The present invention generally relates to scratch-off documents having at least two toner layers deposited on a substrate and more particularly to depositing the underlying toner layer directly on a substrate that includes one or more portions that are easily removed during scratch-off.
Currently, scratch-off documents are used for a variety of applications. One of the most commonly used applications is the use of scratch-off documents for creating lottery tickets. In this application, a person purchases a lottery ticket and uses a hard object to scratch off the portion of the ticket covering hidden information such as a particular number. The use of scratch-off documents has vastly increased over the past years and several prior art documents address creating scratch-off documents.
In this regard, U.S. Patent Application 2007/0281224 is directed to a scratch-off document in which a first layer of toner forms an image and an optional barrier layer, typically clear, is deposited hereon. The first layer is well adhered to the substrate and the barrier layer is well adhered to the first layer. A second removable layer of toner is adhered to the first layer and can be removed when scratched using a hard object, leaving the first layer intact on the substrate. The application of the barrier layer is carried out offline and the document is reprinted with the scratch-off layer.
U.S. Patent Application 2008/0131176 is directed to an apparatus and method for producing a scratch-off document in which front side information containing the information to be hidden prior to scratch-off is first fused or otherwise adhered to the base material prior to the printing of a removable scratch-off layer.
U.S. Patent Application 2009/0263583 is directed to a scratch-off document in which the information layer includes both an indicia and a noise component of varying height. A scratch off layer is deposited over the noise component. This variable height functions to obscure the indicia so that it is not easily seen until scratched off.
U.S. Pat. No. 8,342,576 is directed to a scratch-off document having a first toner layer containing hidden information (i.e., the image that will eventually be revealed to the user after scratch off). The first layer is then covered by a printed, removable, waxy scratch-off layer having a distraction pattern.
Although each is satisfactory, cost efficiency improvements are always needed, as is the need for simple, but efficient scratch-off documents. In this regard, the prior art documents all use a plurality of fusing steps which is both costly and time consuming. The present invention overcomes these shortcomings by using two toner materials having different thermal conductivities so that only a single fixing step (or fusing step) is necessary.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the invention, the invention resides in a method for creating a scratch-off document having hidden information, the method comprising: providing a substrate; depositing a first layer of toner particles on the substrate, wherein the first layer includes at least two thicknesses in which one region is thicker than the other region; depositing a second layer of toner particles on the first layer, wherein the first toner particles have a different thermal conductivity than the second toner particles; and applying heat to the first and second layers simultaneously so that the first layer adheres to the substrate in regions of the lesser thickness of the first toner particles and does not adhere in the regions of greater thickness of the first toner particles; wherein the first and second layers in the regions of greater thickness of the first toner layer can be removed thereby creating or revealing the hidden information.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the present invention, it is believed that the invention will be better understood from the following description when taken in conjunction with the accompanying drawings, and wherein:
Turning now to
Receiver materials such as a substrate 2, as shown in
Each of the printing modules M1-M5 includes a photoconductive imaging roller 111, an intermediate transfer roller 112, and a transfer backup roller 113, as is known in the art. For example, at printing module M1, a particular toner separation image can be created on the photoconductive imaging roller 111, transferred to intermediate transfer roller 112, and transferred again to the substrate 2 moving through a transfer station, which transfer station includes intermediate transfer roller 112 forming a pressure nip with a corresponding transfer backup roller 113.
The substrate 2 can sequentially pass through the printing modules M1 through M5. In some or all of the printing modules M1-M5 a toner separation image can be formed on the receiver material 5 to provide the desired scratch-off document comprising CMYK information hidden by an opaque toner layer. Printing apparatus 100 has a fuser of any well known construction, such as the shown fuser assembly 60 using fuser rollers 62 and 64 or nip-rollers at least one of which is heated. The substrate 2 of the present invention is preferably fused during one pass through the nip-rollers which is advantageous from a cost and time perspective.
