GB2277058A - Thermosensitive stencil sheet and cassette for stencil printer - Google Patents

Abstract

A thermosensitive stencil sheet (21) of a stencil printer is implemented by a thermosensitive resin film, with a functional thin layer formed on both sides of the film and having at least one of an antistatic function, fusion preventing function, water repelling function, and oil repelling function. Such a sheet is held in a cassette, and after the cassette has been mounted on the printer, the stencil is paid out from the cassette and cut by a thermal head to turn out a master. The master is automatically wrapped around and then separated from the drum. The cassette may have two casing parts respectively for a stencil feed shaft and a take-up shaft. <IMAGE>

Description

STENCIL CASSETTE FOR STENCIL P'RINTER AND METHOD OF MOUNTING AND DlSMOUNTING THE SAME The present invention relates a stencil printer to be removably mounted on the drum of a stencil printer for feeding a stencil. and a method of mounting and dismounting the cassette from the stencil printer.

A stencil printer, particularly a stencil printer capable ol tutting a stencil with a thermal head, wrapping it around a drtitn, printing, and discharging the stencil automarically 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 cut a stencil paid out from a stencil feeding section by heat.

Afte the cut portion of the stencil has been brought to a drum by a transport mechanism, a cutter mechanism cuts it out to produce a master. The master is wrapped around the ptrtpherai wall of the drum. As a paper is fed to a prinking session, 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 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 it thereby is needed, increasing the overall size of the printer.

To eliminate the above problems, Japanese Patent Laib Open 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, wraps it around the drum, prints. and then discharges the use d stencil without cutting it off. Specifically. the printer has a stencil feed and discharge unit adjoining and rotatable relative to the peripheral wall of a drum.The feed and discharge unit is made up of a feed section for paying out a stencil from a roll, 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 from the printer unless the stencil attaching procedure is repeated all over again in the entirely reverse order. resulting in complicated steps.

It has been customary with a stencil pnnter to use a thermos Ensit ve stencil made up of a suitable substrate which is permeable to ink, and a thermoplastic resin film formed cn 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 anti static layer on the surface of the thermoplastic resin film, as taught in, for example Japanese Patent Laid-Open Publication Nos. 3 53992, 61-164896, and 1-314191.The fusion preventing laxer is desirable since the surface of the resin film is bought into contact with a thermal head without exception, Ho veer, the fusion preventing payer should only be provided on one side of the resin film that will contact the head.

Morecver, 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 from 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 disclosed in, for example, Japanese Patent Laid-Open Publication Nos. 62-282983 and 63-160895. Further, the stencil jmplemented only by a thermoplastic resin may be provided with an antistatic layer or a fusion preventing layer on one sido 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 torn unless handled with care. Once the stencil is torn, it has to be attached to the take-up shaft all over again.

EtLrthermore, it is likely that this kind of stencil jams the transpart path, wraps around a conveyor roller or otherwise af;-ct transport due to low elasticity thereof. This tendency is particularly prominent with the stencil constituted only by a GherH oplastic resin film.

After printing, ink is left on the stencil in an amount of 5 g/m 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 roll, making storage difficult or giving rise to a problem in respect of dispersal. 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 factors cannot bo set up easily, and that an amount 1 g/m to 3 glnP of ink still retains on a stencil.

It is, therefore, an aim of the present invention to provide a stencil applicable to a stencil printer and consisting of an about 0.5 m to 20 m thick thermoplastic film with an extremely thin substrate or without any substrate and a functional thin layer provided on both sides ot the film.

it is another aim of the present invention to. provide a stencil cassette for a stencil printer which feeds a stencil to a 'drum included in the printer.

Ir ;s another object of the present invention to provide a method of mounting and dismounting such a stencil cassette frcm a stencil printer.

In accordance with the present invention, 8 th rmosensitive stencil for a stencil printer comprises a thermoplastic resin film, and a functional thin layer provided on both sides of the film and having at least one of an antistatic function, fusion preventing function, water repelling function, and oil repelling function.

Also, in accordance with the present invention, a cassette for accommodating a thermosensitive stencil in the form of a roll which is to be cut and then wrapped around a dnam of a stencil printer as a master comprisesa feed shaft loafed with the roll such that the leading edge of the stencil is sequentially paid out while at least the trailing edge of the stencil is left on the feed shaft, a take-up roller for taking up the stencil being paid out from the feed shaft, and a support member comprising holes each fixing one of the feed shaft and take-up shaft in place, and a slit extending from a position where the feed shaft is fixed to the end of the support member via a position where the take-up shaft is fixed.The stencil comprises a thermoplastic resin film, and a functional thin layer provided On both sides of the film and having least one of an antistatic function, fusion preventing fizfiction. water repelling function, and oil repelling function.

