EP0857322A1

EP0857322A1 - Method of operating an electrographic printer using different form lengths

Info

Publication number: EP0857322A1
Application number: EP96920777A
Authority: EP
Inventors: Edmund Creutzmann; Hans Winter
Original assignee: Oce Printing Systems GmbH and Co KG
Current assignee: Canon Production Printing Germany GmbH and Co KG
Priority date: 1995-10-27
Filing date: 1996-06-03
Publication date: 1998-08-12
Anticipated expiration: 2016-06-03
Also published as: DE59606350D1; EP0857322B1; WO1997016767A1

Abstract

The disclosure relates to a method of operating an electrographic printer. A first web section (A) of a web (10) of continuous medium which can be folded in sheets with predetermined form lengths is led past the transfer printing stations (22) of an intermediate image carrier (26). The web (10) is then transported through the printer and offset and optionally also reversed, thus ensuring that an offset second web section (B) is led in one plane next to and with the first web section (A) past the transfer printing station (22) of the intermediate image carrier (26). For form lengths FL1 = (k x 1/2 + 1/6) x LE or FL2 = (k x 1/2 + 2/6) x LE, k being a real integer, the length L of the web (10) from one transfer printing station (22) to another is set to ensure that the quotient n1/3 or n2/3 gives a remainder R = 0, n1 being the rounded up integer value from L/FL1 and n2 the rounded up integer value from L/FL2. This ensures that the adjacent web sections (A, B) are printed on the correct side.

Description

description

Method for operating an electrographic printer using different form lengths

The invention relates to a method for operating an electrographic printer, in which a first and a second web section of a web of an endless carrier material that can be folded in sheets with a predetermined form length are guided past the transfer location of an intermediate image carrier and simultaneously printed.

The invention is concerned with a further development of an electrographic printing device for printing on tape-shaped recording media of different bandwidth according to WO 94/27193. The printing device described there has an electrographically working intermediate carrier, for example a photoconductor drum, with a usable width corresponding to twice the width format of a standard form in accordance with DIN A4. The other units, such as the fixing station, the developer station, the cleaning station, etc., are also designed for this usable width.

Various operating modes are possible with this known printing device. In the so-called simplex mode, a recording medium with up to twice the width of an A4 sheet can be printed in a conventional form. In a parallel simplex mode, two narrow recording media, e.g. with a width according to DIN A4, in juxtaposition through the printing device and printed.

In another operating mode, the monochrome duplex mode, the web of the recording medium is turned during transport through the printing device, so that two web sections result: In a first web section the front of the web is at the transfer location of a transfer station opposite, while in a second web section the back of the web is simultaneously printed at the same transfer location. Two-color duplex operation is also possible by using differently colored color particles in different developer units of the printing unit.

In another operating mode, the two-color simplex operation, the web is offset in parallel by at least one web width during transport in the printing device, and the offset web sections are guided past the transfer location together in juxtaposition. The first time the web passes by at the transfer location, image and text elements are printed with a first color; in the second run along the path with offset, image and text elements are printed with the second color.

When printing on a single web, which is offset in parallel in the printer or offset in parallel and additionally turned and fed to the printing unit of the printing unit and printed again, it must be ensured that when printing the adjacent web sections of the web at the transfer location, the printing locations on the web in one fixed given relationship to each other. This fixed relationship must be maintained during the entire printing operation, otherwise there is an undesirable shift in the printed image.

When using an endless carrier material folded in sheets, which is also referred to as a fan-fold carrier material, the form length in the transport direction is defined by the distance between two successive folds. The form lengths are defined worldwide in inches or fractions thereof - data in metric units are unusual. Therefore, as is generally customary in the field of printer technology, the form lengths are given below in inches; one inch is 25.4 mm long. In practice, formu- lengths of 12 inch, 12 1/2 inch, 12 1/6 inch, 12 2/6 inch etc.

