US3414724A - Method and apparatus for duplicating text, pictures and the like on unprepared copy receiving sheets - Google Patents

Description

DEG 3, 1968 s. B. KVARNEGARD M HOD AND APPARATUS FOR DUPLICATING THE LIKE ON UNPREPARED COPY RECEIVING SHEE Filed nec. 1, 1965 De 3, 1968 s. B. KVARNEGARD 3,414,724

METHOD AND APPARATUS FOR DUPLICATING TEXT. PICTURES AND THE LIKE ON UNPREPARED COPY RECEIVING SHEETS Filed DSC. l. 1965 2 Sheets-Sheet 2 United States Patent O 3,414,724 METHOD AND APPARATUS FOR DUPLICATING TEXT, PICTURES AND THE LIKE ON UNPRE- PARED COPY RECEIVING SHEETS Sven Bertil Kvarnegard, Enebyberg, Sweden, assigner to Aktiebolaget Carl Lamm, Maskinatfar, Stockholm, Sweden, a joint-stock company of Sweden Filed Dec. 1, 1965, Ser. No. 510,833 Claims priority, application Sweden, Dec. 11, 1964, 15,055/ 64 6 Claims. (Cl. Z50-65) ABSTRACT F THE DISCLOSURE A thermographic copying method and apparatus for repeated positive reproduction of an original onto copy sheets, which comprises -a rotary glass drum having an internal source of infrared radiation, the original to be copied being mounted with the heat-responsive indicia thereon in contact with the external surface of the drum and a belt carrying a coating of a heat-fusible dye composition is arranged to be pressed by a roller against the back of the original to cause the dye to be picked up by it at those heated places in register with the indicia to be copied; then a second roller presses a copy sheet of paper against the outside of the original to pick up an imprint of the dye image therefrom whereupon the copy sheet is separated from the original. The latter is then re-coated with dye and the cycle repeated.

This invention relates to a method and an apparatus for Aduplicating on unprepared copy receiving sheet materials such text, pictures and like indicia which have [been previously made by typewriting, printing or by hand on an original record or so-called master sheet in opaque ink or a similar application medium that is capable of absorbing infrared light radiation while thereby increasing its temperature and presupposes the utilization of concentrated light radiation of high intensity particularly within the range of infrared radiation for transferring a fusible copy printing dye composition having a negligible absorption capacity of its own as regards the utilized radiation from a carrier of a thin coating of said dye composition to the copy receiving sheet in accordance with the text and other indicia appearing on the original record.

The invention is based on the well-known fact that, if an original record which has been made in the abovementioned way on a base sheet, preferably of paper, having in itself a comparatively low absorption capacity as regards the said radiation, is exposed to radiation of the kind mentioned during a limited time interval, the text and other indicia applied to it will assume an appreciably 'higher temperature than the blank areas. The difference in temperature thus obtained between different areas olf the original can be utilized for copying purposes by employing a substantially wax-like copy printing dye composition, which is heat-sensitive and fusible in such a way that it melts or softens to the point at which it becomes transferable Within a temperature interval that lies mainly between the temperature obtained in the blank areas of the original record as a result of its exposure to the radiation and the temperature obtained in the indicia bearing areas of the ori-giice nal record under the same circumstances, and by letting this dye composition become subjected to the action of the differently heated areas of the original record under such conditions that dye is transferred only within those areas which correspond to the indicia on the original record.

As already pointed out, the temperature-sensitive copy printing dye composition should have a negligible absorption capacity of its own in regard to the infrared radiation, so that at all events the thin coatings or layers olf dye composition which are required for the copying process cannot themselves absorb such an amount of the radition that they become heated into a transferable or molten condition without the aid of the -additional heat received from the indicia bearing areas of the original recor-d. However, such dye compositions of various kinds an-d colours are Well known in the prior art, and it is also assumed to be known, that a copy produced by means of such a dye composition cannot, as a rule, be used itself as an original or master for renewed duplication according to the same method, because it is for obvious reasons hardly possible to obtain the required temperature difference between the blank and indicia bearing areas of such a copy by subjecting it to radiation.

