WO1991009352A1

WO1991009352A1 - Electrophotographic printer for reel paper with a thermal print-fixing station

Info

Publication number: WO1991009352A1
Application number: PCT/EP1990/002091
Authority: WO
Inventors: Walter Kopp; Josef Windele
Original assignee: Siemens Nixdorf Informationssysteme Aktiengesellschaft
Priority date: 1989-12-13
Filing date: 1990-12-04
Publication date: 1991-06-27
Also published as: EP0505418A1; EP0572050B1; JPH05504634A; EP0572050A2; JP2950985B2; EP0572050A3; EP0505418B1; DE59005481D1; DE59010799D1

Abstract

An electrophotographic printer has an electrothermal fixing station (23) with a heated fixing roll (86) and a feed roll (87) which can be pivoted onto and away from the latter. Before the actual fixing, the reel paper is heated. To this end, it is guided around the fixing roll (86) through a predetermined winding angle (U) by an unheated, pivotable paper guide saddle (93). To ensure offset-free and smudge-free fixing of the printed image on the reel paper (12), the movements of the elements of the fixing station (23) and of the paper transport during starting and stopping are co-ordinated so that there is no relative movement between the fixing roll (86) and the toner image on the reel paper when the reel paper (12) is laid on the fixing roll (86) and when reel paper (12) peels off the fixing roll (86).

Description

Electrophotographic printing device for continuous paper with a thermal pressure fixing station.

Electrophotographic printing devices with thermal printing fixation are generally known. When using thermal printing technology, the record carrier and the toner image lying on the record carrier are carried out between two rotating rollers which touch under pressure. One of the rollers, the so-called fixing roller, is heated. In order to achieve sufficient adhesion of the toner image to the paper by the fixing, it is necessary that the toner particles in the fixing station are heated above a melting point and flow together and that the melted toner particles also bond to the paper structure.

With increasing printing speed and the increased transport speed of the recording medium, the heating up time of the recording medium becomes shorter and thus the achievable fixing temperature on the recording medium. At higher transport speeds of the recording medium, the required fixing temperature can no longer be achieved without additional heating of the recording medium, in particular when the recording medium has a high basis weight.

In electrophotographic printing devices that process continuous paper, this is achieved by means of a preheated paper guide saddle, via which the rear of the continuous paper web is guided and preheated before the actual fixing. Such a thermal pressure fixing device with a preheating saddle is known from US Pat. No. 4,147,922.

This method has the disadvantage that there is no already fixed print on the back of the continuous paper web may, otherwise it will be dissolved and destroyed by the high preheating temperature. Modular operation of two printing devices, the first printing the front and the second printing the back, is therefore not possible. The same also applies to front and back side printing from one and the same printer, the front side being printed on the first batch pass and the rear side being printed on the second batch pass.

In order to be able to process toner with a high melting point at high fixing speed, DE-PS 27 17 260 discloses a heat-melt fixing device for toner images on a recording medium, which has a preheating saddle, the preheating saddle ver¬ in the direction of the fixing roller is pivotally mounted. The wrap angle of the record carrier on the fixing roller can thus be set.

However, this heat-melt fixing device also presupposes the existence of a heated preheating saddle as absolutely necessary for optimal heat-melt fixing.

The aim of the invention is to design an electrophotographic printing device for continuous paper so that the printing device can also be used to print on a recording medium already provided with a fixed toner image without the toner image already on the recording medium being wiped out .

Another object of the invention is to provide a fixing station for an electrophotographic printing device, which is simple in construction and enables high printing speeds.

Another object of the invention is also to design an electrophotographic printing device in such a way that an offset-free and wipe-free fixing of the printed image on an endless paper web is possible during a start and stop process of the paper web. These objects of the invention are achieved with an electrophotographic printing device according to the features of claims 1 and 11.

Advantageous embodiments of the invention are characterized in the subclaims.

If the continuous paper is wrapped around the fixing roller during fixing so that there is a sufficient distance to heat the paper web, it is surprisingly possible to dispense with a preheating saddle and to fix the continuous paper web solely via the fixing roller. In order to enable good heat transfer, the paper web must wrap tightly around the fixing roller, which can be effected by a paper brake. Using this preheating principle, a fixing station can be constructed which is inexpensive and space-saving. This also makes it possible to fix an endless paper web with a toner image, on the back of which there is already a fixed print image.

If, according to the invention, only the fixing roller is used for fixing and preheating, the paper transport in the fixing station must be operated in such a way that no relative movement between the toner image and fixing roller can occur. This danger exists in particular when the paper web is stopped and started. The continuous paper web is peeled off from the fixing roller or placed against the fixing roller.

In the electrophotographic printing device according to the invention, the swiveling in and out of the paper guide saddle and the paper transport are therefore controlled with the aid of a microprocessor-controlled arrangement in such a way that during the movement of the paper guide saddle when the continuous paper is applied to the fixing roller and when the swiveling is carried out Continuous paper from the fuser roller no relative movement can occur in the contact area between the continuous paper and fuser roller. In order to prevent over-fixing of the printed image during the reduction of the fixing roller speed during the stop process, the paper guide saddle is advantageously pivoted away at the time of the fixing roller speed reduction, thereby reducing the preheating distance of the paper web on the fixing roller.

If the recording medium is transported in the transfer printing station of the electrophotographic printing device via a tractor drive, which engages in the transport perforations of the recording medium, and then is fixed in a thermal printing fixing station with a friction drive, a difference between the two paper speeds arises due to tolerances, which can lead to a paper tear or a reduction in the print quality due to fluttering of the recording medium.

In order to prevent this, a loop-puller is advantageously arranged in the invention between the transfer printing station and the fixing station, the position of which is scanned using a scanner. Depending on the position of the loop puller, the drive of the fixing roller is driven faster in one position and slower in the other position than the drive of the constantly running paper transport device of the transfer station.

Embodiments of the invention are shown in the drawings and are described in more detail below, for example. Show it

FIG. 1 shows a schematic basic illustration of the paper guide in an electrophotographic printing device,

FIG. 2 shows a paper divider and insertion device for continuous paper in the operating position (position B) and in the pivoted-down state (position A) with a control arrangement controlling the paper path,

FIG. 3 shows a schematic illustration of the paper guide with the associated units in an electrophotographic printing device,

FIG. 4 shows a schematic sectional illustration of the fixing station of an electrophotographic printing device,

FIG. 5 shows a schematic illustration of the fixing station of an electrophotographic printing device in different operating states,

FIG. 6 shows a schematic representation of the paper transport speed V over time T on the various units of the printing device during the starting process,

FIG. 7 shows a schematic representation of the paper path S of the recording medium delivered or transported by the various units of the printing device as a function of the time T during the starting process,

FIG. 8 shows a schematic representation of the paper speed V on the various units of the printing device as a function of the time T during the stopping process and

Figure 9 is a schematic representation of the paper path S of the the various units of the printing device delivered or transported paper depending on the time T during the stopping process.

