GB2309195A - A stencil printer with a stencil cassette - Google Patents

Description

1 A STENCIL PRINTER WITH A STENCIL CASSETTE 2309195 The present invention

relates to a stencil printer and a stencil cassette to be removably mounted on the drum of the stencil printer for feeding a stencil.

A stencil printer, particularly a stencil printer capable of cutting a stencil with a thermal head, wrapping it around a drum, printing, and discharging the stencil automatically is easy to operate and extensively used in various facilities, e.g., offices and schools for producing various kinds of printings. In this type of printer, a master making section cuts a stencil paid out from a stencil section by heat. After the cut portion of the stencil has been brought to a drum by a transport mechanism, a cutter mechanism cuts it off to produce a master. The master is wrapped around the peripheral wall of the drum. As paper is fed to a printing section, an image is printed thereon via the master. Thereafter, the master is collected in a discharging section.

The problem with the conventional printer described above is that the transport mechanism for implementing such - 2 a procedure is complicated and apt to cause defective transport and other troubles to occur. Moreover, a mechanism for wrapping the master around the the drum and clamping i t thereon is needed, increasing the overall size of the printer.

To eliminate the above problems, Japanese Patent LaidOpen Publication No. 62-73987 proposes a printer in which a stencil feeding section, a stencil discharging section and a master making section are located around the peripheral wall of a drum. This printer cuts a stencil with a thermal head, 1 0 wraps it around the drum, prints, and then discharges the used stencil without cutting it off. stencil feed and discharge unit adjoining relative to the peripheral wall of a drum.

Specifically, the printer has a and rotatable The feed and discharge unit is made up of a feed section for paying out a 1 5 stencil from a Toll, a platen roller, a thermal head, and a discharge or take-up section for taking up the stencil or master used.

However, assume that when the used stencil or webbing is to be removed from the printer, the stencil extends over the take-up shaft and feed shaft with the trailing edge thereof left on the feed shaft. Then, the stencil cannot be removed fro m the printer unless the stencil attaching procedure is repeated all over again in the entirely reverse order, resulting in complicated steps.

- 3 It has been customary with a stencil printer to use a thermosensitive stencil made up of a suitable substrate which is permeable to ink, and a thermoplastic resin film formed on the substrate. After a thermal head has cut the film by heat to form an image, ink is permeated through the cut portion of the stencil, thereby transferring the image to a paper or similar medium. This kind of stencil may be provided with a thermal fusion preventing layer and an antistatic layer on the surface of the thermoplastic resin film, as taught in, 1 0 for example, Japanese Patent Laid-Open Publication Nos. 3 53992, 61-164896, and 1-314191. The fusion preventing layer is desirable since the surface of the resin fi 1 m is brought into contact with a thermal head without exception.

However, the fusion preventing layer should only be provided 1 5 on one side of the resin film that will contact the head.

Moreover, since the resin film is formed integrally with a hygroscopic substrate, e.g., Japanese paper, it sparingly suffers from static electricity. Even if static electricity is generated, the resin film is substantially prevented fro m 2 0 adhering to the operator's hand or the printer by virtue of sufficient elasticity thereof.

There has recently been proposed a printer operable with a stencil substantially implemented only by a thermoplastic resin film, i.e., a film lacking a substrate, as 2 5 disclosed in, for example, Japanese Patent 'Laid-Open - 4 Publication Nos. 62-282983 and 63-160895. Further, the stencil implemented only by a thermoplastic resin may be provided with an antistatic layer or a fusion preventing layer on one side thereof, as proposed in Japanese Patent Laid-Open Publication Nos. 1-238992, 1-237196 and 1-234294 by way of example.

However, the stencil having an extremely thin substrate or substantially implemented only by a thermoplastic resin film is low in mechanical strength and, therefore, apt to be 1 0 tom unless handled with care. Once the stencil is torn, it has to be attached to the take-up shaft all over again.

Furthermore, it is likely that this kind of stencil jams the transport path, wraps around a conveyor roller or otherwise affect transport due to low elasticity thereof. This tendency 1 5 is particularly prominent with the stencil constituted only by a thermoplastic resin film.

After printing, ink is left on the stencil in an amount of g/m3 to 19 g/M3 and simply wasted. Moreover, when the used stencil is rolled up again for storage or disposal, the ink left on the stencil increases the diameter of the Toll, making storage difficult or giving rise to a problem in respect of disposal. We conducted a series of experiments for scraping off the ink left on stencils by use of a blade or similar implement. However, the experiments showed that the blade configuration, squeezing conditions and other facfors cannot be set up easily, and that an amount 1 g/m' to 3 9/m' of ink still remains on a stencil.

It is an aim of the present invention to provide a stencil cassette and a stencil printer which feeds a 5 stencil to a drum included in the printer.