Further, in accordance with the present invention, a cassette for accommodating a thermosensitive stencil in the form' of a roll which is to be cut and then wrapped around a dmm of a stencil printer as a master comprises a take-up shaft for taking up the stencil from the leading end of the stencil, and a support member fixing the take-up shaft in place and comprising a hollow cylindrical bore for accommodating the stencil, and a slit extending to the end of cct support member via a position where the take-up shaft i S fiXed.The stencil comprises a thermoplastic resin film, and a functt'al thin film provided on both sides of the t:iermoplastic resin film and having at least one of an anti static function, fusion preventing function, water repelling function, and oil repelling function.

Morecver, in accordance with the present invention, a cassette for accommodating a thermosensitive stencil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master comprises a take-up shaft for taking up the stencil from the leading end of the stencil, and a support member affixed to the take-up shaft and comprising a projection for retaining the trailing edge of the stencil, and perforations formed in the projection in a horizontal array. The stencil comprises a therrnoplastic resin film, and a functional thin layer provided on both sides of the lhermoplastic resin film and having at least one of an antistatic function, fusion preventing function, water repelling function, and oil repelling function.

In addition, in accordance with the present invention, a cassette for accommodating a thermosensitive stencil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master compreises a first casing part fixing a feed shaft in place from which the S ten ci 1 is sequentially paid out, and a second casing part fixing a take-up shaft for taking up the stencil from the feed shaft in place. The second casing part is mounted on a peripheral wall of the drum.The first and second casing parts are separable from cach other such that they contact, before the stencil is cut, each other only along peripheral edges of longitudinal facing surfaccs thereof to allow the stencil to extend through the casing pasts, while in the event of cutting the stencil, rhe first casing part is moved in an up-and-down direction while the second casing part wraps the stencil, extending from the feed shaft to the take-up shaft, around the drum by pulling the sLc;;lcil. The stencil comprises a thermoplastic resin film, and a functional thin layer provided on on both sides thereof and having at least one of an antistatic function, fusion preventing function, water repelling function, and oil reelling function The above and other aim s-, fcatures and advantages of the present invention will become more apparent from the following detailed description 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 configllration of the cassette; FIGS. 4A and 4B are respectively a perspective view and a side elevation showing a further specific configuration C f the cassette;; FiG. 5 is a section of a drum included in a printer having a stencil feed and discharge unit constructed inlegrally with thD drum and the present invention is applicable; FIG. 6 is a sectional side elevation of the arrangement shown in FIG. 5: FTO. 7 is a section showing a specific arrangement wherein a master ' making section is located outside of the rotation system of the drum; FIG. s is view similar to FIG. 7, showing another specific arrangement wherein the master making section is located outside the drum; FIGS 9A-9D demonstrate a specific procedure for wrapping a stencil around the drum in accordance with the present invention; FIG. 10 is representative of another specific wrapping procedure available with the present invention;; FIGS. llA-IlC show how the cassette of FIGS. 4A and 4B 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 dmm; 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.

DESCRIPTION OF THE PREFERRED EMBODD6iIT To better understand the present invention, a brief reference will be made to a conventional printer having a plaster making section and a printing section constructed integrally with each other. As shown, 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 and a thermal head 72b. A cutter mechanism 73 cuts off a part nf the stencil 70 which has been cut by the head 72b, thereby producing a master, or master sheet, 70a. A transport 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 beat. After the cut portion of the stencil 70 has been brought 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 t h e 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 mechanism 73 to produce the master 70a. The transport mechanism 74 for implementing such a procedure is complicated and apt to cause defective transport and other troubles to occur. Moreover, a mechanism for wrapping the matter 70a around the wall 76a of the drum 76 and clamping it thereon is needed, increasing the overall size of the printer.

FIG. 14 shows a printer taught in Japanese Patent Laid Open Publication No. 62-73987 and elaborated to eliminate that 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 cits a stencil, wraps it around the drum, pnnts, and then discharges the used stencil without cutting it off.

Spec;fically, as shown in FIG. 14, the printer has a feed and discharge unit 81 adjoining the peripheral wall 80a of a drum 80 and rotatable relative to the wall 8Oa. 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 waster used. A part 80a of the drum wall 80 is permcat le to ink. Ink supplied from ink supplying means 87 is fed te a paper, not shown, via the permeable part 80a of the drum wall 87.

