GB2300149A - A cassette for use in a stencil printer - Google Patents

Abstract

The cassette is used in cooperation with a perforated cylindrical drum of a stencil printer, and includes a stencil feed and discharge unit constructed integrally with each other. Hence, a stencil web (21) can be fed, perforated by a thermal head, wrapped around the drum 8, and then discharged without being cut off. The stencil web (21) is taken from a roll on a feed shaft (41) in the cassette, and taken up by a shaft (42) which has been temporarily separated from the cassette and passed once around the drum 8 (fig 12D, not shown). The roll and take up shaft 42 are both provided initially in the same cassette but can be separated from each other.

Description

A CASSETTE FOR USE IN A STENCIL PRINTER The present invention relates to a cassette for use in a stencil printer having a drum and a stencil feed and discharge unit constructed integrally with each other.

A printer of the type described, particularly a 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 feeding 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 sheet. The master sheet 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 sheet. Thereafter, the master sheet 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 sheet around the wall of the drum and clamping it thereon is needed, increasing the overall size of the printer.

To eliminate the above problems, Japanese Patent Laid 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 used 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, this kind of implementation brings about another problem that even the head of the master making section is combined with the drum, increasing the weight of the master making section. This is likely to prevent the drum from rotating smoothly. Also, the wiring for sending signals to the head is complicated. In addition, paper dust and other impurities are apt to deposit on the head to thereby prevent it from cutting the stencil accurately.

A traditional stencil is made up of a porous substrate and a polyester or similar thermoplastic resin film adhered t o the substrate and, therefore, has substantial thickness. There has recently been proposed a printer operable with a stencil having a porous substrate which is as thin as about 3 um to 10 um or a stencil substantially constituted only by a thermoplastic resin film (6 pm to 13 pm thick), as taught in, for example. Japanese Patent Laid-Open Publication Nos. S 240596, 4-7198. and 3-99890. However, since such a film having an extremely thin substrate or lacking a substrate is short of mechanical strength. it tears easily unless handled with care.Moreover. this kind of film is extremely soft and apt to cause defective transport to occur (jam. wrapping around a conveyor roller, etc.) It is, therefore, an object of the present invention to provide means for providing stencil material which can be used, for example, in a printer capable of cutting a stencil with a thermal head, wrapping it around a drum, printing and discharging the stencil without cutting it off.

It is another object of the present invention to provide such means which are useful even with a stencil of a thermoplastic resin film, which is as thin as 0.5 Zm to 20 Fm and has only an extremely thin substrate or even lacks a substrate.

According to the present invention there is provided a cassette for use in a stencil printer, comprising a roll of stencil material; a take-up means for taking up material unrolled from said roll and to which one end of said material is attached; and support means for supporting said roll and said take-up means together; wherein said support means is arranged to allow release of said take-up means to separate said take-up means from said roll so that said stencil material unrolled from said roll may be wrapped around a drum of said printer.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description, meant only 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 according to the present invention, accommodating a roll of stencil therein; Figs. 2A and 2B are respectively a front view and a side elevation showing a specific configuration of another cassette; Figs. 3A and 3B are respectively a front view and a side elevation showing a specific configuration of still another cassette; Figs 4A and 4B are respectively a perspective view and a side elevation showing a specific configuration of a further 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 for use with the present invention; 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; 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-9D demonstrate a specific procedure for wrapping a stencil around the drum; Fig. 10 is representative of another specific wrapping procedure; FIGS. 1 lA-i lC 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 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.

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 Figure 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 and a 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 sheet 70a. A transport mechanism 74 transports the master sheet 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 heat. After the cut portion of the stencil 70 has been brought to the drum 76 by the transport mechanism 7A, the cutter mechanism 73 cuts it off to produce the master sheet 70a.

The master sheet 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 sheet 70a. Thereafter, the master sheet 70a is collected in t h e 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 sheet 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 master sheet 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 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 discharge unit 81 adjoining the peripheral wall 80a of a drum 80 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, this kind of implementation brings about another problem that even the head 85 of the master making section is combined with the drum 80, increasing t h e weight of the master making section. This is likely to prevent the drum 80 from rotating smoothly.Also, the wiring for sending signals to the head 85 is complicated. In addition, paper dust and other impurities are apt to deposit on the head 85 to thereby prevent it from cutting the stencil 82 accurately.

The present invention preventing some of the drawbacks stated above will be described hereinafter. Briefly, in accordance with the present invention, a roll of stencil is provided 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 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 22 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 2B show a specific configuration of another cassette. This configuration differs from the configuration of FIGS. 1A and 1B 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 suppon member 32. The reference numerals 321 and 322 designate holes formed through the support member 32.

Figs. 3A and 3B show a specific configuration of still another cassette. As shown, the cassette has a support member 33 which is simp]er than the support members shown in FIGS. 1A and IB and 2A and 2B.

Perforations 331 are formed through the support member 33 in the 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) 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. Specificallv. 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.

Figs. 4A and 4B show a specific configuration of a further 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 1 0 and 420 contact each other only along the peripheral edges thereof to allow the stencil 21 to extend therethrough. The casing pans 410 and 420 have end walls 411 and 421.

respectively. The feed shaft 41 and take-up shafts 42 are rotatable and slightly protrude respectively from the side walls 411 and 421 of the casing parts 410 and 420 at opposite ends thereof. The reference numeral 422 designates an engaging which will be described.

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, a 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 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 t h e 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 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 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 act on the rotation system of the printer. In the case of the cassette shout n 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 to be wrapped around the drum.