In order to be able to reliably transport the web of the endless carrier material which can be folded in sheets, it contains transport holes at its edges which are at a distance of 3/6 inch from one another. Transport spikes of a transport device arranged near the photoconductor reach into these transport holes. These transport spikes are also 3/6 inch apart. The folds of the web are arranged between the transport holes, which reduces the risk of a sheet tearing out. The fold is preferably arranged centrally between two transport holes. If the web has a form length that is an integral multiple of 1/2 inch, all the folds are in the middle between two transport holes. However, if a form length is used that is not an integral multiple of 1/2 inch, the fold at the beginning of a sheet may still be in the middle between two transport holes, but the fold at the end of the sheet has an off-center position. For form lengths FLI = (k X 1/2 + 1/6) inch or F _L 2 = (kx 1/2 + 2/6) inch, with k a natural integer, two folds follow a centrally arranged fold have an off-center position between two transport holes. Such form lengths FLI and F _L2 are called eccentric form _lengths below.

The two web sections lying next to each other in the printer are guided past the transfer location of the photoconductor using a transport device. With webs with off-center form lengths FLI or FL2 it can now happen that two folds come to lie side by side, the position of which is different from one another between the transport holes. The folds of the adjacent web sections then do not align, with the result that sheets of the two web sections have different starting positions when viewed in the transport direction. So that at the If the correct transfer image is transferred over to the common transfer point sheet by sheet, measures must be taken to prevent an undesirable shift in the transfer image.

It is an object of the invention to provide a method for operating an electrographic printer, in which sheet-precise printing without offset of the printed image is possible even with off-center form lengths.

This object is achieved by method steps according to claims 1, 5 and 10. Advantageous developments of the invention are specified in the dependent claims.

According to a first aspect of the invention, the length L of the web is influenced from transfer location to transfer location to achieve the object. This length L is set in such a way that the integer residual value R = 0 when the ouotient nl / 3 or n2 / 3 is formed, where nl or n2 are rounded-off integer numbers from L / FLI or L / FL2. As ER- imagines that the eccentric form lengths FLI and FL2 i ^n-inch sizes are defined as:

^F L1 ^{= (kx 1/2 + 1/6) inch and} ^F L2 = (kx 1/2 + 2/6) inch,

with k a natural integer

These measures ensure that the folds of the adjacent web sections are aligned with one another, so that when the transfer is transferred at the transfer location, the sheet beginnings of the sheets of both web sections can be printed simultaneously. The printed images can thus be transferred to the page foldable sheet-by-sheet in duplex mode or in two-color simplex mode.

In order to be able to adjust the length of the web in accordance with the relationships mentioned, the web passes through Printing parts to transfer printing a web memory, which is preferably preset to a minimum value LTJSMIN. If the number of sheets n1 or n2 from transfer point to transfer point, which results from the quotients L / FLI or L / FL2, can be divided exactly by 3 and the residual value R = 0, then there are both in the middle between transport holes - Ordered folds as well as folds arranged off-center in different web sections exactly opposite one another. When printing at the transfer location at the same time, there is therefore no offset in the print image in relation to the respective fold or to the beginning of the page in question.

According to a second aspect of the invention, when the two web sections are inserted, the small fold spacing in the transport direction that results from sheet-by-sheet alignment is left. Rather, the generation of the toner images is acted upon and the toner image electronically generated on the photoconductor, for example on the photoconductor drum, for one web section is shifted by the fold distance from the toner image for the other web section. This print image offset by the folding distance is again determined from the residual value R, which results from the quotient nl / 3 or n2 / 3 according to the relationships given above. The print image offset in turn makes it possible for the individual sheets of the web to be printed with the correct sides starting with the beginning of the sheet. Although the folds of the mutually opposite web sections are not exactly aligned with one another, there is therefore no print offset in duplex mode and in two-color simplex mode. In the measures according to the second aspect of the invention, the length of the web from transfer point to transfer point is minimal.