However, the above-described printer has the previously 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 t h e trailing edge thereof left on the feed shaft. Then, the stencil tlas to be removed from the printer by repeating the stencil attaching procedure all over again in the entirely reverse ord t-r, 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. 1A and 1B 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 The The edge of the stencil 21 paid out from the roll is wo@nd a und another shaft or take-up shaft 23 located close to the feed shaft 22. The shafts 22 and 33 are affixed to a support member 31 through holes. A slit 311 is formed trough the support member 31 and extends from the feed shaft 2 to the end of the member 31 via the take-up shaft 23.

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 2EG show another specific configuration of tit cassette. This configuration differs from the catifiguration of FIGS. 1A and 13 in that the feed shaft 22 is absent, in that the stencil 21 is rolled up in such a manner as tc, 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 3B 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. 1A and 1B and 2A and 2B.

Perforations 331 are formed through the support member 33 in tha horizontal direction.

The cassettes shown in FIGS. 1A and 1B and FIGS. 2A and 2B are each mounted to a printer with the feed shaft (feed section '.2 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 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.

f:IGS. 4A and 4B show a further specific configuration of the ca4Sefle. As shown, the cassette has a feed shaft 41 and a take 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 410 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, rgspectively. The feed shaft 41 and take-up shafts 42 are rotatable and respectively slightly protrude from the side we-11.s 411 and 421 of the casing parts 410 and 420 at 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 ≈cileme 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 case where the webbing 21 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 vantageously be made of a weak paste (easily separable piece). The feed shaft is not essential, as shown in FIGS. 2A ana 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 4?0, a person can set the feed shaft and take-up shaft on a printer at the same time. Regarding the cassette of FIGS. 1A and 1 B, 2A and 2B or 3A and 3B, the support member thereof 1 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 act on the rotation system of the printer. In the case of the cassette 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 tbe prerequisite for the webbing 21 to be wrapped around the drum.

Since the stencil 21 is substantially not affixed to the feed shaft 22 or is affixed thereto to an easily removable degree, it can be readily removed from the printer.

Specifically, assume that the stencil 21 of the cassette has been used up and should be removed from the printer. Then, 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 let 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). This kind of adhesive may be implemented by an ordinary composition based on rubber, acryl, block copolymer, silicone, vinyl ether, etc. The adhering force of such adhesive should preferably be less than 10.0 g/mm, more preferably 5.0 gimm to 0.1 glmrn and most preferably 2.5 glrirn to 0.5 glnim, 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 tile shaft 22.

It is dcsirable that the weak adhesive be applied to the fccci 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, Funher, 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 the stencil 21 from the shaft 22 to be reduced.In addition, the shaft 22 is omissible, as shown in FIGS. 2A and 2B or FIGS. 3A and 33.

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 paring 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. Particularly, the advantage is prominent when use is made of a stencil implemented by a substantially thermoplastic resin film lacking a substrate. A stencil constituted only by a thermoplastic resin film will be described hereinafter.

Also, in accordance with the present invention, the tl ermo;lastic 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 polyester (preferably copolymerized polyester), nylon (preferably copolymerized nylon), polyolefin, polystyrene, vinyl chloride, acrylic acid derivative, ethylene, vinyl alcohol, poljcarbonate copolymer, etc. Among them, resins having high perforation sensitivity are desirable. In this respect, the thermoplastic resin forming the film should lie subst. ntially in a range of from the amorphous level to the crystallinity of 15 gte. More preferably, the film should be of substantially amorphous level. Here, the words "film of substantially amorphous level" refer to a film whose material t.as 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.

More preferably, the thermoplastic film should be mainly constituted by copolymerized polyester and be of substantially amorphous level. Most preferably, the copolymerized polyester, as a raw material, should be substarltially amorphous. The words "substantially am orpb o us polyester" refers to polyester other than commercially available ordinate resins whose major component is high crystall:lity polyester terephthalate having a crystal melting point (determined by the DSC method) of 2450C to 2 6 0 C.

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 by the X-ray method. Then, taking such a sample as a sto:nc(cud, 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 m to 20 m thick, more preferably 1 )lm to 10 lXm thick. The fusion start temperature should be 50QC to 3OC, preferably 70 C to 290 C.

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 by a fusion preventing agent or a water or oil repellent having an antistatic function. Then, the other layer may be imrlemented only by an antistatic agent. When an antistatic agent is contained in the resin film to provide it with a certain degree of anti static feature, only one of the two -;icn'onal layers may be constituted by an antistatic agent.