]n accordance with the present invention, there is provided a printer for using a stencil, including:

a drum having a portion permeable to ink in a part of a peripheral wall thereof around which a cut portion of the stencil can be wrapped; ink supplying means disposed in said drum; a stencil feed and discharge unit adjoining the outer periphery of said peripheral wall of said drum, and being rotatable relative to said peripheral wall of said drum, said stencil feed and discharge unit comprising at least a feed section for accommodating fresh stencil material in the form of a roll, a discharge section for taking up and accommodating said stencil used, and a platen roller for use in cutting said stencil; cutting means located independently of a rotation system of said drum for pressing, in the event of making a master, against said platen roller, thereby to cut the stencil by heat, said cutting means and said platen roller being moveable relative to each other in the event of making a master; and a cassette holding said stencil, comprising a take-up shaft to be installed in said discharge section, and a support member supporting said take-up shaft, such that stencil material paid out from said roll is takerizup by said take-up shaft.

is 6 The above and other aims, features and advantages of the present invention will become more apparent from the following detailed description, meant by way of example, taken with the accompanying drawings in which:

FIGS. 1A and 1B are respectively a front view and a side elevation showing a specific configuration of a cassette applicable to the present invention and accommodating a roll of stencil therein; FIGS. 2A and 2B are respectively a front view and a side elevation showing another specific configuration of the cassette; FIGS. 3A and 3B are respectively a front view and a side elevation showing still another specific configuration of the cassette; FIGS. 4A and 4B are respectively a perspective view and a side elevation showing a further specific configuration of the cassette; FIG. 5 is a section of a drum included in a printer having a stencil feed and discharge unit constructed integrally with the drum and the present invention is applicable; FIG. 6 is a sectional side elevation of the arrangement shown in FIG. 5; FIG. 7 is a section showing a specific arrangement wherein a master making section is located outside of the rotation system of the drum; 1 5 FIG. 8 is a view similar to FIG. 7, showing another specific arrangement wherein the master making section is located outside the drum; FIGS. 9A-91) demonstrate a specific procedure for wrapping a stencil around the drum in accordance with the 2 0 present invention; FIG. 10 is representative of another specific wrapping procedure available with the present invention; FIGS. IIA-11C show how the cassette of FIGS. 4A and 413 is mounted to the printer specifically; FIGS. 12A-12E show a procedure in which a stencil is paid out from the cassette of FIGS. 4A and 4B and wrapped around the drum; FIG. 13 shows the general construction of a conventional printer having a master making section and a printing section constructed integrally with each other; and FIG. 14 is a fragmentary sectional side elevation of the conventional printer.

1 0 To better understand the present invention. a brief reference will be made to a conventional printer having a master making section and a printing section constructed integrally with each other. As shown in Fig. 13, a stencil 70 in the form of a roll is paid out from a stencil feeding section 71. A master making section 72 has a platen roller 72a anda thermal head 72b. A cutter mechanism 73 cuts off a part of the stencil 70 which has been cut by the head 72b, thereby producing a master, or master sheet, 70a. A transport 2 0 mechanism 74 transports the master 70a to a printing section 75. There are also shown in the figure a drum 76 having a peripheral wall 76a, a master discharging section 77, and a paper 78. In operation, the master making section 72 cuts the stencil 70 paid out from the stencil feeding section 71 by 2 5 heat.After the cut portion of the stencil 70 has been brought ('Pt 1 5 to the drum 76 by the transport mechanism 74, the cutter mechanism 73 cuts it off to produce the master 70a. The master 70a is wrapped around the peripheral wall 76a of the drum 76. As the paper 78 is fed to the printing section 75, an image is printed thereon via the master 70a. Thereafter, the master 70a is collected in the discharging section 77.

As stated above, the conventional printer cuts t h e stencil 70 at the master making section 72, conveys it to the printing section 75, and then cuts it off with the cutter 1 0 mechanism 73 to produce the master 70a. The transport mechanism 74 for implementing such a procedure is and apt to cause defective transport and other occur. Moreover, a mechanism for wrapping the around the wall 76a of the drum 76 and clamping is needed, increasing the overall size of the complicated troubles to master 70a it thereon printer.

FIG. 14 shows a printer taught in Japanese Patent Laid Open Publication No. 62-73987 and elaborated to eliminate the above-discussed problems. Briefly, this printer locates a stencil feeding section, stencil discharging section and master making section around the peripheral wall of a drum, and cuts a stencil, wraps it around the drum, prints, and then discharges the used stencil without cutting it off.

Specifically, as shown in FIG. 14, the printer has a feed and 2 5 discharge unit 81 adjoining the peripheral wall 80a of a drum -10 and rotatable relative to the wall 80a. The feed and discharge unit 81 is made up of a feed section 83 for paying out a stencil 82 from a roll, a platen roller 84, a thermal head 85, and a discharge or take-up section 86 for taking up the stencil or master used. A part 80a of the drum wall 80 is permeable to ink. Ink supplied from ink supplying means 87 is fed to a paper, not shown, via the permeable part 80a of the drum wall 87.

However, the above-described printer has the previously 1 0 discussed problem. Specifically, assume that when the used stencil or webbing is to be removed from the printer, the stencil extends over the take-up shaft and feed shaft with the trailing edge thereof left on the feed shaft. Then, the stencil has to be removed from the printer by repeating the stencil 1 5 attaching procedure all over again in the entirely reverse order, resulting in complicated steps.

The present invention free from the drawbacks stated above will be described hereinafter. Briefly, in accordance with the present invention, a roll of stencil is received in a cassette. Only if 'the cassette is mounted to a printer, the stencil or webbing can be cut and then wrapped around a drum in a desirable manner. Therefore, the problems described previously are not given rise to so long as the cassette is set in a correct position.