A printing device operating on the principle of electrophotography has a supply table 10 for receiving a supply stack 11 made of pre-folded continuous paper 12. The final paper is fed to the actual electrophotographic printing unit 15 via a paper dividing device 13 and a pivoting actuating rocker 14 provided with paper guide elements. This printing unit 15 has a transfer printing station 17, which can be swiveled in and out of a photoconductor drum 16, and devices which are arranged around the photoconductor drum 16 and are necessary for the electrophotographic process.

To generate a toner image on the continuous paper, the photoconductor drum 16 charged with the aid of a charging device 18 is discharged in a customary manner via an LED character generator 19, and the charge image thus generated in a developer station 20 with a developer mixture of toner. and colored carrier particles. The toner image is then transferred to the continuous paper 12 in the transfer printing station 17. After transfer printing, the photoconductor drum 16 is discharged via an unloading station 21 and cleaned in a cleaning station 22 and recharged via the charging device 18.

Instead of the electrophotographic process described, it is also possible to produce the toner image on the continuous paper 12 e.g. to use an electrostatic process or a magnetic process or even an ink comb that applies ink directly to the continuous paper.

The paper web 12 provided with a toner image is then fixed chemically or by heat in a fixing station 23 and placed on a deposit table 24. In the illustrated embodiment of the printing device, the storage table 24 is connected via a swivel lever 25 to facilitate removal of the designed paper stack 26 designed to swing out.

If the printing device is e.g. coupled with a further printing device, e.g. To enable front or back side printing, the paper web 12 can also be fed directly to the paper dividing device 13 via external paper feed channels 27. Furthermore, it is possible to use an external endless supply stack 28 as a supply stack. Separate paper feed elements with paper rollers 29 may be necessary for feeding the paper web.

In order to prevent particles such as paper clips or other metal parts damaging the photoconductor drum 16 from entering the printing unit 15, a particle trap 30/1, 30/2 is arranged either at the entrance area to the transfer printing station 17 or in the transfer printing station. The printing device also has a paper loading device which can be activated via the actuating rocker 14 and has an associated paper brake 31.

The aforementioned devices of the printing device are now described in detail:

In order to separate paper layers adhering to one another from the continuous paper web 12 drawn off from the stack 11, a paper dividing device 13 is arranged at the entrance to the feed channel to the printing unit 15 above the paper stack 11 (FIG. 2). This paper dividing device contains a first deflection element in the form of a rotatably mounted paper roller 32, which is arranged between two side parts 33 of the actuating rocker 14 at its free pivot end. Furthermore, it contains a second deflection element in the form of a motor-driven paper roller 34, which is arranged in a fixed position on two fixed support elements 35 connected to the housing of the printing device. The motor-driven paper roller 34 is located in the swivel range of the actuating rocker 14. Above the first deflection element (paper roller 32) there is a passage a paper guide element 36 is arranged for the distance forming the paper web. The paper guide element is designed such that it forms, together with other sheet metal elements, a collecting basket 38 for the first peeled-off folder of the paper web.

In operating position (position B), i.e. when the actuating rocker 14 is pivoted upwards, the continuous paper web 12 is first guided in a first deflection direction over the first deflection element 32.

A first paper layer 37 adhering to the outside of the paper web with respect to the paper roller 32 is peeled off with its fold edge from the paper guide element 36 and penetrates into the collecting basket 38. The first paper layer 37 is fanned out during further transport. A second paper layer adhering to the inside of the paper roller 32 is guided by the paper web 12 around the paper roller 32 with the first direction of deflection and then detaches from the second deflection element (paper roller 34) and deflects therefrom below. This also leads to a fanning out of the paper layer, so that an expanded continuous paper web 12 is available for further transport via a paper guide element 40 arranged between the side parts 33 of the actuating rocker 17.

The actuating rocker 14 not only forms part of a paper dividing device 13, but is an essential functional element of a paper insertion device for inserting the continuous paper 12 into the printing device. In order to enable the continuous paper to be inserted, the actuating rocker 14 is mechanically coupled to the transfer printing station 17 such that when the actuating rocker 14 is pivoted from a loading position A into an operating position B, the transfer printing station 17 pivots on the photoconductor drum 16 or when pivoting out Swing position B into position A.

For this purpose, the actuating rocker 14 is in the area of the transfer printing station on an axis 41 fixed to the frame via holding elements. elements 42 rotatably mounted. The transfer station itself is also pivotally mounted on an axis fixed to the frame. The transfer station contains a tractor drive with two tractor belts 44 which laterally engage the edge perforations of the continuous paper 12 with transport nipples 45 arranged thereon. The tractor belts 44 are guided and mounted on two drive wheel pairs 46 which are connected to one another via axles, the drive being the Tractors via a motor M (Fig. 2), which is coupled with the large pair of drive wheels. When the continuous paper 12 is being transported, the continuous paper is in engagement with the tractor belts 44 via its perforation holes in the transport direction of the paper, both before and after the transfer area of the transfer station. As securing and guiding elements for the continuous paper four transport flaps 50 are provided, which press the continuous paper against the traction belt 44 in the area of the perforation holes.

In order not to blur the toner image on the paper web when the transfer printing station with the inserted paper web is pivoted away, the transfer printing station 17 is mounted with respect to its pivot point in such a way that the paper guided in the transfer printing area via the transfer printing station 17 immediately lifts off the photoconductor drum without grinding there.

In the operating position (position B) with the actuating rocker 14 pivoted upward, the transfer printing station 17 is pivoted to the photo conductor 16 and paper guide elements release the transfer printing area. If the actuating rocker 14 is pivoted into position A, a paper guide plate is guided into the area between the photoconductor drum and transfer printing station and an expanded paper guide channel opens between transfer printing station 17 and paper element. The paper guide element protects the photoconductor drum 16 in the transfer printing area against the entry of light and damage.

In the paper transport direction in front of the transfer station 17 is a Paper insertion plate 68 fixedly arranged, which cooperates with a round paper guide area 69 of the actuating rocker 14. The paper guide area 69 serves as a paper deflecting element for the paper web.