According to a third aspect of the invention, the transport device is acted upon to compensate for a possibly occurring fold spacing in the transport direction. The transport device is converted into a first transport unit for the first web section and a second transport unit for the second track section divided. Before the printing operation begins, ie during the insertion operation, the two transport units are detached from one another so that the folds of the adjacent web sections can be aligned with one another. The two transport units are then rotatably coupled again to start printing. With this solution, neither the web memory for recording a certain length of the web nor the toner image generation on the photoconductor has to be changed.

Embodiments of the invention are explained below with reference to the drawings. In it show:

FIG. 1 shows a schematic diagram of a printer that works in duplex mode,

Figure 2 shows the position of the fold at different

Form lengths,

FIG. 3 shows the print image offset of the toner images for a residual value R = 1 according to one aspect of the invention,

FIG. 4 shows the print image offset for adjacent toner images for a residual value R = 2,

Figure 5 shows the adjustment of each other

Transport units with a residual value R = 1 according to a further aspect of the invention and

Figure 6 shows the adjustment of the detached from each other

Transport units to compensate for the folding distance with a residual value R = 2.

Details of the invention are described below using a high-performance printer which operates in the duplex printing mode, the one to be printed Web is a folded (fan-fold) paper web. FIG. 1 shows a schematic representation of the transport path of the web 10 through the printer. The folded web 10 with folds 12 is pulled off a stack 16. The distance between the folds 12 defines the form length FL of a sheet. As mentioned, the form lengths FL in the field of printer technology are usually given in "inches" and fractions thereof, for example 1/6 inch; an inch has a length of 25.4 mm.

A deflection unit 18 with a usable width at least equal to twice the width of the web 10 deflects it and guides it to a transport device, generally designated 20. This transport device 20 guides the web 10 with a first web section A past a transfer printing point 22 of a printing unit 24.

The printer used here works on the principle of electrophotography, in which a photoconductor drum 26 is used as the intermediate carrier, on which a latent charge image corresponding to that to be printed is used with the aid of a light source 28, for example a laser or an LED line Print image is applied. This charge image is converted into a toner image using a developer station 30, this developer station 30 transferring color particles of a desired color to the photoconductor drum 26. At the transfer location 22, the toner image is transferred to the surface of the web section A under the influence of a corona discharge, i.e. onto the front of the web 10. The toner image on web section A, which is now still wipeable, is transported through a fixing station 32 and there is connected to the carrier material of the web 10 in a smudge-proof manner using pressure and temperature.

The web section A is then deflected at a further deflection unit 34 and reaches a turning station 36 in which the web 10 is laterally offset by at least one web width and is turned so that the back of the web 10 can now be fed to the transfer printing station 22. The section of web 10 after turning is referred to as web section B. The web section B is also printed at the transfer printing point 22 and then passed through the fixing station 32. After passing through the fixing station 32 twice, the web 10 arrives at an output roller 38 and from there to an output stack 40, where it is deposited in a sheet-folded condition. Further details of the structure of the printer are described in the aforementioned WO 94/27193, the content of which is attributable to the present disclosure of the invention.

It should be mentioned that for the two-color simplex operation, the turning station 36 is replaced by a transfer station, which moves the web 10 by at least one web width without turning it. The other processes are the same as for the duplex operation described here.

After the turning station 36, the web section B runs through a web loop 41 of a defined length. The web loop 41 forms a web memory and serves to ensure that the web section B of the transport device 20 is fed free of tensile stresses.

The transport device 20 comprises a first transport unit 20a for the first web section A and a second transport unit 20b for the second web section B. Both transport units 20a, 20b are non-rotatably coupled to one another during the printing operation. This ensures that both web sections A, B are transported forward at the same speed, the alignment of the two web sections A, B carried out in the inserting operation being maintained at all times. During the insertion operation, the rotary connection of the two transport units 20a, 20b can be released in certain operating modes, so that a web transport of the second web section B even when it is at a standstill of the first path section A can take place. Different operating modes with coupled and decoupled transport units 20a, 20b are explained further below.