It the resin film can exhibit a sufficient degree of antistatic A;nstio;s alone, the layer to contact the head may be provided with thc fusion preventing function while the other may be provided with the water andlor oil repelling function.

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 to combine a plurality of functions, e.g., the fusion preventing function and the antistatic function or water/oil repelling 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 is 0.001 g/m to 2 g/mZ, preferably 0.05 g/m- to 1 g/m.

To provide the thermoplastic resin film with a n 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 su(phonic acid metal salt or polyalkylene oxide, ester, amine, potyethexy derivative, amine ganidine salt, carbonic acid salt, quairnary ammonium salt, and alkyl phosphoric acid ester.

The amount of application should be 0.001 g I m2 to 2.0 g/m, preferably 0.01 gtmz to 0.5 g/m.

An organic sulphonic acid metal salt is a compound represented by a formula R1 S03X! where R1 and X1 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 may be implemented by octyl, decyl, dodecyl (lauryl), tetradecyl (myristyl), hexadecyl, or octadecyl (stearyl). More specific examples are lauryl sulphonic acid natrium, lauryl sulphonic acid kalium, lauryl sulphonic acid lithium, stearyl sulphonic acid natrium, stearyl suphonic acid kalium, stearyl sulphonic rithium, dodecylbenzene sulphonic acid natri um, dodecylbenzene sulphonic kalium, and dodecylbenzene sulphonic lithium.

Polyalkylene oxide to be contained in the film may be implemented by polyethylene oxide, polypropylene oxide, plyeth ylen e-p olypropyl ene oxide copolymer, or polytetramethylene oxide by way of example.

A conduction agent is also contained in the film and impjemçnted by quaternary ammonium salt represented by a forrnula [R2-N(CH3) < - R3 - where R2, R3 and X are respectively representative of an alkyl radical whose carbon number is 12 to 18, an alkyl or methyl radial whose carbon nember is 12 to 18, and CI or Br; or a mixture of two or more of such salts.

A functional thin layer having the previously mentioned water and/or oil repelling function may provided on the resin layer, as follows. When the printer is operable with oil ink, an oil andlor 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 i S deposited on the above-mentioned side of the film. Further, when the ink is emulsion ink, a water and oil repelling substance is deposited in the same manner. The water repelling substance may be selected from various kinds of Waxes and degenerated silicones. The oil repelling substance may be any one of paraffin, perfluoroalxyl phosphoric ester salt, etc.The water and oil repelling substance may advantageously be implemented by a fluorine compound containing perfluoroalxyl radicals. The amount of application ranges from 0.01 glmt to 2 g/mZ, preferably from 0.005 g/m 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 tallow cylindrical drurn 1 has a peripheral wall 8 and is 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 dive shaft 6 extending from a motor, not shown. The other sidv 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 and 3 and located in the vicinity of the peripheral wall 8 of the drum 1 and inside of the rotation system of the drum 1. The stencil feed and discharge unit 20 was a feed section 51 accommodating a roll of stencil 21, a r te: roller 52, and a discharge or take-up section 53 for tiking up the used part of the stencil 21. The feed section 51, paten 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 mounted on the side plate 2 so as to feed a drive signal to the motor 54.The cnnection 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 sido 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 drum 1. The head 6Oa is driven by a cam, solenoid, crank or similar mechanism, not shown, to mofre between the position where it does not obstruct the rotation of the drum 1 (inoperative position), and a position 60A where it presses against the platen roller 52 (operative position). Only when the printer makes a master out of the stencil 21, the head 60 a is brought into contact with the platen roller 52 with the intermediary of the stencil 21.

Alternatively, as shown in FIG. 8, an arrangement may b e 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, 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 6(;a - 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 inoperative 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. The 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 S 1 is affixed to t h e discharge or take-up section 53, while the roll is locked in a position outside of the rotation system of the drum l (F1G.

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 is fixed in place in the take-up section 53.

The-eafter, 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 9C). 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 I.

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 conventional means.

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 i S brought to the position bOA 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 reaches a predetermined position, an image signal is fed to the head fOa. 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 section 53 is interrupted to complete the master making operation. Thereafter, the signal cable 57 is removed from 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 21.