Although the basic principles of the copying method mentioned above, hereinafter simply called the thermographic fusible dye process, have been known for a long time, the method has still its perceptible limits, at least in the forms it has hitherto been more commonly practised. Despite the geniality of the basic idea and the considerable advantages of the process in question over other copying methods it has so far not been possible Ifor practical reasons to use the thermographic fusible dye process for quick duplication of a plurality of copies from a single original record. This invention offers a solution of this particular problem and makes it possible to apply the thermographic fusible dye process in the speedy production of practically unlimited series of copies from an original record in about the same manner as has hitherto only been possible by making use of the well-known spirit or stencil duplicating processes.

Compared to the latter processes, which have hitherto been practically the only ones used in the office branch, the thermographic fusible dye process according to this invention offers great and obvious advantages, above all because it makes it unnecessary to use so-called master sheets with easily spoiled and quickly consumed dye layers, transfer or hectographic carbon sheets with easily-soluble, finger-soiling dye coatings and bad-smelling or otherwise disagreeable liquids, or smeary colours and stencil sheets which are very ditiicult to store between uses respectively. Furthermore, the thermographic fusible dye process offers valuable advantages when it comes to copying of only selected portions of the original record, which advantages are very expedient in connection with so-called selected line-transfer works and similar cases when it is desirable to make a copy only of certain selected parts of the text etc. on the original record.

If the thermographic fusible dye process shall at all be able to offer a practically valuable and thus competitive alternative to spirit or stencil duplicating processes, it must, however, be carried out in such a manner that the copy printing dye composition is transferred to the front surface of the copy receiving sheet, so that the use of particularly thin and transparent copy sheets is not necessary and so that different reproductions can be made on the respective sides of a given copy sheet when so desired. This requirement is well satisfied in accordance with the invention which as far as the character of the copy sheet is concerned does merely require that the surface of the copy sheet shall lbe able to give hold for the dye composition when the latter tends to adhere to it. On the other hand, the invention requires that the original record shall be made on a sheet material which only to a negligible degree impedes the passage of the radiation used, in which case the text indicia are applied in mirror image on the back of the record, or preferably, on a sheet mate` rial which is so thin or otherwise so constituted that it permits a heat transmission-either by conduction or by so-called dark radiation-from the heat-absorbing inkcoated portions on the one side thereof to its other side surface without appreciable dispersion in the plane of the sheet, which could make the copy obscure, in which case the text indicia can be applied in ordinary, true fashion on the front side of the original record.

The mirror image text just mentioned can, of course, be easily produced by placing an ordinary carbon paper in reversed position on the rear side of the original when the latter is typed in a typewriter or prepared by handwriting, provided that the carbon paper is coated with an opaque, radiation-absorbing ink. In many cases a combination of a true image writing on the front face of the original record and a mirror image writing prepared as just explained on the back thereof may be found particularly advantageous to obtain more distinct copies.

The method according to the invention is now mainly characterized in that the original record while performing an uninterrupted cyclical movement is first passed through a zone i-n which the one side of the original record is exposed to said concentrated light radiation, while at substantially the same time the other side thereof is brought into intimate contact with the dye-coated surface of said carrier, which is moved synchronously with and in the same direction as the passing original record so that a first transfer of dye composition from said carrier to those areas on said other side of the original record which correspond to the text and other indicia is effected, then separated from said dye-coated carrier and pressed with the side now partly covered with dye composition against said copy receiving sheet for a second transfer, in which the dye composition spots, on the original record previously received from the carrier are brought to adhere, at least to a substantial extent, to the copy receiving sheet, and finally separated from the copy receiving sheet, now bearing the finished copy, to be immediately ready for repeating its operating cycle.