The transport device 20 comprises caterpillar units (not shown) with transport spikes which engage in transport holes on the edge of the web 10. After the web 10 has been inserted, flaps (not shown) are folded over its edges, which hold them firmly with the transport holes on the transport spikes. This type of transport mechanism for foldable webs is generally known and is not explained in more detail here.

FIG. 2 shows the position of the folds 12 with different form lengths FL. In the upper part of the figure, a web 10 is shown, of which four sheets or pages 1 to 4 are to be examined in more detail. In this case, the form length FL of the web 10 is FLO = kx 1/2 inch, with k an integer number, for example FLO is ¹² 1/2 inch. The beginning of page 1 is formed by a fold 12 which coincides with a center line M between two successive transport holes 42 (for reasons of clarity, only one transport hole is provided with the reference symbol 42). The distance between two successive transport holes 42 is a = 3/6 inch when viewed in the transport direction. The fold 12 at the end of the side 1 also coincides with the center line M between two transport holes 42, ie the fold 12 of the following side 2 is arranged centrally between two transport holes 42 as in the case of page 1. Accordingly, the folds 12 for the following pages 3 and 4 are also arranged centrally between the transport holes 42 as seen in the transport direction.

In the middle part of FIG. 2, the web 10 is given for an off-center form length FLI ⁼ (k ^χ 1/2 ⁺ 1/6) inch. A typical form length is FLI ⁼ 12 1/6 inch. The fold 12 at the beginning of page 1 falls with the center line M together. The fold 12 at the end of the page 1 is shifted to the right by 1/6 inch relative to the center line M, that is to say it is arranged off-center by 1/6 inch. The following page 2 is delimited at its end by a fold 12 which is shifted to the left by 1/6 mch with respect to the center line M. The fold 12 at the end of page 3 again coincides with the center line M. The following side 4 has fold layers like page 1. Thus, of three consecutive sides of the web 10, at least one side has a fold 12 at its beginning, which is arranged centrally between two transport holes 42.

A web 10 with an off-center form length FL2 = (k X 1/2 + 2/6) inch is shown in the lower part of the figure. A typical form length is FL2 ⁼ 12 2/6 inch. Again, the fold 12 is arranged centrally between two transport holes 42 at the beginning of the page 1. Due to the form length FL2, the fold 12 at the end of the page 1 is shifted to the left by 1/6 inch from the center line M. The fold 12 at the end of the following page 2 is arranged shifted 1/6 inch to the right outside the center line M. The fold at the end of the following page 3 again coincides with the center line M. The side 4 has a fold position like the side 1. It can be seen that in this example too the fold 12 is arranged at the beginning of at least one side of three successive sides in the middle between two transport holes 42 of the web 10. The fold layers are repeated at three-sided intervals; the local period is therefore three pages or three leaves.

If, in the case of a printer in duplex mode or in two-color simplex mode, the web 10 is transported through the printer in such a way that it is offset and, if necessary, additionally turned over, so that it passes a first toner image and is provided with a second toner image during the second passage past the transfer printing location 22, it can happen with the eccentric form lengths FLI and FL2 that the folds 12 of the adjacent mutually lying path sections A, B are not exactly aligned. If no further measures were taken, the toner images, viewed in the transport direction, could differ from one another by ± 1/6 inch in relation to a sheet start or a start page of web section A compared to those of web section B.

According to a first aspect of the invention, the length L of the web 10 is from 22 to transfer printing transfer point 22 so einge- that the folds 12 of the web 10 to form lengths FLI and FL2 a the transfer printing location ⁿ 12 are aligned. The condition then has to be observed that the quotient of nl / 3 or n2 / 3 results in a residual value R = 0, where nl is the rounded integer value from L / FLI and n2 is the rounded integer value from L / FL2.

