DE102016208479A1 - Electrophotographic large format color printer - Google Patents

Abstract

The invention relates to a large format electrophotographic printer having a printing width greater than 0.5 m, in particular large format color printer having a plurality of printing stations (1, 1C, 1M, 1Y, 1K, 22), each printing station comprising a photoconductive drum (2), a loading unit ( 5), an exposure unit (4), a developer station (3, 23), an erasing device (7), a cleaning device (6), and a housing (10), each having an anode roller (8, 8C, 8M, 8Y, 8K) for each printing stations (1, 1C, 1M, 1Y, 1K, 22), with one over deflection rollers (28), between anode rollers (8, 8C, 8M, 8Y, 8K) and printing stations (1, 1C, 1M, 1Y , 1K, 22) guided transfer belt (9), with a voltage applied to transfer roller (29) for transfer of toner images on a medium to be printed (30), with a fixing station (31), with a cleaning station (32) and with a support frame , Such a printer should be designed to save space, be converted into different performance classes and be operable without interference. For this purpose, it is proposed that the support frame be provided as receiving means for the directly behind each other arranged different colors (cyan, magenta, yellow, black) containing printing stations (1, 1C, 1M, 1Y, 1K, 22) that the printing stations (1, 1C , 1M, 1Y, 1K, 22) in the support frame and / or the developer stations (3, 22) are interchangeable with identical or different printing stations (1, 1C, 1M, 1Y, 1K, 22) and / or developer stations (3, 23) , and that the printing stations (1, 1C, 1M, 1Y, 1K, 22) each have a depth of less than 160 mm, preferably less than 150 mm, most preferably less than 140 mm

Description

The invention relates to an electrophotographic large format printer with a print width greater than 0.5 m. in particular large format color printer having a plurality of printing stations, each printing station comprising a photoconductive drum, a charging unit, an exposure unit, a developer station, an erasing device, a cleaning device, and a housing, each having an anode roller for each printing station, one via deflection rollers, between anode rollers and Printing stations guided transfer belt, with a tension applied transfer roller for transferring toner images on a medium to be printed, with a fuser, with a cleaning station and with a support frame.

Such electrophotographic printers are both the monochrome and color general state of the art. The underlying technologies are z. In the book "Handbuch der Printmedien" by Helmut Kipphan (ed.), Springer-Verlag Berlin Heidelberg 2000, pages 61ff , described.

First follows a brief description of the technology for a single color, a monochrome process. Typically, the electrophotographic process consists of six steps. Essential for the electrophotographic process is the structure of the photoconductor. Very often, aluminum drums are used as the substrate, which are coated with a special organic photoconductive material about 20 μm thick. An essential feature of the photoconductor is a high electrical resistance in the absence of light and a significantly lower electrical resistance in lighting. The aluminum drum is electrically grounded.

In a first step, the surface of the photoconductor is generally electrically negatively charged, as a rule. This is usually done via corona units or in direct contact with a located at a high voltage elastomeric charging roller.

The second step is the exposure. Here are z. B. electronically controllable LED exposure modules with a resolution of, for example, 600 dpi used to transfer the desired pattern on the photoconductor. Alternatively, this can also be done via a correspondingly modulated laser. In the exposed areas, the electrical resistance decreases so that the charge can flow away there and the exposed areas are charged more positively. This creates a charge pattern.

In a third step "development" this invisible pattern is made visible. For this purpose, the photoconductor is brought into contact with electrically charged color particles of a defined polarity, usually a negative charge, a toner having a particle size typically in the range of 5 to 10 microns. Slightly easier, the particles adhere to the positively charged sites, so that the image on the photoconductor is visible.

The fourth step is the toner transfer. Concretely, the toner image is transferred from the photoconductor to a medium (for example, paper). Most of this is done in an unwinding, wherein the transfer of the electrically charged toner particles is supported by an electric field. The electric field may be generated by a corona or a tensioned elastomeric roller on the back of the medium.

In a fifth step, the toner is fixed on the medium. For this purpose, hot rolls are usually used. In addition to pigments and other excipients, the toner consists of a polymeric material which melts under the action of the high temperature of the hot rollers, so that the toner permanently adheres to the medium.

In the sixth and last step, the photoconductor is unloaded and cleaned to be ready for the next revolution and pressure in the original condition. About an erase unit such as an LED line, the photoconductor is uniformly exposed over the entire width, so that the previous charge image disappears. The cleaning can be done for example via elastomeric blade or rotating brush. They remove the remnants of toner, as the transfer to the medium usually does not succeed completely.

For full color prints, the prior art conventionally overlays the colors cyan, magenta, yellow, and black. For the realization in detail there are manifold possibilities in the literature, for example at Kipphan a. a. O., described. In addition, there are a variety of devices on the market that use this and similar technology.

For a more detailed explanation of the invention, the design "tandem architecture with intermediate carrier tape" will now be described, as they are state of the art, for example in the US 4,903,067 in particular the 9 is performed. In this way of producing color prints, for each of the four colors, there is a printing unit of the above-described electrophotographic units for a monochrome printer except for fixing. Thus, on each photoconductor a toner image in the respective color cyan, magenta, yellow and black is developed. However, the toner is not transferred directly to the medium but first to an intermediate carrier. This intermediate carrier is usually designed as a special endless belt, which is referred to as a transfer belt.