The stencil printer 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.

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 bv a thermoplastic resin film will be described hereinafter.

The thermoplastic resin film may be produced by a n 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, polycarbonate copolymer etc. Among them, resins having high perforation sensitivity are desirable. In this respect, the thermoplastic resin forming the film 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 of substantially amorphous level" refer to a film whose material 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.

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 substantially amorphous. The words "substantially amorphous polyester refers to polyester other than commercially a'ailable ordinary resins whose major component is high crystallinity polyester terephthalate having a crystal melting point (determined by the DSC method) of 2450C to 2 60 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 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 fusion start temperature should be 50 C to 300 C. preferably 7 OOC to 290 C.

To prevent the film from melting and adhering to a thermal 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/m2 to 2 g/m-, preferably 0.05 g/m to 1 g/m.

To provide the thermoplastic resin film with a n anti static feature, an antistatic agent may be uniformly applied to the film or may be contained in the film. If desired, the antistatic agent may be mixed with the abovementioned anti-adhesion agent before application to the film.

The anti static agent may be selected from a family of conventional agents including organic sulphonic acid metal salt or polyalkylene oxide, ester, amine, carbonic acid salt, quaternary 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 g/m to 0.5 gIr &

When the antistatic agent is to be contained in the film, use may be made of organic sulphonic acid metal salt o r polyalkylene oxide, a mixture of one or more quaternary ammonium salts.

An organic sulphonic acid metal salt is a compound represented by a formula Rl SO3Xl where Rl and t 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 rithiurn, stearyl sulphonic acid natrium, stearyl suphonic acid kalium. stearyl sulphonic rithium. dodecylbenzene sulphonic acid natrium dodecylbenzene sulphonic kalium, and dodecylbenzene sulphonic rithium.

On the other hand, the content of organic sulphonic acid metal salt in the thermoplastic resin film is 0.1 Wt% to 2 Wt%, preferably 0.2Wt% to 1.5 Wt%; contents smaller than 0.1 Wt% degrade the antistatic effect while contents greater than 2 Wt% roughen the surface of the film.

Polyalkylene oxide to be contained in the film may be implemented by polyethylene oxide, polypropylene oxide, polyethylene-polypropylene oxide copolymer, or po]ytetramethylene oxide by way of example. The molecular weight of polyalkylene oxide is 40 to 500,000, more preferably 1,000 to 50,000. The content of polyalkylene oxide in the film is 0.1 Wt% to 5 Wt%, preferably 0.2 Wt% to 4 Wit%.

Contents smaller than 1 Wt% degrade the antistatic effect while contents greater than 5 Wt% lower the dynamic energy of the film A conduction agent is also contained in the film and implemented by quaternary ammonium salt represented by a formula 1R--N(CH3)o- R3IXn 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 number is 12 to 18, and CI or Br; or a mixture of two or more of such salts. The content of ammonium salt in the film is 1 Wtic to 50 Wtic, preferably 2 Wt% to 30 Wt%.

A reference will be made to FIGS. 5 and 6 for describing printer for use with the present invention. As shown, a hollow cylindrical drum 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 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 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 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 21. The feed section 5 1 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 mounted on the side plate 2 so as to feed a drive signal to the motor 54. The 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 drum 1. The head 60a is driven by a cam, solenoid, crank or similar mechanism, not shown, to move between the position where it does not obstruct the rotation of the drum I (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 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, 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. 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 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 is fixed in place in the take-up section 53.

Thereafter. 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 1.

To effect the above procedure, a manual switch may be operated to control the rotation of the drum I. 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.

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 5 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 reaches 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 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 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 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. l lA, to mount the cassette to the 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. 1 lA a guide roller 73 for guiding the webbing 21. As shown in FIGS.

1 lB 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 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 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 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. 12C). After the drum 1 has rotated substantially one rotation (FiG. 12D), 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 preferably be provided with a reconnectable structure to facilitate the collection of the used webbing 21. For this purpose, the connecting 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, it 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.

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 o f 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 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 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 6.3 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 (US-270 available from Toa Synthetic Chemicals (Japan)), and an antistatic agent implemented by quaternary ammonium salt dodecyltrimethyl ammonium chloride (Cl2Ho 25N(CH3)2CH3Cl). These two agents are in a ratio of 1:1 and 0.1 g/m2 heavy when dried. Such a webbing 21 is rolled up and installed in the cassette shown in FIG. 4A and 4B. 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.

Claims (7)

1. A cassette for use in a stencil printer, comprising

a roll of stencil material; a take-up means for taking up material unrolled from said roll and to which one end of said material is attached; and support means for supporting said roll and said take-up means together; wherein said support means is arranged to allow release of said take-up means to separate said take-up means from said roll so that said stencil material unrolled from said roll may be wrapped around a drum of said printer.

2. A cassette according to claim 1, wherein said roll is mounted on a roll shaft.

3. A cassette according to claim 1 or 2, wherein said take-up means is removable from said support means and said support means is removable from said roll.

4. A cassette according to any one of claims 1 to 3, wherein said support means is separable into two portions for supporting the roll and the take-up means separately.

5. A cassette according to claim 4, wherein said two portions comprise casings, the casing for supporting said takeup means having attachment means for attachment to said drum.

6. A cassette according to any one of claims 1 to 5, wherein said take-up means comprise a take-up shaft.

7. A cassette constructed and arranged substantially as hereinbefore described with a reference to and as illustrated in one or more of Figures 1 to 4 and 10 to 12 of the accompanying drawings.