DE10060712A1 - Electrostatic printing device; has primary image-generating element and moving transfer element, where relative tangential movement directions of element surfaces are not exactly parallel - Google Patents

Abstract

The device has a moving primary image-generating element to support a toner particle image and a moving transfer element. The elements define the contact surface of a gap formed between them. Devices adjust an electrical transfer field for electrostatic transfer of the single-colour toner particles between the elements. The relative tangential movement directions of the element surfaces are not exactly parallel. An Independent claim is included for a method for using the device.

Description

The present invention relates to electrostatography, in particular a method and a device for transferring toner images to transfer elements.

In a device for multicolor electrostatographic reproduction, as in the WO 98/04961 describes the two or more single color imaging units has, a toner image is first electrostatically from a primary imaging Element (PIFM) e.g. B. a photoconductor (PC) or an electrostatic Transfer exposure surface to a transfer element (ITM) and then electrostatically transferred from the ITM to a sheet of paper or plastic. In known electrostatographic devices is the transfer of a toner image incomplete, especially at low toner coverage and therefore when two Transfers are made using a handover element to a Bringing the toner image from the PC to paper, a high transfer efficiency in both Broadcasts necessary to create high quality playback.

A known method for achieving high transmission efficiency is to use a PC with a low surface energy, e.g. B. by doing that Provides the photoconductor with a suitable polymer coating, or by a polymeric binder used with one or more monomers, the Photoconductor can give a low surface energy. However, this is expensive. In addition, the second toner transfer from the PC tends to the ITM to be faulty when an ITM also with a low surface energy is provided to ensure high transmission efficiency between the ITM and a To achieve the receiving element made of paper.

Another known method for improving toner transfer is to a photoconductor surface with a suitable micro-roughness, e.g. B. by that Apply fine particles to the surface. This procedure has the  Disadvantage of high wear. On the other hand, the photoconductivity in Generally affected when using a photo semiconductor with a polymeric binder to produce a suitable micro-surface roughness, that of wear withstands fine particles because the particles catch charge carriers.

Another method to improve the transfer of colored toners, especially for low coverage colored toners, use a colorless one Layer of toner between a PC surface and a colored layer of toner to be transferred. However, this method leads to the use of more complicated ones Machines and at high cost.

A widely used method to improve toner transfer from one Photoconductor on another element consists of the smallest particles, e.g. B. made of silicon, Aluminum or titanium compounds (so-called surface additives or Surface additive particles) to attach to the surfaces of the toner particles, whereby the so-called surface-treated toners are generated. Surface treated Toners have a weaker adhesive force on the PC surface and can therefore be more efficient be transferred electrostatically from the PC.

It is also a known method to apply an ITM with an elastic blanket layer Mistake; it has been found that this is the transfer of toner from the PC to it an ITM and also greatly improved from an ITM to a receiving element.

However, to get the highest print quality in electrophotography or electrography To achieve dry toner, it is advisable to have very high overall transfer efficiencies to reach across the entire color gamut. If e.g. B. overall at all densities an ITM is used, a transmission efficiency of 95% or more can be achieved means that the first and the second transmission each have an efficiency of achieve an average of more than 97%. To achieve such transmission efficiency values is particularly difficult in low density areas of a print, in which the Transmission efficiency is rather low due to the fact that it is usually one  small residual amount of toner particles that are difficult or impossible to transfer can, and the non-transferable particles contribute to a large part of the total low coverage. Even if surface-treated toners are used, To increase the transmission efficiency, a certain small proportion of Toner particles are not transferred electrostatically by conventional means. In addition, it is known that in imaging technology using the raster process and is particularly important for grids with a grayscale scale in each colored particle, that a transfer as complete as possible is achieved for medium densities. This is particularly important at a gray level of around 30% where the human eye is particularly sensitive to fluctuations or deviations in color.

US 4,448,872 describes a method for duplex imaging. A first toner image is transferred to a transfer melter. A recording sheet is made by a nip passed through the transfer fuser roll which is the first transferred toner image and an imaging roller carrying the second toner image is formed so that both toner images are transferred simultaneously and both to the front as well as be transferred to the rear surface of the receiving element. The axis the transfer fuser roller is to the axis of the imaging roller skewed to increase transmission efficiency.

No. 4,619,515 describes a method for the simultaneous transmission and melting down a toner image on paper by printing, in which the axes of a Imaging roller and a transfer fuser roller at an angle of about 1.1 degrees skewed to each other.

US 4,894,687 describes a high pressure transfer of the toner to one Recording sheet with simultaneous melting, the axes of one Imaging roller and a transfer fuser roller at an angle between 0.5 and 1.5 degrees to each other are skewed. A lateral shift that caused by a skew, supposedly caused the strong  Improvement that was observed in the efficiency of toner transfer compared to a method without wind skew (parallel roller axes).

US 5,870,659 describes a possibility of skewing between one ITM and a PC drum.

In order to achieve an improved transmission efficiency, an intentional slip, parallel to the direction of processing at the interface between a PIFM and a ITM or at the interface between an ITM and a recording surface are generated mechanically.

Embodiments 6 and 7 of US 5,438,398 describe the use of different speeds to improve toner transfer between the PC drum and an ITM and between an ITM and a transfer drum.

The US 5,519,475 describes the formation of a slip, so that a The peripheral speed of an ITM is higher than the peripheral speed of a PC Drum is. It is demonstrated that a speed difference of between 0.5% and 3.0% is said to improve toner transfer efficiency.

In order to have a surface slip between rollers using mechanical means generate parallel axes, e.g. B. by a gear, as in US 5,438,398 described, a more expensive device with strictly controlled tolerances is required. This is the only way to damage the pictures, e.g. B. due to irregularities in the Gear movement caused can be prevented.

It is expensive to make high tolerance rolls, and it is costly to use roller mounts that are also accurate parallelism the roller axes and provide an even system. For a pressure nip that between an ITM with an elastic surface coating and a Photoconductor imaging roller is formed, it is known that nip widths of 5 mm or  can occur more. Even if an elastic surface coating on the ITM is very uniform in its properties and in its thickness, what Usually difficult and expensive, there are several reasons for one inconsistent gap width, such as. B. not exact parallelism of the roller axes, an oblique running roller, warping or bending of a roller, uneven contact or a varying, inadequate concentricity along a roller. Differences in Gap widths can have a strong impact on controlling the local efficiency of the Toner transfer because of these differences local pressure changes in one Cause gap. When electrostatically transferring toner from a PIFM to An ITM can have a wider gap in some places, which can be replaced by a gap in these places higher pressure causes better adhesion to a PIFM, whereby the transmission efficiency is reduced at this point.

Photoconductor drums or transfer drum drums are usually manufactured by coating hollow cylindrical bodies, usually made of aluminum exist so that the large rollers do not become too heavy. If the walls of the body are too thin, these rollers tend to curve or bend due to the high pressure, which is created in the gaps by being attached to other rollers be formed, e.g. B. in a gap by pressing a photoconductor roller against a Transfer roller is formed. Warping or bending of the rolls forming the gap leads to an uneven pressure along the gap and thus to a deviation in the gap width. Deviations in the gap width and resulting pressure lead usually to unwanted irregularities in the transmission efficiency.