FIGS. IA and IB show a specific configuration of such a cassette. As shown, the cassette has a feed shaft or roll shaft 22 around which a stencil 21 is wound in the form of a roll. The edge of the stencil 21 paid out from the roll is wound around another shaft or take-up shaft 23 located close to the feed shaft 22. The shafts 22 and 23 are affixed to a support member 31 through holes. A slit 311 is formed through the support member 31 and extends from the feed shaft 2 to the end of the member 31 via the take-up shaft 23.

1 0 A hole 312 is formed through the support member 31. After the cassette has been mounted to the printer, the hole 312 is used to remove the support member 31.

FIGS. 2A and 213 show another specific configuration of the cassette. This configuration differs from the 1 5 configuration of FIGS. IA and IB in that the feed shaft 22 is absent, in that the stencil 21 is rolled up in such a manner as to form a cylindrical through bore at the center thereof, and in that the outer periphery of the roll 21 and take-up shaft 23 are held by a support member 32. The reference numerals 321 and 322 respectively designate a slit and a hole formed through the support member 32.

FIGS. 3A and 313 show still another specific configuration of the cassette. As shown, the cassette has a support member 33 which is simpler than the support members shown in FIGS. IA and IB and 2A and 2B.

- 1Z - Perforations 331 are formed through the support member 33 in the horizontal direction.

The cassettes shown in FIGS. IA and IB and FIGS. 2A and 2B are each mounted to a printer with the feed shaft (feed section) 22 supported by a shaft, which is not related to the rotation of a drum, and with the take-up shaft (discharge section) 23 supported by a shaft movable in interlocked relation to the rotation of the drum. Thereafter, the support member 31, 32 or 33 is removed. Specifically, the support 1 0 member 31 or 32 can be removed only if a finger is put in the hole 312 or 322 and moved forward to pull the member 31 or 32. Also, the support member 33 can be removed only if it is torn off along the perforations 331.

FIGS. 4A and 4B show a further specific configuration of 1 5 the cassette. As shown, the cassette has a feed shaft 41 and a take-up shaft 42 which are separated from each other by two separable support members or casing parts 410 and 420.

However, in the longitudinal direction, the casing parts 4 10 and 420 contact each other only along the peripheral edges thereof to allow the stencil 21 to extend therethrough. The casing parts 410 and 420 have end walls 411 and 421, respectively. The feed shaft 41 and take-up shafts 42 are rotatable and respectively slightly protrude from the side walls 411 and 421 of the casing parts 410 and 420at opposite ends thereof. The reference numeral 422 designates an engaging member which will be described later.

In any one of the four specific cassette configurations, the edge of the stencil 21 paid out from the roll may be attached to the take-up shaft 23 or 42 by any conventional scheme, e.g., a two-sided adhesive tape, adhesive, slit formed in the shaft 23 or 42, or magnetism. The stencil 21 may be attached to the feed shaft 22 or 41 in the same manner as it is attached to the take-up shaft 23 or 42. However, in the 1 0 case where the webbing 2 1 should be fully taken up by the shaft 23 or 42 up to the end of the roll, it is preferable not to fix the end of the webbing 21 to the shaft 22 or 41; use may advantageously be made of a weak paste (easily separable paste). The feed shaft is not essential, as shown in FIGS. 2A and 2B and 3A and 3B.

Since the feed section and discharge or take-up section associated with the stencil 21 are connected together by the support member 31, 32 or 33 or the casing parts 410 and 420, a person can set the feed shaft and take-up shaft on a pr-inter 2 0 at the same time. Regarding the cassette of FIGS. IA and IB, 2A and 2B or 3A and 3B, the support member thereof is removed after the two shafts have been set on a printer. This reduces the moment of inertia of a drum included in the printer and, therefore, causes a minimum of load to lact on the 2 5 rotation system of the printer. In the case of the cassette - 1 it - shown in FIGS. 4A and 4B, it is only necessary that the casing parts 410 and 420 be separable after the cassette has been mounted to the printer. This is the prerequisite for the webbing 21 Since feed shaft degree, it Specifically, to be wrapped around the drum.

the stencil 21 is substantially not affixed to the 22 or is affixed thereto to an easily removable can be readily removed from the printer.

assume that the stencil 21 of the cassette has been used up and should be removed from the printer. Then, 1 0 the stencil 21 can be fully taken up by the take-up shaft 23 away from the feed shaft 22, i.e., from the drum while being left on the printer.

To removably connect the stencil 21 to the feed shaft 22 of the cassette, there should preferably be used a weak adhesive (easily removable adhesive).

may be implemented by an ordinary rubber, acryl, block copolymer, silicone adherinp- force of such adhesive should 1 5 This kind of adhesive composition based on vinyl ether, etc. The preferably be less than 10.0 g/mm, more preferably 5.0 gImm to 0.1 glmm and most preferably 2.5 glmm to 0.5 glmm, in terms of separation strength as measured when the stencil 21 is pulled at the portion thereof connected to the shaft 22 in a direction normal to the periphery of the shaft 22.

It is desirable that the weak adhesive be applied to the 2 5 feed shaft 22. Should the adhesive be applied to the stencil 21, most of it would remain on the stencil 21 after the separation of the stencil 21 from the shaft 22 and again cause the stencil 21 to adhere during transport along the transport path in the printer, thereby affecting the transport.

