for showing a releasing means when installed; Fig. 8 is a sectional view taken along a line B-B of Fig. 7; Fig. 9 is a sectional view showing a releasing operation of the releasing means when installed; and Fig. 10 is a perspective view of a known stencil printing apparatus. Fig. 1 is a top plan view showing a transparent plate to be used in a stencil printing apparatus of one preferred embodiment of the present invention. Fig. 2 is a sectional view taken along a line A-A of Fig. 1. In these figures, the same elements as those of the prior art are denoted by the same reference numbers. A transparent pressing flat plane (a transparent plate) 8 having a predetermined thickness is formed by synthetic resin and the like. This transparent plate 8 is arranged at a side of the pressing plate 2 of the device, i.e. at a plane facing against the base seat 4 on the base 1. This transparent plate 8 is formed to have a larger size than a width and a length of the stencil sheet so as to engage with and hold the stencil sheet. Engaging means (side guides) 9 projecting from a plane 8a of the transparent plate 8 are arranged continuously at both sides of the transparent plate 8 over a predetermined length. Each of the side guides 9 is bent oppositely from each other and formed into an virtual L-shape, and both sides of a stencil sheet 5 inserted from the upper part shown in Fig. 1 into these opposite guides 9, 9 are engaged and held while they are being guided. A stopper guide 10 is similarly arranged at a front end (a lower part as viewed in this figure) in an inserting direction of the stencil sheet 5 so as to engage with and hold the front end of the stencil sheet 5. Thus, the stencil sheet 5 is engaged and held at a total number of four locations of a pair of side guides 9, the stopper guide 10 and a holding guide 11 arranged at positions facing against the stopper guide 10. Fig. 3 is a partial sectional view for showing the side guide 9. A width L of the side guide 9 is set to be a length where it is contacted with a frame part 5a of the stencil sheet 5 and located more outside than a printing-enabled region (a perforating/printing plane) 5b. As shown in Fig. 1, supporting means (ribs) 12 in parallel with the side guides 9 are projected continuously and formed on the plane 8a of the transparent plate 8 and from the end surface positions of the side guides 9 to their inner sides (for example, a height of 0.5 mm). Each of both ends 12a of the ribs 12 is formed into a tapered shape and projected from above the plane 8a without any step. As shown in Fig. 3, the rib 12 is formed with a slant surface 12b having a predetermined angle directed toward the side guide 9. A clearance S between the upper surface of the rib 12 and the lower surface of the guide 9 is formed to be virtually equal to a thickness of the stencil sheet 5 or slightly larger than that. More practically, when a thickness of the frame member 5a of the stencil sheet 5 is 1.3 mm, the clearance S is 1.5 mm. Then, installing of the stencil sheet 5 having the aforesaid configuration is carried out such that as shown in Fig. 1, the stencil sheet 5 is inserted between the side guides 9, 9. Each of both sides of the stencil sheet 5 is guided by the side guides 9 and advances in a longitudinal direction of the device. At this time, as shown in the operational diagram of Fig. 4, the stencil sheet 5 is lifted up at its inner position from both side edges and this stencil sheet 5 is warped like a pot-belly shape. With such an arrangement as above, the stencil sheet 5 advances while the central part 5b of the stencil printing surface of the stencil sheet 5 forms a clearance M spaced apart from the plane 8a of the transparent plate 8 by a predetermined amount. Thus, the stencil sheet 5 does not contact the transparent plate 8 when installed and does not scratch the transparent plate 8. Accordingly, even in the case that the light radiating device 3 is operated to perforate an original image onto the stencil sheet 5, it can be perforated under a state in which no scar is produced on the transparent plate 8, resulting in that the perforating can be performed well. Upon completion of formation of the perforated plate, the ribs 12 may form the clearance M between the stencil sheet 5 and the transparent plate 8 also in the case that the stencil sheet 5 is removed from the pressing plate 2, so that the transparent plate 8 may not be damaged also when its removing operation is carried out. In addition, in the case that the ribs 12 are provided with slant surfaces 12b, setting or removing of the stencil sheet 5 can be easily carried out against the side guides 9, the stencil sheet 5 is entirely warped along the slant surfaces 12b and a local bending force is not applied to the sheet, resulting in that the stencil sheet 5 may not be damaged. In addition, after making the perforated plate, the stencil sheet 5 is removed from the pressing plate, ink is fed on the sheet, the sheet is set again at the pressing plate, a paper to be printed is placed on the base seat 4 to perform a printing operation, wherein also during this printing operation, the ribs 12 may form a clearance M between the