Then the four colors are collected and then transferred all together in one step on the medium. Both the transfer from the photoconductors to the tape and from the tape to the medium is carried out electrostatically analogously to the transfer described above for a monochrome process from the photoconductor to the medium. Finally, the toner is fixed on the medium.

For large-format electrophotographic printers with a printing width of more than 0.5 m, the developer station in particular presents a challenge. It is difficult to achieve a uniform and stable coloration over the entire width. This is made more difficult with additional technical and commercial requirements such as high speed, compact design and low cost.

Basically, a variety of embodiments of developer stations is known. An overview can be found z. In the book "Handbuch der Printmedien" by Helmut Kipphan (ed.), Springer-Verlag Berlin Heidelberg 2000, chapter 5.2.3 "Inking unit (development unit) and toner", pages 726 to 730 ,

One distinguishes between so-called 1K and 2K systems. One-component (1K) systems use only toner particles, while two-component (2K) systems use a "carrier". These are magnetic particles that are larger than the non-magnetic toner particles. Toner particles and carrier particles are electrically charged in rubbing contact triboelectrically with opposite polarity. Due to the opposite charge, the toner particles adhere to the carrier particles. The mixture of non-magnetic toner and magnetic carrier is called a developer.

The following briefly describes the technology of 1K and 2K systems. For details please refer to the o. G. Book by Helmut Kipphan (ed.) A. a. O. referenced.

In 1K systems, one has a reservoir of toner, a so-called feed roller, a developer roller, and a squeegee unit. The feed roller, such as a foam roller or a brush roller, rotates to transport toner from the reservoir to the developer roller, which may be, for example, an electrically semiconductive elastomeric roller. There is an overlap between the two rollers, so that the moving toner particles are exposed to friction. They are charged triboelectrically with a defined polarity. Adhesion forces and electrostatic forces leave a substantial amount of toner adhered to the developer roller. The developer roller continues to rotate and transports the toner to the doctor unit. This can, for. B. be designed as a fixed doctor blade or as a rotating roller. It typically presses against the developer roller with a defined force and, in conjunction with the rotation of the developer roller, produces a toner layer with a defined thickness of usually a few monolayers. This toner layer is offered to the photoconductive drum. The developer roller is at an electrical potential, which lies between the potentials "discharged" and "charged" on the photoconductor drum. In accordance with the forming electric field, toner particles are transferred to the photoconductor drum or remain on the developer roller. This is how the charge pattern on the photoconductor drum is developed.

In 2K systems you have a reservoir of developer, a magnetic roller and a doctor unit. The magnetic roller usually consists of a rotating non-magnetic sleeve and fixed magnets inside. The magnets are used to bring the developer to the sleeve. The surface of the sleeve has a defined roughness and transported by a rotation of the developer to the doctor unit. This is usually carried out as a fixed doctor blade at a defined distance to the magnetic roller. In conjunction with the rotation of the magnetic roller so a defined amount of developer is generated on the surface thereof. In the course of the further rotation of the developer of the photoconductor drum is offered. The magnetic roller has an electrical potential which lies between the potentials "discharged" and "charged" on the photoconductive drum. According to the forming electric field, toner particles are transferred to the photoconductor drum or remain on the magnet roller. This is how the charge pattern is developed on the photoconductor. The magnetic carriers are held by the suitably arranged magnets on the magnetic roller.

1K systems are usually found in the market in the so-called "low-end" area, ie. H. at rather low speeds and systems with a rather short life, but in a relatively compact design. For faster printing speeds, the somewhat more expensive and therefore more expensive 2K systems are usually used, which often have a larger design.

In large format electrophotographic printers, monochrome models are known with both 1K and 2K development stations. In large-format electrophotographic color printers, only comparatively slow 1K development stations have hitherto been used.

These printers are also not "compact". It should be noted that a typical Printing width for large format in electrophotography 36 '' (ie about 914 mm), ie the width of the printer is to be printed on the A0 can not be reduced. The well-known large format color printers also have dimensions over 0.9 m in the other two dimensions (height and depth) of the device, so that transport through conventional doors with widths of less than 0.9 m is not directly possible, let alone fit Large format color printer in standard passenger lifts.

In order to be transported to the site, the well-known large format color printer are broken down into several parts and assembled on site at the user of two or more parts. This is much more complex and therefore clearly more expensive for users and manufacturers than a compact device that fits through conventional doors and does not have to be mounted on site.

It is in addition to the transport costs of the space requirement known large format color printer to consider. For users where z. For example, if a monochrome large format printer is to be replaced with a large format color printer, there will typically be little room (for monochrome model) in the given premises, so that smaller size color systems are preferred.

Another advantage of a compact device is that the manufacturer can fully test and adjust the device after assembly at the factory. Additional on-site work would be required for on-site assembly work, as the final tests and adjustments are only possible after full on-site assembly.