Further, at the position where the edge of the stencil 21 is adhered to the shaft 22, the former is bent inwardly of the latter. This allows the surface of the stencil 21 where the adhesive is deposited to be the surface which does not contact the thermal head, or allows the force for separating 1 0 the stencil 21 from the shaft 212 to be reduced. In addition, the shaft 22 is omissible, as shown in FIGS. 2A and 213 or FIGS. 3A and 3B.

The present invention is practicable with any conventional ink supply means having an ink reservoir, pump, ink supply tube, squeegee roller or blade, doctor roller, etc. The functions included in the ink supply means may be distributed to a plurality of locations and may be located on side walls associated with a drum, the inside of the drum, and even at locations other than the location adjoining the drum.

The peripheral wall of the drum may be implemented by a mesh of metal or chemical filaments with or without plating and may be configured in any conventional manner.

In accordance with the present invention, the support member described above is advantageous for an extremely thin stencil to be set on a printer and cut. Particu.1arly, the is made of a stencil resin film advantage is prominent when use implemented by a substantially thermoplastic lacking a substrate. A stencil constituted only thermoplastic resin film will be described hereinafter.

Also, in accordance with the present invention, the thermoplastic resin film is provided with a functional thin layer on both sides thereof. The resin film may be produced by an extrusion method or similar conventional method.

Regarding a material, use may be made of a resin based on 1 0 polyester (preferably copolymerized polyester), nylon (preferably copolymerized nylon), polyolefin, polystyrene, vinyl chloride, acrylic acid derivative, ethylene, vinyl alcohol, polycarbonate copolymer, etc. Among them, resins having high perforation sensitivity are desirable. In this respect, 1 5 the thermoplastic resin forming the fillm should lie substantially in a range of from the amorphous level to the crystallinity of 15 %. More preferably, the film should be of substantially amorphous level. Here, the words "film o f substantially amorphous level" refer to a film whose material 2 0 has hardly any melting point when subjected to a DSC method, a film whose crystallization was suppressed by, for example, quenching or similar treatment, etc. While crystallinity can be determined by an X-ray method, it may be determined in terms of the area ratio of melting energy by the DSC method.

by a - (_7 - More preferably, the thermoplastic film should be mainly constituted by copolymerized polyester and be of substantially amorphous level. Most preferably, copolymerized polyester, the as a raw rnaterial, should be substantially amorphous. The words "substantially amorphous polyester" refers to polyester other than commercially available ordinary resins whose major component is high crystallinity polyester terephthalate having a crystal melting point (determined by the DSC method) of 245C to 260'C.

1 0 Specifically, assume that a singular polymer, a polymer made up of mixture components, a mixture of polymers, or a mixture of polymers each being made up of mixture components is sufficiently annealed to equilibrium, and then the annealed composition has the crystallinity thereof fixed 1 5 by the X-ray method. Then, taking such a sample as a standard, the substantially amorphous polyester mentioned above should have crystallinity less than 10 %, preferably less than 5 %; more preferably, it has hardly any melting point when subjected to the DSC method. When this kind of low crystallinity type thermoplastic film is used, it can be perforated by heat sufficiently even through the energy of a thermal head may be small.

The thermoplastic resin film should preferably be 0.5 pm to 20 pm thick, more preferably 1 pm to 10 pm thick. The - 1:5 - fusion start temperature should be STC to 300'C, preferably 7 OOC to 2900C.

The functional thin layers formed on opposite sides of the thermoplastic resin film may be identical or different in function with or from each other. Specifically, when both the functional layers have an antistatic function, they will successfully prevent the stencil, or roll, from adhering despite static electricity when mounted to the printer. Assume that one of the two functional layers is constituted 1 0 by a fusion preventing agent or a water or oil repellent having an antistatic function. Then, the other layer may be implemented only by an antistatic agent. When an antistatic agent is contained in the resin film to provide it with a certain degree of antistatic feature, only one of the two functional layers may be constituted by an antistatic agent. If the resin film can exhibit a sufficient degree of antistatic function alone, the layer to contact the head may be provided with the fusion preventing function while the other may be provided with the water andlor oil repelling function. if 20 desired, each layer on the resin film may contain a wax capable of leveling the fine undulations of the film. Such a wax will promote close contact of the film with the head and increase the apparent thermal sensitivity of the stencil, thereby enhancing accurate cutting. Moreover, it is possible 2 5 to combine a plurality of functions, e.g., the fusion preventing - lq 1 0 function and the antistatic function or waterloilrepelling function if adequate substances are selected.

To prevent the film from fusing and adhering to the head due to heat, fatty acid metal salt, phosphor acid ester type surface active agent, silicone oil or similar fluid lubricant, or fluorin compound having a perfluoroalkyl radical or similar agent may be uniformly applied to the surface of the film that contacts the head. The amount of application of such an agent 2 2 2 2 is 0.001 g/m to 2 g/m, preferably 0.05 g/m to 1 g/m To provide the thermoplastic resin film with an antistatic feature, an antistatic agent may be uniformly applied to the film. The antistatic agent may be selected from a family of conventional agents including organic sulphonic acid metal salt or polyalkylene oxide, ester, amine, 1 5 polyethexy derivative, amine ganidine salt, carbonic acid salt, quaternary ammonium salt, and alkyl phosphoric acid ester.