According to the invention, depending on the number of sheets or pages of the web 10 between the transfer point 22 and transfer point 22, there are so many additional pages with form length FLI or FL2 that the total number n1 or n2 of the pages from transfer point 22 to transfer point 22 without any remainder is divisible by 3. The additional pages are recorded in the web store 41. This web store 41 thus has a double function: on the one hand, it is intended to provide some compensation for length tolerances in the form lengths FL of the web 10 as a result of shrinkage or other changes in length; on the other hand, it should take up a sufficient number of pages with off-center form ^lengths FLI ^unc * ^F L2 in order to allow the folds 12 of the adjacent web sections A and B to be aligned at the transfer printing point 22.

With a minimum transport Lyu ^of transfer point 22 to 22 transfer printing capacity _{Lrj> s} ^de s track memory is proposed, provide einzu- 42 depending on the integer residual value R. The relationships apply:

^χ l = ⁽ l-UU + L _DS MIN ⁾ / ^F L1 ' x2 = (L _UT j + L _D SMIN ^{/ F} L2 'where xl, x2 are rounded integer values.

R is then determined from xl / 3 or x2 / 3

For R = 0, L _DS = L _DSMIN ,

R = 1 is L _DS = LDSMIN ^{+ 2F} L1 or L _DS = L _DSMIN + 2F _L2 , and R = 2 is L _DS = L _DSMIN + F _L1 or L _DS = L _DSMIN + F _L 2 •

If these relationships are observed, the required web loop in the web store 41 is minimal; The web store 41 can be designed to be correspondingly small in terms of its capacity.

In another exemplary embodiment of the invention, the small fold spacing of the adjacent web sections A and B, which are aligned sheet by sheet, is maintained at the transfer location 22 in the transport direction. As mentioned, the individual pages of the web sections A and B are printed sheet by sheet with toner images, the position of which relative to one another is precisely defined. For example, the toner images should have a defined position at the top of each page. Due to the fold spacing for off-center form lengths FLI and FL2, this positional relationship cannot be maintained exactly without additional measures. It is therefore provided according to the invention that the second toner image assigned to the second web section B is printed over the fold distance from the first toner image assigned to the first web section A. This fold distance depends on the

Residual value R determined for a form length FLI ⁼

(kx 1/2 + 1/6) inch or F _L 2 = (kx 1/2 + 2/6) inch, with k a natural integer, from the quotient nl / 3 or n2 / 3, where nl is the rounded integer from L / FLI and n2 the rounded integer from L / FL2 and L is the length of the web 10 from transfer location 22 to transfer location 22.

In FIG. 3, the fold distance resulting for the residual value R = 1, by which the toner images of the two web sections A and B belonging to each page are shifted, for the form lengths L / FLI (left part of the image) and L / F _L 2 (right part of the picture). In practice, the procedure is such that web section A is first inserted while web 10 is being inserted. A fold 12, which coincides with a center line M, then lies against a marking MJJ, which is assigned to the form length FLI or FL2 used. The web section B is then inserted and guided past the transfer printing point 22. As can be seen in the left part of the figure in FIG. 3, with a residual value R = 1, a fold spacing of the opposing folds 12 of +1/6 inch is produced, based on the transport direction. According to the invention, the toner image for web section B is now also shifted by +1/6 inch and transferred sheet by sheet to web section B. The offset of the toner image by the fold distance generally takes place when the charge image is applied. The charge image for an entire side of the web section B is accordingly generated a time T earlier than for the web section A, for example by writing on the photosensitive surface of the photoconductor drum 26 by the laser beam or by the LED line. This time T is calculated from the fold distance divided by the peripheral speed of the photoconductor drum or the transport speed during the pressing.

In the right part of the figure, for a residual value R = 1 and the form length FL2 ZU, it can be seen that the fold spacing or the print image offset is -1/6 inch. The toner image for the sides of the web section B is therefore to be printed with a shift of the folding distance -1/6 inch relative to that of the web section A, in order to obtain correctly printed images on the mutually assigned sheets of the web sections A and B.