The invention is initially based on the task of designing an electrophotographic large format printer, in particular large format color printer, such that the described space problems do not occur. Furthermore, the invention is based on the object that the correspondingly compact large format printer according to different speed and performance classes according to individual user needs correspondingly easily adaptable, and that trouble-free operation is always ensured with sufficient toner supply across the width of the photoconductor drum.

These objects are achieved according to the invention for an electrophotographic printer of the type mentioned by the features specified in the claims 1 and 3 features. Advantageous embodiments are specified in the dependent claims.

The first object is achieved in that the support frame is provided as receiving means for immediately behind the other arranged, different colors (cyan, magenta, yellow, black) containing printing stations that the printing stations each have a depth less than 160 mm, preferably less than 150 mm, most preferably smaller 140 mm, wherein the photoconductive drum has a diameter less than or equal to 60 mm, preferably less than 55 mm, most preferably less than 51 mm, and the diameter of the remaining process rollers are adapted to the small diameter of the photoconductor drum, and that the exposure unit has a depth of less than 45 mm , preferably less than 40 mm, most preferably less than 35 mm.

Further advantages in the compactness of the printer can be achieved if the printing stations each have a height of less than 120 mm, preferably less than 100 mm, most preferably less than 90 mm.

It is advantageous that the exposure unit has at least two cascaded LED exposure modules, wherein the LED exposure modules are fixed on a torsion-resistant support that the LED exposure modules are focused on their distance from the photoconductor drum equal and fixed or manually adjustable, and that the exposure unit is associated with a control device, the error which can be caused by a non-optimal distance between the exposure unit and the photoconductor drum in the exposure of the photoconductor drum, can compensate dynamically by influencing the data given to the exposure unit. This ensures that the much space-demanding drives for adjusting the exposure unit over the photoconductive drum can be saved. In addition to a cost advantage, there are large space savings, making each print station and ultimately the printer is more compact.

As a result of the arrangement of the printing stations in succession, the printer does not build up as high as if the printing stations were arranged one above the other as stated in the prior art. Due to the low height of the printing stations, not only one but two drawers with 2 reels each of the medium to be printed can be accommodated under the printer, and in addition a scanner can be placed on the printer without the entire device having the above-mentioned 0.9 m exceeds in height. If you do not need the scanner, you can even place 3 drawers with 2 rolls each, as was previously not possible, under the printer without exceeding the target height. Due to the compact design of the printing stations, the depth of the printer is also kept less than 0.9 m in their succession arrangement.

The further object is achieved in that the support frame is provided as receiving means for directly behind each other arranged different colors (cyan, magenta, yellow, black) containing printing stations that the printing stations in the support frame and / or the developer stations are interchangeable, with an exchange against same (1K vs. 1K or 2K vs. 2K) or different (1K vs. 2K or 2K vs. 1K) printing stations and / or developer stations is possible.

It is particularly advantageous if the replaceably constructed printing stations and / or developer stations have the compact construction according to claim 1 or 2.

By adopting these measures to provide the printer with either one-component, one-component, lower-speed, or size-optimized, two-component development stations for higher speeds, various speed and power classes can be customized to meet customer needs and a compact printer can be manufactured. Thus, both the entry-level model and the model can be realized on a basis with high printing speed. Of course, if necessary z. For example, a (fast) 2K developer station for the color black, for a fast monochrome operation and one (slower) 1K developer station for the colors cyan, magenta, yellow are used.

It has proven to be advantageous if the housing of the printing stations with the same holders and / or same attachment points and / or with equal accesses for the supply of fresh toner and / or with the same interfaces for mechanical drive units and / or electrical voltages to be switched and / or control technology connections are formed.

It is advantageous if the photoconductive drum has a diameter less than or equal to 60 mm, preferably less than 55 mm, most preferably less than 51 mm, and the diameters of the remaining process rollers are adapted accordingly to the small diameter of the photoconductor drum.

It has been found that the developer station for a one-component toner of a printing station of an electrophotographic printer preferably has a toner transfer roller with a diameter of less than 44 mm, preferably less than 35 mm, most preferably a diameter of 33 mm, two mixing screws with a diameter less than 20 mm a diameter of 18 mm, a toner charging roller having a diameter of less than 26 mm, preferably a diameter of 24 mm and a doctor roller having a diameter of less than 27 mm, preferably a diameter of 25 mm, and when the charging unit in the form of a charging roller has a diameter of about 20 mm.

It is worth noting when the developer station for a two-component toner, a developer consisting of toner and carrier, a printing station of an electrophotographic printer, a magnetic roller for the transfer of the toner on the photoconductor drum, two arranged around the magnetic roller, they act in a developer upper and a lower transport chamber arranged mixing screws and a doctor unit for adjusting the layer thickness of the developer on the magnetic roller, wherein the magnetic roller has a diameter of less than 44 mm, preferably less than 35 mm, most preferably a diameter of 33 mm, the mixing screw diameter of about 21 mm and a charging unit in the form of a charging roller should have a diameter of about 20 mm.