In position A of the actuating rocker 14, the continuous paper 12 can now be easily guided around the transfer station 17 via the paper guide area 69, the paper feed plate 68 and the paper guide element of the transfer station 17 and inserted into the tractor belt on the output side.

A paper guide channel 80 is provided above the transfer station 17 in the paper transport direction. This paper guide channel 80 consists of a flat traverse 81 with a cover plate covering the width of the paper web and a wall plate 82 arranged at a distance from it. At the entrance of the paper guide channel there is a paper guide plate 84 (paper guide flap) which can be pivoted about an axis 83 and which counteracts the force of a spring, not shown here, can be pivoted about the axis 83. The paper guide plate has the function of a loop puller and serves as a paper length buffer in order to compensate for different paper transport speeds between transfer printing station 17 and fixing station 23 due to mechanical tolerances, different types of drive (friction drive-tractor drive) etc., also as a sensor for the paper transport speed. The position of the paper guide flap 84 is scanned by two sensors 84/1 and 84/2 and the drive of the fixing station 23 is controlled as a function thereof. E.g. runs If the fixing station is driven faster than that of the transfer printing station 23, the lower sensor 84/2 is actuated and the fixing station 23 is braked. If the transfer printing station 23 runs slower than the fixing station, the paper flap 84 is deflected more strongly and this deflection is detected by the sensor 84/1.

A suction chamber 85 is also arranged in the paper guide channel 80 and extends over the entire width of the paper guide extends channel and cooperates with a vacuum generating device, not shown here. The suction chamber has the function of a paper brake in order to be able to brake the paper safely when the paper transport is interrupted and to ensure a uniform retention force of the paper during transport through the fixing station.

Instead of a suction chamber as a paper brake, any other type of paper brake that can be regulated can be used, e.g. by means of a mechanical deflection point or a braked pin wheel which engages in the edge perforations of the continuous paper 12.

The paper guide channel -80 feeds the paper to the fixing station 23. The fixing station 23 is designed as a thermal fixing station. It consists of a heating roller 86 heated by radiators and a pressure roller 87 which can be pivoted and pivoted onto the heating roller 86 by an electric motor via a cam 87/1. Furthermore, it has an oiling device 88 which serves to apply separating oil to the heating roller 86 and the heating ¬ the roller may need to be cleaned. The oiling device 88 has an oil pan 89, one side wall of which serves as a paper guide element for the continuous paper. Below the oil pan 89 of the oiling device there is a cooling profile 90, through which air flows for heat dissipation. Furthermore, is below the

An outlet roller saddle 91 is arranged on the heating roller and the pressure roller, on which paper rollers are arranged and which serves to pass on the continuous paper after the fixing. Between the fixing station with the heating roller 86 and the pressure roller 87 and the paper guide channel 80 there is a paper guide saddle 93 which can be pivoted about an axis 92 and which, with the aid of a cam 94 driven by an electric motor, depends on the position of the cam on the heating roller 86 can be pivoted. The cam 94 enables three positions of the paper guide saddle 93 in principle. These positions are identified by AP, BP and CP. In the position AP, the paper guide saddle 93 is almost on the heating roller 86 pivoted. This represents the operating situation or

Print position. In this printing or operating position, the continuous paper is guided around the heating roller 86 in a wrap angle designated by U. The pressure roller 87 is pivoted to the heating roller 86. Depending on the pivoting position of the paper guide saddle controlled by the cam 94, the wrap angle U can be controlled. In a position BP, the paper guide saddle 93 is in a loading position. It is pivoted away from the heating roller 86 at a distance, the distance being dimensioned such that in this state the continuous paper can be easily passed through the fixing station without coming into contact with the heating roller 86. In this loading position, the pressure roller 87 is also pivoted down. A paper feed-through channel is thus formed through the fixing station via the paper guide saddle and the fixing station in the open state in connection with the runout roller saddle.

The further pivoted position CP of the paper guide saddle 93 defines the so-called standby position. This is the position in which the paper web is completely exposed. This position is taken when printing is interrupted.

Downstream of the fixing station 23 in the paper transport direction is the pivotable storage table 24 for receiving the printed continuous paper. In order to be able to deposit the continuous paper securely on the deposit table 24, a stacking device 99 is arranged. This stacking device can be shifted in position with the aid of a drive device 101 (electric motor) with respect to the storage table 24. It contains funnel-shaped insertion profiles 95, which serve to take over the continuous paper in the raised state of the stacking device and to safely feed the paper guided over the outlet roller saddle 91 to two paper transport rollers 96 driven by an electric motor. The paper transport rollers 96 are conventional paper rolls with a rubber covering. Downstream of the paper transport rollers 96 is a paper guide channel 97, which is formed by guide plates, a scanning device 98 for the continuous paper being arranged in the paper guide channel 97. The scanning device is designed as a conventional light barrier. The stacking device 99 also has paddle shafts 100 for the secure storage of the endless paper 12.

To control the various units of the printing device, e.g. A microprocessor-controlled control arrangement D is provided for the paper transport, the transfer printing station, the fixing station and the stacking device 99 (FIG. 2). The control arrangement D can be part of the device control C, which e.g. can be designed according to US Pat. No. 4,593,407. The control arrangement D regulates the paper transport during the automatic loading of the paper and during the printing operation including start-stop operation. It monitors and regulates the function of the various units of the pressure device, e.g. the elements of the fixing station 23, the drive of the paper transport rollers 96, the drive of the cams 94 and the tractor drive M (motor) of the transfer station 17. Furthermore, it detects a large number of input signals, e.g. the scanning signal of the scanning device 98 or a switch 120 scanning the position of the actuating rocker 14 and the position of the sensors 84/1 and 84/2.

The function of the electrophotographic printing device is now explained in more detail using the various operating states:

Loading continuous paper in the printing device:

After inserting the paper stack 11 on the supply table 12, the actuating rocker 14 is pivoted into the position A by means of a handle 81. This position is sensed via switch 82 (FIG. 2). The transfer printing station 17 is pivoted away and paper guide elements cover the photoconductor drum 16 and open a wide paper insertion channel. The paper can be sen paper insertion channel carried out by the printing station and hooked into the tractor belts 44 on the output side. They are hung in such a way that the end of the first sheet comes to rest on the flap of the paper guide plate 84 which acts as a loop puller. The first sheet of continuous paper is thus located in the feed region of the paper guide channel 80. The transport flaps of the tractor belts on the output side are then closed. Now the actual insertion procedure controlled by the control arrangement D begins.