The amount of application should be 0.001 g 1 m2 M-, to 2.0 g/ 2 2 preferably 0.01 g/m to 0.5 g/m An organic sulphonic acid m eta] salt is a compound represented by a formula RIS03) where R' and X4 are representative of an aliphatic radical, alicylic radical or aromatic radial and Na, K, Li or similar metal, respectively.

Specific examples are alkyl sulphonic acid metal salt and alykybenzene sulphonic acid metal salt. In this case, alkyl 2 5 may be implemented by octyl, decyl, dodecyl (lauryl), -ZO tetradecyl (myristyl), hexadecyl, or octadecyl specific examples are lauryl sulphonic acid sulphonic acid kalium, lauryl sulphonic acid sulphonic acid natrium, stearyl suphonic acid sulphonic rithium, dodecylbenzene sulphonic dodecylbenzene sulphonic kalium, and sulphonic rithium.

Polyalkylene oxide to be contained in the film may be implemented by polyethylene oxide, polypropylene oxide, 1 0 polyethylene-polypropylene oxide copolymer, or polytetramethylene oxide by way of example.

A conduction agent is also contained in the film and implemented by quaternary ammonium salt represented by a formula f R2 -N (CH3) 2 - R3 1X2 where R2, R3 and X2 are respectively representative of an alkyl radical whose carbon number is 12 to 18, an alkyl or methyl radial whose carbon number is 12 to 18, and Cl or Br; or a mixture of two or more of such salts.

A functional thin layer having the previously mentioned water andlor oil repelling function may provided on the resin layer, as follows. When the printer is operable with oil ink, an oil and/or water repelling substance is applied to or otherwise deposited on the side of the resin film where the ink penetrates into the film. When the ink is water ink, either an oil repelling substance or a water repelling substance is (stearyl). More natrium, lauryl rithium, stearyl kalium, stearyl acid natrium, dodecylbenzene - Z 1 - deposited on the above-mentioned side of the film. Further, when the ink is emulsion ink, a water and oil repelling The water is deposited in the same manner.

substance may be selected from various kinds of substance repelling waxes and degenerated silicones. The oil repelling substance may be any one of paraffin, perfluoroaIxyl phosphoric ester salt, etc. The water and oil repelling substance may advantageously be implemented by a fluorine compound containing perfluoroaIxyl radicals. The amount of application 1 0 ranges from 0.01 g/m2 to 2 g/m2, preferably from 0.005 g1M2 to 1 g/m A reference will be made to FIGS. 5 and 6 for describing a printer to which the present invention is applied. As shown, a hollow cylindrical drum 1 has a peripheral wall 8 and is 1 5 provided with side plates 2 and 3 at opposite ends thereof. A stationary shaft 4 extends throughout the drum 1. The side plate 2 is supported by the shaft 4 through a clutch 5 and a drive shaft 6 extending from a motor, not shown. The other side plate 3 is supported by the shaft 4 through a clutch 7.

When the clutches 5 and 7 are uncoupled, the side plates 2 and 3 and the peripheral wall 8 of the drum 1 are rotatable independently of each other. A part of the wall 8 of the drum 1 that constitutes a print surface is implemented as a portion 9 permeable to ink. An ink supply unit 10 is disposed in the drum 1 and affixed to the shaft 4. The ink supply unit 10 has an ink distributor 11 and an ink roller unit 12.

A stencil feed and discharge unit 20 is supported by the side plates 2 and3 and located in the vicinity of the peripheral wall 8 of the drum 1 and inside of the system of the drum 1. The stencil feed and discharge rotation unit 20 has a feed section 51 accommodating a roll of stencil 21, a platen roller 52, and a discharge or take-up section 53 for taking up the used part of the stencil 2 1. The feed section 5 1, 1 0 platen roller 52 and discharge section 53 extend in parallel with the axis of the drum 1. The platen roller 52 and discharge section 53 are rotated by a motor 54 via a pulley 55. A cable 57 is connected to a connector 56 rnounted on the side plate 2 so as to feed a drive signal to the irnotor 54. The 1 5 connection of the cable 57 to the connector 56 may be implemented by conventional mechanical or electrical means.

The connector 56 may also function as means for fixing the side plate 2 in place.

As shown in FIG. 7, a head unit 60 has a thermal head, or cutting means, 60a and is located to face the platen roller 52 at a position where it does not obstruct the rotation of the dru m 1. Tle head 60a is driven by a cam, solenoid, crank or similar mechanism, not shown, to imove between the position where it does not obstruct the rotation of the drum 1 2 5 (inoperative position), and a position 60A where it presses -Z3 against the platen roller 52 (operative position). Only when the printer makes a master out of the stencil 21, the head 6 0 a is brought into contact with the platen roller 52 with t h e intermediary of the stencil 21.

Alternatively, as shown in FIG. 8, an arrangement may be made such that the platen roller 52 is movable between an inoperative position inside of the rotation system of the drum 1 and an operative position 52A where it presses against the head 60a located outside of the rotation system. Further, 1 0 both the head 60a and the platen roller 52 may be constructed to be movable. Specifically, it is possible to locate the head 60a outside the rotation system of the drum 1, move the head 60a between the operative position where it contacts the platen roller 52 and the inoperative position outside of the rotation system, and move the roller 52 between the operative position and the inoperative position outside of the rotation system.