stencil sheet 5 and the transparent plate 8. With such an arrangement as above, since a middle part of the stencil sheet warped at its part M is continuously projected toward the base seat 4 during this printing operation, this middle part can be positively contacted with the paper to be printed and it becomes possible to prevent a blurred image in the prior art from being produced. In addition, the ribs 12 in the aforesaid preferred embodiment may be formed in a rectangular shape as viewed in their section. Further, in the case that the ribs 12 are arranged just below the side guides 9, the side guides 9 are inclined to have a predetermined angle toward the central part of the transparent plate 8 as shown in Fig. 5. With such an arrangement as above, the stencil sheet 5 is partially inclined by the side guides 9 and the inclined surfaces 12b of the ribs 12 as shown in the figure and the sheet can be warped entirely like a pot-belly shape in the same manner as that shown in Fig. 4. Then, setting or removing configuration of the light radiating device 3 against the pressing plate 2 will be described. As shown in Fig. 6, an opening 2a is formed at the upper surface of the pressing plate 2 at the corresponding position in the transparent plate 8, and the light radiating device 3 having its corresponding shape is removably installed at the opening 2a. An mounting piece 3a is projected and formed at one end part of the light radiating device 3 and the other end of the light radiating device is provided with electrical conducting contact points 3b and 3c. The pressing plate 2 is opened and formed with an mounting hole 2b corresponding to the mounting piece 3a, and the other end of the opening 2a is provided with contact points 2c, 2d contacted with the contact points 3b, 3c, respectively. Then, the light radiating device 3 is installed at the opening 2a while the mounting piece 3a is being engaged with the mounting hole 2b. Upon installation, the light radiating device 3 is connected in circuit through contact points 3b, 3c, 2c and 2d to a power supply such as a battery cell or the like stored in the pressing plate 2, and the light source such as flash bulbs or the like becomes a state in which light can be emitted. Then, at a central position of the stopper guide 10 is arranged an installing state releasing means 20. This installing state releasing means 20 enables the light radiating device 3 to be installed at the pressing plate 2 only when the stencil sheet 5 is set at its specified position in the side guides 9 of the pressing plate 2. Fig. 7 is a front elevation view partly broken away to show the installing state releasing means 20 and Fig. 8 is a sectional view taken along a line B-B. Between the transparent plate 8 and the stopper guide 10 is projected a contact piece 21a of a turning lever 21, wherein the turning lever 21 is pivotaly supported at its shaft 21b to a supporting part 2f of the pressing plate 2. This turning lever 21 is provided with a connecting surface 21c on a position where it passes through the shaft 21b. The connecting surface 21c forms a predetermined angle with the contacting piece 21a around the shaft 21b and it is contacted with an abutting surface 22a of the stopper member 22. The stopper member 22 is provided with a stopper piece 22b having a predetermined width at its upper part, and slide projections 22c at both sides are freely fitted in the linear grooves 2h formed in the pressing plate 2. The stopper member 22 can be slid along the linear grooves 2h and always urged toward the turning lever 21 by a spring 23 inserted between it and the pressing plate 2. Then, as shown in Fig. 8, in a state in which the stencil sheet is not set on the transparent plate 8, it is stopped in a state in which the abutting surface 22a of the stopper member 22 is abutted against the entire surface of the connecting surface 21c of the turning lever 21, and the stopper piece 22b of the stopper member 22 closes the mounting hole 2b. In this state, since the mounting piece 3a of the light radiating device 3 can not be inserted into the mounting hole 2b, the light radiating device 3 can not be installed at the opening 2a of the pressing plate 2. As described above, the installing state releasing means 20 prohibits a setting of the light radiating device 3 in respect to the pressing plate 2 in a state in which the stencil sheet 5 is not set in the pressing plate 2 so as to prevent the perforated plate from being made, resulting in that an erroneous perforating of the stencil sheet can be prevented. With such an arrangement as above, making of the perforated sheet with the light radiating device 3 in a state having no setting of stencil sheet 5 at the pressing plate 2 is prohibited, thereby a disadvantage that the original image is adhered by heat directly to the plane 8a of the transparent plate 8 can be prevented in advance. In turn, as shown in the operational block diagram of Fig. 9, when the stencil sheet 5 is set on the transparent plate 8, the extremity end of the stencil sheet 5 is contacted with the contact piece 21a of the turning lever 21 of the installing state releasing means 20 and presses it