The double transfer of the dye composition first from the carrier to the original record and subsequently therefrom to the copy receiving sheet may seem complicated at the rst glance but is very easy to accomplish in practice, as will appear from the following, and the method has proved to give a surprisingly good copy clearness while at the same time offering possibilities for very advantageous apparatus constructions.

Although not always necessary, the original record can to advantage be exposed to a second irradiation of infrared light while being pressed against the copy receiving sheet, whereby the dye composition may more easily be given away from the same. This second irradiation may in many cases be less intensive than the first one and independent thereof and is preferably produced by a second source 0f radiation which is separate from the first source but also irradiates through the envelope wall of the drum. When such double radiation is utilized, it may also be found advantageous to cool the original record between the two irradiations in order to govern any tendency of the dye composition to ow out, with obscure copies as a result. Howe-ver, in most cases such cooling is unnecessary.

In principle the carrier of the thin coating of copy printing dye composition may, of course, be any suitable surface which has been coated with the dye composition in question and which can be brought into close contact with the rear side of the original record during the first irradiation. It has, however, been found most suitable to use a carrier in the form of an endless web which can be passed, as its dye composition coating is successively consumed during the copying process, through a dye applicating, coating renewing device or mechanism before it is again brought into contact with the original record. Alternatively there may be used a long and easily exchangeable precoated web running lbetween two spools.

As already mentioned the invention is also concerned with a duplicator apparatus operating in accordance with the directions given hereinbefore and this apparatus is of the kind comprising a rotary drum, the envelope wall of which at least partially consists of a material, preferably glass, having a high permeability to infrared light radiation, a radiation source unit mounted inside said envelope wall of the drum and having a high intensity particularly within the infrared radiation range, said unit being adapted to deliver a concentrated radiation through the radiation-permeable envelope wall portion of the drum to at least one radiation zone that extends axially relative to the drum, and a feeding mechanism for the copy receiving sheets including among other details a pressure roller adapted to be resiliently pressed towards the drum, and is mainly characterized in that said drum is adapted to detachably hold on its outside an original record so that the latter will at least partly extend over the radiation-permeable portion of the envelope wall of the drum and partake in the rotation thereof, that a movable carrier having a surface coated with a thin layer of a fusible copy printing dye composition is arranged first to go into intimate contact with the outside of said original record on said drum within said zone which said radiation source unit irradiates through the radiation-permeable envelope wall portion of the drum, and then to depart from said drum, that said pressure roller serving to press the copy receiving sheets against the original record held around the drum is mounted behind the point, as viewed in the direction of rotation, in which said dye-coated carrier departs from the drum, and that said feeding mechanism includes, in adidtion to said pressure roller, members serving to part the finished copy from the original record at a point behind the pressure roller.

With an apparatus of the type thus defined it is possible to produce large series of copies of one and the same original record in rapid succession Without in any way subjecting said original record to Wear or damage so that it becomes difiicult to store or inapt for completion with additional text if so should be desirable.

For a further elucidation of the invention reference is made in the following to the accompanying drawings, in which FIG. 1 illustrates in a greatly enlarged and rather diagrammatical form the duplicating method according to the invention and at the same time the basic mode of operation of the duplicating apparatus forming part of the invention, while FIG. 2 shows, on a reduced scale, a longitudinal section through a complete duplicating apparatus embodying the invention in which, however, some detail arrangements have been given a very simplified and diagrammatical form for the matter of simplicity, since it is believed that a man skilled in the art will be fully capable to understand how to construct those details himself after having read the following description and directions.

