Patent Application
20100051165
This invention relates in general to electrographic printing, and more particularly to printing with metallic thin film elements and, in one embodiment, to electrographic patterning of electrically-conductive thin films comprising a support, and a digitally patterned electrically-conductive layer. More specifically, this invention relates to using electrographic imaging processes employing electrographic toners where the image patterns are created using marking or non marking toner particles.
One method for printing images on a receiver member is referred to as electrography. In this method, an electrostatic image is formed on a dielectric member by uniformly charging the dielectric member and then discharging selected areas of the uniform charge to yield an image-wise electrostatic charge pattern. Such discharge is typically accomplished by exposing the uniformly charged dielectric member to actinic radiation provided by selectively activating particular light sources in an LED array or a laser device directed at the dielectric member. After the image-wise charge pattern is formed, the pigmented (or in some instances, non-pigmented) marking particles are given a charge, substantially opposite the charge pattern on the dielectric member and brought into the vicinity of the dielectric member so as to be attracted to the image-wise charge pattern to develop such pattern into a visible image.
Thereafter, a suitable receiver member (e.g., a cut sheet of plain bond paper) is brought into juxtaposition with the marking particle developed image-wise charge pattern on the dielectric member. A suitable electric field is applied to transfer the marking particles to the receiver member in the image-wise pattern to form the desired print image on the receiver member. The receiver member is then removed from its operative association with the dielectric member and the marking particle print image is permanently fixed to the receiver member typically using heat, and/or pressure and heat. Multiple layers or marking materials can be overlaid on one receiver, for example, layers of different color particles can be overlaid on one receiver member to form a multi-color print image on the receiver member after fixing.
Metal films, such as aluminum and gold, are commonly used in the manufacture of metal coated printed articles and electrical circuits in the commercial printing business. Currently there are commercial devices that stamp metal films, including a wide variety of reflective and electrically conductive thin films on various substrates. There is a critical need in the art for a technique to create patterned conductive or reflective thin film structures in a cost effective manner for short runs or with variable information. In addition to providing superior electrode performance, these thin film conductive layers also must be digitally patterned, must resist the effects of humidity change, and be manufacturable at a reasonable cost.
It is toward the objective of providing both such improved decorative reflective articles as well as electrically conductive, digitally patterned thin film coated articles that more effectively meet the diverse commercial needs than those of the prior art, that the present invention is directed.
The tin film layer(s) of this invention are patterned by application of one of more toners using the electrographic development process. The final pattern is “fixed” by means of pressure and (or) heat fixing step, whereupon the toner particles interacts with the thin film layer to adhere the thin film to a substrate.
In view of the above, this invention is directed to electrographic printing using both toner and films to form one or more layers, with a particular pattern, which can be printed by electrographic techniques. Such electrographic printing includes the steps of forming a desired image, electrographically or with inkjet, on a receiver member and using that image to selectively adhere one or more thin films into a desired in registration design. The patterning process of this invention combines the application of electrophotographic marking toner and thin metal films that are applied in conjunction with the EP printing process.
The device and related method control registration by using a registration mark assigned for each sheet or set of sheets and defined with respect to its position. The marks are applied to a substrate or to a support for the substrates or sheets with a specified distance relative to the thin film
In the detailed description of the preferred embodiment of the invention presented below, reference is made to the accompanying drawings, in which:
Referring now to the accompanying drawings,
An electrographic printer apparatus 100 has one or more printing modules shown here as five tandemly arranged electrostatographic image forming printing modules M1, M2, M3, M4, and M5 and a finishing assembly 101, that in one embodiment includes a thin film applicator 102 so that the film is activated by the digitally patterned image in a fuser at the same time the film is applied. Additional modules may be provided. Each of the printing modules generates a single-color toner image for transfer to a receiver member successively moved through the modules. The finishing assembly has a fuser roller 104 and an opposing pressure roller 106 that form a fusing nip 108 there between. The printer shown also includes a film application device 110. The receiver member 20 (R), during a single pass through the five modules, can have transferred, in registration with the help of a register device or registration method 60, up to five single-color toner images to form a pentachrome image. As used herein, the term pentachrome implies that in an image formed on a receiver member combinations of subsets of the five colors are combined to form other colors on the receiver member at various locations on the receiver member, and that all five colors participate to form process colors in at least some of the subsets wherein each of the five colors may be combined with one or more of the other colors at a particular location on the receiver member to form a color different than the specific color toners combined at that location.
