US3828355A

US3828355A - Continuous ink-jet recording

Info

Publication number: US3828355A
Application number: US00398334A
Authority: US
Inventors: R Wick; R Meyer; K Hoffmann
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1972-09-23
Filing date: 1973-09-18
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06
Also published as: FR2200714A1; BE805003A; DE2246797B2; CA984892A; JPS5653512B2; DE2246797C3; SE397729B; FR2200714B1; JPS4971814A; CH558619A; DE2246797A1; GB1421043A

Abstract

The ink-jet recording system comprises a rotor on whose cylindrical surface rests a recording support, and a annular inkjet nozzle system which is stationary in relation to the rotor. At least one supply roll and one take-up roll for the sheet-form recording support are arranged on the rotor. These rolls are connected to the rotor so that the recording support makes both a rotary and a translatory movement in operation relative to the stationary nozzle system. In a preferred embodiment the rotor in the form of a solid cylinder and the recording support is guided externally over the surface of the rotor. In this embodiment, the stationary annular nozzle system is arranged over the surface of the rotor.

Description

United States Patent [191 Wick et al. Au 6 1974 [54] CONTINUOUS INK-JET RECORDING 3,416,153 12/1968 Hertz et al. 346/75 [75] Inventors: Richard Wick, Munich; Rudolf Meyer; Klaus Hoffmann, both of Primary Examiner-Joseph W. l-lartary Leverkusen, all of Germany Attorney, Agent, or Firm-Connolly and Hutz [73] Assignee: Agfa-Gevaert Aktiengesellschaft,

Leverkusen, Germany [57] ABSTRACT [22] Filed: Sept. 18, 1973 I Y The inket recordlng system comprises a rotor on PP whose cylindrical surface rests a recording support, 1 and a annular ink-jet nozzle system which is stationary [30] Foreign Application Priority Data in relation to the rotor. At least one supply roll and t 23 1972 Gama 2246797 one take-up roll for the sheet-form recording support ep are arranged on the rotor. These rolls are connected I to the rotor so that the recording support makes both [52] 178/66 a rotary anda translatory movement in operation relative to the stationary nozzle system. In a preferred eml' Gold 1 21 6 bodiment the rotor in the form of a solid cylinder and 6 the recording support is guided externally over the surface of the rotor. In this embodiment, the station- 56] References Cited ary annular nozzle system is arranged over the surface of the rotor.

UNITED STATES PATENTS 3,130,931 *4/1964 Hautly 346/l38 UX 20 Claims, 14 Drawing Figures Pmmmms 61974 saw an or 1o PAHNIEDMB 14 Y 3.8%.355

sum :05 or 10 PAIENTEU MIC 74 saw as or 1o PATENTEU AUG 6 I974 sum 07 or 10 FIG. 70

PAIENIEDAUB 6:914

saw '08 or 10;

Axsmwwe 61914 3.828.355

' sum "09 or 1o FIG. 72

ummus SIHH 3.828.355

sum '10 or 10 CONTINUOUS INK-JET RECORDING This invention relates to an apparatus for continuously recording ink-jet pictures. It comprises a rotor on whose cylindrical surface rests a recording support, and an annular ink-jet system.

In ink-jet recording, ink or coloured liquid is extruded under high pressure through a nozzle (capillary), Immediately downstream of the noule is an annular control electrode. A voltage U is applied between this electrode and the'conductive ink or coloured liquid. When U exceeds a certain limit (about 200 volts), the jet of ink breaks up into small droplets. The higher the voltage U, the greater is the degree of disintegration.

The unbroken jet passescompletely through a small diaphragm aperture-and strikes the support guided past the diaphragm'However, the droplets diverted from the linear path drop onto the diaphragm and are filtered off under suction through a sintered metal filter. The higher the voltage U, the smaller the quantity of ink or coloured liquid which'reaches the support. The principle of this process is described in detail in German Auslegeschrift 1,271,754.

One serious disadvantage attending most conventional ink-jet recording processes is that they are not continuous (US. Pat. No. 3,404,221). The recording material in the form of paper or film is stretched in the form of a single sheet across a rotating roller and has to be removed on completion of a picture whose size is limited by the size of the drum casing.