For illustrating the duplicating method according to the invention reference is primarily made to FIG. 1, in which numeral 1 designates a part o-f the envelope wall of a rotary drum, which envelope wall is made of glass or some other material that is highly permeable to the infrared radiation used in the duplicating process. The drum 1 encloses a radiation source unit, generally designated by 2, which in any suitable manner is stationary but possibly adjustably mounted, so that the envelopel wall of the drum 1 moves past it when revolving in the direction indicated by the arrow A Preferably, but not necessarily, the radiation source unit consists of two separate and elongate radiation sources 3, and 4 respectively, of the tubular infrared-radiator type, in which a normally coiled resistance wire is mainly centrally supported in a cylindrical quartz tube, and each radiation source is provided with a substantially elliptical reflector 5, and 6 respectively, capable of concentrating the radiation so that it passes through the envelope wall of the drum 1 and forms two radiation zones 7, and 8 respectively, of a very constricted width and which are peripherally separated and extend axially relative to the drum. Instead of using two radiation sources, it may in some cases be sufficient to use a single one, which should then be arranged similarly to the radiation source 3 to provide the radiation zone 7, which is the most important one. It is also possible to distribute the radiation from a single radiation source to both the two radiation zones 7 and 8 by means of a reflector arrangement, although this will ordinarily bring about rather considerable radiation losses and accordingly an unnecessarily high heating of the space within the drum as well as problems with the adjustment of the radiant power in the two radiation zones.

Retained in some suitable manner on the outside of the envelope wall of the drum 1 is an original record 9 which is, in the example shown in FIG. 1, provided with text indicia on its front side, i.e. the side facing the drum 1, whereby this text can be made true in the normal manner, provided that the original record 9 is made on a base sheet, e.g. of paper, which allows heat transmission through it without too much dispersion. The text indicia 10 are made by the application of an opaque, radiation-absorbing ink or the like, and the base of the original must be of such a nature that its textfree, blank areas will only absorb a very inferior quantity of the infrared radiation. As already mentioned in the introduction the original record 9 may, however, alternatively be made on a base sheet which in itself does only insigniiicantly or not at all inhibit the passage of the infrared radiation from the radiation source unit 2, in which case the text indicia can be applied by means of an opaque, radiation-absorbing ink or pigment in reversed or mirror writing on the rear side of the record, i.e. the side thereof which is turned away from the drum, or even on both sides of the base sheet. Thus, the essential thing is that, during the irradiation from the radiation source unit 2, the surface temperature of those portions or spots on the rear or outer surface of the original record 9, which correspond to the text indicia, shall become distinctly increased relative to the surface temperature of all the other areas of the same rear surface of the record which correspond to blank or indicia-lacking portions of the record.

Disposed substantially right in front of the first radiation zone 7 through which the original record 9 attached to the outside of drum 1 is passing during the rotation of the drum in the direction indicated by arrow A and pressed against the outwardly facing rear side of record 9 and radially towards the drum l-at least during the copying process-is a comparatively soft, e.g. spongerubber-coate-d, roller 11 over which passes a conveyorlike carrier web 12, which can to advantage be made of paper with great tensile strength, plastic sheeting (preferably nylon) or any other suitable iiexible material, and which carries on its outer surface, when arriving to the roller 11, a thin and uniform coating 13 of the previously specified copy printing dye composition which is transferable after having been heated into a softened or molten state. By means of the conducting roller 11 fresh parts of the dye-coated web 12 are perpetually pressed against the rear side of the passing original record 9, and due to the nature of the dye composition at least parts of this composition coating will then be transferred from the web 12 to those portions or spots on the rear side of the record 9 which corresponds to the text. indicia appearing on that record. Consequently the original record itself will, when being subsequently separated from the web 12 as a result of the web deliecting function of the roller 11, take over and with it certain limited portions or spots 14 of the dye composition coating 13 of the web 12, so that the said coating on the web 12 is partly consumed as shown diagrammatically in FIG. l. It will be obvious that this partial transfer of the portions 14 of the dye composition coating 13 requires that the surface of the original record sheet must be of such a nature that the dye composition in its heated or molten state will readily adhere to it. With this transfer the first stage `of the duplicating process according to the invention is finished, and the original record has thereby in itself become a sort of master prepared for the duplicating 'task proper and to a certain extent resembling an inked lithographie printing plate, although produced in a different way.