In one embodiment, printing module M1 forms black (K) toner color separation images, M2 forms yellow (Y) toner color separation images, M3 forms magenta (M) toner color separation images, and M4 forms cyan (C) toner color separation images. Printing module M5 may form any other fifth color separation image or be clear. It is shown here as a color toner or clear toner that acts as a thin film adhesive (A) when activated by heat, pressure or other known method. In the electrographic printer apparatus, the toner in M5 lays down a pattern which is used as the film image pattern since the toner 30, described in detail below, acts as a thin film adhesive. Accordingly in the patterned areas are laid down in a pattern of toner 40, contacted by the thin film layer 10 and activated by heat, pressure and/or other activation methods to produce a digitally patterned thin film print 50 useful for decorative images, such as logos, for image protective purposes, for scratch offs and embossing and/or for conductive or electrical purposes. In the embodiment shown in
In this embodiment, where the color toner is not fused before the application of the thin film, it is important to stabilize the color image so it does not interfere with the thin film application process. A first method is to use a UV curable color toner for the non-film patterned image and cross linking this first toner before the thin film is applied and fused to the toner. A cold stamping foil, such as the Kurz Alufin® foil, would be used as a foil that would work well in this method. Alternatively the thin film patterned image can be laid down in an inverse manner forming essentially a negative image of the desired image that will prevent the thin film from adhering where the toner is laid down and allow all the toner to be fused at the same time. An example of a toner that would work well as the negative image thin film toner is the wax-based toner, as is described below in more detail. A hot stamping foil would be used as a foil that would work well in this method, such as the Kurz hot stamp foils.
The embodiment shown in
Receiver members (Rn-R(n-7), where n is the number of stations as shown in
A power supply unit 128 provides individual transfer currents to the transfer backup rollers TR1, TR2, TR3, TR4, and TR5 respectively. A logic and control unit 130 (
a and 4b show two embodiments of a thin film application device 110, including the thin film applicator 102, located next to one or more heated roller(s) 112, shown here as internally heated, and the film supply device 114. The thin film applicator 102 has a set of driven inlet rollers 140 and a set of outlet rollers 142. Alternatives include a stamp machine and other thin film applicators. In the thin film application device 110 the thin film material 10 is drawn from a roll 140 to a pick-up roller 142 in the supply device 114 and laid on a surface of the receiver 20 adjacent the heated roller 112 at the nip 144. After the thin film 10 is applied the receiver progresses on in the printer as shown in
The logic and control unit (LCU) 130 includes a microprocessor incorporating suitable look-up tables and control software, which is executable by the LCU 130. The control software is preferably stored in memory associated with the LCU 130. Sensors 134 associated with the fusing assembly provide appropriate signals to the LCU 130. In response to sensors 134, the LCU 130 issues command and control signals that adjust the heat and/or pressure within fusing nip 108 and otherwise generally nominalizes and/or optimizes the operating parameters and to reduce errors which are attributable to the printing process and more particularly to the film application. Also feedback from the sensors associated with the fusing and glossing assemblies provide appropriate signals to the LCU 130. The film applicator device 110 can also have separate controls providing control over temperature of the application roller and the downstream cooling of the film and control of application nip pressure for the film applicator.
Subsequent to transfer of the respective (separation) multilayered images, overlaid in registration, one or more of the respective printing modules M1-M5, the receiver member is advanced to a finishing assembly 101 (shown in
The toner used as the thin film toner adhesive can be the Kodak EP toner or Kodak chemically prepared dry ink (CD1). The toner used to form the final thin film pattern layers can be styrenic (styrene butyl acrylate) type used in toner with a polyester toner binder. In that use typically the refractive index of the polymers used as toner resins have are 1.53 to almost 1.102. These are typical refractive index measurements of the polyester toner binder, as well as styrenic (styrene butyl acrylate) toner. Typically the polyesters are around 1.54 and the styrenic resins are 1.59. The conditions under which it was measured (by methods known to those skilled in the art) are at room temperature and about 590 nm. One skilled in the art would understand that other similar materials could also be used. Electrographic (EP) marking particles can be deposited in accordance with an image pattern upon a receiver thin film surface to define the electrode pattern after development. The phrase “electrographic marking particles” is used herein broadly to include electrically photosensitive particles used in migration imaging processes and any other material used to develop and define an electrographic image pattern such as, for an example, electrographic toners, liquid droplets, resin or polymer particles. Such marking particles may be a composite particle and may contain a colorant.