A logic and control unit (LCU) 230 can include one or more processors and in response to signals from various sensors (CONT) associated with the electrophotographic printer apparatus 100 provides timing and control signals to the respective components to provide control of the various components and process control parameters of the apparatus as known in the art. In the present invention, the LCU 230 is used to vary the thickness of the toner deposited on the substrate 2 at predetermined portions, as will be described in more detail below.
Although not shown, the printer apparatus 100 can have a duplex path to allow feeding a receiver material having a fused toner image thereon back to printing modules M1 through M5. When such a duplex path is provided, two sided printing on the receiver material or multiple printing on the same side is possible.
Operation of the printing apparatus 100 will be described. Image data for writing by the printer apparatus 100 are received and can be processed by a raster image processor (RIP), which can include a color separation screen generator or generators. The image data include information to be formed on the receiver material, which information is also processed by the raster image processor. The output of the RIP can be stored in frame or line buffers for transmission of the color separation print data to each of the respective printing modules M1 through M5 for printing color separations in the desired order. The RIP or color separation screen generator can be a part of the printer apparatus or remote therefrom. Image data processed by the RIP can at least partially include data from a color document scanner, a digital camera, a computer, a memory or network. The image data typically include image data representing a continuous image that needs to be reprocessed into halftone image data in order to be adequately represented by the printer.
Referring to
Turning now to the details of the first and second layers 10 and 20, the first toner layer 10 and second toner layer 20 both include toner particles, and the first toner layer 10 includes first toner particles that comprise at least one pigment or at least one dye or a combination thereof. The second toner layer 20 is formed by second toner particles that have a significantly lower thermal conductivity as compared to the first toner particles. This is preferably accomplished by adding one or more suitable additives listed in Table 1. The first tier 13 of the first toner layer 10 is preferably applied at a mass lay-down of toner greater than or equal to 0.60 mg/cm2. The second toner layer 20 is deposited on the first toner layer 10 uniformly in excess of 1.0 mg/cm2. The difference in thermal conductivity and mass laydown of the first toner layer 10 and second layer 20 makes the first tier 13 and the toner layer 20 in registration with the first tier 13 less adhesive to the substrate 2. This permits it to be scratched off using a fingernail, a hard rigid object or any object suitable for scratch off after fusing the first layer 10 and second layer 20 to the substrate 2.
The thermal conductivity of the second toner particles of second toner layer 20 may be less than or equal to 90% of, preferably less than or equal to 70% of, the thermal conductivity of the first toner particles of first toner layer 10 so that first toner layer 10 melts more readily than second toner layer 20. The maximum mass laydown for toner layer 10 for achieving good adhesion to substrate 2 when overcoated with second toner layer 20, will be a function of the thermal conductivities of the toners used for first and second toner layer (10 and 20 respectively) as well as the thickness of second toner layer 20 and the relevant fusing process conditions, e.g. operating temperature and nip dwell time for a set of nipped, heated fusing rollers. This maximum mass laydown functional dependence may be determined empirically using various methodologies including one as follows: for first and second toners having different thermal conductivities, a full factorial set of test patches are printed using a series of mass laydowns for both first and second toner layers (10 and 20 respectively) ranging from low to high levels for various combinations of fusing process condition setpoints. The patches are then tested for scratch-off so as determine the maximum mass laydown of first toner layer 10 as a function of the ratio of first and second toner thermal conductivity, second toner layer 20 mass laydown, and fusing process condition setpoints. This information may be stored in LCU 230 in the form of a lookup table (LUT) enabling determination of acceptable toner laydown for each of the tiers so as to provide the scratch-off capability. The maximum mass laydown functional dependence is used to determine the maximum mass laydown allowable for second and third tiers 11 and 14 for a given mass laydown of second toner layer 20 so as to have good adhesion to substrate 2. First tier 13 is then given a mass laydown in excess of this maximum, again for a given mass laydown of second toner layer 20, so as to have poor adhesion to substrate 2 and therefore enable the scratch-off functionality.