The invention is accordingly based on the object for a high quality Imaging a method and an apparatus for improving the To create transmission efficiency across the entire color gamut and at the same time the To make transmission efficiency relatively insensitive to what deviations in the Gap width concerned, the z. B. from outside the tolerance range manufacturing caused and deviations on the rollers, curvatures or Bends in the rolls or inaccurate roll alignments.  

This object is achieved by the features of claims 1 and 2. Further features of the invention are contained in the subclaims.

The invention relates to an electrostatographic method and a electrostatographic device for the electrostatic transfer of a toner image, which is a movable primary imaging element (PIFM) and a movable Transfer element (ITM) preferably comprises an elastic surface, which form a transfer gap such that the tangential directions of movement of the contacting surfaces of the PIFM and the ITM are not arranged completely parallel, the tangential directions of movement are arranged in a surface that coincides with the boundary contact surface of the gap covers. A PIFM preferably comprises a roller (FlUR) and an ITM also includes a roller (ITR), which the PIFR by friction drives so that the axes of the two rollers through a small angle, preferably in a measuring range between 0.1 and 0.3 degrees, skewed to each other.

The invention is more preferred below with reference to the drawings Embodiments described.

The drawings show:

Fig. 1 spatially twisted, skewed or twisted and skewed axes to illustrate the concepts that are described using preferred embodiments.

Fig. 2 (a) and 2 (b) front views of a pair of rollers, wherein for each pair of rollers a rotation without skewing the axis of one roller to the axis of the other roller is shown.

Fig. 2 (c) is a side view of the section line ZZ of the pair of rollers shown in Fig. 2 (b).

Fig. 3 (a) and 3 (b) are respectively a plan view of a pair of rollers, wherein for each pair a Windschief sites without rotating the axis of a roller is shown with the axis of the other roll.

Fig. 4 (a) is a schematic representation of a surface voltage distribution in an elastic roll which forms a pressure nip with another roller, the axis of one roller is rotated about the axis of the other roller. One of the rollers that form the gap is shown in the drawing.

Fig. 4 (b) is a side view from the section line RR to illustrate the direction of a voltage vector.

Fig. 5 in graphical form optical transmission densities of residual toner on the PIFR surface and along a direction parallel to the axis of the PIFR measured after the transfer of flat black toner images with different gray values to a transfer roller, the PIFR and the ITR for each gray value in the same twisted relation to each other are arranged, but are not essentially skewed.

Fig. 6 in graphical form the effect of skew angles on optical transfer densities of toner residues on the PIFR surface and along a direction parallel to the axis of the PIFR measured after the transfer of flat black toner images with maximum density from the PIFR to the transfer roller, wherein the PIFR and the ITR are rotated with respect to one another and are arranged in the same rotated relation to one another for each wind skew position angle.

Fig. 7 as a function of the skew angle, a graphical representation of the maximum differential transfer densities and average transfer densities at the toner residues on the PIFR surface measured after the transfer of a flat black toner image with maximum density to an ITR, the PIFR and the ITR to each other are twisted and arranged in the same twisted relationship to each other for each skew angle.

Figure 8 is a schematic side view, according to the invention a single-color toner image is electrostatically transferred to an ITR of the, so that in each color module, the axis of PIFR by a small angle skew. A copying apparatus or printer with four color modules, each color module includes a photoconductive PIFR to the axis of the ITR, with an endless belt and a web-driving mechanism to facilitate the electrostatic transfer of the monochrome toner image from the ITR to a pick-up element mounted on the endless web and carried by it through each of the four color modules, wherein only the basic components are shown for clarity.

Fig. 9 is a pair of rollers in a skewed relationship; Fig. 9 is used to show a lateral displacement or slip direction between the rollers.

The invention will now be illustrated on the basis of selected exemplary embodiments.

Fig. 1 refers to the examples 1-3 below and represents a twisting or skew of the two axes to each other. Three spatial axes, the X.. .X, Y.. .Y and A.. .A are drawn at right angles to each other and have the intersection point O. Another spatial axis that with B.. .B is parallel to the axis A.. .A and cuts X.. .X in a point O '. The axes A.. .A and B.. .B can correspond to the axes of rotation of two parallel rollers, each about the axes A.. .A and B.. .B rotate.

The axes A.. .A and X.. .X define a plane AX. As can be seen from Fig. 1, a new axis alignment A '. , .A 'by rotating the axis A.. .A at a point O by an angle γ in the plane AX about the axis Y.. .Y can be created. The new axis alignment A '. , .A 'is considered to be at an angle γ to the axis B.. .B twisted defined.

In Fig. 1, the axes A. define. .A and Y.. .Y one level AY. Another new axis alignment A "... A" can be done by rotating the axis A.. .A at a point O by an angle β in the plane AY about the axis X.. .X can be created. The new axis alignment A "... A" is as by an angle β to the axis B.. .B Defined skewed. An axis X.. .X is defined as an axis of the skew position or wind skew position axis, and β is defined as an angle of the wind skew position or wind skew position angle.

In Fig. 1, the axes A "... A" and X.. .X a plane A "X. After A.. .A by an angle β to the axis orientation A". , .A "has been shifted, a further axis alignment A '''..A''' is generated by the axis A". , ..A "is rotated at a point O by an angle γ 'in the plane A" X. The axis alignment A '''. , .A '''is connected to the axis B. by a combination of skew points and twisting. .B creates.

In order to facilitate the understanding of the twisting and skewing in Fig. 1, the axis A.. .A as to axis B.. .B been moved. It is generally assumed that the axes of rotation A.. .A and B.. .B a mutual angular relationship that is created by the twisting or skewing regardless of which axis is moved. In the practical implementation of the invention, the axes A.. .A and B.. .B represent axes of rotation of a PIFR or an ITR, and one or both axes can be moved with respect to a non-twisted or skewed condition in which the axes would be parallel to each other.

Fig. 2 (a) shows a front view of a twisted but not skewed pair of non-contacting rollers, which are generally cylindrical in shape and may have different diameters, for further illustration purposes. The pair of rollers is designated by the reference symbol 20 . An upper roller 21 in Fig. 2 (a) can extend around a central axis or a rotation axis that is related to C.. .C is designated and is rotated to the central axis or axis of rotation by an angle α (with α ≠ O), to a central axis or axis of rotation of a lower roller 22 , which with D.. .D is designated, rotate, the axes of the two rollers being arranged rotated relative to one another. For clarification, the size of the angle α is shown oversized. Fig. 2 (b) shows a front view of a similarly twisted but not skewed contacting pair of rollers, designated by reference numeral 30, which is applied to a pressure nip, the lower roller having an elastic surface. The axes of rotation E.. .E and F.. .F of the rollers, which are designated by the reference numerals 31 and 32 , are rotated relative to one another by an angle denoted by α ', the angle α' being small enough to produce an application contact essentially along the two rollers. An upper roller 31 may e.g. A primary image forming roller (PIFR) or a primary image bearing roller, and a lower roller 32 may e.g. B. an elastic intermediate transfer roller (ITR), the two rollers are not attached or applied parallel to each other, e.g. B. because of low tolerance of the fastening or contact means, the fastening and contact means are not shown here. For clarification, the size of the angle α 'is shown oversized in FIG. 2 (b) and also the deformation of the lower elastic roller 32 . It is evident that the pressure on the nip and the nip width is greatest at the end of roller 32 because the compression is greatest there and that the nip width will tend to narrow or towards the end where the compression most smallest is to fall off gradually. It is important for the understanding that the gap width W, as shown in FIG. 2 (c), represents a contact length in the gap in the direction of movement of the rolls in the gap at all times.