In order to obtain continuous picture recording, it has now been proposed to fit a number of nozzles togetherin a row to form a nozzle comb and to arrange several such nozzle combs one behind the other in a staggered pattern so that the openings of all the nozzles lie in one plane. A sheet guided past in this plane is then uniformly covered with parallel rows of drops (cf. for example DOS 1,941,680). In this arrangement, therefore, each picture line is recorded by a different nozzle. This calls for an extremely large number of nozzles for producing high-resolution pictures and since each nozzle together with its control unit takes up a certain amount of space, it is alsonecessary to have a number of nozzle rows which have to be adjusted in relation to one another.

It has also been proposed to record continuously on supporting sheets by guiding the droplet generators arcuately over the recording support in the scanning direction, rather than arranging them fixedly or advancing them slowly at right angles to the scanning direction, in which case the sheetform recording material makes a slow translation movement (DOS 1,936,518), or by mounting the droplet generators inside a semicylinder for rotation about the axis of this cylinder and having them spray onto the recording support which is advanced on the inside of the cylinder in the axial direction.

Unfortunately, all arrangements in which the droplet generators are moved quickly in the scanning direction are attended by the disadvantage that electrical signals, high pressures and coloured liquids have to be transmitted to components rotating at high speed. In many cases, this means that picture quality is adversely af fected.

An object of the invention is to provide an apparatus for the continuous recording of ink-jet pictures which gives high picture quality and is relatively simple and compact in structure. It is armed to do this with as few ink nozzles as, possible so that only a correspondingly small number of transmission channels need be used. A small number of transmission channels means less Outlay in terms of electronics ans also far less troubleprone operation.

According to invention, here is provided an apparatus for continuously recording ink-jet pictures comprising a rotor having a cylindrical surface, and an annular ink-jet nozzle system, wherein the ink-jet nozzle system is stationary in relation to the rotor, and at least one supply roll and one take-up roll are arranged on the rotor for at least one recording support in guided sheet form each of which is guided over the rotor surface being connected to and rotating with the rotor so that the or each recording support simultaneously makes a rotary and translatory movement in relation to the stationary nozzle system.

In one embodiment of the invention, the rotor is in the form of a hollow cylinder and the recording support is guided over the inner surface of this hollow cylinder. In this embodiment of the invention, the stationary, annular nozzle system is arranged inside the hollow cylinder. In another preferred embodiment of the invention, the rotor is in the form of a solid cylinder and the recording support is guided externally over the surface of the rotor. In this case, the stationary annular nozzle system isarranged over the external rotor surface.

The sheet-form recording material is guided'over the rotor surface either helically or parallel to the rotor axis. I Guide rollers are advantageously arranged in the vicinity of the supply rolls'and take-uprolls to guide the sheet from the supply rolls onto the rotor surface and from the rotor surface to the take-up rolls.

In one preferred embodiment, the supply roll and take-up roll are arranged inside the rotor and their axes are inclined towards the rotor axis in accordance with the directions in which the sheet runs onto and off from the rotor surface. The supply roll and take-up roll are preferablyarranged on the rotor axis. In this case, the

axes of the guide rollers have to be inclined relative to the rotor axis in such a way that the recording sheet is turned through 90 into a plane tangential to the rotor surface. The angle of inclination a of the guide rollers with respect to the rotor axis is advantageously selected to correspond to the relation a yU where a is the angle at which the sheet runs onto and off from the rotor surface, whilst U is the degree of looping around the guide roller. In a further improvement, the degree of looping around the guide rollers is kept constant. For this purpose, additional guide rollers are arranged in the vicinity of the supply and take-up rolls.

The rate of sheet advance is determined by the guide rollers. For this purpose, at least one of the guide rollers is driven.

The drive system is preferably such that the ratio of the peripheral speed V of the rotor to the rate of sheet advance V is constant.

In the embodiment in which the recording sheet is guided parallel to the rotor axis, the supply rolls and take-up rolls are advantageously distributed uniformly around periphery of the rotor at both ends thereof. The supply rolls and take-up rolls are arranged opposite one another.

In another embodiment, the supply rolls are arranged at one end and the take-up rolls at the other end of the rotor adjacent one another on the rotor axis. In this way, imbalance of the rotor is minimised from the outset.

According to another aspect of the invention, contact rollers are provided on the rotor surface, bringing the recording sheet into contact with the rotor surface in the vicinity of the nozzle system. In an alternative embodiment, the recording sheet is drawn onto the rotor surface by means of a-vacuum. For this purpose, the rotor surface is provided with bores'and the inner v compartment of the rotor connected to a vacuum pump.