Means is provided for detecting the trailing edge of the part of the stencil cut by the head 60a, i.e., master 21.

Specifically, an end mark sensor, not shown, is implemented by conventional optical means and located at a position where it does not obstruct the rotation of the drum 1. 71e end mark sensing means is movable, as needed.

Referring to FIGS. 9A and 9D, a procedure for wrapping the cut stencil or master 21 around the drum 1 in accordance with the present invention will be described. The edge of the webbing 21 paid out from the feed section 51 is affixed to the discharge or take-up section 53, while the roll is locked in a position outside of the rotation system of the drum 1 (FIG. 9A). The roll 21 is rotatable about the axis thereof. In practice, the previously stated feed shaft 22 or the cylindrical center bore of the cassette is fixed in place at the outside of the rotation system of the drum, while the take-up shaft 23 Thereafter, 1 0 1 5 is fixed in place in the take-up section 53.

the support member 31, 32 or 33 is removed. In this condition, the drum 1 is driven by the drive shaft 4 to wrap the master 21 around the peripheral wall 8 of the drum 1 (FIGS.9B and 9Q. The drum 1 is rotated until the feed section 51 reaches a predetermined position adjoining the roll 21, and then the rotation is stopped. Finally, the roll 21 is unlocked and then set in the feed section 51 (FIG. 9D). By such a. procedure, the master 21 is wrapped around the drum To effect the above procedure, a manual switch may be operated to control the rotation of the drum 1. Alternatively, the rotation of the drum 1 may be automatically controlled in response to information fed back from a position sensor, not shown, mounted on the drum 1. Further, the stencil 21 may be automatically set in the feed section 51 by wnventional means.

1 0 1 5 In the event of cutting the stencil 21, the feed and discharge unit 20 is held in a predetermined position (raised position). The platen roller 52 is moved from the inoperative position inside of the rotation system of the drum to the operative position 52A where it contacts the head 60a fixed in place, as shown in FIG. 8; or the thermal head 60a is brought to the position 60A into contact with the platen roller 52, as shown in FIG. 7; or both of them are moved into contact with each other. On the other hand, when the discharge section 53 is rotated in the direction indicated by an arrow A in FIG. 5, the wall 8 of the drum 1 is also rotated in the direction indicated by an arrow B. As a result, the master or used part of the stencil 21 is taken up by the discharge section 53. At the same time, a fresh part of the stencil 21 is paid out from the feed section 51, and the drum wall 8 is rotated. When the wall 8 in rotation Teaches a predetermined position, an image signal is fed to the head 60a. Hence, the fresh part of the stencil 21 is sequentially wrapped around the wall 8 while being cut by the head 50a.

When the drum 1 reaches a predetermined position, i.e., when a necessary image has been fully cut in the stencil 21, the signal to the head 60a disappears. Then, the head 60a or the platen roller 52 is retracted to the original position thereof.

Subsequently, as the drum wall 8 reaches a predetermined position, the drive transmission to the wall 8 and discharge -Z6 - section 53 is interrupted to complete the master making operation. Thereafter, the signal cable 57 is 'removedfrom the connector 56, and then the feed and discharge unit 20 is rotated together with the drum 1 to print the image on a sheet via the master 2 1.

How the cassette shown in FIGS. 4A and 4B is mounted to the printer will be described with reference to FIG. 10. As shown, the engaging member 422 provided on the bottom of the take-up casing part 420 mates with a retaining lug 79 1 0 formed on the surface of the drum 8. The configuration of the member 422 and lug 79 shown in FIG. 10 is only illustrative and may be replaced with any other configuration so long as it can removably affix the casing part 420 to the surface of the drum 8. As shown in FIG. 11 A, to mount the cassette to the 1 5 printer, the feed shaft 41 is connected to a feed shaft 71 which is movable up and down, but not rotatable. The take-up shaft 42 is connected to a take-up shaft 72 which is rotatable with the drum 1. There is also shown in FIG. 11 A a guide roller 73 for guiding the webbing 21. As shown in FIGS.

11B and 11C, the configuration of the take-up shaft 72 and the configuration of one end of the take-up shaft 42 match each other. When the part of the cassette adjoining the drum 1 (casing part 420) is moved due to the rotation of the drum 1, the cassette is separated into the casing parts 410 and _Z1 - 1 5 420; a gap which does not obstruct the rotation of the drum 1 is formed.

Specifically, as shown in FIG. 12A, the cassette having the engaging member 422 is set in a predetermined position on the drum 1. llen, the easing part 410 accommodating the feed shaft 41 is separated from the casing part 420 upwardly away from the drum wall 8 and then fixed in place (FIG. 12B).

The casing part 420 accommodating the take-up shaft 42 is affixed to the drum 1. While this part 420 of the cassette is 1 0 rotated together with the drum 1 in a direction indicated by an arrow, the webbing 21 is sequentially paid out from the feed shaft 41 (FIG. l2Q. After the drum 1 has rotated substantially one rotation (FIG. 1213), the casing part 410 is moved toward the drum (FIG. 12E). Consequently, the stencil or master 21 is wrapped around the drum.