This begins first by closing the actuating rocker 14. This closing process is sensed by the switch 82 and thus a slow creeper operation of the continuous paper 12 is triggered, which serves to thread the paper with its perforated edge into the transport nipple 45 of the tractor belts 44 in the correct position.

If the actuating rocker 14 is closed, this position is sensed via a further switch 120 and communicated to the control arrangement D. The paper web is now passed through the paper dividing device 13 and the actual automatic insertion of the continuous paper into the fixing station 23 begins.

Automatic threading of the continuous paper through the printing device:

In the crawl path, the continuous paper is further pushed over the cover plate of the traverse 81, which is located between the transfer printing station 17 and the fixing station 23, and the suction chamber 85. During further threading, the paper guide saddle 93 is brought into the loading position B via the cam 94 via the control arrangement D. This creates in the fixing station 23, formed from the elements paper guide saddle 93, oiling pan 89 and cooling profile 90, a paper guide system inclined at approximately 60 °, which is suitable for using the further paper transport device. Thrust through the transfer printing station 17 and, taking advantage of the natural downward gradient, to bring the continuous paper through the insertion profiles 95 into the area of the paper transport rollers 96 (pulling rolls) of the stacker 99 which is moved close to the fixing station 23.

After the paper transport rollers 96 of the stacking device 99 have grasped the continuous paper, it is transported on to the scanning device 101 of the paper guide channel 97.

The control arrangement D switches off the further paper transport and moves the paper guide saddle 93 into the standby position CP. This creates a loop of continuous paper. The length of paper released in this process is transported out via the paper transport rollers 96, which are then switched off.

Function of the fuser in printing

General (Figure 5)

In the heat setting station 23 the continuous paper 12 and the toner image lying on the continuous paper 12 are passed under pressure between two rotating rollers, namely the fixing roller 86 and the pressure roller 87, the fixing roller 86 being heated. In order to achieve sufficient adhesion of the fixed toner image on the continuous paper 12, it is necessary for the toner particles to be warmed beyond their melting point and to flow together and for the melted toner particles to bond to the paper structure. If, for example, polystyrene-butyl-methacrylate-based toner is used, this is done, as experiments have shown, if the paper temperature is higher than 110 ° C. Instead of polystyrene-butyl-methacrylate toner, it is also possible to add polyester-based toner The material used for the recording medium is standard IT paper.

With increasing paper speed in the fixing station, the heating-up time of the paper web becomes shorter and thus also the achievable paper temperature. At higher paper speeds, generally greater than 350 mm per second, the required paper temperature can no longer be achieved without additional heating of the paper web, especially when high paper basis weights, for example of 160 gr per square meter and larger and papers must be fixed with a high proportion of water. The water content in the paper can be up to 10 percent by weight. In order to be able to fix at high paper transport speeds, it is therefore necessary to preheat the paper sufficiently before the actual fixing in the fixing nip between the fixing roller and the pressure roller. According to the illustration in FIG. 5, the paper web 12 is therefore wrapped around the fixing roller 86 at a wrap angle U such that a sufficiently long distance is available for heating the paper web. This wrap angle U depends on the one hand on the upper surface temperature of the fixing roller 86 and the transport speed of the paper. The fixing roller 86 is heated by means of a radiator module 201 in the form of a plurality of halogen lamps arranged in the center of the fixing roller 86, the surface temperature of the fixing roller 86 being detected by temperature measuring sensors for the fixing roller temperature 202 arranged on the periphery of the fixing roller. The temperature of the fixing roller 86 is regulated via the control arrangement D, specifically as a function of various operating parameters by switching the radiator module 201 on and off.

The wrapping of the paper web U around the fixing roller 86 is achieved by the swivel saddle 93 (paper guide saddle), which is not heated and which therefore has the room temperature of the device. The paper web is guided over this swivel saddle and then wraps around the fixing roller 86 in accordance with the wrap angle U. When the printing operation is started, the swivel saddle 93 is swiveled from the position CB (standby) to the operating position AB.

As a result, the paper web 12 bears against the fixing roller 86. The point PA denotes the first point of contact of the recording medium 12 with the fixing roller 86. The preheating ends at the point PB and the actual fixing gap begins, which extends to the point PC. The length of the fixing gap between point PB and PC is dependent on the pressure force of the pressure roller 87 on the fixing roller 86, the pressure roller 87 being covered with an elastic material on the circumference, so that the pressure roller 87 is flattened in the fixing gap area is coming. The distance between point PA and point PB on the fuser roller defines the actual preheating area.

As it moves from point PA to point PB, ie in the preheating area, the paper web lies tightly against the fixing roller 86 by the vacuum brake 85 (suction chamber). This tightening of the paper web by the vacuum brake 85 ensures good thermal contact between the paper web and the fixing roller 85 generated in the wrapping area. After the point PB has been reached, the preheating of the paper and the toner image is completed. The slightly pasty toner is then rolled into the paper structure under pressure and heat in the area of the fixing gap (distance PB to PC). The fixing nip (radians between PB and PC) must be chosen so high that the paper web after leaving the point PC having a temperature of greater than or equal to 110 minde¬ least ^β C. The paper speed and the fixing roller surface temperature are specified. In the case of the described toner and recording medium material, in the exemplary embodiment shown there is a wrap angle U of the paper web around the fixing roller of 60 ° due to the paper speed of 487 mm per second and a fixing roller temperature of 220 ° C.

This type of paper web preheating enables a cost-effective and space-saving construction of the fixing station, it also being possible to fix a paper web with a toner image, on the back of which there is already a fixed printed image. The fusing station described can therefore be used in electrophotographic printing devices in which the paper web is printed on both sides. A prerequisite for realizing this solution, however, is that no relative movement between the toner image and the fixing roller 86 can occur during the stopping and starting process of the paper web. The greater the preheating wrap U of the paper web 12 around the fixing roller 86, the greater this risk.

Function of the fuser in print mode in detail

As already described, the paper web 12 with the still wipeable toner image moves into the fixing station 26 at almost constant speed during printing operation. The cold, unheated paper guide saddle 93 (swivel saddle) loops the paper web 60 "around the fixing roller 86. In this wrap around area U, the recording medium 12 and the toner image are preheated to such an extent that after the subsequent pressure fixing in the Fixing nip between fixing roller 86 and pressure roller 87 a good fixing quality is achieved. Preheating is necessary so that the melted toner is adequately bonded to the paper structure.