Fig. 3 (a) and 3 (b) relate to the below Examples 2 and 3 and show plan views of roll pairs whose diameter may vary, so that for each pair the axis skew with a roller to the axis of the other roller ( but not twisted). Fig. 3 (a) shows a pair of skewed rollers, which are identified by reference numeral 40 . The respective axes of rotation G.. .G and H.. .H of the skewed rollers, which are denoted by 41 and 42, are rotated to each other by an angle β. If there was no skew position, ie if β = 0, the axes would be G.. .G and H.. .H essentially parallel to each other, with one axle being mounted directly above the other. The wind skew position axis runs perpendicular to the plane of the drawing and is therefore only shown as point X ( FIG. 3 (a)). In practicing the invention, one or both of the rollers can be rotated about an axis X from a nominally non-skewed position perpendicular to the direction of operation. Fig. 3 (b) shows a pair of skewed rollers, designated by reference numeral 50 . With this pair of rollers, a wind skew position angle β 'between the roller axes I.. .I and J.. .J are created in a similar manner by placing a skew axis X 'near one of the ends of rollers 51 and 52 . According to the invention and with particular reference to a pair of rollers comprising a PIFR and an ITR, it becomes clear that a wind skew position axis can be arranged anywhere along a pair of rollers.

Fig. 4 relates to Examples 1-3 below and shows a schematic representation of a surface tension distribution in an elastic roller which forms a gap with another roller, the axis of rotation of one roller being rotated relative to the axis of rotation of the other roller. More specifically, FIG. 4 (a) schematically shows a consistent surface voltage distribution in a contact surface of a flattened gap, the relatively stiff by the interaction between a rotating elastic ITR and a rotating in the opposite direction PIFM is formed, the axes of both of the ITR and the PIFM are twisted towards each other. The stress vectors (SV) that are assigned to the twist are shown to either run in the same direction or counter to the tangential speed. The twist creates a gap where the contact changes continuously along the gap. At some point in any flattened portion of the resilient ITR there is generally a changed local periphery of the roll which has that point compared to the undeformed roll. It is apparent that a permanent surface tension distribution, shown in a highly simplified form in Fig. 4 (a), is associated with the formation of a relative slip between the rolls, the degree of slip depending on the position along the nip. Without a skewed position, the relative slip direction is parallel to the tangential velocity vector of the roller at one end of the nip and opposite to a tangential velocity vector of the roller at the other end. The degree of relative slip is directly related to the surface tension distribution, ie it is greatest at each end of the gap and decreases steadily towards 0 at one point approximately half the gap length. FIG. 4 (b) shows a section of a twisted pair of rollers and shows the direction SV of the tension vector at this point, which is shown in FIG. 4 (a) with reference to section RR.

FIG. 8 shows an image-forming reproduction device or printer according to a preferred embodiment of the invention, which is designated by the reference number 10 . This duplicating device or printer 10 is shown in the form of an electrographic duplicating device, more precisely a color duplicating device, in which color separation images are formed in each of the four color modules and are transferred in register to a printing material if the printing material is moved through the device while it is moving is held on a printing material conveying path (PTW) 516 . The device has four color modules, although this invention is applicable to one or more such modules. A detailed description of such a device can be found in WO 98/04961, the content of which is referred to in this document, and the following description shows the structure and procedure of improvements in such a device using an example for using the method and the Device of the invention.

Each ink module ( 591 B, 591 C, 591 M, 591 Y) has the same structure, except that, as shown, a web 516 carrying the printing material, which can be in the form of an endless belt, interacts with all ink modules, and that the printing material is guided from the color module to the color module by the PTW 516 . The elements in FIG. 8, which are similar from color module to color module, are provided with similar reference numerals, which each carry a suffix B, C, M or Y, which relates to the respective color module to which they are connected, that is black, cyan, magenta and yellow. Four substrates or sheets 512 a, b, c, and d are shown, which simultaneously take images of the different color modules, wherein, as already mentioned above, each substrate can take a color image of each module and in this example up to four color images of any substrate can be added. The movement of the printing material on the PTW 516 is such that each transfer of a color image onto the printing material at the transfer nip of each color module is a transfer that is in register with the previous color transfer, so that a four-color image is printed on the printing material is formed, which has colors in a register-related superimposed relationship on the substrate. The printing materials are then released in succession by the PTW and sent to a melting point (not shown) in order to melt the dry toner images into the printing material or to fix them thereon. The PTW is reworked for reuse by placing a charge on both surfaces, e.g. B. is generated using opposing corona chargers 522 , 523 , which neutralize the charge on the two surfaces of the PTW.

Each color module includes a primary imaging element (PIFM), e.g. B. A drum 503 B, C, M, or Y. The PIFM may be a web passed at a nip around a drum, or a web passed between two drums, but is preferably in the form of a roller or drum . Each PIFM 503 B, C, M, and Y has a photoconductive surface on which a pigmented ink particle image, or a series of different colored ink particle images, is formed as the PIFM rotates about its respective axis of rotation, as shown by the arrows in FIG. 8. To generate images, the outer surface of the PIFM is supported by a primary loading device, e.g. B. each a corona charger 505 B, C, M and Y or another suitable charger, z. B. Chargers for rollers or brushes evenly charged. The evenly charged surface is exposed to suitable exposure means such as e.g. B. each exposed to a laser 506 B, C, M and Y or better an LED or other electro-optical exposure device or even an optical exposure device to selectively change the charge on the surface of the PIFM. The electrostatic image is developed by applying the pigmented coloring particles through a developer unit 581 B, C, M and Y to the latent image-bearing photoconductor drum. The developer unit is assigned a special color from pigmented toner coloring particles. Each color module creates a series of differently colored ink particle images on the respective photoconductor drum. Instead of a photoconductor drum, which is preferably used, a photoconductor tape can also be used.

As an alternative to electrophotographic recording, electrographic recording can also be used Record each primary color image using pen electrodes or others known recording methods can be used to create a toner image that is electrostatic to be transferred to an ITM, on a dielectric primary imaging Record item. More generally, it means that the primary image is based on electrostatography, which includes electrophotography and electrography, is formed.