It is recommended that the lower transport chamber of the developer supply for the magnetic roller and the upper transport chamber for discharging and processing of the developer are assigned, and that the doctor unit is arranged on the lower transport chamber, and that at least the lower mixing screw and / or the lower transport chamber such is formed / are that results over the width of the lower transport chamber uneven, decreasing capacity of the mixing screw.

It is advantageous that the mixing screws of the transport chambers are designed such that a sufficient distribution of the developer in the transport chambers is ensured by the fact that the transport chambers is tapered across the width of the developer station and / or that the pitch of the mixing screws across the width of the developer station and / or that the core diameter of the screw shafts varies across the width of the developer station and / or that the rotational speed of the screw shaft is adaptable to the toner requirement of the developer station.

It is expedient that the upper transport chamber in the transport direction at its beginning a discharge station for toner and / or carrier wherein the discharge station to regulate the discharge of the toner and / or carrier depending on the toner / carrier saturation of the developer at the entrance of the lower transport chamber can.

Further advantages arise when the magnetic roller to a negative DC voltage is created, which is superimposed on a controllable AC voltage.

An advantage arises when at least one printing station is assigned a control device which evaluates an image or image to be printed and determines the toner quantity required for the image to be printed, and the control device is connected to the developer station and / or toner supply for controlling the required amount of toner wherein the control device can control the mixing process of the mixing screws in the developer station and / or the toner supply, and wherein sensors can detect the level of the developer station and report it to the control device for evaluation.

It is noteworthy that a fuser is arranged in the printing direction behind the printing stations and modularly adapted to the printing speed of the printing stations used accordingly. The fixing unit may consist of a separate module, which is simple, z. B. for transport, are housed by the main part of the printer in which, among other things, the printing stations are separated. When setting up the printer, only little or no adjustments are required after a corresponding transport when joining the main part with the fixing unit.

The invention is explained in more detail with reference to embodiments shown in the drawing. Show it:

1 a schematic sectional view of a printing station with a photoconductor drum, a 1K developer station, an exposure station, a loading unit, cleaning and erasing station for the photoconductor drum and a transfer unit,

2 a schematic sectional view of a printing station with a photoconductor drum, a 2K developer station, an exposure station, a loading unit, cleaning and erasing station for the photoconductor drum and a transfer unit,

3 a first example of the design of mixing screws

4 another example of the design of mixing screws,

5 a schematic representation of a multi-color printer, each with a printing station for each of the colors according to the CMYK color model, and

6 an inventive design of the toner control.

In the 1 is a schematic, greatly simplified sectional view of a monochrome printing station 1 a large format LED printer with a photoconductor drum 2 (OPC, organic photo conductor drum). The photoconductive drum 2 has a diameter of z. B. 50 mm. To the photoconductor drum 2 are a charging unit in clockwise direction 5 with a diameter of, for example, 20 mm, an exposure unit 4 z. An LED exposure module, a 1K developer station 3 for one-component toner, a transfer or anodic roller 8th , an extinguishing device 7 and a cleaning device 6 arranged one behind the other. Between the photoconductive drum 2 and the transfer or anode roller 8th runs an endless transfer belt 9 , These components are on and in a housing 10 housed, which is only partially shown.

The 1K developer station 3 has a toner transfer roller 11 with a diameter of 33 mm, a mixing unit with a lower mixing screw 12 and an upper mixing screw 13 , each with a diameter of 18 mm, and a toner charging roller 14 with a diameter of 24 mm. The toner transfer roller 11 is a so-called Doctor Roller 15 with a diameter of 25 mm - a squeegee, scraping or scraping roller - associated with a cleaning lip 16 is provided. By this choice of diameter and the advantageous arrangement of the other components to the photoconductive drum 2 the printing unit acquires a very compact construction and only has a depth of less than 140 mm.

The described compact construction of the printing stations 1 also has the advantage that in color printers, where four printing stations 1 For the process colors cyan, magenta, yellow and black, the printer itself has a much smaller depth, so that the printer can still be transported through doors with a clear width less than or equal to 900 mm here a clear width of 800 mm, without the printer must be dismantled.

The surface of the anti-clockwise rotating photoconductive drum 2 is by means of the charging unit 5 electrostatically negatively charged. The charge on the photoconductor drum 2 is now by exposure according to the information of the image or image to be printed by means of the exposure unit 4 deleted at the points where the toner on the photoconductor drum 2 should be applied. This is done by the fact that by the exposure unit 4 exposed areas of the photoconductor drum 2 becomes conductive and consequently loses its charge. In the mixing unit is through the mixing screws 12 and 13 the toner is mixed and passed through the toner charging roller 14 the 1K developer station 3 to the toner transfer roller 11 transfer.

The photoconductive drum 2 will now be in its direction of rotation 20 rotated further so that the exposed areas according to the image in the immediate vicinity of this toner transfer roller 11 be brought in the direction of rotation 21 circles. Because of the toner transfer roller 11 Adhesive toner is negatively charged, it is only at the neutralized by exposure, positive charged areas of the photoconductive drum 2 transfer.