It has `been observed in some cases that the portions or spots 14 of the dye composition transferred from the layer 13 to the rear or outer surface of the original 9, may show a tendency to iiow out and so render the contours of the indicia images obscure. The cause of this may be either that the surface of the original record sheet is not quite ideal (possibly too porous so that a sort of blotting-paper-effect results), that the melting heat requirement of the dye composition is much too low, or that the heat quantity produced by the radiation is not very well balanced to the actual working conditions of the apparatus, i.e. the nature of the original, the properties of the available dye composition, and the radiation intensity. Such flowing out tendencies can, however, be governed in a very simple way by providing the apparatus with a tubular nozzle 15 mounted for instance at a guide plate 16 as shown in the drawing and supplying cooling air to the rear side of the original record 9 from a suitable little pump or compressor (not shown in the drawing) within the area immediately behind the roller 11. However, if the apparatus is intended for work with only one single, predetermined type of original records and with a dye composition having permanently the same properties, such cooling may of course be dispensed with and the radiation intensity in the zone 7 instead be exactly adjusted once for all. The cooling nozzle 15 can also be omitted when some obscurity of the copy can be accepted, for instance to cut the manufacturing costs for the apparatus.

As a result of the rotation of the drum 1 the prepared original record is in the example shown in the drawing very soon brought to pass through the second radiation zone 8, in which the infrared radiation need not necessarily be as intensive as in the radiation zone 7. In the radiation zone 8 a second absorption of radiation will take place within the text indicia bearing areas 10 of the record 9 and thus also an indirect heating of the portions or spots 14 of fusible dye composition adhering to the outer rear side of the record. The very moment these dye composition portions or spots reach the temperature needed to become fused or at least sticky, the rear side of the original record '9 is brought into contact with a copy receiving sheet 17, e.g. a sheet of ordinary paper, cardboard or the like, which the guide plate 16 steers in between the drum 1 and a pressure roller 18. The said roller 18 is pressed radially against the drum during the duplication and has a comparatively hard surface of rubber or a similar material with a high friction coefficient. In certain cases a slight preheating of the copy receiving sheet 177 before it is brought into contact with the original record 9, may be found advantageous, but normally such special steps are not required. The copy receiving sheet does not need to be of any particular quality nor does it need any preparation `for instance with chemicals, but it should obviously afford a good base of adhesion for the dye composition. Of course, the copy receiving sheet 17 does n-ot need to be transparent nor to have any specific properties with respect to the infrared radiation used in the copying process. The dye composition portions or spots 14 previously transferred to the rear side of the original record 9 and softened through heating in the second radiation zone 8 will, of course, readily adhere to the copy receiving sheet 17 when the latter is pressed against the record at a point located substantially right in front of or, as has been shown, slightly after the radiation zone 8. As pointed out already, the radiation zone 8 may be omitted but, if so, the distance between the radiation zone 7 and the pressure roller 18 should be chosen as short as possible, or the drum 1 should rotate at quite a high speed. Furthermore the cooling nozzle 1S should in such a case be dispensed with.

Already immediately behind the pressure roller 18, but preferably a little farther away from it, as shown, the copy sheet 17 is in its turn separated from the original record 9 as indicated by the arrow B. The portions or spots 14- of the dye composition will at this time be at least partially transferred to the copy sheet and form on the latter a true copy of the text and other indicia on the original record. It is true that certain residues of the dye composition will normally be left on the rear side of the original record but these residues have proved completely harmless for the utilization of the same record 9 in the repeated duplicating process and also for the filing and handling of the original record after duplication, since the dye composition will not give off any dye and is not sticky at normal room temperature or, as a rule, at temperatures below approximately to 40 C.

How far the copy receiving sheet 17 should follow the original record 9 before being separated therefrom depends very -much on the nature of the dye composition and must thus be determined empirically in each particular case. Commonly it seems to be so, however, that a very early separation of the copy from the original record results in transfer of only a smaller part or thickness of the dye composition than a more postponed separation. The reason for this may be that the dye composition congeals so to say layer by layer in the direction from the comparatively cold copy sheet 17 toward the comparatively warm original record 9.