It is known for high quality electrostatographic color exposure small toner particles are needed. Small toner particles are preferred used that have an average diameter of between 2 and 9 microns, as with a suitable, commercially available particle size measuring device, such as. B. a Coulter Multisizer can be determined. Even more advantageous in relation to the present Invention would be the use of toner particles with a diameter of between 6 and 8 µm. Preferably, toner particles are used that have a Glass transition temperature of more than 54 degrees C. A widespread Method of improving toner transfer is to make toner particles the smallest Contain particles of silicon, aluminum or titanium compounds, or the like To use compounds attached or attached to the surface of the toner particles are glued on (so-called surface additives). In the practical implementation of the The present invention is preferably a surface additive that is smallest Has hydrophobic particles of a silicon compound used, but also others Formations from surface additives with the smallest particles can be used. In a preferred embodiment of the invention, the developer composition consists of a two-component dry developer composition, the magnetic Carrier particles and, in relation thereto, smaller toner particles with the above  Additive contains. During development, the toner particles with the additives optionally deposited on the respective PIFM.

Each ink particle image formed by selectively placing the toner particles on a respective PIFM is applied to an outer surface of a respective secondary or transfer element (ITM), e.g. B. a transfer drum 508 B, C, M and Y transmitted. According to the invention, the axes of rotation of each pair of PIFM and ITM rollers, e.g. B. 503B and 508B, skew to each other. Likewise, 503C is skewed to 508B, and the same applies to the other color modules. A preferred wind skew position angle is in the range from 0.03 to 0.45 degrees and in particular in the range between 0.1 and 0.3 degrees.

In a less preferred skew position, the skew position is accomplished by pivoting each ITM 508 B, C, M, and Y about a respective skew position axis, and each PIFM 503 B, C, M, and Y is oriented so that the axis of rotation is one each PIFM 503 B, C, M and Y is arranged perpendicular to the processing direction, the processing direction being defined as parallel to the direction of movement of the PTW 516 . A skewed position axis is preferably located substantially near one end of the pressure nip formed by the contact of each respective pair of the PIFM and ITM rolls, see Figs. see Fig. 3 (b).

Particularly preferred is a wind skew position axis which is located substantially halfway along the pressure nip formed by the contact of each pair of the PIFM and ITM rolls, see FIG. see Fig. 3 (a). It may also be useful to place a skewed position axis at any other convenient position along the gap. In the optimal case, there is no twist between the axes of rotation of each pair of PIFM and ITM rollers, which makes the gap widths in the ink modules uniform. In addition, the rotation axes of the backing rollers (TBRs) B, C, M and Y during the toner transfer from each ITM 508 B, C, M and Y to a substrate conveyed by the PTW 516 are perpendicular to the processing direction, ie not pivoted about the skewed position axis, arranged.

It makes less sense to skew the rotation axis of the ITM relative to the processing direction, because skewing an axis of an ITM 508 B, C, M, or Y relative to an axis of a respective TBR 521 B, C, M, or Y side force on PTW 516 and thus also on a recording sheet which is transported by PTW 516 and comes into contact with an ITM 508 B, C, M or Y, whereby difficulties with register accuracy and web guidance can arise.

In a particularly preferred wind skew position, the wind skew position is achieved by pivoting each PIFM 503 B, C, M and Y about a wind skew position axis and not pivoting each ITM 508 B, C, M and Y. Therefore, the axis of rotation of each ITM 508 B, C, M and Y is perpendicular to the processing direction, the processing direction being parallel to the direction of movement of the PTW 516 . Less preferred is a wind skew position axis for each PIFM, which is substantially near an end of the nip formed by the attachment of each pair of PIFM and ITM rollers, Figure 3 (b). In contrast, a skewed position axis is preferred, which is located essentially halfway along the pressure gap which is formed by the attachment of each pair of PIFM and ITM rollers ( FIG. 3 (a)). It may also be convenient to place a skewed position axis at any other convenient position along the pair of rollers. In the optimal case, there is essentially no twist between the axes of rotation of each pair of PIFM and ITM rollers, with the gap widths being made substantially uniform in each of the ink modules.

After being transferred to the respective primary transfer nip of each color module, the toner image is removed from the surface of the photoconductor drum by a cleaning device 504 B, C, M and Y in order to prepare the surface for recycling to form further toner images. The transfer drum or ITM preferably comprise a hollow cylindrical metallic (e.g. aluminum), conductive core 541 B, C, M and Y and an elastic blanket layer 543 B, C, M and Y. The elastic layer or so-called blanket layer becomes made of an elastomer, e.g. B. polyurethane or other materials known from the published literature. Sufficient conductive material (such as antistatic particles, ionically conductive materials, or electrically conductive additives) has been added to the elastomer to have a relatively low resistivity (e.g., a volume resistivity of approximately 10 ⁷ to 10 ¹¹ ohms -cm). In addition, the elastic blanket layer is thicker than 1 mm, preferably between 2 mm and 15 mm thick, and has an elastic modulus in the range from approximately 0.1 MPa to 10 MPa, in particular between 1 MPa and 5 MPa. A thin (2 µm-30 µm) hard top layer lies on the rubber blanket layer; the cover layer has a modulus of elasticity which is preferably greater than 100 MPa. The hard cover layer can have a higher volume resistance than the rubber blanket layer. With such a relatively conductive transfer drum, the transfer of monochrome marking particle images to the surface of the ITM can be achieved with a relatively narrow gap (preferably 2-15 mm), and a relatively small potential of e.g. B. 600 volts suitable polarity is by a voltage or current source such. B. a power supply 552 on the conductive core 541 B, C, M and Y passed. The ITMs can be supplied with different electrical voltages or currents for the individual color modules.

A monochrome marker particle image formed on the surface 542B (the others are not labeled) of each transfer drum is transferred to a substrate that is in a nip between the transfer drum and a platen roller (TBR) 521B , C, M and Y is introduced. A suitable electrical bias is generated in the backing roller by power supply 552 to cause the charged toner particle image to transfer to a printing substrate. Different voltages and currents can be present for transmission at respective secondary transmission columns. The substrate is supplied from a suitable supply (not shown) and moves in sequence into each of the columns 510 B, C, M and Y, where it takes the respective marking particle toner image in a suitable register-accurate ratio to form a multicolor image. It is known that colored pigments can overlay each other to form areas of color different from the color of the pigment. The printing material emerges from the last nip and is conveyed by a suitable conveying mechanism (not shown) to a melting device, where the marking particle image is fixed on the printing material using heat and / or pressure, preferably heat and pressure. A charging element 524 can be provided, which applies a neutralizing charge to the printing material in order to facilitate the removal of the printing material from the tape 516 . The substrate with the fixed image is then transported to a remote location so that it can be removed by a machine operator. The respective ITMs are each cleaned by a respective cleaning device 511 B, C, M and Y for reuse. Although the ITM is preferably a drum, a tape can be used instead of an ITM.