Toner particles having a lower thermal conductivity can be prepared by the direct addition of low thermal conductivity additives in the toner formulation during the melt compounding process or during the formation of the toner particles via chemical methods such as Limited Coalescence, Emulsion Aggregation (EA) or Suspension Polymerization. The reduced thermal conductivity materials can be solid or can be present inside the toner in the form of holes or pores. It is also possible to use toner additives having a flat platelet-like structure with the thermal conductivity in the normal direction of the plate being at least 5 times lower than the thermal conductivity in the planar direction of the flakes. One example of such a material is natural mica having a thermal conductivity in the planar direction 10 times higher than the thermal conductivity in the normal direction. There are many other low thermal conductivity materials that can be incorporated in the first or second toner particles. A partial list of some of these low thermal conductivity materials is summarized in Table 1. One experienced in this field would recognize that many other types of low thermal conductivity additives can be used for this purpose. There is a strong inter-relationship between the additive type (thermal conductivity), additive loading by weight amount, and fusing conditions (for example, fusing temperature and dwell time). The loading of these additives into a toner formulation typically range from 10% to 40% by weight. For comparison purposes, the thermal conductivity of binders used in toner compositions typically range from 0.30 to 0.70 W/(m-° K) and more commonly between 0.4 to 0.5 W/(m-° K).
Referring to
It is also noted that the height difference as shown
After scratching off the first tier 13 (
It is noted for clarity that the first toner layer 10 and second toner layer 20 are deposited as described above by having the LCU 230 (See
In an alternative embodiment, also represented by
Referring to
Referring to
Referring to
In another embodiment of the indicia image 75, the indicia image 75 is printed and fixed on the substrate 2 before applying the first toner layer 10, and the first tier 13 is in registration with the printed indicia image 75 as before. However, in this embodiment, the first toner layer 10 is rendered more thermally insulating by the addition of one or more suitable additives into the first toner particles. For this case, first tier 13 is deposited in excess of 1.0 mg/cm2 in order to be removable.
Referring to
Another embodiment utilizing an inverse mask laydown of the second toner layer 20 is the case where the first toner layer 10 is formed by first toner particles having a significantly lower thermal conductivity as compared to the second toner particles, and the second toner layer 20 is deposited on the first toner layer 10 in an inverse mask in which the second toner layer 20 is in inverse proportion to the first toner layer 10, then the removable portions will be those having the thicker first toner layer 10, preferably in excess of 1.0 mg/cm2, and therefore, the thinner second toner layer 20. For example, referring again to
In yet another embodiment, an indicia image 75 (as shown in
In yet another embodiment, an indicia image 75 (as shown in
Uniform toner patches were prepared on a NexPress SE3000 Digital Color Production Press using standard CYMK toners in printing modules M1-M4 and a toner with reduced thermal conductivity additive in Printing Module M5. Prints were made on a Sterling Ultra Digital Gloss coated paper (118 gsm) at a speed of 83 ppm, fusing at a temperature of 163° C. and a dwell time of 0.050 sec. Color patches of various mass laydowns using the standard toners in printing modules M1-M4 were deposited and fused and subsequently tested for scratch off. For comparison, color patches of various mass laydowns using the standard toners in printing modules M1-M4 were deposited with various mass laydowns of the inventive toner deposited over the color patches and fused simultaneously. The composite images were again tested for scratch-off performance. The scratch-off results for the images are summarized below in Table 2.
The results in Table 2 show that when first toner layer 10 is greater than or equal to 0.60 mg/cm2 and the second toner layer exceeds 0.60 mg/cm2, preferably exceeding 1.0 mg/cm2, the image can be removed easily using various techniques. However, when either first toner layer 10 or second toner layer 20 fails to meet the minimum mass laydown requirements, the image was found to be well fused and could not be scratched off or easily removed by other means.
The present invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
Reference is made to commonly assigned U.S. patent application Ser. No. ______ (Docket K001499) filed concurrently herewith by Zaretsky et al, entitled “A Scratch-Off Document Having Layers of Different Thermal Conductivity,” the disclosures of which are herein incorporated by reference.