FIG. 2 shows more in detail how a complete duplicator apparatus embodying the invention can be constructed. The drum 1 is rotatably mounted between two longitudinally extending side walls on the apparatus, one of which is visible at 20. Mounted between the side walls are also two feeding rollers 21 and 22 one of which, 22, is driven and circumferentially covered with sponge rubber. The feeding rollers 21 and 22 serve to feed the copy receiving sheets 17 to the pressure roller 18 past the guide plate 16 previously referred to as wcll as further guide plates 23, 24 and 25 respectively, from a feed table 26 at the front end of the machine, on which the fresh copy receiving sheets are suitably stored in a pile. Any suitable known devices may, of course, be used to automatically feed the copy receiving sheets 17 one by one onto the feeding rollers 21 and 22. The pressure roller 18 is mounted between two bell-crank levers 27, the downwardly extending arms of which are actuated by tension springs 28, the tension of which can -be varied by turning an eccentrically mounted rod 29 in order to adjust the pressure exerted by the pressure roller 18 against the drum 1.

The conducting roller 11 of the belt-like carrier web 12 is in its turn mounted between side walls 30 belonging to an insert, which is removably suspended in the front part of the duplicator apparatus and is shaped so as t0 urge the roller 11 towards the drum 1 by its own weight. In fact, this insert forms a complete dye applicating unit comprising a trough 31 containing the dye composition 32, and an electrically heated transfer roller 33 dipping its underside into the trough so that it can, during its rotation, apply fresh dye composition to the passing web 12 and smooth out the remaining coating of dye composition thereon so as to completely restore said coating. A likewise electrically heated scraper device 34 serves to scrape off superfluous dye composition from the web 12 and so bring the coating 13 (FIG. l) on the latter to the appropriate thickness-ordinarily not exceeding some hundredths of a millimeter. The scraper device 34 also dips its lower portion into the trough 31 and is shaped as a pocket 35, in which sticks or like pieces of fresh dye composition can be received and melted to thereafter enter the trough 31 in a uid state. Having passed the scraper device 34 the web 12 is bent over a cooling roller 36 which is mounted between two pivoted arms 37, which are loaded by springs 38 in order to keep the endless web 12 well stretched. Preferably, the cooling roller 36 is cooled by an air stream from a fan (not shown). After having passed the cooling roller 36 the web 12 is ready to return to the conducting roller 11.

Behind the drum 1 there is provided a belt or rubber string conveyor which serves to separate the finished copies from the original record 9 on the drum and transport them to a discharge table 40 provided at the top 0f the rear part of the duplicator apparatus, so that the operator can continuously check the copying result even when standing, as is normally the case, in front of the apparatus, i.e., to the left in FIG. 2. The said conveyor comprises several endless rubber belts or strings 41 running parallelly to each other between lower and upper pulleys 42, and 43 respectively, and the endless belts or strings are driven by contact with a common, transverse driving roller 44. Those parts of the belts or strings 41 which pass closest to the drum 1 cooperate with one lower and one upper row of pulleys 45, and 46 respectively, which are mounted between a plurality of parallel, interconnected plates 47 which form another detachable insert in the apparatus, and the lower ends of which are pointed and adapted to aid in separating the front edge of the copies from the original record on the drum 1. Mounted on freely swingable arms 48 between the upper ends of the plates 47 are free-running auxiliary pulleys 49 which serve to direct the copies discharged between the belts 41 and the plates 47 so that -they become neatly piled on the table 40.