Suitable, known sensors (not shown) such. B. mechanical, electrical or optical sensors are used in the duplicator 10 to provide the device with control signals. These sensors are arranged along the transport path of the printing material from the printing material supply through the various gaps to the melting device. Additional sensors may be connected to the primary imaging member photoconductor drum, the transfer member drum, the transfer support member, and various image processing sites. The sensors detect the position of the printing material and the position of the photoconductor drum of the primary imaging element in relation to the imaging and image processing locations and accordingly generate suitable signals. These signals are passed on as input information to a logic and control unit LCU which, for. B. comprises a microprocessor. On the basis of these signals and a suitable program for the microprocessor, the control unit LCU generates signals for controlling the timing of the various electrographic process points that carry out the printing process and for controlling the drive by the motor M of the various drums and belts. One skilled in the art is familiar with writing a program for a number of commercially available microprocessors suitable for use in this machine. The individual details of such a program would of course depend on the structure of the respective microprocessor.

The endless substrate-carrying web 516 is stretched around a multitude of support elements. As shown in Fig. 8, the plurality of support elements z. B. from rollers 513 , 514 , the roller 513 is preferably driven by the motor M as shown, and the drive for the roller 513 is used to drive the web 516 (of course, other support elements, such as skids, would also be or strips suitable for use with this invention). Preferably, the substrate conveying web 516 frictionally drives each of the ITMs, and each ITM frictionally drives a respective PIFM with which it is in contact. However, other drive devices can also be used. The substrate conveying web 516 can be made of any flexible material, e.g. B. a fluorinated copolymer (z. B. polyvinyl fluoride), polycarbonate, polyurethane, polyethylene terephthalate, polyimides (z. B. Kapton ^™ ), polyethylene naphthoate or silicone rubber. Whatever material is used, the web material can be an additive, e.g. B. include an antistatic (e.g. metal salts) or small conductive particles (e.g. carbon) to produce the desired resistivity of the web. If high resistivity materials are used, additional corona charging may be required to discharge a residual charge that is still on the web after the substrate has been removed. The web may include an additional conductive layer under the resistive layer that is electrically biased to effect the marker particle image transfer; however, it is particularly preferred to use an arrangement without the conductive layer and instead to apply the transfer bias either using one or more back-up rolls or using a corona charger. It is also envisaged that the invention can be used in an electrostatographic color printing machine in which a continuous paper web is used as printing material, so that a separate paper-conveying web is not necessary. These continuous webs typically come from a roll of paper that is supported to allow the paper to unwind from the roll as the paper travels through the machine as a usually continuous sheet. Printing material is then to be understood in the sense of a single sheet which is held on the paper-conveying web or a surface of a continuous paper or plastic web to which the toner image is to be transferred.

When a sheet of paper is fed onto a tape 516 , charge can be generated by the loading device 526 on the sheet to electrostatically attract the tape 516 or otherwise attach it to the tape 516 . A pressure rail 527 , which is connected to the loading device 526 , can be provided in order to press the printing material onto the tape and to remove the air which is between the printing material and the tape.

A printing material in the form of a sheet can interact at times with more than just one image transmission gap and is preferably not located in the melting gap and an image transmission gap at the same time. The path of the substrate, which takes up the different color images by transfer in turn, is usually straight, so that the use of substrates of different thicknesses is facilitated. Supports 575 a, b, c, d and e are provided in front of the entry and exit positions of each transfer nip to grasp the tape on the back and change the straight line of the tape path to partially tape the tape around each ITM can be wrapped. This partial wrap allows a reduced electric field before the gap and ion charge after the gap. The gap is where the pressure roller contacts the back of the tape or, if no pressure roller is used, where the electric field is essentially applied. Nevertheless, the gap's image transmission environment is smaller than the entire winding. The wrapping of the tape around the ITM provides a path for the leading edge of the substrate that follows the curvature of the ITM but is not in contact with the ITM as it travels along a line that is substantially tangent to the surface of the cylindrical ITM . The pressure exerted by the rotating counter-pressure rollers (TBRs) 521 B, C, M and Y acts on the back of belt 516 and forces the surface of the elastic ITM to conform to the shape of the substrate during transfer. The TBRs are preferably used, whereby they can also be replaced by corona loaders, prestressed pressure rails or prestressed brushes. Substantial pressure is provided in the transfer nip in order to realize the advantages of the elastic transfer element and in particular to achieve maximum conformity of the transferred image with the original. The pressure may be from the transfer biasing mechanism alone or additional pressure from another element, e.g. B. a roller, jaw, pressure bar, a knife or a brush. Nevertheless, all transfers are carried out without the use of heat, so that there is essentially no melting or sintering of the toner image until the melting, which takes place in the fusing rollers. The toners that are preferably used have a glass transition temperature that is higher than the temperature at which the transfer occurs in both the primary and secondary transfer columns.

The following examples are intended to simplify the explanation of the invention.

example 1 Effect of twisting on the transmission without wind skew points

Fig. 5 relates to a transfer device and shows in graphic form optical transfer densities of toner residues on a PIFR surface after the electrostatic transfer of flat black toner images of different gray values from the PIFR to a transfer roller, the axis of the PIFR being the axis of the ITR is twisted. The optical transmission densities are proportional to the relatively small amounts of toner remaining on the PIFR measured in a direction parallel to the axis of rotation of the PIFR along the entire gap where the toner has been transferred. The flat toner images that were originally formed at PIFR ranged from a low density (7% gray value) to a high density (100% gray value). A 100% gray value corresponds to Dmax, where Dmax denotes the maximum toner density of 1.8, which corresponds to a maximum deposition of 0.7 mg / cm ² . The toner particles comprised a polyester binder and were treated with minute particles of surface additive containing hydrophobic silicon compounds. The glass transition temperature of the toner particles is 54 degrees C. As regards this example, the PIFR and the ITR were not skewed to one another and for each gray value, that is to say for each curve in FIG. 5, the PIFR and the ITR were in the same rotated position to one another . The twisting resulted in a series of nip widths that were flattened along the pair of rollers and each had widths of 5 mm at the end with the lowest pressure and the lowest attachment to 7 mm at the end where the attachment was greatest. The PIFR is 181 mm in diameter and the ITR is 174 mm in diameter, the practice of the invention is not limited to these diameters, and PIFRs and ITRs with other suitable diameters can be used. The length of the ITR is 350 mm and the length of the PIFR is 395 mm. The thickness of the elastic polymer coating of the ITR was 10 mm, the elastic layer being covered with a ceramic layer 6 μm thick. The processing speed was 300 mm / sec, although the practice of the invention is not limited to this speed, and the speed can be increased or decreased. The ITR and the PIFR were provided with axes. The distance between the axes could be determined using pneumatic pressure media and precisely defined stopping points, so that the axes of the ITR and PIFR drums formed a uniformly flattened gap. In this example, there was essentially no skew within a tolerance of ± 0.01 degrees.