How the cassette shown in FIGS. 4A and 4B is mounted tD the printer will be described with reference to FIG. 10. As sho vn, the engaging member 422 provided on the bottom of the ake-up casing part 420 mates with a retaining lug 79 fon lr:d on the surface of the drum 8. The configuration of the member 422 and lug 79 shown in FIG. 10 is only illustrative and Nlay 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 printer, the feed shaft 41 is connected to a feed shaft 71 whicb 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. 11A a guide roller 73 for guiding the webbing 21. As shown in FIGS.

t 1 ER and 11 C, 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 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. Then, the casing part 410 accommodating the feed shaft 41 is separated from the casing part 420 upwardly aw.'y from the drum wall 8 and then fixed in place (FIG. 123).

Tl,e casing part 420 accommodating the take-up shaft 42 is affixed to the drum 1. While this part 420 of the cassette is rotated together with the drum 1 in a direction indicated by an snow, the webbing 21 is sequentially paid out from the feed shaft 41 ( < :IG. 12C). After the drum 1 has rotated substantially one rotation (FIG. 12D), the casing part 410 is moped toward the drum (FIG 12E). Consequently, the stencil or master 21 is wrapped around the drum.

The casing parts 410 and 420 should preferably be provided with a reconnectable structure to facilitate the collection of the used webbing 21. For this purpose, the ct lnecting portions of the casing parts 410 and 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 sheet may be constituted by a label indicating, for example, 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 takeup 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.

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 coy156, rotted 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 PIG. 1213. In this condition, the two casing parts 410 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 m 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 (US-270 available from Toa Synthetic Chemicals (Japan)), and an antistatic agent implemented by quaternary ainmoniurri salt dodecyltrimethyl ammonium chloride (C12H25N(CH3)2CH3Cl). These two agents are in a ratio of 1:1 and 0.1 g/me 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 [C12H25(CH3)2CEIgCI]) which are mixed in a ratio of 1:2 and 0.3 g I m2 heavy when dried.Such a webbing 21 is rolled up and installed in the cassette shown in FIG. 4A and 43. The casings 410 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 1B, 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 m 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 dodecyltrimethyl ammonium chloride (C, 5N(C)OCl), which were respectively a fusion preventing agent and an anti static 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 in the cassette, as shown in FIGS. 4A and 4B. The casing parts 410 and 420 were made of acryl.

After 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 rotated, as indicated by an arrow (FIGS. 12A 123), while paying out the outermost portion of the stencil from the feed shaft 41. As a result, the stencil was wrapped around the drum S. 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 r?latj've to the periphery of the drum 8. At this instant, the ke-up shaft 42 was driven by a motor. not shown, to :equentially take up, or discharge, the stencil at the same 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. 12D, and then the take-up shaft 42 was rotated to the position shown in FIG 12B. Thereafter, the cassette, í.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, Exampics 2. 3 and 4 A stencil identical with the stencil of Example 1 was configured as shown in FIGS. lA and 1B (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.

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 (C12H25(CH3)3CH3Cl) were mixed in a ratio of 1:1 and applied to the surface of the film that contacts a thermal head, forming a functional thin layer (fusion preventing and anti tatic agent). This layer was 0.2 g/m- heavy when dried.

T:e 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 dedecyltrimetbyl ammonium chloride (Cl 5(CH3)2q3Cl) so as to form a functional thin layer (water and oil repelling and anti static agent); the layer was 0.3 g/cms 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 t h e stencil, The stencils of Example 5 and Comparative Example 1 were each used to form a master including a black solid image at 20 C and 25 %RH. The resulting masters were each set on Preport SS95f, a printer available from Ricoh (Japan), to produce printings. Use was made of W/O emulsion type ink (water content of 70 %). After the production of twenty printing, 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 an d image quality. The results of measurement and evaluation are shown in Table 1 below.

Table 1

IMAGE STATIC ELECINK LEFT Ex. 5 good none 0.7 g/m Com. Ex. 1 good intense 2.3 g/m 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 roll 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 thermoplastic resin film, e.g., a porous film 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 (16)