In cases where the recording sheets are guided parallel-to the rotor axis, it is of advantage to bevel the rotor surface frusto-conically towards its ends. The flat recording sheets are thengradually converted into the curved form. In this-embodiment as well, the guide rollers arepreferably inclined to the rotor axis in such a way that the recording sheets are always through 90 into .a plane tangentialto'the rotor surface." As in the helical sheetguide system, additional guide rollers are again arranged in the vicinity of the supply rolls and take-up rolls to ensure that the looping angle around the guide rolls remains constant. I

'The recording sheets should slide over the rotor surfacewith minimal frictional resistance. In this respect, it is'proved to be of advantage for the rotor surface to consist of a hydrophobic material.

An advantage of the invention is that a large number sociated control systems. The recording support is in the form of paper sheeting 8 which is guided helically over the rotor surface 5 by means of guide ridges 9. The

supply roll and the take-up roll for the recording paper are situated inside the rotor 2. Guide rollers 10a and.

10b are provided on the rotor surface 5 which make it easier for the paper 8 to run onto and off from the rotor surface 5. Accordingly, the paper 8 slides helically over the rotor surface 5 and passes through beneath the stationary nozzle system 6. In order to reduce friction, the rotor surface is coated with a hydrophobic material.

of ink-jet pictures can be continuously recorded without any need for complicated manipulation of the recording apparatus. The recording support does not have to be continually refitted as before. Control of the nozzle system involves relatively little outlay in terms of electronics and the probability of faults occurring through the electronics is thus reduced.

Embodiments of the invention are described by way of example. below with reference to the accompanying drawings, wherein:

FIG. 1 illustratesthe principle of ink-jet recording (prior art). Y

FIG. 2 is a diagrammatic perspective view illustrating the recording apparatus according to the invention.

FIG. 3 illustrates an embodiment in which the recording support is guided over the inner surface of a hollow rotor.

FIG. 4 shows a rotor of the kind illustrated in FIG. 2, in which the recording sheet is guided helically over the outer surface.

FIG. 5 is a side elevation of the rotor shown in FIG.

FIGS. 6 to 8 show how the sheet is guided from a supply roll to the rotor surface by means of obliquely arranged guide rollers.

FIG. 9 shows the extent to which recording is governed by angle in the case of helical guiding.

FIG. 10 shows an embodiment in which the recording sheet is guided parallel to the rotor axis.

paper 8 makes a rotary and translatory movement in relation to the stationary nozzle system 6. In this way,

each point of the recording paper describes a helical linein relation to a stationary nozzle 7 aslong as it is situated on the rotor surface. '1

FIG. 3 shows an embodiment in which the rotor 2 is in the form of a hollow cylinder. In this case, the nozzle system 6 is installed inside the rotor 2. The nozzles are connected to a supply through ink lines 6a. The recording sheet 8 is guided over the" concave inner surface of the rotor 2. The rotor casing is provided with bores 11 which open into vacuum chambers 12. The'recording sheet 8 is drawn onto the rotor surface under the effect of the vacuum and is in complete surface contact with it; 1 i Some difficulties are involved in guiding the recording sheet from the supply roll to the take-up roll. This operation is described below with reference to FIG. 4.

. As in FIG. 2, the recording sheet 8 is guided helically FIG. 11 shows the arrival of the recording sheet on over the outer surface 5 of the rotor. The sheet 8"is guided from a supply roll 13 situated inside the rotor 2 overthe guide rollers l0aand 10b onto the rotor sur'-' face 5. At the other end ofthe rotor 2, it is guided over similar guide rollers to a take-up roll 14. The take-up roll 14 is driven by an electric motor through a friction clutch. However, the sheet is actually advanced by the guide rollers 10b in the vicinity of the take-up roll 14. In order to ensure that the sheet is always in firm contact with the rotor surface and does not flap, the

guide rollers 10a and the supply roll 13 are provided with a friction brake. In addition, the friction brake on the supply roll 13 ensures that it is only the required length of sheeting which is run-off. The axes of the supply 'roll 13 and take-up roll 14 are inclined towards the rotor axis 15 in accordance with the directions in which the sheet runs onto and off from the rotor surface. This inclined arrangement prevents the recording sheet 8 from shooting out sideways.

FIG. 5 is a side elevation of the arrangement illustrated in FIG. 4. The recording sheet 8 runs onto the rotor surface 5 from the supply roll 13 over the guide rollers 10a. There is a recess in the rotor surface in the vicinity of the guide rollers 10a. The outside of the nozzle system 6 is arranged concentrically around the rotor 2.