The toner-prone areas of the photoconductive drum 2 be up to the anode roller 8th and the transfer band 9 further rotated where the negatively charged toner of the photoconductive drum 2 from the anode roller 8th is attracted and on the intermediate transfer belt 9 adheres. The transfer band 9 then transported in a known manner, as based on the 3 will be explained in more detail, the toner image to the medium to be printed in a transfer station.

Upon further rotation of the photoconductor drum 2 is by means of the extinguishing device 7 the charge on the photoconductor drum 2 evened out and then the remaining residual toner from the photoconductive drum 2 through the cleaning device 6 eliminated. This cleaning device 6 consists of a roller-shaped cleaning brush 18 holding the remaining toner from the photoconductor drum 2 removed, and one on the photoconductor drum 2 adjacent cleaning lip 17 , the remaining residual toner completely from the photoconductor drum 2 strips off, as well as a residual toner screw 19 which promotes the residual toner into a waste toner container.

In the 2 is a monochrome printing station 22 a large format LED printer with a developer station 23 for two-component toner, wherein the 1 identical components are provided with the same reference numerals. The photoconductive drum 2 has a diameter of 50 mm. To the photoconductor drum 2 are clockwise the charging unit 5 in the form of a charging roller with a diameter of, for example, 20 mm, an exposure unit 4 , z. An LED exposure module, the 2K developer station 23 , the transfer or anode roller 8th , the extinguishing device 7 and the cleaning device 6 arranged one behind the other. Between the photoconductive drum 2 and the anode roller 8th the transfer belt runs 9 ,

The 2K developer station 23 has a magnetic roller 24 with a diameter of, for example, 35 mm, the outer tube knurled and provided in its interior of the carrier with glued magnets. The magnetic roller 24 is with a gap of about 0.3 mm to the photoconductor drum 2 arranged and turns in the direction of rotation 25 opposite to the direction of rotation 20 the photoconductor drum 2 , Furthermore, two optionally slanted mixing screws are 12 ' and 13 ' with diameters of for example 21 mm and a doctor unit 26 provided for adjusting the layer thickness. At the upper mixing screws 13 ' is a toner density sensor 27 arranged to measure the mixing ratio of the developer.

The values given are merely exemplary dimensions, changes are entirely conceivable. However, with variations in the dimensions, the ratio should remain reasonably constant and the diameters of the magnet roll 24 , the loading unit 5 and the mixing screws 12 ' and 13 ' to the small diameter of the photoconductor drum 2 be adjusted accordingly.

The two mixing screws 12 ' and 13 ' communicate with each other at their longitudinal ends. Because the mixing screws 12 ' and 13 ' are arranged so that they promote the developer in opposite directions, the developer can be circulated.

These components are on and in the housing 10 housed, which is only partially shown. This corresponds to the dimensions and shapes of the housing 10 the printing station 1 with the 1K developer station 3 for one-component toner.

Through this choice of dimensions attains the printing station 1 a very compact construction with low height and shallow depth, so that with four such arranged in series printing stations 1 or 22 provided large format color printer also has only a small total depth. The combination of low height and shallow depth of print station ensures that a printer which with four media rolls and a scanner on top or 6 rollers and scanners still reaches the outside dimensions required for a transport, and which also provides good operability due to the Height is given.

As already mentioned above, in a first step, the active layer of the completely discharged photoconductor drum 2 by means of the elastomeric charging unit 5 electrically charged. In the direction of rotation 20 the photoconductor drum 2 Following is the homogeneous charging by exposure by means of the exposure unit 4 discharged in accordance with the desired print image, by passing through the exposure unit 4 exposed areas of the photoconductor drum 2 becomes conductive and consequently loses its charge. As the more positive charged areas subsequently attract the toner, the photoconductor drum becomes 2 developed a corresponding picture.

The 2K developer station 23 for a two-component toner is in the direction of rotation 20 the next position of the photoconductor drum 2 , From itself in the lower transport chamber 33 rotating lower mixing screw 12 ' takes over the magnetic roller 24 whose direction of rotation 25 opposite to the direction of rotation 20 the photoconductor drum 2 is the mixture of toner and carrier, the developer passing through the squeegee unit 26 is brought to a uniform layer thickness. In the vicinity of the magnet roller 24 to the photoconductive drum 2 The fine toner particles are applied to the photoconductor drum 2 transferred, with only the more positively charged regions of the surface of the photoconductor drum 2 take over the negatively charged toner while the carrier on the magnetic roller 24 sticks, leaving the latent charge image on the photoconductor drum 2 becomes visible through the application of toner. The toner partially depleted developer is released from the magnetic roller 24 transported further and in an upper transport chamber 34 in which the upper mixing screw 13 ' turns, thrown off.