The marking particle or toner is typically, although not necessarily, brought into contact with the image pattern in an electrogaphic developer composition comprising a carrier vehicle and the marking particle. The phrase “electrographic developer composition” includes any composition comprising a carrier and the electrographic marking particles of the present invention and is intended for use in developing electrographic image patterns, however formed, including but not limited to, the methods of electrophotographic, electrophoretic migration imaging and modulated electrostatic printing. In general, the novel electrographic marking particles of the present invention can be used to imagewise deliver a desired concentration of the conductivity modifier regardless of how the image pattern is formed if the image pattern is developed with marking particles.
The thin film layer(s) of this invention are patterned by application of one of more toners using the electrographic development process. These toners use electrographic marking toner particles as described in U.S. Pat. No. 5,948,585 hereby incorporated by reference. Some of these limited coalescence techniques used to prepare CDI are described in patents pertaining to the preparation of electrostatic toner particles because such techniques typically result in the formation of toner particles having a substantially uniform size and uniform size distribution. Representative limited coalescence processes employed in toner preparation are described in U.S. Pat. Nos. 4,833,018 and 4,965,131, hereby incorporated by reference. In one example a pico high viscosity toner, of the type described above, could form the first and or second layers and the top layer could be a laminate or an 8 micron clear toner in the fifth station thus the highly viscous toner would not fuse at the same temperature as the other toner.
In the limited coalescence techniques described, the judicious selection of toner additives such as charge control agents and pigments permits control of the surface roughness of toner particles by taking advantage of the aqueous organic interphase present. It is important to take into account that any toner additive employed for this purpose that is highly surface active or hydrophilic in nature may also be present at the surface of the toner particles. Particulate and environmental factors that are important to successful results include the toner particle charge/mass ratios (it should not be too low), surface roughness, poor thermal transfer, poor electrostatic transfer, reduced pigment coverage, and environmental effects such as temperature, humidity, chemicals, radiation, and the like that affects the toner or paper. Because of their effects on the size distribution they should be controlled and kept to a normal operating range to control environmental sensitivity. This toner also has a tensile modulus (103 psi) of 150-500, normally 345, a flexural modulus (103 psi) of 300-500, normally 340, a hardness of M70-M72 (Rockwell), a thermal expansion of 68-70 10−6/degree Celsius, a specific gravity of 1.2 and a slow, slight yellowing under exposure to light according to J. H. DuBois and F. W. John, eds., in Plastics, 5th edition, Van Norstrand and Reinhold, 1974 (page 522).
An important aspect of the process is the accurate registration process. In the registration process of the electrophotographic (EP) printer 100 there is for each sheet at least one register mark, such as per color printing unit, of the multi-color printing machine. The registration mark is produced and assigned to each sheet and defined with respect to its position, preferably relative to one of the marks themselves as applied to
In one embodiment, as illustrated in
The printer controls registration in the digital printer 100 during the printing process in another embodiment that prints four or more colors as well as the thin film application, as shown in
In this embodiment as shown in
These register marks are then detected by a registration sensor 180 (register mark sensor) and can thus be analyzed as described in the incorporated references mentioned above. The analysis of the register marks permits an inventive control of the subsequent printing of sheets in the same printing process. The control on the basis of a register mark that has just been detected by registration sensor 180, however, can be used at the earliest for a sheet which arrives as the next sheet at the lead edge sensor 136, such as one before the thin film applicator, because the sheet still has all the other printing units ahead of it. However, because transport belt 116 is utilized better, additional sheets are already between any two sensors.