The amount of preheating of the paper 12 in the wrapping area U depends, among other things, on the force with which the paper web 12 nestles against the fixing roller 86. For this reason, the vacuum suction chamber 85 is located in the paper inlet area of the fixing station 23. By generating a vacuum in the vacuum suction chamber 85, the recording medium 12 is pulled against a suction plate 85/1 with through-holes and thereby exerting a frictional force on the recording medium 12. Due to the friction effect of the pressure roller 87 in connection with the fixing roller 86 and the retaining force of the suction chamber 85, the paper web 12 between the fixing roller 86 and the suction chamber 85 is pulled tightly over the fixing roller 86 and the paper guide saddle 93. During preheating and fixing, the cold paper web 12 is heated and thus heat is constantly being removed from the fixing roller 86. In order to maintain a constant fixing quality, it is therefore necessary to keep the temperature of the fixing roller surface constant.

For this purpose, the non-contact temperature sensors 202 record the surface temperature and report this in the form of electrical signals to the control arrangement D. This compares the measured surface temperature with a predefinable stored setpoint and regulates the switching on and off of the infrared as a function thereof Halogen lamp module 201 in the center of the fixing roller.

In order to obtain optimal rejection of the toner particles from the fixing roller surface, 88 oil is applied to the fixing roller 86 with the help of the oiling device 88. For this purpose, the oiling device 88 has a silicone metering tube 88/1 arranged in a holder. This tube is provided with fine metering holes, from which constantly Silicone oil is pumped from a storage area to a felt 88/2. The felt impregnated with silicone oil is guided past the surface of the fixing roller 86 with the aid of an electromotive drive device 88/3 and thereby oiles the surface of the fixing roller 86. Since the fixing roller 86 continuously releases silicone oil in very small amounts of toner image and paper 12 this used silicone oil is conveyed through the felt 88/2.

The fine pores of the felt, however, slowly fill with paper dust toner and resinified silicone oil during the fixing process and thus close. It is therefore necessary, via the drive 88/3, to fill the oiling area of the oiling device 88 with constantly new felt from one. Feed the supply area and wind up the used felt in a winding area.

The paper 12 has a very high dust content. This paper dust would be absorbed by the felt 88/2 and together with the silicone oil would result in a doughy mass, which is sporadically entrained by the fixing roller 86 and transferred to the paper.

In order to avoid this, the speed of the felt winding (filegroup renewal) would have to be considerably higher. This would result in an unreasonably high felt consumption. For this reason, a dirt-wiping rubber lip 88/4 is arranged between the fixing gap (PB / PC) and the actual oiling area of the oiling device 88 and floats on the surface of the fixing roller and wipes off any paper dust that has been taken up. With the aid of a swiveling device 88/5, the rubber lip is pivoted away in a controlled manner by the control arrangement D when the pressure is interrupted, and the dirt that is picked up is thrown into the collecting pan 89 underneath.

The paper can have a very high water content, which can be up to 10 percent by weight. Since the paper 12 has to be heated to over 100 ° C. in the 60 ° looping zone U, some of the water in the paper also becomes vaporized brought. This water vapor is sucked out of the fixing station 23 by means of a fan 203 with an associated suction hose 204.

As already described, the paper web 12 is transported in the area of the fixing station by friction between the electromotive driven fixing roller 86 and the paper 12 under pressure from the pressure roller 87.

Since the transfer printing station transports the continuous paper 12 via transport perforations (tractor belt 44), a difference in the paper speeds in the transfer printing station 17 and the fixing station 23 arises due to tolerances of the fixing roller diameter, the transport perforation tolerances and so on lead to a paper loop between transfer printing station 17 and fixing station 23.

The sensors 84/1 and 84/2, which scan the positions of the paper guide flap 84, ensure that the drive of the fixing roller is regulated as a function of the position of the paper guide flap 84 via the control arrangement D. If the paper guide flap 84 is in an upwardly pivoted position with the paper loop pulled out, the speed of the fixing roller 86 is controlled by its drive motor, increased by the control arrangement D by 1.5% with respect to a standard speed. If the paper guide flap 84 is in the area of the lower sensor 84/2, the speed of the fixing roller 86 is reduced by 1.5% with respect to a standard speed. The paper transport speed in the area of the transfer station 17 is kept constant via the tractor drive 44.

This can result in torn paper or an uncontrolled paper loop between transfer printing station 17 and fixing station 23.

Mechanical construction of the fuser

The fixing station used according to FIG. 4 contains the fixing roller 86, which is mounted on a frame 205 of the printing device, and the pressure roller 87 made of a steel tube covered with rubber. The pressure roller 87 is mounted on two rockers 206 and can be pivoted on and off with the aid of two electromechanically driven cam disks 87/1 via attachments 207 to the fixing roller 86 (arrow direction). The rockers 206 are pivoted about an axis 209 against the force of springs 208. The position of the pressure roller 87 on the rocker 206 is scanned by scanning the position of the cam disk 87/1 via a sensor 210 arranged on the axis of the cam disks 87/1 in the form of a Hall generator. The Hall generator (sensor 210) supplies position signals to the control arrangement D, which controls the position of the cam disks 87/1 and thus the pressure position of the pressure roller 87 via a drive motor 211 driving the cam disks 87/1, which is only shown schematically here.

Functional description of the units of the paper transport during the printing operation

During the printing operation, the transfer printing station 17 delivers printed and fixed paper to the fixing station 23 at a constant speed. In the fixing station 23, the paper web is transported under pressure between the fixing roller 86 and the pressure roller 87. Since the speed of the record carrier (paper 12) in the transfer printing station and the speed of the paper 12 in the fixing station 23 can never be the same (tolerances due to the fixing roller diameter, transport, perforation distance, etc.) is located between the fixing station 23 and transfer printing station 17 Loop puller in the form of the paper guide flap that can be swiveled in and out against a spring force with sensors 84/1 and 84/2, which are assigned to the upper and lower rocking positions.