In the uppermost curve for a 100% gray value in FIG. 5 there is a maximum in the amount of toner residues on the PIFR. This point is approximately half the length of the PIFR. The amount of toner residue decreases sharply towards each end of the PIFR. This suggests a large improvement in transfer efficiency towards the respective end of the nip compared to a minimum transfer efficiency at the point where the toner residues are at a maximum. This can be explained with reference to Fig. 4, which predicts that the slip increases from the gap center towards the gap ends and that this slip improves the transmission efficiency. The relative direction of slippage between the rollers is opposite to each end, with essentially no slippage at the point that corresponds to the maximum of the 100% gray scale curve. The toner residue is steadily decreasing to about a third of the maximum amount at the end of the nip where the pressure is lowest (5 mm nip width) and about half at the end of the nip where the pressure is highest (7 mm gap width). This can be explained by the fact that the toner transfer efficiency decreases as the nip pressure increases, as measured independently in separate experiments using parallel rollers.

As can be seen from FIG. 5, all gray values show a similar behavior. A separate experiment using a gap that flattened from 6.9 mm to 3.7 mm and comparing the transfer of a flat image of maximum density and a 50% gray value gave qualitative results similar results for a slightly stronger twisting.

It appears from these data that undesirable deviations in the Gap width, as z. B. of twisted rollers or geometric Roll irregularities are caused, accordingly, deviations in the Cause transmission efficiency that a high-quality imaging counteract. However, a certain amount of twisting can be tolerated because this, as shown below, compensated for by skewing a roller can be. Therefore, cheaper roll structures or supports can be used than were previously considered suitable for high-quality image reproduction.

Example 2 Effect of twisting and skewing on the transmission

This example illustrates the impact of different angles of skew applied to a PIFR with respect to an ITR. Here, a slightly different electrostatic transmission device with similar components as in Example 1 was used. The PIFR was first skewed to the ITR and then twisted, whereby the flattened gap created at the cutting surface of the two rolls. Wind skewing was accomplished by placing the wind skew position axis near the ends of the PIFR and ITR drums, as shown schematically in Figure 3 (b), with the PIFR axis always remaining perpendicular to the direction of processing. The tolerance of the attachment means of the ITR and PIFR drums as well as the dimensions of the drums themselves were precisely determined, so that a wind skew angle used was within a tolerance range of ± 0.01 degrees. Further tests with a skewed position axis, which is essentially half the length of the rollers, led to similar results.

The curves in Fig. 6 show transfer densities of residual toner on the PIFR after transfer of flat black toner images with maximum density from the PIFR to the LFR. The densities were measured in a direction parallel to the PIFR axis, the measurement starting near one end of the PIFR and ending near the other end. The different curves were created using different skew angles, the PIFR and ITR also used to form a gap that flattened in the gap width from 7 mm to 5 mm (the flattening was measured for a non-skew position) were twisted. The uppermost curve, which was created without a skew position, is qualitatively similar to the uppermost curve in FIG. 5, that is to say that it had a strongly pronounced maximum at the location with the least slip because the transmission was least efficient there. In comparison, the improved transfer and lower residual toner levels are found near the ends of the PIFR where the slippage was greatest. While there are some differences between the top curves in Figures 5 and 6, they do not significantly affect this important fact. For example, the top curve in Fig. 6 has a lower maximum than that in Fig. 5, possibly due to a different accumulation of toner or possibly due to the different size of the electric field applied across the transfer nip. Likewise, the top curve in Fig. 6 is less symmetrical than that in Fig. 5 and its maximum is slightly shifted. The shifted maximum is probably caused by the increased pressure and thus by the larger residual amounts of toner which are located at the wider points of the gap. However, the similar amounts of toner residue at each end of the roller are not easy to explain, although the reduction to approximately half the maximum amount is in fair agreement with the data in FIG .

Next, the effects of skewing are considered. In Fig. 6, data for wind skew position angles from -0.015 degrees to +0.016 degrees can be found. These angles are nominally the same size within the measurement accuracy. A positive skew angle includes a direction of rotation about the skew axis that is opposite to that of a negative skew angle. The results are clearly independent of the sign of the wind skew angle. These data indicate that the smallest of the small skew angles have an unexpectedly strong impact on the amount of toner residue on the PIFR, and in particular that the maximum amounts have been reduced by approximately 20% compared to a zero skew angle . The asymmetry of the curves stands out much more at skew angles of -0.015 degrees and +0.016 degrees than at zero-degree skew angles, which in turn is due to the higher pressure and the lower transmission efficiency where the gap pressure is highest. is due. However, the main characteristic of these two curves, ie the smaller size of their maxima, is due to the wind skewing itself.

For the skewed angles of -0.077 degrees and +0.078 degrees (the two lowest curves in Fig. 6), the results are even more striking, with the amount of residual toner remaining almost the same across the flattened gap, and maxima almost gone. Even for these larger skew angles, improvements in transmission efficiency are unexpectedly achieved.

For other tests (not shown in a figure) where a twisted PIFR, which forms a higher pressure gap, which flattens from 8.2 mm to 6.6 mm, and Wind skew angles of zero, 0.17, 0.22, and 0.33 degrees were used a similarly noticeable decrease in the density of toner residues was observed on the PIFR. The The drop was particularly noticeable at 0.17 degrees; a much smaller improvement  could be achieved at 0.22 degrees, and almost no improvement could be achieved at 0.33 degrees determine. For both 0.22 and 0.33 degrees, the amount of toner residue shows no maximum along the PIFR. As expected, further enlargement of the Windschief position angle to 0.83 degrees no further decrease in the density of the Toner residues within the experimental measurement errors with regard to density (0.01 density units).

It has been observed that there is only insignificant toning or in the wind skew actuator Smearing of the toner on the surfaces revealed either the PIFR or the ITR. In addition, the sharpness of the transferred image was not noticeable impaired.

A geometrical observation shows that the wind skewing is a lateral one Causes displacement. In a hypothetical example, one of two is skewed provided, contacting rollers under frictional contact around the other roller moves that is fixed and does not turn. The position of a contact point on the fixed Roller with a given point on the moving roller spins along the fixed roller, after each rotation of the moving roller around the axis of the fixed Roller. The moving roller may ultimately be out of contact with the fixed roller devices. When the end positions of the two rollers are fixed, as in the present one In the event of a PIFR in contact with an ITR, a force vector is formed that leads to a lateral one There is a shift between the PIFR and the ITR along a direction that the Longitudinal contact gap cuts in two. The direction of the side Shift has a component that is perpendicular to the direction of processing and the extent of the lateral displacement is the same everywhere along the gap.

It has been observed that the above lateral shift caused by one Skew angle caused also caused the toner image was accordingly skewed after it was transferred from the PIFR to the ITM was.  