FIG. 4 shows the fold spacing or the respective print image offset with a residual value R = 2 for the form lengths FLI and F _L 2. The fold spacing or the print image offset for the form length FLI is -1/6 inch as seen ^{in the} transport direction; for FL2 it is +1/6 inch.

With the residual value R = 0, the folds 12 of the neighboring ones are aligned

Web sections A and B after insertion; the fold distance is 0, a print image offset of the toner images is not necessary.

According to a further aspect of the invention, the fold offset or the fold spacing in the transport direction can be compensated for eccentric form lengths F _L ι or FL2 by moving the web sections A, B relative to one another before the start of the printing operation, so that the folds 12 of the adjacent web sections A, B are aligned. To make this possible, the transport device 20 is divided into a first transport unit 20a for the first web section A and a second transport unit 20b for the second web section B (cf. FIG. 1). After the insertion of the web section A into the transport device 20, the web 10 is transported through the printer so that the web section B can be inserted into the transport unit 20b, whereby the sheets of the web sections A and B lying side by side are aligned.

When using off-center form lengths FLI or FL2, a fold offset or a fold spacing can occur when viewed in the transport direction. If the fold distance differs from 0, the rotary connection of the two transport units 20a, 20b is released and the second web section B is transported by web relative to the first web section A by this fold distance, the web 10 of the web section A being still. stands. After compensation of the fold spacing such that the opposing folds 12 of the web sections A and B are aligned with one another, the transport units 20a, 20b are coupled to one another in a rotationally fixed manner for the printing operation. Since in practice only fold spacing of +1/6 inch and -1/6 inch occurs, the transport device 20 can be designed in such a way that the two transport units 20a, 20b can only be rotated by these values. This twisting can be done manually by an operator or automatically by the printer controller.

The rail transport of rail section B is determined depending on the residual value R. This residual value R is determined from the quotient of nl / 3 or n2 / 3 for a form length FLI ~ (kx 1/2 + 1/6) inch or F _L 2 = (kx 1/2 + 2/6) inch . In these relationships, nl is the rounded integer value from L / FLI and n2 is the rounded integer value from L / FL2 / π ^ it L the length of the web 10 from transfer location 22 to transfer location 22.

5 shows states when the web sections A and B are inserted for the residual value R = 1. The state of the form length FLI after inserting the web section A and the web section B is shown in the upper left part of the picture. Viewed in the direction of transport, there is a fold spacing or fold offset of +1/6 inch. The rotary connection of the transport units 20a, 20b is now released and the transport unit 20b is adjusted by -1/6 inch with respect to the stationary transport device 20a. The result can be seen in the lower left part of the picture. The folds 12 of the adjacent web sections A and B are now aligned with one another, so that the toner images on both web sections A, B can be re-printed simultaneously with uniform alignment to the beginning of the page.

In the top right part of FIG. 5, the fold spacing or the fold offset is -1/6 inch for the form length FL2 after inserting the two web sections A and B Darge¬ represents. The transport unit 20b is adjusted by +1/6 inch so that the opposing folds 12 of the web section A and the web section B are aligned with one another (picture part on the bottom right). The two transport units 20a, 20b are then coupled in a rotationally fixed manner and printing operation can begin.

In FIG. 6, in the manner of FIG. 5, states after the insertion of the web sections A, B and after the adjustment of the transport units 20a, 20b for eccentric form lengths FLI ^and d ^F L2 are shown with a residual value R = 2. For the form length FLI there is a fold offset of -1/6 inch, and for the form length FL2 a fold offset of +1/6 inch after inserting the web sections A, B. Accordingly, for the form length FLI ^e; - ⁿ web transport by adjusting the transport units 20a, 20b against each other by +1/6 inch and with a form length FL2 by -1/6 inch, so that the opposing folds 12 are aligned with one another. After the transport units 20a, 20b have been adjusted, they are connected to one another in a rotationally fixed manner and printing operation is started.