One particularly advantageous embodiment uses an oblique guide roller 16 (FIGS. 6 to 8). In this arrangement, the supply roll 13 is arranged on the rotor axis 15 and not inclined thereto. The recording sheet 8 is directed into a helical path on the rotor surface by the guide roller 16 whose axis is directed obliquely of the rotor axis 15 and hence obliquely of the axis of the supply roll. The angle of inclination 'y, at which the recording sheet 8 moves into its helical path, is governed both by the angle a of the axis of the guide roller 16 with respect to the rotor axis and by the looping angle g of the recording sheet 8 around the guide roller 16. The values of -y, a and g are related by the equation a 'y-g. If, for example, the looping angle g is one-half, the angle a between the guide roller 16 and rotor axis 15 is half as large as the angle y at which the recording sheet 8 moves into its helical path. Since as operation continues the diameter of the supply roll 13 becomes progressively smaller, the looping angle g and hence the helical-path angle 7 would alter continuously in the absence of any additional measures. For this reason, additional guide rollers 17 are provided to ensure that the looping angle g remains constant. Similarly, guide

rollers

16 and 17 are also arranged in the vicinity of the take-up roll at the other end of the rotor. One of the guide rollers 16 is again responsible for sheet advance.

FIGS." 2m 5 show the nozzle system fixedly arranged in a circle around the rotor 2 in the middle between the offwinding guide rollers a and the onwinding guide rollers 10b. The number of loops of the recording sheet 8 around the rotor 2 between entry and contact determines the size of the area available for the ink nozzles 7. For one complete loop, this area is equal to zero. In the case of a double loop, and if it is assumed that the sheets 8 lie close together, the area F available for the ink nozzles 7 is given by:

F=B Z B where B is the width of the recording support and d the diameter of the rotor 2. More generally, when the looping angle U is included,

Since, in the method of picture recording described here, the picture trace of an ink nozzle 7 appears as a spiral line on the stretched recording support due to the rotation and simultaneous translation of the recording sheet, it is important to know the extent of the interval, more particularly the vertical interval, between two picture traces because this interval determines the number of ink nozzles 7 which have to be used to fill the gap between these ink traces with further ink traces.

FIG. 9 illustrates parameters governing this which are explained in the following, and the flattened recording sheet of one loop in its correct position to the rotor axis with the ink traces produced on the basis of the V speed of the recording support relative to the rotor V resulting speed of the recording support when V and V have substantially the same direction. The angle at which this speed is reached is desig- VI rEs uIti ngspeed of the recording support when V and V are substantially oppositely directed. The corresponding angle is designated B If the conditions are calculated with the parameters defined abovggz cording to FIG. 9, then:

B 1/-= V a a vl dn V1 111 The conditions are illustrated by the following numerical example. Suppose that d cm B 10 cm V 500 cm/sec V 50 cm/sec.

The following intervals are then obtained for b and If it is desired to fill this gap with inknozzles in a den sity of 10 nozzles/mm, it is necessarythat z 91 and z l l l ink nozzles. If it is calculated that each ink nozzle with its associated control system occupies about 1 cm the looping angle U can be approximately determined as being U =1.l; U l.15.

In cases where it is desired to apply multicolour information, the number of ink nozzles is increased accordingly, as is the space requirement and looping angle.

It is possible with a predetermined number of nozzles, z, recording-support width B and rotor diameter d, to determine the ratio of the speeds V /V It is of the utmost importance to'maintain the ratio V /V in operation in order to ensure-the precise connection of two scan zones after one revolution of the rotor. For this reason, a regulating mechanism (not shown) is incorporated in the arrangement, being responsible not only forthe constancy of revolution but also for the constancy of V /V Since an asymmetrical distribution of mass about the rotor axis is present in the rotating system with all its fittings, the system has to be balanced by applying additional masses to it before operation in order to minimise the forces acting on the bearings. It is even of advantage, in the interests of highly desirable synchronism which promotes picture quality, to arrange additional flywheel masses in order to correct minor fluctuations in regulation.

The arrangement described above is distinguished by the fact that, in addition to the rotation of the rotor 2, the recording sheet makes a helical movement onthe rotor surface 5. Accordingly, the recording sheet 8 spontaneously makes both a rotary and also a translatory movement.