In the digital printer 100 as shown in
In the embodiment shown in
In a model of the viewed or observed system (system model) 223, it is assumed, using a controlled system as basis, that within the already described “dead time”, during which a sheet moves from lead edge sensor 180 to registration sensor 180′ and is processed by the LCU, the circumferential register assigned to this sheet is subject to a drift and to statistical noise, in which case said drift is to be quasi counter-controlled by reverse “presentation” for correction. For example, a substantially linear systematic drift (system drift) is assumed, which said drift is superimposed by said noise and over time leads to position changes of the register marks, as illustrated in region 220. This is the ACTUAL value which is generated in the system and which is present at point 229. If the drift is corrected out, as shown in region 222, only the statistical noise around the requested NOMINAL zero value (SOF value) remains, whereby said noise cannot be further removed by correction.
In order to achieve the desired control, the system is reproduced on the side of an “observer” via the control loop. On the observer 224 side of the observed system, the drift of the system is observed and taken into account in point 225 via the ACTUAL value obtained in point 229. In order to synchronize the observer with the system, the dead time already mentioned in conjunction with system model 223 must be taken into consideration.
The ACTUAL value obtained at point 225 from the system, as shown in region 220, is input—in order to smooth said value and eliminate the noise—as filter input data (FilterIn) in a filter 226 labeled “PT1”, said filter being essentially configured or acting as a low-pass filter. This is achieved by means of the following FilterIn algorithm shown below:
with the current control step i and dead time d. The parameters of said algorithm are largely self-explanatory, i.e., “FilterIn” represents the input value for filter 226, “DriftCorrection” represents the drift to be corrected in view of the dead time, “RegError” represents the registration error to be corrected, “RegData” represents the registered register mark data (ACTUAL values), and “DesiredValue” represents the desired register mark data (SET values). In so doing, the determination of the difference (i−d) takes into consideration that correction starts in the region of lead edge sensor 180, i.e., registered by dead time d earlier than the registration of register mark data in the region of registration sensor 180′ (at “time” i). This determination of the difference can also be understood as the determination of the average over this period of time.
The FilterOut then results due to filter 26 in terms of:
FilterOut(i)=a0·FilterIn(i)+(1−a0)·FilterOut(i−1) (2)
with the current control step i and the previous control step (i−1). a0 is a filter coefficient expressed in terms of:
where Δt is the time between the current and the previous control steps t(i)−t(i−1), and τ is a time constant of filter 226. Considering an artificial prespecified value, in particular an increase of Δt, the value of the filter coefficient or the weighting factor a0 can be varied and, thus, also portions of the two addends in equation (2) can be prespecified. This determines the degree of the “hardness” or “softness” that is being considered in view of current or previous data during control. In particular at the start of a printing process, initially a harder control should be preferable.
Finally, in equation (2), the FilterOut value, which is represented as the observed value (Observed Drift) and is shown in region 221, and the smoothed drift which has been freed of noise, as described above, are taken into consideration for the next control at point 228 in terms of:
DriftCorrection(i)=FilterOut(i) (4)
In any contact fusing the speed of fusing and resident times and related pressures applied are also important to achieve the particular final desired film layer. Contact fusing may be necessary if faster tunarounds are needed. Various finishing methods would include both contact and non-contact including heat, pressure, chemical as well as IR and UV. The described toner normally has a melting range between 50-150 degrees Celsius. An example of two types of toner that work well to adhere the digitally patterned foil include toner that is can be heated to a temperature close to the softening point (i.e. Tg) and/or has a relatively high molecular weight, such as the Kodak MICR toner. Toner that has a higher molecular weight and a high cohesive strength when in the melt state maximizes the adhesive force between the substrate and the thin film. Surface tension, roughness and viscosity should be such as to yield a efficient transfer. Surface profiles and roughness can be measured using the Federal 5000 “Surf Analyzer’ and is measured in regular units, such as microns. Toner particle size, as discussed above is also important since larger particles not only result in the desired heights and patterns but also results in a clearer thin film pattern layers since there is less air inclusions, normally, in a larger particle. Color density is measured under the standard CIE test by Gretag-Macbeth in colorimeter and is expressed in L*a*b* units as is well known. Toner viscosity is measured by a Mooney viscometer, a meter that measures viscosity, and the higher viscosities will keep an thin film pattern layer's pattern better and can result in greater height. The higher viscosity toner will also result in a retained form over a longer period of time.