1. CLAx A thermosensitive stencil sheet Vor a stencil printer, comprising a thermoplastic resin film, and a functional thin layer provided on both sides of said thermoplastic resin fi 1 m and having at least one of an antistatic function, a fusion preventing function, a water repelling function, and an oil repelling function.
2. 2. A cassette for accommodating a thermosensitive stencil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master, said cassette comprising: a feed shaft loaded with the roll such that a leading edge of the stencil is sequentially paid out while at least a railing edge of said stencil is left on said feed shaft; a take-up roller for taking up the stencil being paid out from said feed shaft; and a support member comprising holes each for fixing one of said feed shaft and said take-up shaft in place, and a slit extending from a position where said feed shaft is fixed to an end of said support member via a position where said take-up shaft is fixed; the stencil comprising a thermoplastic resin film, and a functional thin layer provided on both sides of said thermoplastic resin film and having least one of an antistatic function, a fusion preventing function, a water repelling function, and an oil repelling function.
3. 3. A cassette for accommodating a thermosensitive stencil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master, said cassette comprising: a take-up shaft for taking up the stencil from a leading end of said stencil; and a support member fixing said take-up shaft in place and comprising a hollow cylindrical bore for accommodating th e stencil, and a slit extending to an end of said support member via a position where said take-up shaft is fixed; the stencil comprising a thermoplastic resin film, and a functional thin film provided on both sides of said therrr.oplastic resin film and having at least one of an antistatic function, a fusion preventing function, a water repelling function, and an oil repelling function.
4. 4. A cassette as claimed in claim 2 or 3, wherein when said cassette is mounted to the stencil printer, said support member is removed by having said slit spread.
5. 5. A cassette for accommodating a therinosensitive stencil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master, said cassette comprising: a take-up shaft for taking up the stencil from a leading end of said stencil: and a support member affixed to said take-up shaft and comprising a projection for retaining a trailing edge of the x ancil, and perforations formed in said projection in a horizontal array;; the stencil comprising a thermoplastic resin film, and a t'unctional thin layer provided on both sides of said th. rmoplastic resin film and having at least one of an antistatic function, a fusion preventing function, a water repelling function, and an oil repelling function.
6. 6. A cassette as claimed in claim 5, wherein when said cassette is mounted to the stencil printer1 said support riember is removed by being torn off along said perforations.
7. 7. A cassette for accommodating a thermosensitive stew coil in the form of a roll which is to be cut and then wrapped around a drum of a stencil printer as a master, said cassette comprising: a first casing part fixing a feed shaft in place from which the stencil is sequentially paid out; and a second casing part fixing a take-up shaft for taking up the stencil from said feed shaft in place, said second casing part being mounted on a peripheral wall of the drum; said first and second casing parts being separable from each other such that said first and second casing parts contact, before the stencil is cut, each other only along peripheral edges of longitudinal facing surfaces thereof to allow the stencil to extend through said first and second casing parts, while in the event of cutting said stencil, said first casing pairt is moved in an up-and-down direction while said second casing part wraps said stencil, extending from said feed shaft to said take-up shaft, around the drum by pulling said stencil;; the stencil comprising a thermoplastic resin film, and a functional thin layer provided on on both sides thereof and having at least one of an antistatic function, a fusion preventing function, a water repelling function, and an oil repelling function.
8. 8. A cassette as claimed in claim 7, wherein said first and second casing parts are removed from the stencil printer wken the stencil in said cassette is fully used.
9. 9. A cassette as claimed in any one of claims 22,., wherein the stencil is substantially not affixed to or separably affixed to said take-up shaft.
10. 10. A cassette as claimed in claim 9, wherein the stencil is separably affixed to said take-up shaft by a weak paste.
11. 11. A cassette as claimed in any one of claims 2-10, wherein the stencil is separably affixed to said feed shaft by a weak paste.
12. 12, A method of mounting said cassette as claimed in any one of claims 2-6 to a stencil printer, comprising the steps of: (a) causing said support member to be engaged with or affixed to a stencil feed section included in said stencil printer; (b) causing said take-up shaft supported by said support member to be engaged with or affixed to a take-up section included in said stencil printer; (c) causing said support member to be removed; and (d) moving the leading edge of the stencil and the roll, from which said stencil is paid out, away from each other t o thereby wrap said stencil around said drum.
13. 13. A method of mounting said cassette as claimed in claims 7 and 8 to a stencil printer, comprising the steps of: (a) causing said support member to be engaged with or affixed to a stencil feed section included in said stencil printer; (b) causing said take-up shaft to be connected to a takeup section included in said stencil printer; (c) separating said fir5t and second casing parts from each other; and (d) moving the leading edge of the stencil and tbc roll, from which said stencil is paid out, away from each other to thereby wrap said stencil around said drum.
14. 14. A stencil sheet constructed and arranged to operate substantially as hereinbefore described, with reference to and as illustrated in Figures 1 - 12 of the accompanying drawings.
15. 15. A cassette for a stencil roll constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in Figures 1 - 12 of the accompanying drawings.
16. 16. A method of mounting and dismounting a cassette substantially as hereinbefore described with reference to Figures 1 - 12 of the accompanying drawings.