The fixing roller 86 is driven by a stepper motor 86/1, which is operated at two exact speeds. One speed gives a fuser roll paper speed

1.5% above the target paper speed of the paper transport determined by the transfer printing station 17, the second speed is a fixing roller paper speed which is 1.5% below the target paper speed of the transfer printing station 17. If the fixing roller 86 runs at the higher speed, the loop puller 84 is pulled downward through the paper web 12 and reaches the lower sensor 84/2, which emits a corresponding control signal to the control circuit D. The control circuit D switches the stepper motor 86/1 and thus the fixing roller 86 to a required lower speed. The loop puller 84 now moves via its own spring, which presses up against the paper web 12, until the upper sensor 84/1 is reached. The upper sensor 84/1 in turn outputs control signals to the control arrangement D, which switches the drive 86/1 of the fixing roller 86 to the required higher speed. This regulation process continues. The unfixed paper web 12 runs from the transfer printing station 17 via the loop puller 84 to the vacuum brake 85, which tightens the paper web 12 over the swivel caliper 93. This has the task of looping the paper web 12 around the fixing roller 86, for example at an angle of 60 "(wrap angle U) and of offering the paper web 12 to the fixing roller 86 in an exactly guided manner. In the wrap-around area between the points PA and PB of the fixing roller 86, the paper web 12 is preheated on the fixing roller 86 with the print image arranged thereon and then fixed under pressure and heat in the fixing gap between the fixing roller 86 and the pressure roller.

The pulling rollers 96 arranged below the fixing station 23 on the stacking device 99 transport the paper webs 12 further onto the stacking table 84 or to a post-processing system, e.g. a cutting device.

When fixing during the continuous printing operation, the problem of the relative movement between the paper web 12 and the fixing roller 86 does not arise. This means that no blurring and no offset printing can occur.

Function of the units of the printing device assigned to the paper transport during the start-stop processes of the paper web.

In electrophotographic printing devices which are used as a fast printing device together with data processing devices, the paper web must be accelerated to a constant speed or decelerated to zero again, depending on the data available. This means that the paper web must be brought into contact with the hot fixing roller with the data print image to be fixed and then decontacted again.

If this process does not take place exactly between the fixie roller and the printed image to be fixed, there is a slight blurring of the printed image on the paper. Even the smallest blurs that are barely visible to the eye can cause parts of the toner image to be transferred to the fuser roller. These toner particles can then be transferred to the paper web again with the next rotation of the fixing roller. This so-called offset of To¬ nerteilchen the printed image to the fixing roller is possible because the mechanical connection of the toner particles was intercuspation with each other and reaches to the paper structure by the acting electrostatic forces during the transfer printing event, is achieved by blurring ^".

In order to obtain a movement sequence of the paper web 12 that is as relatively free of movement as possible with the toner image arranged thereon for the fixing roller 86 in the start-stop mode, the function of the units involved in the paper transport with their paper transport elements must be precisely coordinated. This applies in particular to the mutual coordination of the transfer printing station 17, which determines the paper transport, which supplies the paper web to be fixed, the swivel saddle 93, which defines the wrap angle U of the paper web 12 around the fixing roller 86, the fixing roller 86, which forms the toner image fixed on the paper web 12 and the paper web 12 transported and the pressure roller 87 which determines the fixing pressure and the friction pressure for transporting the paper web 12.

The time sequence of the paper transport elements relative to one another during the stopping process will now be described with reference to the diagrams in FIGS. 8 and 9. FIG. 8 shows the course of the paper speed V in millimeters per second as a function of the time in milliseconds in the transfer printing station 17 (solid curve) (VP), on the fixing roller 86 (dash-dotted line) (VF) and on the swivel saddle 93 (dotted line) (VS).

FIG. 9 in turn shows the paper path S delivered or removed by the individual units of the paper transport in millimeters as a function of the time T in milliseconds. The solid line shows the course of the paper path to be delivered from the transfer printing station 17 to a standstill (SP), the dash-dotted line (SF) the paper path to be transported away from the fixing roller 86 and the dotted line (SS) the paper path supplied by the pivoting saddle 93 during the swiveling back of the swivel saddle 93 from the position AB into the position CP when stopping.

At the time TK, the paper web 12 is in the state of continuous printing. If no print information is supplied by an EDP system coupled to the printing device, the paper web must be stopped at time TO. This stopping process proceeds as follows: The last page developed on the photoconductor drum 16 is printed on the continuous paper 12 in the transfer station 17. If the last possible line of the page is reprinted, the paper web 12 is separated from the photoconductor drum 16 and the transfer printing station 17 reduces the paper speed to zero in the period between the times TO to Tl. At the same time TO when the Transfer printing station 17 begins to delay the paper web 12, the paper speed in the fixing station 23 is reduced via the fixing roller 86 and the pivoting saddle 93 pivots from the position AB (printing mode) to the position CP (standby mode). From the time T0 to the time Tl, the fixing roller 86 is decelerated relatively sharply in accordance with FIG. From the time T1 to the time T2, which defines the end position or rest position of the fixing station, the pivoting saddle 93 is pivoted back with a delay, specifically in accordance with the decelerated speed of the fixing roller 86. The paper speed VP determined by the transfer printing station 17 is the difference between the fixing roller determines the paper transport speed VF when the paper is being transported minus the paper speed VS of the continuous paper 12 released when the swivel plate 93 is pivoted away.

During this swiveling process of the swivel saddle 93, there is a paper lot between transfer printing station 17 and fixing roller 86, which must also be transported away from the fixing roller 86 and thus peels off the paper web from the fixing roller 86, specifically from the 60 "wrap to a 0 ° wrap. The fixing roller 86 In this case, paper has to be transported away (TO to T1 to T2) until the transfer station 17 and the swivel saddle 93 no longer deliver paper. This is the case at the time T2. If this is the case, the speed of the Continuous paper 12, which is transported away from the fixing roller 86, should be 0. A reduction in the fixing roller speed during the stopping process at full contact pressure, which would be required to transport the paper web 12, would result in a visible overfixing of the printed image Overfixing is avoided by immediately reducing the speed during the fixing roller speed reduction from the times TO to the time T2 pivoting saddle 93 is pivoted away in accordance with the course shown in FIG. 8 and the preheating section (wrap angle U) of the paper web is reduced as a result.

During the stop process, the paper transport in the fixing station 23 and the transfer printing station 17 should be coordinated with one another in such a way that no movement takes place at the loop puller 84. If this is the case, then a relatively movement-free stopping process between the printed image on the paper 12 and the fixing roller 86 has taken place. For this purpose, the following conditions shown in FIGS. 8 and 9 must be fulfilled during the entire stopping process. With regard to the paper path, these are:

SP = SF - SS

SP is the paper path delivered from the transfer printing station 17 in millimeters to a standstill at the time T1.

SS is the released paper path provided by the swivel saddle 93 when swiveling the swivel saddle 93 back from the position AB at time TO in position CP at time T2.

SF is the paper path in millimeters to be transported away by the fixing roller 86 up to the point in time T2 at which the pivoting saddle 93 is in the position CP.