An alternative embodiment which has also proved to be effective is shown in FIG. 10. In this case, the recording sheet 8 only makes a translatory movement. The rotary movement relative to the stationary nozzle system 6 is made solely by the rotor 2. In this case, the supply rolls 13 and take-up rolls 14 are arranged opposite one another at the ends of the rotor 2. The recording sheet 8 runs over the rotor surface parallel to the rotor axis 15. Since the recording sheet 8 is fairly thin and is not very stiff against flexure according to its inner consistency, it is readily possible by maintaining a certain minimum interval between the supply rolls 13 and take-up rolls 14, to deform the sheet in such a way that it applies itself uniformly to the cylindrical rotor surface. In addition, pairs of contact rollers 18 ensure that the recording sheets 8 are uniformly applied to the rotor surface in the vicinity of the annular, stationary nozzle system 6.

The entire system, including the supply rolls l3 and take-up rolls 14, rotates about the rotor axis 15. At the same time, the recording sheets 8 follow a translatory path, i.e. from the supply rolls 13 to the take-up rolls 14 in the direction of the rotor axis 15. The annular nozzle system is arranged substantially in the middle of the-rotor 2. The interval b between two ink traces after one revolution is given by the relation where V sheet speed in the direction of the rotor axis V, tangential speed of the rotor at the rotor surface,

B width of the recording sheet.

The transition of the recording sheet 8 from the flat form at the supply rolls 13 into the curved form onthe rotor surface 5 is facilitated by a special configuration of the rotor 2 at its ends'(cf. FIGS. 11 and 12). The delivery rolls 19 guide the flat sheet from the supply rolls 13 towards the rotor 2. The beginning of the rotor 2 is frusto-conical so that the flat recording sheet 8 is gradually converted into an arcuate form. The frustoconical portion stops in the vicinity of the nozzle system 6 where the recording tape 8 follows the rotor surface particularly closely under the effect of the contact rollers 18. FIG. 12 is a sideelevation of FIG. 11. The gradual transition of the recording sheet from its flat form into its arcuate form can be seen particularly clearly in FIG. 12. Instead of providing contact rollers 18, the rotor can alternatively be in the form of a suction roller. In this case, the recording sheet 8 is drawn onto the rotor surface by vacuum.

The arrangement of the supply rolls 13 and take-up rolls 14 is by no means confined to the embodiment shown in FIG. 10. It can be used in the same way as in the case of the hollow cylinder rotor shown in FIG. 3.

In the arrangment shown in FIG. 10, where the supply rolls l3 and take-up rolls 14 are distributed uniformly over the periphery of the rotor 2, there is a relatively high moment of inertia. For this reason the rotor bearing has to be made correspondingly strong. Much more favourable in this respect is an embodiment in which the supply rolls 13 are arranged at one end and the take-up rolls 14 at the other end of the rotor 2 alongside one another on the rotor axis 15. In this case, as in the embodiment shown in FIGS. 6 to 8, the recording sheet 8 is turned through 90 into a tangential plane to the rotor surface by oblique guide rollers 16 and additional guide rollers 17. This embodiment is shown in FIGS. 13 and 14. As already described, the direction followed by the recording sheet 8 after it has left the guide roller 17 is determined by its inclination in relation to the rotor axis 15 and its looping angle by the recording sheet 8. FIGS. 13 and 14 again show the frusto-conical incline of the rotor and the gradual transformation of the recording sheet into an arcuate form.

What we claim is:

1. An apparatus for continuously recording ink-jet pictures comprising a rotor having a cylindrical surface, and an annular ink-jet nozzle system, wherein the ink-jet nozzle system is stationary in relation to the rotor, and at least one supply roll and one take-up roll are arranged on the rotor for at least one recording support in guided sheet form each of which is guided over the rotor surface being connected to and rotating with the rotor so that each recording support simultaneously makes a rotary and translatory movement in relation to the stationary nozzle system.

2. An apparatus as claimed in claim 1,wherein the rotor is in the form of a solid cylinder and each recording support is guided externally over the surface of the rotor, the stationary annular nozzle system being arranged over the external surface of the rotor.

3. An apparatus as claimed in claim 1, wherein the rotor is in the form of a hollow cylinder each recording support is guided over the inner surface of the hollow cylinder, the stationary annular nozzle system being arranged inside the hollow. cylinder.

4. An apparatus as claimed in claim 3, wherein each recording support is guided helically over the rotor sur face from the supply roll to the take-up roll.

5. An apparatus as claimed in claim 4, wherein guide rollers are arranged on the rotor in the vicinity of the supply and take-up rolls for guiding each recording support supply roll onto the rotor surfaceand from the rotor surface onto the take-up roll.