The drum 1, the envelope wall of which consists for the largest part of a material readily letting through the infrared radiation from the radiation source unit 2 disposed inside the drum, is provided with an axially extending out or slot in which is provided a filler member 50 accommodating two series of movable jaws, by means of which the original record, and a covering sheet for partial covering of said record respectively, can be attached to the drum 1. Two guide plates 51 and 52 are provided on the front side of the drum to guide the original record, and the covering sheet respectively, towards the said jaws in the location where the ller member Sil of drum 1 is normally intended to stop when the apparatus is to be prepared for a new duplicating procedure. The drum 1 is, in fact, rotary mounted between two annular end pieces 53 located one at each end of the drum and in their turn rotary mounted between external supporting rollers 54, secured to the respectively side walls 20 of the apparatus, and furthermore interconnected by a screen 55 of limited peripheral extension, which is concentric with the drum 1 and placed on the inside of the latter. The drum 1 can be locked to the end pieces 53 by means of a locking device indicated at 56 and is driven via the end pieces 53, to which is primarily transmitted the rotary motion that is to be imparted to the drum 1 for execution of the duplication.

The screen 55 has for its object to permit switching on of the radiation source unit 2 slightly prior to the moment when the original record attached to the outside of the drum 1 should be irradiated, and this is particularly valuable when using intermittent operation of the radiation source unit which has proved most advantageous, because in this way the total energy consumption of the apparatus can be reduced to a certain degree and thus also the problem of removing the superfluous heat that is inevitably produced within the drum 1 while the radiation source unit is in operation. The screen 35 can also be utilized to screen off a selected part of the original record attached to the outside of the drum, so that the text on this part will not be reproduced. To this end, the locking device 56 is released and the drum rotated so far relative to the screen 55 as is necessary to screen off the desired part of the original record.

Inside the screen 55 there is provided, also concentrically with the drum, an additional diaphragm screen 57 carried between two spring-loaded arms 58, which are centrally pivoted relative to the drum 1. The diaphragm screen 57 is only swingable to a limited extent in the downward direction, so that it will temporarily screen off the radiation source unit 2 from the inside of the drum when each single copying process is iinished, and particularly so when it is desired to effect a so-called line transfer, i.e., to prevent duplication of a certain number of text lines on the lower portion of the original record. In the example shown, the diaphragm screen 57 is actuated through friction by a crcumferentially adjustable wart or driver 59 provided on the end piece 53, and as soon as this wart has passed the swung-down diaphragm screen, the latter is restored automatically by its springs. However, at this moment the -radiation source unit 2 has already been switched off, and the radiant power possibly remaining after the switch-olf moment has had no possibility to reach the original record and to thereby cause any undesirable copy producing result. Of course, the diaphragm screen 57 does not need to be used when the entire original record is to be reproduced.

The radiation source unit 2 is carried by a stationary cylinder 60 inside the drum 1, and suitable fans (not shown) provide for -an axial iiow of cooling air at least through the annular space lbetween the drum 1 and the cylinder 60. The power supply to the radiation lsource unit 2 takes place preferably from a built-in transformer 61, while an electromotor 62 drives the driving roller 44 of the belt conveyor as well as the feeding roller 22 and the drum 1 via the end pieces 53. Special couplings (not shown) are used to lallow an interruption of the drum rotation when so desired in order to prepare the apparatus for a new duplicating procedure. When necessary, a driving motion can also be imparted to the web 12 passing through the described dye applicator mechanism in order to prevent it from sliding when in contact with the original record attached to the outside of the drurn 1.

Of course, the duplicator apparatus hereinbefore described can easily be provided with a plurality of complementary devices, such as means for stepwise rotational adjustment of the drum 1 relative to the end pieces S3 as well as for accurate peripheral adjustment of the wart or diaphragm screen driver 59 by operation of an easily accessible lever or key. The web 12 passing through the dye applicator mechanism can, of course, be replaced by a roller of suitable size serving in itself as a carrier of a thin coating of dye composition and being supplied with fresh dye composition during every full revolution in some suitable manner. In a further thinkable modification the apparatus can be charged with a supply roll or spool of web, which has been coated with dye composition and can be collected and supplied with fresh dye cornposition in a separate dye application mechanism, or be discarded, after having passed lthe roller 11 or its equivalent replacement. It should thus be understood, that the invention is not conned to the embodiment described above and illustrated in FIG. 2, although this embodiment has proved to work very satisfactorily in prototype tests.