The paper speeds in the transfer printing station 17, on the fixing roller 86, and on the swivel saddle 93 must have the following relationship to one another during the stopping process, as shown in FIG. 8:

VP = VF - VS

Here: VP is the paper speed in the transfer station. VS the paper speed on the swivel saddle and VF the paper speed in the area of the fixing gap of the fixing roller 86.

During the stopping movement process of transfer printing station 17, fixing roller 86 and pivoting saddle 93, the pressure between pressure roller 87 and fixing roller 86 is simultaneously reduced. Immediately after the end of the stopping process (approx. 10 ms) after time T2, the pressure is 0 and the two rollers 86 and 87 are separated from one another.

Once this separation process has been completed, the entire paper web 12 is pulled back by the paper transport in the transfer printing station, specifically by a predetermined distance of 19/6 ", for example, in order then to be positioned for the subsequent starting process.

The sequence of the functions of the transfer printing station, fixing roller and swivel caliper during the starting process.

The course of the paper movements caused by the fixing station 17, fixing roller 86 and pivoting saddle 93 when the printer is started is described in more detail below with reference to FIGS. 6 and 7. Before the start of the start, the paper web 12 is in a state such as was reached at the time T2 after the end of the FIGS. 8 and 9.

The EDP system coupled to the electrophotographic printing device supplies information which is written on the photoconductor drum 16. The paper web is accelerated from time to time T1 from zero to final speed in such a way that the toner image on the photoconductor drum 16 is moved synchronously with the paper web 12.

In the area of the transfer station 17, the photoconductor drum 16 and the paper web 12 are contacted with one another such that a transfer of the toner image between the photoconductor drum 16 and the paper web 12 can take place. Before the paper transport is accelerated, 80% of the total fixing pressure was reached by swiveling together between the pressure roller 87 and the fixing roller 86. At the same time TO at which the transfer printing station begins to accelerate the paper web 12, the pivoting of the swivel saddle 93 from the position CP (standby position) into the operating position AB also begins. In order to be able to carry out this pivoting process of the pivoting saddle 93, the pivoting saddle requires paper 12 from the transfer printing station. At the time TO, acceleration of the fixing roller 86 is also started, which transports away the remaining paper path, which was supplied too much by the transfer printing station 17. During the pivoting process of the swivel saddle 93 from the position CP into the position AB from the time TO to the time T3, the dependencies shown in FIGS. 6 and 7 between the paper transport elements of the transfer station 17, the fixing roller 86 and the swivel saddle must be 93 must be fulfilled. This means that the paper speed in the transfer printing station 17 and in the fixing station 23 during the starting process must be such that the loop puller 84 does not move. If the loop puller 84 is motionless, a relatively motion-free starting process takes place between the printed image on the paper 12 and the fixing roller 86. To do this, the following conditions must be met Paper path as a function of time (Figure 7):

SPS = SFS + SSS

SPS = paper path in millimeters supplied by the transfer station during the start-up process (TO - T3)

SFS = paper path transported away by the fixing roller 86 during the starting process (time TO until the end of the starting process at time T3)

SSS = paper path required to start swiveling out the paper guide saddle 93 (To - T3)

Analogously to this, for paper speeds V during the starting process there is the relationship shown in FIG. 6, the following condition having to be fulfilled for a relatively motion-free starting process to take place:

VPS = VFS + VSS

The following applies: VPS = paper speed in the transfer station 17

VFS = paper speed in the fusing nip

VSS = paper speed contribution by the swivel saddle 93 during the swiveling of the swivel saddle from the position CP to the position AB from the time TO to the time T3

According to the illustration in FIGS. 6 and 7, the

Starting process in summary as follows:

At time TO, the paper in the transfer printing station is accelerated in accordance with curve VPS up to time T1, at the same time pivoting saddle 93 is pivoted in accordance with curve VSS and fixing roller 86 is moved in accordance with curve VFS. At the time T1, the paper 12 in the transfer printing station 17 reaches the final speed, the swivel saddle 93 continues to be moved outward in an accelerated manner, but the removal of the fixing station 23 of the paper provided via the fixing roller 86 is delayed. At time T2 the Fixing station 23 constantly fed paper via transfer printing station 17. The pivoting of the swivel saddle 23 into the operating position AB is delayed, but the removal of the paper via the fixing roller 86 is accelerated again. The starting process is completed at time T3 and the electrophotographic printing device is in continuous printing operation.

As already explained, the control of the paper transport takes place during the printing operation and during the start-stop operation via the control arrangement D, which is designed as a microprocessor-controlled control arrangement. The sequence of paper movements during the stop and start process, which can be seen from FIGS. 6 to 9, is stored in the memory of the microprocessor-controlled control arrangement and is called up from the memory by the operator when a start or stop procedure is called up. The starting or stopping process then runs automatically, controlled by the control arrangement D.

Reference list

10 storage table

11 piles, stock piles

12 continuous paper, paper web, recording medium

13 paper divider

14 control arm

15 electrophotographic printing unit

16 photoconductor drum

17 transfer station

18 loading device

19 character generator

20 developer station

21 unloading station.

22 cleaning station

23 fuser

24 storage table

25 swivel levers

26 printed stacks of paper

27 external paper feed channels

28 external stacks

29 separate paper guide elements (rollers)

30/1 particle trap arranged in the entrance area of the transfer station

30/2 particle trap integrated in the transfer station

31 paper brake

32 paper roller

33 side panels

34 motorized paper roll

35 carrier elements

36 paper guide elements

37 first layer of paper

38 collecting basket

39 second layer of paper

40 paper guide elements

41 axis

42 holding elements 44 tractor belt

45 transport nipples

46 drive wheels

50 transport flaps, tractor flaps

80 paper guide channel

81 traverse

82 wall plate

83 axis

84 Paper guide plate, paper guide flap 84/1, 84/2 sensors

85 suction chamber

86 heating roller, fixing roller

87 pressure roller

87/1 cams for moving the pressure roller

88 oiling device

89 sump

90 cooling profile

91 discharge roller saddle

92 axis

93 Paper guide saddle, paper guide element

94 cams, swivel device U wrap angle

AP operating position

BP charging position

CP standby position

95 insertion profiles

96 paper transport rollers

97 paper guide channel

98 scanner

99 stacking device

100 paddle waves

101 Drive device D control arrangement

C Device control

120 scanners, switches on the actuation rocker 14

M motor for paper transport

811 handle 201 spotlight module

202 temperature sensors for the fuser roller

85/1 suction plate

88/1 dosing tube for silicone oil

88/2 felt

88/3 drive, felt

88/4 dirt wiper rubber lip

88/5 swivel device

203 fan

204 suction hose

205 frame

206 swing

207 approaches

208 feathers

209 axis

210 sensor

211 engine

86/1 stepper motor

V paper speed

T time

VP paper speed in the transfer station when stopping

VS paper speed on the swivel saddle when stopping

VF paper speed in the fuser when stopping

S Paper path SP Current paper path to be delivered from the transfer station until the printer has come to a standstill