The casing parts 410 and 420 should provided with a reconnectable structure to collection of the used webbing 21. For this connecting portions of the casing parts 410 and preferably be facilitate the purpose, the 420 may be bonded together by a weak paste having such a capability or may be coupled together by structural members. If the weak paste is not sufficient alone from the handling standpoint, i t may be reinforced by a removable sheet up to the time when the cassette is to be mounted to the printer. This kind of 2 5 sheet may be constituted by a label indicating, for example, -zi - the kind of the stencil contained therein. This eliminates the need for an extra label and, therefore, reduces the cost. In the case where the cassette lacks the feed shaft, only the take-up shaft will be collected.

When the cassette of FIGS. 4A and 4B is used, the head 60a is urged against the platen roller 52. The head 60a cuts the stencil 21 while the drum wall 8 is rotated, i.e., while the feed shaft 41, take-up shaft 42, head 60a and platen roller 52 are rotated around and relative to the drum wall 8. The take 1 0 up shaft 42 is driven by a motor. not shown, to take up the webbing 21 at the same speed as the peripheral speed of the drum wall 8. A mechanism for determining the amount of webbing 21 remaining in the cassette is provided and preferably implemented as an end mark sensing mechanism.

1 5 As this mechanism determines that the webbing 21 is short, a further master making operation is inhibited. In this condition, the webbing 21 or, in the event of replacement, the remaining webbing 21 and master are fully taken up by the shaft 42. At this instant, the drum wall 8 is, of course, rotated at the same peripheral speed as the webbing transport speed. After the entire webbing 21 has been taken up by the shaft 42, the casing part 410 with the feed shaft 41 is retracted to the position shown in FIG. 12D. Then, the casing part 420 with the take-up shaft 42 is brought to the position shown in FIG. 12B. In this condition, the two casing Irarts410 - 261 - and 420 are again coupled together. The used cassette, i.e., the coupled casing parts 410 and 420 are taken out from the printer and replaced with a new cassette.

The webbing 21 applicable to this kind of cassette is constituted by a thermoplastic resin film which contains coplymerized polyester as a major component and is about 2.0 pm thick and substantially amorphous (crystallinity of 1 %). The surface of the film that contacts the head 60a is coated with a fusion preventing agent implemented by acryl silicon 1 0 (US-270 available from Toa Synthetic Chemicals (Japan)), and an antistatic agent implemented by quaternary ammonium salt dodecyltrimethyl ammonium chloride (Cl 213 SN(CH3) 2 CH3 Q' These two agents are in a ratio of 1:1 and 0.1 g/m2 heavy when dried. The other surface of the film is coated with a water and oil repellent (Scotch Guard available from 3M) and an antistatic agent (ammonium salt dodecyltrimetyl ammonium chloride represented by [Cl 21, (CH3)2CH.C11) which are mixed in a ratio of 1:2 and 0.3 g/M2 heavy when dried. Such a webbing 21 is rolled up and 2 0 installed in the cassette shown in FIG. 4A and 4B. 'Me casings 4 10 and 420 are made of acryl. This kind of webbing 21 is also applicable to any one of the cassettes shown in FIGS. 1A and IB, 2A and 2B, and 3A and 3B.

Examples of the cassette mounting and dismounting method in accordance with the present invention will be described hereinafter.

Example 1

There was prepared an about 2.0 pm thick thermoplastic resin film which was mainly constituted by copolymerized polyester and was substantially amorphous (crystallinity of 1 %). Acryl silicone (US-270 availble from Toa Synthetic Chemicals) and ammonium salt dodecyl tri methyl ammonium 1 0 chloride (C, H, N(CH3).CH3C1), which were respectively a fusion preventing agent and an antistatic agent, were applied in a ratio of 1:1 to the surface of the film that would contact a thermal head. This mixture was 0.01 g/m-' heavy when dried on the film. The resulting stencil was rolled up and then set 1 5 in the cassette, as shown in FIGS. 4A and 4B. The casing parts 410 and 420 were made of acry].

A fter the cassette was mounted to a predetermined position of the drum in a predetermined condition, the mechanism for separating the feed shaft 41 of the cassette was operated to move the shaft 41 away from the drum and then fix it in place. Subsequently, the take-up shaft 42 and drum 8 were Totated, as indicated by an arrow (FIGS. 12A12E), while paying out the outermost portion of the stencil from the feed shaft 41. As a result, the stencil was wrapped around the drum 8. After substantially one rotation, the feed shaft 41 was again set on the drum 8.

To make a master, the head 60a mounted on the printer body was urged against the platen roller 52. The stencil was cut by the head 60a while the feed shaft 41 and the take-up shaft 42, thermal head 60a and platen roller 52 revolved relative to the periphery of the drum 8. At this instant, the take-up shaft 42 was driven by a motor, not shown, to sequentially take up, or discharge, the stencil at the same 1 0 peripheral speed as the periphery of the drum 8.

When a mechanism for sensing the remaining amount of the stencil or webbing (preferably an end mark sensing mechanism) determined that the remaining amount is small, any further master making operation was inhibited. To replace the webbing, the remaining webbing was fully taken up by the take-up shaft 42. At this instant, the periphery of the drum 8 was, of course rotated at the same speed as the stencil. Subsequently, the feed shaft 41 was moved to the position shown in FIG. 121), and then the take-up shaft 42 was rotated to the position shown in FIG. 12B. Thereafter, the cassette, i.e., casing parts 410 and 420 were again coupled together, as shown in FIG. 12A. In this condition, the used cassette was removed from the printer and replaced with a new cassette.