down. Then, the turning lever 21 is rotated in the direction C as viewed in the figure around the shaft part 21b and the end part 21ca of the connecting surface 21c pushes against the abutting surface 22a of the stopper member 22, resulting in that the stopper member 22 is slid in the direction D as viewed in the figure against a urging force of the spring 23. Accordingly, a stopper piece 22b of the stopper member 22 is retracted from the mounting hole 2b and the mounting hole 2b is opened. In this state, the mounting piece 3a of the light radiating device 3 can be inserted into the mounting hole 2b and the light radiating device 3 can be installed at the pressing plate 2. In this way, the installing state releasing means 20 allows the light radiating device 3 to be installed against the pressing plate 2 in response to the fact that the stencil sheet 5 is already in the pressing plate 2 and then the perforating the stencil plate can be performed. Upon completion of printing after making of the perforated plate and upon removal of the stencil sheet 5 from the transparent plate 8 after removal of the light radiating means 3, the installing state releasing means 20 returns back the state shown in Fig. 8 by a urging force of the spring 23, wherein the stopper piece 22b of the stopper member 22 closes the mounting hole 2b so as to prohibit a setting of the light radiating means 3. This installing state releasing means 20 is constructed such that it is arranged inside the stopper guide 10 and it can not be directly touched with a hand and further it can be operated only through its contact with the stencil sheet 5, resulting in that its erroneous operation or improper use can be prevented. In addition, in the case that this installing state releasing means 20 is placed in the device in which the stencil sheet 5 is slid along the surface of the transparent plate 8 and set, it is preferable that it is installed at a downstream side rather than an upstream side inserting direction, in particular, at the front end as found in the aforesaid preferred embodiment. If it is placed at the downstream side, there is no possibility that the installing state releasing means 20 is released under a condition in which the installing of the stencil sheet 5 is incompletely carried out. In addition, in the case that the stencil sheet 5 is fixed on the transparent plate 8, the spring 23 pushes the end part 21ca of the turning lever 21 through the stopper member 22. In this way, the turning lever 21 is urged in such a direction as one in which the contact piece 21a pushes the extremity end of the stencil sheet 5. Thus, the stencil sheet 5 fixed on the transparent plate 8 is pushed toward the holding guides 11 and its rear end is pushed against the holding guides 11, so that it is held more positively on the transparent plate 8 as compared with that of its holding only with the side guides 9 or the ribs 12 and the like. In the aforesaid preferred embodiment, although the configuration in which the stencil sheet 5 is inserted from a longitudinal direction of the device has been described in reference to a vertical-type device, similar actions and effects may also be attained for a lateral-type device. In the lateral-type device, the mounting means 9 which are continuous in opposition to the lateral direction are provided and the stencil sheet 5 is set from this lateral direction. In the case of the device in which a sheet is set from a lateral direction, the installing state releasing means 20 is arranged at a lateral position. However, even if the installing state releasing means 20 is placed in a lateral direction, a similar installing or releasing operation can be carried out. The supporting means for supporting the peripheral part of the stencil sheet while being projected from a plane facing against the base is installed near the mounting means for mounting the stencil sheet, so that when the stencil sheet is projected by a predetermined amount toward the base and the pressing plate is turned toward the base during perforating operation and printing operation, the stencil sheet can be positively contacted with either the original or an item to be printed on the base seat at its entire surface. Although the stencil sheet which can be set or removed is slid on the pressing plate along the mounting means, the stencil sheet can be set or removed while the sheet is warped and is forming a predetermined clearance between itself and the pressing plate due to the fact that the supporting means are projected and arranged at the sides of the mounting means, and further this pressing plate may not be damaged. Accordingly, a perforating operation can be performed well without being influenced by scar. In addition, if the supporting means is formed with inclined surfaces of predetermined angle facing toward the mounting means as described in Claim 3, the entire stencil sheet can be warped like a pot-belly shape along the inclined surfaces ranging from the mounting means to the inside portion, a local bending force is not applied to the stencil sheet, the sheet may not be damaged and its central portion can be spaced apart positively from the pressing plane.