Claims

claims

1. A method of operating an electrographic printer in which a first web section (A) of a web (10) of a continuous carrier material that can be folded in sheets with a predetermined form length is guided past the transfer location (22) of an intermediate image carrier (26), then the web (10) transported through the printer and thereby displaced and, if necessary, additionally turned, so that a displaced second web section (B) in a plane in juxtaposition with the first web section (A) at the transfer location ( 22) of the intermediate image carrier (26) is passed, wherein each sheet of the web (10) with the first pass by the intermediate image carrier (26) with a first toner image and when passing again at the transfer location (22) with a second toner image, which has a defined position has first toner image, is printed, and in which the transport of the first and the second web section (A, B) by a near the image intermediate Carrier (26) arranged transport device (20) with transport spikes, which are engaged with transport holes (42) in the web (10) and which move at the same speed, the transport holes (42) in the transport direction a distance of 3/6 x LE have one another, where LE is a unit of length typical of form lengths, the fold (12) of at least one sheet of three successive sheets is arranged centrally between two transport holes (42) of the web (10), and for a form length FLI ⁼ (- * ^x 1/2 ⁺ 1/6) x LE or F _L 2 = (kx 1/2 + 2/6) x LE, with k a natural integer, the length L of the path (10) from Transfer point (22) to transfer point (22) is set so that the quotient of nl / 3 or n2 / 3 results in a residual value R = 0, where nl is the rounded-off integer value L / FLI and n2 is the rounded integer value from L / F _L 2.

2. The method according to claim 1, characterized in that the web (10) passes through a web storage (41), the capacity of which is at least 2FLI or 2FL2, during its transport from the transfer location (22) to the transfer location (22).

3. The method according to claim 1 or 2, characterized in that the web memory (41) is preset to a minimum value LΓJSMIN.

4. The method according to claim 3, characterized in that for a transport route Lyu ^{from transfer} location (22) to transfer parts (22) the capacity LJJS of the web store (42) depending on the integer residual value R from the quotient xl / 3 or x2 / 3 is set, wherein xl of aufgerun¬ finished integer value from (LGY + LΓJSMIN) / ^F L1 ^un d * 2 is the rounded integer numerical value of (Lyu ⁺ ^L DSMIN) / ^F L2 ^is' wherein, for R = 0, the Kapaziät LΓJS = LrjsMIN ' ^{for R =} 1 the capacity Lps = LTJSMIN ⁺ 2FLI or ^L D _S ^{= L} DSMIN ⁺ 2F _L 2 and for R = 2 the capacity L ^ s = ^L DSMIN ^{+ F} L1 ° ^{d der} L _D s = ^ DSMIN ^{+ F} L2 ^is *

5. A method for operating an electrographic printer, in which a first web section (A) of a web (10) of a continuous carrier material that can be folded in sheets with a given form length is guided past the transfer location (22) of an intermediate image carrier (26), subsequently the web (10) is transported through the printer and thereby displaced and possibly additionally turned, so that a displaced second web section (B) in one plane in juxtaposition with the first web section (A) at the transfer printing place (22) of the intermediate image carrier (26) is passed, wherein the folds (12) of the sheets of the adjacent web sections (A, B) are flush with one another or have a small folding distance in the transport direction, and in which the transport of the first and second web sections (A, B) by a close the image intermediate carrier (26) is arranged a transport device (20) with transport spikes which engage with transport holes (42) in the web (10) and which move at the same speed, the transport holes (42) being a distance of 3 / 6 x LE in the transport direction from each other, whereby LE is a unit of length typical for form lengths, the fold (12) of at least one sheet of three successive sheets is arranged centrally between two transport holes (42) of the web (10), each Sheet of the web (10) the first time passing the intermediate image carrier (26) with a first toner image and when passing again at the transfer location (22) with a tw Since the first toner image has a defined position with respect to the first toner image, the first toner image is printed over the second toner image, offset by the folding distance, which is determined as a function of a residual value R, which is for a form length FLI = (k X 1/2 + 1/6) x LE or F _L 2 = (kx 1/2 + 2/6) x LE, with k a natural integer, from the quotients nl / 3 or n2 / 3, where nl the rounded integer value from L / FLI and n2 the rounded integer value from L / FL2 and L is the length of the web (10) from transfer location (22) to transfer location (22).