I claim:

1. An apparatus for series-duplicating on unprepared copy receiving sheets of heat radiation absorbent text, pictures and like indicia appearing on an original While making use of the thermographic fusible dye process and utilizing the original as an intermediate means for transferring selected spots of dye composition from a carrier of a thin coating of said composition to each copy receiving sheet, said apparatus comprising in combination:

(A) a rotary drum, the envelop wall of which partially consists of a glass material having a high permeability to infrared light radiation;

(B) means on said drum for detachably mounting the original on the outside thereof in such a manner that it will be at least partly extend over the radiationpermeable wall portion of the drum and partake in the rotation of the drum;

(C) a radiation source unit mounted inside said drum and having a high intensity, panticularly within the infrared radiation range, said unit being adapted to deliver a concentrated radiation through said radiation-permeable wall portion of the drum to form at least one radiation zone extending axially along the drum;

(D) a movable carrier in the form of a belt-like web having its one side coated with a thin layer of the fusible copy printing dye composition;

(E) conducting means for said coated carrier web including a conducting roller arranged to be resiliently pressed towards said drum for bringing the coated side of the carrier web into intimate contact with the outside of the original mounted on said drum within said one radiation zone and for subsequently bringing it to depart therefrom;

(F) a feeding mechanism for copy receiving sheets including a pressure roller arranged to be resiliently pressed towards said drum at a location behind that, where said conducting roller is located, as viewed in the direction of rotation of the drum, said pressure roller being adapted to press each copy receiving sheet against the original mounted on the drum, and means for separating each such sheet with #the copy thereon from the drum-mounted original at a location behind said pressure roller.

2. An apparatus according to claim 1, wherein said conducting roller for the coated carrier web has a cornparatively soft, elastically yielding surface and said pressure roller for the copy receiving sheets has a comparatively hard, elastic surface.

3. An apparatus according to claim 1, wherein said radiation source unit comprises two separate, elongated radiation sources provided with each a related reector, one of said radiation sources being arranged and directed to form said one radiation zone and the second one being arranged and directed to form a second radiation zone extending axially along the drum in the neighborhood of the line of contact between said pressure roller for the copy receiving sheets and said drum.

4. An apparatus according to claim 1, wherein said belt-like web is endless and wherein a dye applicator mechanism passed by said endless web is provided to apply fresh dye composition thereto, said applicator mechanism comprising a trough holding the dye composition, heated means for distributing the dye composition on said passing web, and means for cooling 'the dye-coated web to a temperature below the softening temperature of the composition before the web is again brought into contact with the original.

5. An apparatus according to claim 1, wherein a radiation-impermeable screen is provided between said radiation unit and the inside of the envelope wall of said drum and concentric therewith, said screen having a limited circumferential extension as compared with the drum and partaking in the rotation thereof so a-s to cover a portion of said drum and substantially concentric therewith, said peripherally adjustable relative to said drum in order to permit screening olf of a selected portion of the original held on the outside thereof.

6. An apparatus as claimed in claim S, wherein an additional diaphragm screen is provided between said radiation source unit and the inside of the envelope wall of said drum and substantially concentric therewith, and diaphragm screen being movable to screen olf said radiation source unift when said drum with the original record held thereon has accomplished a preadjustable part of a full revolution, all in order to permit the apparatus to reproduce only selected lines of the original record.

References Cited UNITED STATES PATENTS Roshkind Z50-65.1 Limberger 25 O-65.1 Strozynski Z50-61.1 Kalmanson Z50-61.1

RALPH G. NILSON, Primary Examiner. 10 A. L. BIRCH, Assistant Examiner.

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