Melting point, discussed above, is often not as important of a measure as the glass transition temperature (Tg). This range is around 50-100 degrees Celsius, often around 118 degrees Celsius. Permanence of the color and/or clear under UV and IR exposure can be determined as a loss of clarity over time. The lower this loss then the better the result. Clarity, or low haze, is important for thin film pattern layers that are transmissive or reflective wherein clarity is an indicator and haze is a measure of higher percent of transmitted light. When no cooling device is used prior to the separation of the thin film support from the substrate the toner preferably has a high cohesive strength when in the melt state to maximize its adhesive force to the thin film.
In one embodiment of the present invention, as shown in
The method shown in
This could be done from the two positions as shown in
Registration is controlled as described above between the color toner lay down for colored images and the thin film patterned toner image to adhere the thin film. Note that the colored toner could alternately be a clear toner having various characteristics. The registration of the colored toner layers to the DPTFI can be further improved by using feed forward and or feed back algorithms based on sensors that measure the location of the transport web and imaging elements in time and/or characterize the printing system in a mode prior to the printing mode. Algorithms that compensate for factors that cause the position of the substrate to be altered can be used to accurately register the subsequent toner images to the DPTFI. Alternatively, when a common transport web is not used for printing the DPTFI and the subsequent toner images, marks can be printed on the substrate when the DPTFI is created. These marks are read with sensors and used to accurately control the printing of the subsequent toner images. Another improvement to aid in registering the images is to accurately measure the position of the substrate by detecting the location of one or more edges of the substrate at specified locations. Edge detection can be used with any of the described techniques.
This method can use conductive metal films and produce electronic circuits and/or any metal or other films to produce desired decorative images including scratch-offs. The film can produce embossed items and can use raised clear to give height.
When marking toner(s) are applied on top of the DPTFI it is preferred that the toner(s) are not opaque so that a metallic color image is created. Thus the final image (after the final fusing step) contains a layer or layers of transparent or semi-transparent ink layers that allow the reflective properties of the DPTFI to be visualized. This method permits a wide variety of metallic colors to be created. An optional glossing step can also be used to produce a glossy decorative image. We have found that higher gloss marking images on top of the DPTFI produce more luster and thus using an in line or off line finishing step to create a glossier image is a preferred mode.
Another method of the present invention for forming a thin film pattern, such as an electrode pattern, by an electrographic imaging process is off line as shown in
This method can use conductive metal films and produce electronic circuits and/or any metal or other films to produce desired decorative images including scratch-offs. The film can produce embossed items and can use raised clear to give height and could be used in conjunction to the first method for more options.
As described in this application a clear toner can be deposited so that the clear toner forms the negative image when the inverse mask mode is selected for the fifth image-forming module M5 in accordance with the information for establishing or printing a negative in clear toner in the referenced application. Image data for the clear toner negative is generated in accordance with paper type and the pixel-by-pixel locations as to where to apply the clear toner. Information regarding the multicolor image is analyzed by a Raster Image Processor (RIP) associated with the LCU 130 to establish on a pixel-by-pixel basis as to where pigmented toner is located on the thin film printed patterned receiver member. Pixel locations having relatively large amounts of pigmented toner are designated as pixel locations to receive a corresponding lesser amount of clear toner so as to balance the overall height of pixel locations with combinations of pigmented toner and clear toner. Thus, pixel locations having relatively low amounts of pigmented toner are provided with correspondingly greater amounts of clear toner. In the printing of the clear toner as an negative, the negative image data may be processed either as a halftone or continuous tone image. In the case of processing this image as a halftone, a suitable screen angle may be provided for this image to reduce moire patterns.
Further shown in
The invention will be described and illustrated herein in connection with the patterning of thin film electrode layers by the techniques of electrophotography, electrophoretic migration imaging and modulated electrostatic printing. It will be readily understood by those skilled in the art that the invention will be in general, applicable to any electrographic technique which uses marking particles for defining image patterns.