6. The method according to claim 5, characterized in that the folding distance is 0 for a residual value R = 0.

7. The method according to claim 5, characterized in that for a residual value R = 1, the folding distance for the formu- lar-long FLI is equal to 1/6 x LE and for form length F _L 2 is equal to - 1/6 LE.

8. The method according to claim 5, characterized in that for a residual value R = 2, the folding distance for a form length FLI is -1/6 x LE and for a form length F _L 2 is +1/6 x LE.

9. The method according to any one of the preceding claims 5 to 8, characterized in that the charge image on the

Intermediate image carrier (26) for generating a toner image on the second web section (B) with respect to the charge image for the toner image of the first web section (A) is generated offset by a time T which is divided by the folding distance by the transport speed results during the pressing.

10. Method for operating an electrographic printer, in which a first web section (A) of a web (10) of a continuous carrier material that can be folded in sheets with a given form length is guided past the transfer location (22) of an intermediate image carrier (26), then the web (10) is transported through the printer and thereby displaced and, if necessary, additionally turned, so that a displaced second web section (B) in one plane in side-by-side position together with the first web section (A) at the transfer printing point (22) of the intermediate image carrier is passed, the folds (12) of the sheets of the adjacent web sections (A, B) being aligned with one another or having a small fold spacing in the transport direction from one another, and in which the transport of the first and the second Web section (A, B) by a transport device (20) arranged near the intermediate image carrier (26) with transport spikes, which with transport punch (42) are engaged in the web (10) and move at the same speed, the transport holes (42) being at a distance of 3/6 x LE in the transport direction, LE being a unit of length typical of form lengths, the fold (12) at least one sheet of three successive sheets is arranged centrally between two transport holes (42) of the web (10), each sheet of the web (10) having a first toner image when passing the image intermediate carrier (26) for the first time and passing it again a second toner image, which has a defined position relative to the first toner image, is printed on at the transfer printing location (22), the transport device (20) having a first transport unit (20a) for the first web section (A) and a second transport unit (20b ) for the second Bahnab¬ section (B), and wherein the rotary connection of the two transport units (20a, 20b) are released during the insertion operation and a Ba The second web section (B) is transported relative to the first web section (A) by the fold distance, and then the two transport units (20a, 20b) are rotatably coupled to one another for printing operation with simultaneous pressure on the web sections (A, B).

11. The method according to claim 10, characterized in that the web transport of the second web section (B) takes place at a standstill of the first web section (A).

12. The method according to any one of the preceding claims 10 or 11, characterized in that the web transport is automatically triggered by the control of the printer.

13. The method according to any one of the preceding claims 10 or 11, characterized in that the rail transport is determined depending on an integer residual value R, which is for a form length FLI = (kx 1/2 + 1/6) x LE or F _L 2 = (kx 1/2 + 2/6) x LE, with k a natural integer, from the quotients nl / 3 or n2 / 3, where nl is the rounded integer value from L / FLI and n2 the rounded integer numerical value from ^L / ^F L2 and L is the length of the web (10) from the transfer location (22) to the transfer location (22).

14. The method according to claim 13, characterized in that for a residual value R = 1, the fold distance for the form length FLI is equal to 1/6 x LE and for the form length F _L 2 is equal to - 1/6 x LE.

15. The method according to claim 13, characterized in that for a residual value R = 2, the fold distance for a form length FLI is -1/6 x LE and for a form length FL2 is +1/6 x LE.

16. The method according to any one of the preceding claims 1 to

15, characterized in that the length unit LE 25.4

17. The method according to any one of the preceding claims 1 to

16, characterized in that a photoconductor (26) is used as the intermediate image carrier.