6. An apparatus as claimed in claim 5, wherein the or each supply roll and take-up roll are arranged inside the rotor, and their axes are inclined towards the rotor axis by an amount dependent on the direction in which each sheet recording support runs onto and off from the rotor surface.

7. An apparatus as claimed in claim 5, wherein each supply roll and take-up roll is arranged on the rotor axis and the axes of the guide rollers are inclined in relation to the rotor axis in such a way that the recording support is turned through into a plane tangential to the rotor surface.

'8. An apparatus as claimed in claim 7, wherein the angle of inclination a of the guide rollers relative to the axis of the rotor is selected in accordance with the relation a y-U where 'y is the angle at which the or each recording support runs onto and off from the rotor surface and U is the looping angle around the guide roller.

9. An apparatus as claimed in claim 8, wherein additional guide rollers are arranged in the vicinity of each supply roll and take-up roll to keep the looping angle U around the guide rollers constant.

10. An apparatus as claimed in claim 5 wherein at least one of the guide rollers is driven and determines the recording support advance.

11. An apparatus as claimed in claim 5, wherein the ratio of the peripheral speed of the rotor to the rate of recording support sheet advance is constant.

12. An apparatus as claimed in claim 5, wherein a plurality of supply rolls are arranged at one end and a corresponding plurality take-up rolls at the other end of the rotor adjacent one another on the rotor axis.

13. An apparatus as claimed in any claim 12, wherein the axes of the guide rollers extend obliquely of the rotor axis and each recording support is turned through 90 into a plane tangential to the rotor surface.

14. An apparatus as claimed in claim 13, wherein additional guide rollers which keep the looping angle around the guide rollers constant are arranged in the vicinity of the supply rolls and take-up rolls.

15. An apparatus as claimed in claim 5, wherein the rotor surface is hydrophobic.

16. An apparatus as claimed in claim 3,'wherein each recording support is guided over the rotor surface parallel to the rotor axis from the supply roll to the take-up roll.

17. An apparatus as claimed in claim 16, wherein there are a plurality of supply rolls and take-up rolls which are arranged at the ends of the rotor and distributed uniformly over its periphery and perpendicularly of the rotor axis in such a way that the supply rolls and take-up rolls are opposite one another.

18. An apparatus as claimed in claim 17, wherein contact rollers are provided on the rotor surface so that the recording supports are in close contact with the rotor surface in the vicinity of the nozzle system.

19. An apparatus as claimed in claim 18, wherein the rotor surface is bevelled frusto-conically towards its ends so that each flat recording support is gradually converted into an arcuate form.

20. An apparatus as claimed in claim 17, wherein the rotor surface is provided with bores and means for generating a-vacuum inside the rotor so that the sheet recording supports are drawn onto the rotor surface.

Claims

2. An apparatus as claimed in claim 1, wherein the rotor is in the form of a solid cylinder and each recording support is guided externally over the surface of the rotor, the stationary annular nozzle system being arranged over the external surface of the rotor.

3. An apparatus as claimed in claim 1, wherein the rotor is in the form of a hollow cylinder each recording support is guided over the inner surface of the hollow cylinder, the stationary annular nozzle system being arranged inside the hollow cylinder.

4. An apparatus as claimed in claim 3, wherein each recording support is guided helically over the rotor surface from the supply roll to the take-up roll.

5. An apparatus as claimed in claim 4, wherein guide rollers are arranged on the rotor in the vicinity of the supply and take-up rolls for guiding each recording support supply roll onto the rotor surface and from the rotor surface onto the take-up roll.

7. An apparatus as claimed in claim 5, wherein each supply roll and take-up roll is arranged on the rotor axis and the axes of the guide rollers are inclined in relation to the rotor axis in such a way that the recording support is turned through 90* into a plane tangential to the rotor surface.

8. An apparatus as claimed in claim 7, wherein the angle of inclination Alpha of the guide rollers relative to the axis of the rotor is selected in accordAnce with the relation Alpha gamma .U where gamma is the angle at which the or each recording support runs onto and off from the rotor surface and U is the looping angle around the guide roller.

13. An apparatus as claimed in any claim 12, wherein the axes of the guide rollers extend obliquely of the rotor axis and each recording support is turned through 90* into a plane tangential to the rotor surface.

16. An apparatus as claimed in claim 3, wherein each recording support is guided over the rotor surface parallel to the rotor axis from the supply roll to the take-up roll.

20. An apparatus as claimed in claim 17, wherein the rotor surface is provided with bores and means for generating a vacuum inside the rotor so that the sheet recording supports are drawn onto the rotor surface.