At the inlet of the lower mixing screw 12 ' The correct developer mixture is supplied, which depletes the developer locally over the width but depending on the degree of blackening of the image information. Therefore, the lower mixing screw 12 ' and / or the lower transport chamber 33 be designed so that at the end enough developer is present. The developer is transferred from the outlet to the upper transport chamber 34 conveyed and there together with the directly from the magnetic roller 24 discarded toner depleted residual developer enriched with fresh toner. The one at the upper transport chamber 34 arranged toner density sensor 27 Determines the required toner requirements and then controls the toner supply. The upper mixing screw 13 ' then transports the enriched developer back to the inlet of the lower transport chamber 33 ,

The 3 shows a first example, as the augers 12 ' . 13 ' can be trained. Here both the transport chamber rejuvenate 33 , the worm thread 35 and the worm shaft 25 , This will ensure that even the farther from the enema 37 the screw conveyor 12 ' remote areas are quickly and safely supplied with sufficient developer. Instead of the tapering of all components but also the diameter of the worm shaft 36 stay constant. In contrast, the diameters of the transport chamber 33 and the worm thread 35 kept constant, to achieve the same effect, a reduction of the active cross section, the worm shaft 36 are thickened towards the outlet, since in general the flow rate depends on the speed, the inner and outer diameter, the pitch, the degree of filling and the friction of the medium on the auger. This inventive design results in an uneven, decreasing capacity of the mixing screws 12 ' . 13 ' so that as uniform as possible filling level of the transport chambers 33 and 34 is reached.

Based on 4 Now another variant of the mixing screw 12 ' shown, in which the slope of the worm thread 35 shortened. This is illustrated by the track ratio A> B. This also ensures that there is an uneven, decreasing capacity of the mixing screw 12 ' yields, thus one over the width of the mixing screws 12 ' as uniform as possible level is reached.

The 5 now shows the series arrangement of the individual printing stations 1C . 1M . 1Y and 1K the multi-color printer according to the CMYK color model, the process colors cyan, magenta, yellow and black on the transfer ribbon 9 as a color carrier. Same components are provided with the same reference numerals but the corresponding indices of the process colors.

At the end of the printing stations 1C . 1M . 1Y and 1K the transfer belt is running 9 around a pulley 28 to a transfer role 29 a transfer station, on the transfer belt 9 located multicolored toner image on a medium 30 is transferred, which then a fuser 31 passes through a heated fuser roller and an opposing pressure roller. To the toner particles to create a stable printed image on the medium 30 To anchor to a melting and thus consolidating the color on the medium 30 via heat supply through the fixing roller and pressure contact by means of the pressure roller. The transfer band 9 will continue through a cleaning station 32 around another pulley 28 back to the first printing station 1C recycled.

As printing stations 1C . 1M . 1Y and 1K can the printing stations 1 with the 1K developer stations 3 for one-component toner or, if necessary, the printing stations 22 with the 2K developer stations 23 be used for two-component toner. In order for this exchange to take place smoothly, all dimensions of the printing stations are 1 and 22 and connections designed the same. The for both printing stations 1 and 22 common components are housed in a support frame, not shown, at which the attachment points and connectors for the printing stations 1 and 22 are provided in the on the housings 10 the printing stations 1 and 22 attached brackets can intervene connections and connectors and thus produce a mechanical and electrical connection.

This causes the printing station 1 with the 1K developer station 3 for one-component toner and the printing station 22 with the 2K developer station 23 for two-component toner in the dimensions and shapes of the housing 10 , the brackets on the housing 10 , the additions for the supply of fresh toner, the interfaces for the mechanical drive unit and the electrical voltages and control connections to be switched, both pressure stations can be 1 exchange at any time. Instead of changing the printing stations 1 and 22 It is also conceivable to train them in such a way that only the developer stations 3 and 23 can be replaced.

The 6 shows a toner control for a printing process according to the invention, in which an image to be printed 38 or image by means of a control device 39 evaluated and it is determined from how much toner for the image to be printed 38 will be required. Based on this evaluation, the mixing process of the mixing screws 12 . 13 and 12 ' . 13 ' in the developer station 3 . 23 and the toner supply 40 controlled and the level in the developer station 3 . 23 automatically adjusted to the predicted toner consumption. By controlling the toner supply 40 the toner will not come out of the toner cartridge 41 provided when needed, so that aging of the toner z. By unnecessary mixing in the developer station 3 . 23 is avoided. If necessary, sensors detect the level of the developer station 3 . 23 and report it to the controller 39 , which determines the current toner requirements.

In summary, it should be noted that the subject matter of the present invention provides a platform for electrophotographic printers, optionally with one-component 3 or two-component development stations 23 can be equipped, especially for large-format color printers in a compact design similar to a modern S / W printer, so as to cover different speed and performance classes in a printer optional. By compared to the cited prior art compact design, these printers can still be transported through doors with a clear width of less than 900 mm without disassembly and installed. This is very customer-friendly, as customers often do not have enough space or want to provide enough space.

In addition to this compact design is either the use of a size optimized 1K printing station 1 for lower speeds as well as for higher speeds a size optimized 2K printing station 22 can be used. This solution makes it possible for the first time to build a compact printer, which can be customized to customer needs. Thus, both the entry-level model and the model can be realized at high speed on a single basis.

The solution according to the invention is the printer and the printing stations 1 and 22 so that in each case either a 1K or a 2K development station 3 and 23 can be used. These are the development stations 3 and 23 designed in housing and interfaces so that they are interchangeable at any time. Specifically, this means the same holders on the housing, equal access for the supply of fresh toner, the same interfaces for the mechanical drive unit and the electrical voltages and control connections to be switched.