A direction of lateral displacement associated with skew between two fixed rolls can be understood with reference to FIG. 9. Fig. 9 schematically shows a top view of a pair of rollers ( 60 ) rotating in opposite directions (one rotates clockwise and one rotates counterclockwise). The rollers are in contact with each other so that they form a pressure gap (the directions of rotation are not specified). The individual rollers, which are provided with the reference numerals 61 and 62 , are skewed to one another, but are not rotated. The rollers continue to have the same diameter; they both have the same angular rotation speed because one roller drives the other roller by friction. The projected area of the printing nip, which is located under the roller 61 , is denoted by the hatched area, which is provided with the reference number 63 , and since there is no twisting, the nip area 63 does not flatten out. The axis of rotation 62 (not shown) should be perpendicular to the direction of processing, which with P.. .P is designated. The axis of rotation of the roller 61 (not shown) is pivoted about a skewed position axis, which is shown here with its end point and bears the reference symbol Q. The wind skew position axis is shown as being arranged symmetrically on half the length of the two rollers. A line O.. .O halves the gap area 63 in the longitudinal direction. In Fig. 9 is a lateral displacement along line O. between the rolls 61 and 62. .O instead. In the structure shown, the direction of the lateral displacement is not perpendicular to the processing direction P.. .P, yet a large component is perpendicular to P.. .P stored. In a more general case, a processing direction P.. .P any alignment to O.. .O and the line O.. .O can represent the bisecting line of a flattened gap if there is twisting and skewing at the same time, or if the skewing position axis is arranged in a different position than in the center position shown. In the practical implementation of the invention, P.. .P often arranged perpendicular to the axis of rotation of one of the rollers, as shown in Fig. 9.

Example 3 Average transmission results for twisting and skewed areas

This example combines the averaged results from several different transfer tests (using similar Dmax) performed on the same apparatus and toner as in Example 2. The gap flattening was also the same. The results are summarized in the two curves in FIG. 7. The dashed line shows the transfer density generated from the average amount of toner residue on the PIFR after the electrostatic transfer of a flat toner image from the PIFR to the ITR as it is along the entire gap (in a direction transverse to the transport direction) for both positive and negative wind skew angle was also measured. Even the smallest of the small wind skew angles reduce the average amount of toner residue to a large extent. The solid line in FIG. 7 shows the deviation of the residual toner density on the PIFR transversely to the direction of transport as an average for all different tests, wherein maximum values of the transfer density of the residual toner minus the average of all minimum values of the transfer density of the residual toner were shown as values. It is apparent that although the residual toner density on the PIFR across the direction of transport is still decreasing for skewed angles approaching ± 0.08 degrees, any further improvement for skewed angles of approximately ± 0.3 degrees except Be careful.

Further tests were carried out in which the thickness of the elastic layer of the ITR increased from 10 mm to 15 mm and reduced to 5.7 mm. The effects of Twisting and skewing to reduce the amount of toner remaining transversely to the direction of transport from Dmax transmissions were similar in both cases.

Example 4 Thinner roller body

Two PIFR / ITR roller combinations were tested to determine which one Impact the use of roller bodies with walls of different thickness  has a smooth electrostatic transmission. The coating of the roller body was the same as that used in the previous examples. In the first In combination, the bodies of the PIFR and the ITR each had a hollow Aluminum cylinder with a wall thickness of 5 mm and 19 mm thick. In the In the second combination, the wall thickness of the PIFR and the ITR was greatly reduced to 4 mm and 6 mm respectively.

In the transmission tests where no skewing or twisting is applied and the first roller combination used was the usual one Irregularities in the amounts of toner residue observed on the PIFR, such as B. differences in the size of the rollers or tolerance errors in the roller attachments caused. The use of small skew angles similar to that wind skew angles used in Examples 2 and 3, i. H. Angle of 0.015 degrees or more, but still relatively small, gave similarly strong ones Improvements in transmission uniformity and transmission efficiency.

In tests to compare the transmission without using wind skew points or Twisting, in which the second roller combination was used, led to the Using bodies with thinner walls to a high rise from Transmission irregularities caused by the bending and bending of the rollers were caused. The use of small skewed angles, as they do applied in Examples 2 and 3 led to major improvements in the Transmission uniformity and efficiency, comparable to the results of the Examples 2 and 3 wherein uniformity and transfer efficiency values were measured that were unexpectedly comparable to those that were more similar in use Wind skew angles were observed with the first roller combination.

From the examples above it can be concluded that a small lateral Shift in a direction perpendicular to the direction of the process of promoting a Transfer toner from a PIFM to a more efficiently and evenly elastic ITM is very beneficial. More specifically, it can be a useful side  Shift can be created by using a PIFR and an elastic ITR be, whose axes to each other by a small angle, which is preferably at a Measuring range is between 0.1 and 0.3 degrees, are skewed. According to the invention reduces skewed places by small angles and in places with low ones Nip pressure the manufacturing tolerances for both rollers and for the attachment means the rollers are required, costs are reduced and the gap width is improved. It continue to notice that the application of a small skew angle between a PIFR and an elastic ITR the use of much thinner Bodies enabled, these rollers made lighter and the costs further reduced can be. Therefore, cylindrical metal and preferably aluminum bodies with a thickness in a measuring range of 1-6 mm can be used, this body Elemental tubes without internal support elements on their long sides (except on the Ends) are. They are considered suitable for use in a PIFR and / or an ITR, so if they are skewed and this one discussed, different pressure levels, still for one uniform transmission can ensure even if the gap width is 10% or more may vary along the long side of the PIFR-ITR gap (i.e. from one end of one Roll to the other end of the roll where the gap is). The gap widths change due to the tendency of the rollers to bend or curve. So can The gap width between two rollers can be measured by first using a thin one Uniform coating of toner or ink on one of the rollers over its length is applied, the circumferential length of the coating being much larger than the expected Gap width is. The thickness of the coating should be thin enough so that the gap width not significantly changed by the thickness of the coating (less than about 20 µm) becomes. Then the rollers are brought out of contact and the area with the Coating is rotated into an area adjacent to the second roller so that the Coating when the rollers are in contact with each other is in the area of the gap. The rollers then slowly come into contact with each other and thus into theirs Operating position brought. Next, the rollers are separated. During the Contacting and disconnection must not rotate the rollers. The width of the  Coating (along the circumference of the roller) that is transferred to the second roller was measured as the gap width.

A lateral shift resulting in a skew of a PIFR and a is due to elastic ITR, accordingly causes a wind misalignment of the transmitted image as described in Example 2 above. This Wind skew is preferably compensated for by the fact that the write head to the PIFR is so skewed that the toner image with regard to the Processing direction is directed.

In the embodiment of Fig. 8 z. For example, the exposure source or write head 506 B, C, M, Y is shown in the form of a known laser light beam write head or LED printhead writer, which is shown in the 12 o'clock position with respect to its respective PIFM 503 B, C, M, Y . If each PIFM is skewed by the predetermined small angle within the measuring range shown here, in which the respective ITM 508 B, C, M, Y remains parallel to the respective TBR 521 B, C, M, Y, and if the main exposure line of the scanner image, which runs parallel to the respective central axes and rotational axes of the respective ITM or the respective TBR, then the preferred compensation of the print head is created so that the toner image is correctly aligned in the processing direction.