SS Current paper path to printer standstill on the swivel saddle when swiveling back

SF current paper path to be removed by the fixing roller until the printer has come to a standstill

SPS currently available paper path from the transfer printing station to printer start

SSS current paper path when starting the printer on the swivel saddle when swiveling SFS currently to be removed by the fusing roller

Paper path when printer VPS starts Paper speed in the transfer station at

Printer start VFS paper speed in the fuser

(Fixing gap) when the printer starts VSS paper speed on the swivel saddle

Printer startup

Claims

1. Electrophotographic printing device for continuous paper (12) with a) a transfer printing station (17) with an integrated paper transport device (44) for transfer printing a toner image produced and colored on an intermediate carrier (16) onto the continuous paper (12) b) an electrothermal fixing station (23) arranged downstream of the transfer station (17) for the toner image in the paper transport direction with an electrically heated fixing roller (86) b2 driven by an electric motor) 87) and b3) an unheated paper guide saddle (93) which can be swiveled in and out on the fixing roller (86) and via which the enduro paper (12) for preheating before the actual fixing in one by the pivoting position of the paper guide saddle (93 ) predeterminable wrap angle (4) is guided around the fixing roller (86) and c) a paper width upstream of the fixing station (23) in the paper transport direction mse (85) for tightening the continuous paper (12) between the fixing area (PB-PC) and the paper guide saddle (93) as required.

2. Printing device according to claim 1, dadurchge ¬ indicates that a paper transport through the fixing station (23) detecting paper transport sensor arrangement (84, 84/1, 84/2) is provided, which with a control arrangement (D) for the Fixing station (23) is coupled, the control arrangement (D) depending on signals from the paper transport sensor arrangement (84, 84/1, 84/2) the fixing roller drive of the fixing roller (86) according to the paper transport speed of the transfer station (17th ) regulates.

3. Printing device according to one of claims 1 or 2, characterized in that between the transfer station (17) and the fixing station (83) a loop puller (84) with a movable, resiliently against the continuous paper (12) paper guide flap (84) is arranged.

4. Printing device according to claim, that the position of the paper guide flap (84) sensing sensors (84/1, 84/2) are arranged to design the paper guide flap (84) as a paper transport sensor arrangement in the region of the paper guide flap (84).

5. Printing device according to one of claims 1 to 4, d a d u r c h g e k e n n z e i c h n e t that the Papier¬ brake (85) has a vacuum suction chamber.

6. Printing device according to one of claims 1 to 5, characterized in that an eccentric actuatable eccentric device (94) is provided for swiveling the paper guide saddle (93) about an axis (92) assigned to a paper feed region of the fixing station (23) is.

7. Printing device according to one of claims 1 to 6, characterized in that the transfer printing station (17) on the intermediate carrier (16) is designed to be pivoted on and off and a paper inserting device (14) can be pivoted on and off for inserting the continuous paper ( 12) in the transfer printing station (17).

8. Printing device according to one of claims 1 to 7, characterized in that at least the fixing roller (86), the pressure roller (87) and the paper guide saddle (93) are arranged such that they can move in relation to one another in a paper loading state of the fixing station (23) Paper feed-through channel through the fixing station (23) for automatically threading the continuous paper (12) through the fixing station (23) via the paper transport device (44) of the transfer printing station (17) is formed.

9. Printing device according to one of claims 1 to 8, characterized in that the And roller (87) on a pivotable about an axis (209) H tion (206) and that a coupled to the holder (20) electromotively driven pivoting device (87 ) / l) is provided in the form of an eccentric device.

10. Printing device according to claim 9, d a d u r c h g e k e n n z e i c h n e t that a position sensor (210) is assigned to scan the position of the pressure roller (87) of the eccentric arrangement (87/1).

11. Method for operating a continuous paper (12) print electrophotographic printing device with the following char

- A continuous paper (12) is printed on a toner image in a transfer printing station (12) and the continuous paper (12) is transported to the transfer printing station (17) associated with the paper transport direction (44).

- The toner image is thermo-pressure fixed in a fixing station (23) in a xier area between a heated fixing roller (86) and pressure roller (87).

- For preheating the continuous paper (12) before actually fixing the continuous paper (12) during the print bed bes a predetermined wrap angle (U) around the fixed roller (86) with the help of a pivotable paper guide sa (93) guided tight.

- If the printing operation is interrupted, the paper guide saddle (93) is pivoted down and a fixing area (PB-PC) is g net, so that the continuous paper (12) does not abut the fixing roller (86) and

- The pivoting of the paper guide saddle (93) u the paper transport in the fixing station (23) is controlled so that during the movement of the paper guide saddle (93) when applying the continuous paper (12) to the Fixierw (86) and when peeling the continuous paper (12) from the xierwalze (86) no relative movement occurs in the contact area's continuous paper (12) and fixing roller (86).

12. The method of claim 11, d a d u r c h g e k e z e i c h n e t that during a startup phase at the Sta

The following conditions are met during printing and / or during printing:

(1) PLC = SFS + SSS

(2) VPS = VFS + VSS where applies

SPS = paper path supplied by the transfer station (17) (SFS = paper transported away by the fixing roller (86) SSS = paper path (S) required by the paper guide saddle (93) depending on the pivoting position VPS = paper speed in the transfer station (17) VFS = paper speed (V) in the fixing area (PB-PC) VSS = paper speed contribution (V) through the paper guide saddle (93) during the swinging out of the paper guide saddle (93) into the operating position (AB).

13. The method of claim 11, d a d u r c h g e k e z e i c h n e t that the following conditions are met during a stop phase when the printing operation is initiated

(1) SP = SF - SS (2) VP = VF - VS where applies

SP = the paper path supplied by the transfer printing station (17) SF = the paper path (S) supplied by the paper guide saddle (99) depending on the pivoting position SS = the pier path (S) to be transported away by the fixing roller (86) VP = the paper speed (V) in the transfer printing station VF = the paper speed (V) in the fixing area (PB-P VS = the paper speed (V) on the paper guide (93).