In addition, all printing stations are arranged one behind the other, so that they can be easily exchanged.

In order to realize the compact design according to the invention, the fixing station is arranged in the printing direction behind and below the printing stations and can be modularly adapted to the appropriate printing speed, possibly even in a separate easily removable design.

LIST OF REFERENCE NUMBERS

1

printing station

2

Photoconductor drum

3

1K developer station

4

illuminator

5

charging unit

6

cleaning device

7

extinguishing device

8th

Transfer or anode roller

9

transfer tape

10

casing

11

Toner-transfer roller

12

lower mixing screw

13

upper mixing screw

14

Toner charging roller

15

Doctor roller / roller for adjusting the layer thickness

16

Cleaning lip for Doctor Roller

17

Cleaning lip for photoconductive drum

18

roller-shaped cleaning brush

19

Waste toner auger

20

Direction of rotation of the photoconductive drum

21

Direction of rotation of the toner transfer roller

22

printing station

23

2K developer station

24

magnetic roller

25

Direction of rotation of the magnetic roller

26

squeegee unit

27

Toner density sensor

28

guide rollers

29

Tensioned transfer roller

30

Medium (eg paper)

31

fuser

32

cleaning station

33

lower transport chamber

34

upper transport chamber

35

Worm

36

worm shaft

37

enema

38

image to be printed

39

control device

40

toner supply

41

toner cartridge

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4903067 [0011]

Cited non-patent literature

• "Handbuch der Printmedien" by Helmut Kipphan (ed.), Springer-Verlag Berlin Heidelberg 2000, pages 61ff [0002]
• "Handbuch der Printmedien" by Helmut Kipphan (ed.), Springer-Verlag Berlin Heidelberg 2000, Chapter 5.2.3 "Inking unit (development unit) and toner", pages 726 to 730 [0014]

Claims (17)