Claims: A stencil printing apparatus comprising: a base (1) on which an original is to be set during a perforating operation and an item to be printed is to be set during a printing operation; a pressing member (2) pivotally attached to one end of said base (1) and having mounting means (9) for mounting a stencil sheet (5) in a plane facing against said base (1); and supporting means (12) projecting near said mounting means (9) of said pressing member (2) positioned to support a part of peripheral edges of a stencil sheet (5) upon engagement of the stencil sheet with the mounting means (9). A stencil printing apparatus adapted to be used with a stencil sheet, said stencil printing apparatus comprising: a base (1) on which an original is to be set during a perforating operation and an item to be printed is to be set during a printing operation; a pressing member (2) pivotally attached to one end of said base (1) and having a through-pass opening (2a) formed therein; a transparent plate (8) arranged at the opening (2a) of said pressing member (2), said transparent plate (8) having a pressing plane (8a) facing against said base (1); mounting means (9) arranged at said pressing plane (8a) facing against said base (1) and positioned to contact with the peripheral edges of a stencil sheet when facing against said base and to engage with said stencil sheet (5); and supporting means (12) placed at a position inside said mounting means (9) and outside a printable region of said stencil sheet (5) when engaged with said mounting means (9) in said pressing plane (8a) facing against said base (1), the supporting means (12) being arranged along said mounting means (9) and so as to project a stencil sheet, when engaged with said mounting means (9), toward the base (1). A stencil printing apparatus as set forth in Claim 2 in which said mounting means (9) are formed along a setting or a removing direction of said stencil sheet (5). A stencil printing apparatus as set forth in Claim 3 in which said mounting means (9) are pair of parallel mounts which extend in the setting or a removing direction of a stencil sheet (5). A stencil printing apparatus as set forth in Claim 2 in which said supporting means (12) are projections formed along a setting or a removing direction of a stencil sheet (5). A stencil printing apparatus as set forth in Claim 5 in which said supporting means (12) are located so as to contact both sides of a stencil sheet (5) in parallel with a setting or a removing direction of said stencil sheet (5). A stencil printing apparatus as set forth in Claim 6 in which said supporting means (12) have inclined surfaces of a predetermined angle at sides facing against said mounting means (9). A stencil printing apparatus as set forth in Claim 6 in which both ends of said supporting means (12) rise gradually from said pressing plane (8a). A stencil printing apparatus as set forth in Claim 2 including a stencil sheet (5) in which a space in a thickness direction of said stencil sheet (5) between a contact position between said supporting means (12) and said stencil sheet (5) and a contact position between said mounting means (9) and said stencil sheet (5) is set to be substantially equal to or more than a thickness of said stencil sheet (5).

Inventors: KODAMA KENGO, YAMAGISHI HIDEAKI, KODAMA, KENGO, YAMAGISHI, HIDEAKI, Kodama, Kengo, c/o Riso Kagaku Corp. R&amp;D Center, Yamagishi, Hideaki, c/o Riso Kagaku Corp R&amp;D Ctr
Applicants: RISO KAGAKU CORP, RISO KAGAKU CORPORATION
Application year: 1996
Main classification: B41L13
IPC codes: B41C1, B41L13