Examples 2. 3 and 4 A stencil identical with the stencil of Example 1 was configured as shown in FIGS. IA and IB (Example 2), FIGS. 2A and 2B (Example 3), or FIGS. 3A and 3B (Example 4). When such a stencil was mounted to the printer having the feed and discharge unit 20 shown in FIG. 5, it was free from creases.

In addition. since the support member supporting the shafts 41 and 42 was disposable, loads to act on the rotation system for the drum 8 were reduced.

1 0 Example 5

A film identical with the film of Example 1 was used.

Acryl silicone (US-270 available from Toa Synthetic Chemicals) and ammonium salt dodecytrimethyl ammonium chloride (C, J12.,(CH3)2CH3C1) were mixed in a ratio of 1:1 and 1 5 applied to the surface of the film that contacts a thermal head, forming a functional thin layer (fusion preventing and antistatic agent). This layer was 0.2 glm'- heavy when dried.

The other surface of the film (where ink starts penetrating) was coated with a 1:2 mixture of Scotch Guard available from 3M and ammonium liquid dedecyltrimethyl ammonium chloride (C12H2_.(CH3)2CH3C1) so as to form a functional thin layer (water and oil repelling and antistatic agent); the layer was 0.3 glcml- heavy when dried.

Comparative Example 1 Example 5 was repeated to prepare a stencil, except that the stencil of Comparative Example 1 lacked the functional thin layer on the side where ink penetrates into the stencil.

The stencils of Example 5 and Comparative Example 1 were each used to form a master including a black solid image at 200C and 25 %RH. The resulting masters were each set on Preport SS955, a printer available from Ricoh (Japan), to 1 0 produce printings. Use was made of W/0 emulsion type ink (water content of 70 %). After the production of twenty printings, the ink on the ink penetrating side of each master sheet was scraped off by a glass doctor, and then the amount of remaining ink was measured. Further, the two different stencils were evaluated with respect to static electricity and image quality. The results of measurement and evaluation are shown in Table 1 below.

Table 1

DJAGE STATIC ELEC INK LEFT Ex. 5 good none 0. 7 g 1 M'-' Com. Ex. 1 good intense 2.3 g/m2 0 1 5 As Table 1 indicates, the stencil of Example 5 is far smaller than the that of Comparative Example 1 with respect to static electricity and the amount of remaining ink.

Furthermore, the cassette of the present invention not only facilitates the manual mounting of the stencil or Toll on the printer, but also readily implements the automatic setting of the stencil on, among others, an integral drum.

Particularly, the present invention is desirably practicable with a stencil substantially implemented by a 1 0 thermoplastic resin film, e. g., a porous fl 1 m having an extremely thin substrate or a thermoplastic resin film lacking a porous substrate.

Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.

Claims (10)

1. A printer for using a stencil, including: a drum having a portion permeable to ink in a part of a peripheral wall thereof around which a cut portion of the stencil can be wrapped; ink supplying means disposed in said drum; a stencil feed and discharge unit adjoining the outer periphery of said peripheral wall of said drum, and being rotatable relative to said peripheral wall of said drum, said stencil feed and discharge unit comprising at least a feed section for accommodating fresh stencil material in the form of a roll, a discharge section for taking up and accommodating said stencil used, and a platen roller for use in cutting said stencil; cutting means located independently of a rotation system of said drum for pressing, in the event of making a master, against said platen roller, thereby to cut the stencil by heat, said cutting means and said platen roller being moveable relative to each other in the event of making a master; and a cassette holding said stencil, comprising a take-up shaft to be installed in said discharge section, and a support member supporting said take-up shaft, such that stencil material paid out from said roll is taken-up by said take-up shaft.

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2. A printer as claimed in claim 1, wherein said cassette is mounted in said feed section, with said take-up shaft installed in said discharge section, said support member removed, the stencil being wrapped around said drum while being cut, and the paid out material and the roll of material moved relative to and away from each other.

3. A printer as claimed in claim 1, wherein said cassette further comprises a feed shaft around which said roll is provided, and said support member is separable in two and further supports said feed shaft.

4. A printer as claimed in claim 3, wherein said cassette is mounted in said feed section, with said take-up shaft installed in said discharge section, said separable support member separated in two, the stencil being wrapped around said drum and cut, and the two separated parts of said support member moved relative to and away from each other.

5. A printer according to claim 4, wherein said support member comprises a first casing part containing said feed shaft and a separable second casing part containing said take-up shaft.

6. A printer according to claim 5, wherein said second casing part is mounted on said drum.

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7. A printer as claimed in any one of the preceding claims, wherein said cutting means is movable relative to said platen roller, between an operative position for pressing against said platen roller and an inoperative position located outside of said rotation system of said drum.

8. A printer as claimed in any one of claims 1 to 6, wherein said platen roller is movable relative to said cutting means, between an operative position for pressing against said cutting means and an inoperative position located inside of said rotation system of said drum.

9. A printer as claimed in any one of the preceding claims, wherein, in use, the stencil material, as it is paid out from said roll, passes around said drum, sequentially away from said roll and then toward said roll.

10. A printer constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figures 10 to 12 of the accompanying drawings.