Large format electrophotographic printer with a printing width greater than 0.5 m, in particular large format color printer with multiple printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ), each printing station having a photoconductive drum ( 2 ), a loading unit ( 5 ), an exposure unit ( 4 ), a developer station ( 3 . 23 ), an extinguishing device ( 7 ), a cleaning device ( 6 ), and a housing ( 10 ), each having an anode roller ( 8th . 8C . 8M . 8Y . 8K ) for each printing station ( 1 . 1C . 1M . 1Y . 1K . 22 ), with a top pulleys ( 28 ), between anode rollers ( 8th . 8C . 8M . 8Y . 8K ) and printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) guided transfer belt ( 9 ), with a tension applied to the transfer roller ( 29 ) for transferring toner images onto a medium to be printed ( 30 ), with a fuser ( 31 ), with a cleaning station ( 32 ) and with a support frame, characterized in that the support frame as receiving means for directly behind the other arranged, different colors (cyan, magenta, yellow, black) containing printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) is provided that the printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) each have a depth of less than 160 mm, preferably less than 150 mm, most preferably less than 140 mm, the photoconductive drum ( 2 ) has a diameter of less than or equal to 60 mm, preferably less than 55 mm, most preferably less than 51 mm, and the diameters of the remaining process rolls to the small diameter of the photoconductive drum ( 2 ) are adjusted accordingly, and that the exposure unit ( 4 ) has a depth of less than 45 mm, preferably less than 40 mm, most preferably less than 35 mm. An electrophotographic printer according to claim 1, characterized in that the printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) each have a height less than 120 mm, preferably less than 100 mm, most preferably less than 90 mm. An electrophotographic printer according to claim 1 or 2, characterized in that the exposure unit ( 4 ) comprises at least two LED exposure modules arranged in cascaded fashion, the LED exposure modules being fixed on a torsion-resistant support, the LED exposure modules being spaced apart from the photoconductive drum ( 2 ) are focused equal and fixed or manually adjustable, and that the exposure unit ( 4 ) is associated with a control device, the errors which by a non-optimal distance between the exposure unit ( 4 ) and the photoconductive drum ( 2 ) in the exposure of the photoconductor drum ( 2 ) by influencing the exposure unit ( 4 ) dynamically compensate given data. Large format electrophotographic printer with a printing width greater than 0.5 m, in particular large format color printer with multiple printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ), each printing station having a photoconductive drum ( 2 ), a loading unit ( 5 ), an exposure unit ( 4 ), a developer station ( 3 . 23 ), an extinguishing device ( 7 ), a cleaning device ( 6 ), and a housing ( 10 ), each having an anode roller ( 8th . 8C . 8M . 8Y . 8K ) for each printing station ( 1 . 1C . 1M . 1Y . 1K . 22 ), with one over pulleys ( 28 ), between anode rollers ( 8th . 8C . 8M . 8Y . 8K ) and printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) guided transfer belt ( 9 ), with a transfer roller ( 29 ) for transferring toner images onto a medium to be printed ( 30 ), with a fuser ( 31 ), with a cleaning station ( 32 ) and with a support frame, characterized in that the support frame as receiving means for directly behind the other arranged, different colors (cyan, magenta, yellow, black) containing printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) is provided that the printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) in the support frame and / or the developer stations ( 3 . 23 ) are exchangeable, with an exchange for identical or different printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) and / or developer stations ( 3 . 23 ) is possible. Electrophotographic printer characterized by the features of claims 1 or 2 or 3 and 4. Electrophotographic printer according to one of claims 1 to 5, characterized in that housing ( 10 ) of the printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) are formed with the same brackets and / or same attachment points and / or with equal accesses for the supply of fresh toner and / or with the same interfaces for mechanical drive units and / or switching electrical voltages and / or control connections. Electrophotographic printer according to one of Claims 1 to 6, characterized in that the developer station ( 3 ) for a one-component toner of a printing station ( 1 ) of an electrophotographic printer, a toner transfer roller ( 11 ) with a diameter of less than 44 mm, preferably less than 35 mm, most preferably a diameter of 33 mm, two mixing screws ( 12 . 13 ) having a diameter of less than 20 mm, preferably a diameter of 18 mm, a toner charging roller ( 14 ) with a diameter of less than 26 mm, preferably a diameter of 24 mm and a Doctor Roller ( 15 ) having a diameter of less than 27 mm, preferably having a diameter of 25 mm, and that the loading unit ( 5 ) in the form of a charging roller has a diameter of about 20 mm. Electrophotographic printer according to one of Claims 1 to 6, characterized in that the developer station ( 23 ) for a two-component toner - a developer consisting of toner and carrier - a printing station ( 22 ) of an electrophotographic printer, a magnetic roller ( 24 ) for the transfer of the toner to the photoconductor drum ( 2 ), two around the magnet roller ( 24 ), they act with developer, in an upper and a lower transport chamber ( 33 . 34 ) arranged mixing screws ( 12 ' . 13 ' ) and a doctor blade unit ( 26 ) for adjusting the layer thickness of the developer on the magnetic roller ( 24 ) having. An electrophotographic printer according to claim 8, characterized in that the magnetic roller ( 24 ) has a diameter of less than 44 mm, preferably less than 35 mm, most preferably a diameter of 33 mm, the mixing screws ( 12 ' . 13 ' ) Diameter of about 21 mm and a loading unit ( 5 ) in the form of a charging roller have a diameter of about 20 mm. An electrophotographic printer according to claim 8 or 9, characterized in that the lower transport chamber ( 33 ) of the developer supply for the magnetic roller ( 24 ) and the upper transport chamber ( 34 ) are assigned to the derivative and preparation of the developer, and that the Doctor Roller ( 15 ) at the lower transport chamber ( 33 ), and that at least the lower mixing screw ( 12 ' ) and / or the lower transport chamber ( 33 ) is / are formed such that across the width of the lower transport chamber ( 33 ) an uneven, decreasing capacity of the mixing screw ( 12 ' ). Electrophotographic printer according to one of claims 8 to 10, characterized in that the mixing screws ( 12 ' . 13 ' ) of the transport chambers ( 33 . 34 ) are formed such that a sufficient distribution of the developer in the transport chambers ( 33 . 34 ) is ensured by the fact that the transport chambers across the width of the developer station ( 23 ) is tapered and / or that the slope of the mixing screws ( 12 ' . 13 ' ) across the width of the developer station ( 23 ) and / or that the core diameter of the screw shafts ( 36 ) across the width of the developer station ( 23 ) and / or that the rotational speed of the worm shaft ( 36 ) the toner requirement of the developer station ( 23 ) is customizable. Electrophotographic printer according to one of claims 8 to 11, characterized in that the upper transport chamber ( 34 ) in the transport direction at its beginning a discharge station for toner and / or carrier wherein the discharge station, the discharge of the toner and / or carrier depending on the toner / carrier saturation of the developer at the entrance of the lower transport chamber ( 33 ) can regulate. Electrophotographic printer according to one of claims 8 to 12, characterized in that the magnetic roller ( 24 ) is applied to a negative DC voltage, which is a controllable AC voltage superimposed. Electrophotographic printer according to one of claims 1 to 13, characterized in that at least one printing station ( 1 . 1C . 1M . 1Y . 1K . 22 ) a control device ( 39 ) associated with an image to be printed ( 38 ) or image and the image to be printed ( 38 ), and that the control device ( 39 ) with the developer station ( 3 . 23 ) and / or toner supply ( 40 ) is connected to control the required amount of toner. An electrophotographic printer according to claim 14, characterized in that the control device ( 39 ) the mixing process of the mixing screws ( 12 . 13 ; 12 ' . 13 ' ) in the developer station ( 3 . 23 ) and / or the toner supply ( 40 ) controls. An electrophotographic printer according to claim 14 or 15, characterized in that sensors monitor the level of the developer station ( 3 . 23 ) and send it to the control device ( 39 ) report for evaluation. Electrophotographic printer according to one of claims 1 to 16, characterized in that a fuser ( 31 ) in the printing direction behind the printing stations ( 1 . 1C . 1M . 1Y . 1K . 22 ) and modular to the printing speed of the printing stations used ( 1 . 1C . 1M . 1Y . 1K . 22 ) is adaptable accordingly.

Images