In other embodiments, the exposure position of the respective print head can do not correspond to the 12 o'clock position of the respective PIFM. In these cases, can Wind-skewed positions of the PIFM require an adaptation of the write head to the PIFM, to ensure the appropriate distance correction to the PIFM, so that the Main exposure scanner line on the PIFM in the correct focus of the printhead located. Furthermore, the main exposure scanner line is then in a corresponding one Windschief position angle aligned, the size of the small Windschief- Position angle between the PIFM and the respective ITM is similar, this However, make up for a line of exposed pixels during development  create that are arranged perpendicular to the direction of processing when they are on a Transfer sheet to be transferred.

The small angles that are preferred here are small enough so that when they can be used with the PIFRs, without any of the diameters listed here Problems with adjusting the distance on the print head can be used because the depth of focus of the print head can be exploited. An LED Printhead recorder has e.g. B. a series of several thousand LEDs, which are optional are activated in response to image data. The light from it is through a Selfoc lens shown, which has a depth of focus. Similarly, laser emitters send one Scanning beam, which is imaged by a lens on the PIFM.

Although the print head is skewed to the PIFM to do this Wind skew points of the PIFM to compensate for the ITM, regardless of whether it is PIFM is that skewed to the TBR, or ITM that skewed to the TBR it is obvious that other entities that interact with the PIFM e.g. B. loading unit, developer unit and cleaning unit, not skewed to the PIFM must be posed.

The particularly preferred embodiment of a transmission device according to the invention comprises:

• - An ITR, which has an aluminum body with 4-10 mm thick walls and further comprises an elastic coating, which is 10 mm thick and has a volume resistivity, which is preferably between 10 ⁷ and 10 ¹¹ ohm-cm, and a thin has a hard outer coating, the thickness of which is 6 µm;
• - A PIFR with a relatively rigid, electrically conductive body, such as. B. one Aluminum body of 3-10 mm thickness;  
• - A skewed position angle between PIFR and ITR, which is in a measuring range is between 0.1 and 0.3 degrees;
• - Toner particles with a binder that has a glass transition temperature of more than 54 degrees has and furthermore has the smallest particles with surface additives, in to which the transmission is carried out without the application of heat, so that no Melting of the toner occurs during the transfer;
• - a processing speed of 300 mm / sec, though Processing speeds of 20 to 3000 mm / sec can be considered; and
• - A transfer gap for electrostatic transfer of the toner particles from the PIFR on the ITR, the gap being an attachment pressure in a measuring range between 20-3000 kPa and preferably from 80-160 kPa, and a gap width in a measuring range from 3.5 to 7.5 mm. The gap attachment pressure is measured by taking the force applied to the two rollers and by the Gap area divides, that is the average gap width times the length of one Roller.

All values listed for the representation of a measuring range include the listed ones Start and end values and the units refer to all units in this Measuring range.  

List of reference numbers

10th

Duplicator or printer

20th

twisted but not skewed pair of non-contacting rollers

21

top roller

22

lower roller

30th

twisted but not skewed pair of contacting rollers

31

top roller

32

lower elastic roller

40

skewed pair of rollers

41

lower rollers

42

upper rollers

50

skewed pair of rollers

51

lower roller

52

top roller

60

pair of rollers rotating in the opposite direction

61

top roller

62

lower roller

63

projected area of the pressure gap
503B, C, M, Y Primary Imaging Element (PIFM)
505B, C, M, Y corona charger
506B, C, M, Y exposure source
508B, C, M, Y transfer element (ITM)
510B, C, M, Y gap

511

Cleaning device
512a, b, c, d substrate

513

roller

514

roller

516

Printing material conveyor belt (PTW)
521 B, C, M, Y counter pressure roller

522

Corona charger

523

Corona charger

524

Charging element

526

Loading device

527

Pressure rail
541B, C, M, Y conductive core

542

surface
543B, C, M, Y elastic blanket layer

552

Power supply
575a, b, c, d support device
581B, C, M, Y developer unit
591B, C, M, Y color modules
A.. .A axis
A '. , .A 'axis
A "... A" axis
A '''. , .A '''axis
B.. .B axis
C.. .C central axis / axis of rotation
D.. .D central axis / rotational axis
E.. .E rotation axis
F.. .F axis of rotation
G.. .G axis of rotation
H. . .H axis of rotation
I.. .I roller axis
ITM handover element
ITR transfer roller
J.. .J roller axis
LCU control unit
O.. .O line
P processing direction
PIFM primary imaging element
PIFR primary imaging roller
Q Skewed position axis
RR section
SV voltage vector
W gap width
X.. .X axis
X Skewed position axis
X 'Skewed position axis
Y.. .Y axis
Z.. .Z cutting line
α angle
α 'angle
β angle
β 'Wind skew angle
γ angle
γ 'angle

Claims (12)

1. An apparatus for transferring a toner image having a movable primary imaging element (PIFM) carrying a marking particle toner image and a movable transfer element (ITM), wherein there is pressure contact attachment between the PIFM and the ITM, thereby forming a gap with a gap width , and wherein the PIFM and ITM define a boundary contact surface of the gap width; with means for establishing an electrical transmission field for the electrostatic transmission of the inking concrete particle image from the PIFM to the ITM, characterized in that the tangential directions of movement of the contacting surfaces of the PIFM and the ITM are not completely parallel to one another. 2. Device according to claim 1 characterized, that a predetermined small angle between the respective tangential There are directions of movement. 3. Device according to claim 2 characterized, the tangential directions of movement are in the surface that are with the boundary contact surface of the gap width. 4. Apparatus according to claim 2 or 3, characterized, that the predetermined angle is between 0.03 and 0.45 degrees. 5. Device according to one of the preceding claims, characterized,  that the ITM has an elastic layer. 6. Device according to one of the preceding claims, characterized, that the primary image bearing element (PIFM) comprises a photo semiconductor. 7. Device according to one of the preceding claims, characterized, that the PIFM comprises a substantially cylindrical roller (PIFR), and an ITM is also a substantially cylindrical one, in the opposite Direction rotating roller includes, the axes of rotation of the two rollers are skewed to each other by a predetermined small angle. 8. Device according to one of the preceding claims, characterized, that the ITR drives the PIFR through friction. 9. Device according to one of the preceding claims, characterized, that in the transmission gap between ITM and PIFM a pressure between 20 and 300 kPa is present. 10. A toner image transfer method in which a toner image is on a rotating one primary image-bearing element, and in that that the toner image electrostatically from the primary image bearing member to a surface of a rotating transfer element is transmitted in a transmission gap, wherein the transmission gap due to pressure contact attachment between the primary image-bearing element and the transfer element is formed, characterized,  that the axis of rotation of the primary image bearing member by one predetermined small angle to the axis of the transfer element skewed is posed. 11. A method for toner image transfer according to claim 10, characterized, that the given small angle in a measuring range between 0.03 and 0.45 degrees lies. 12. A method for toner image transfer according to claim 10 or 11, characterized, that the pressure in the transfer gap in a measuring range between 20 and 300 kPa.