This invention relates generally to laser printing from a printer or a copier wherein added security features are provided to a printing medium such as laser toner.
Over the past decade there have been many introductions of anti-fraud technologies to protect products and documents from counterfeiting or digital replication, and to assist in providing simple verification of authenticity. Many of these technologies require the use of sophisticated and costly equipment to be implemented and can not be altered if the user wishing protection so chooses, as one might change one's password. For example, coating a document or article with a color shift coating often requires that article to be placed in vacuum deposition chamber so be successfully coated. The equipment is costly and the set up time to print a batch of articles is considerable.
Of course labels having security features manufactured into or upon the label can be adhesively mounted to a document or article, however such labels visible to counterfeiters are often copied, and often these counterfeits pass scrutiny without question. Furthermore, in some instances labels can be peeled off and reused on other documents or packages fooling the public into thinking that the article is genuine.
This invention provides an affordable solution offering substantial security to laser printed documents, heretofore not known.
Laser printers are ubiquitous and using a laser printer or copier requires very little skill. With the press of a button, a user can request a document on his or her computer be printed. Millions of individual users have laser printers, laser copiers, or multi-function laser printer-copiers coupled to their personal or work computers. These laser printers and copiers use laser toner that is specifically formulated and housed in a cartridge customized to fit within the particular printer or copier. Many of these laser printer/copier cartridges are refillable and can therefore be refilled and reused a number of times. Over the years, laser printing has evolved and toners have also; one can now purchase color laser printers having toners in a plurality of colors capable of printing a colored image. Those involved in improving laser printers have been able to manufacture printers with higher resolution capabilities, printing a greater number of pages per minute and with toners that are more robust, and with the ability to print on both sides of the page. Notwithstanding, laser printer functionality has not evolved far beyond this.
The present invention relates in general to a toner composition. More specifically, the present invention relates to a toner composition having an external additive with specific characteristics present, preferably in a specific ratio in the form of covert taggents, useful in verifying the authenticity of the printed document. For example, some classified documents or documents that serve as passes or entry to restricted areas often need to be authenticated. Once this laser toner is used to print a document, the taggents hidden with the printed document to the human eye are visible with magnification so that a document's authenticity can be verified. There are an infinite number of different taggent designs that can be used thereby increasing the level of security. Furthermore different taggent combinations can be used together increasing the level of security.
In recent years, electrophotographic image forming apparatuses such as laser printers, fax machines, and copiers have been widely used to obtain the benefit of high-speed operation and high quality images thereof.
Numerous US patents describe the laser printing process, for example descriptions can be found in U.S. Pat. No. 4,847,652, U.S. Pat. No. 4,685,793 and U.S. Pat. No. 4,174,170, incorporated herein by reference for all purposes.
In some other printers, the charges may be reversed. In this instance, a positive charged electrostatic image is created on a negative background.
In some current more advanced printers, the paper is strongly electro-statically charged to assure an adequate pull and transfer of the particles of toner from the image drum. To fix the toner within the paper, the paper passes between heated rollers or fuser. The heat and pressure applied by the rollers melts the toner so that it fuses with the fibers of the paper.
In a related printing technology, magneto-graphic printing, the photoconductor and toners are magnetic. The drum is charged, imaged, and toned for the first impression and recharged and toned for succeeding impressions.
A detailed explanation of laser printing can be found in the internet at the following Internet sites:
http://computer.howstuffworks.com/laser-printer.htm
http://en.wikipedia.org/wiki/Laser_printer
Laser toner, in a standard black-and-white laser printer, is a mixture of carbon, polymeric resins (styrene acrylate or polyester resin), additives for controlling the electrostatic properties, fluidizing and lubricant agents, etc. In operation, when printing, the polymer of the toner particles is melted by the fuser causing the carbon particles to stick to the paper or medium upon which the image is to be printed. Colored pigments are used for cyan, magenta, and yellow for color laser toners and magnetic iron oxide particles are used for magnetic toners. Particle size, shape and distribution are a very important and influence the flow and the electrostatic properties of the toner.
Early laser printers used toners with a particle size in the range of 14-16 microns. However more current state-of-the-art laser printers have a reduced average toner particle size to approximately 8 microns, thus improving the image resolution to about 600 dots per inch.
Optimal image quality is dependant to a large extent on providing laser toner particles with narrow size distributions, i.e. centered around a mean diameter of 8 μm-10 μm, and particles which have narrow shape distributions, i.e. being substantially similar in shape, and ideally having a cross-section that is circular or square, and pixel-like.
In accordance with this invention, we have produced shaped, and, or symboled flakes or manufactured structures to add to laser toner or binder with sizes similar to the average particle sizes of typical toners. Advantageously these flakes or structures can easily be seen with magnification and the print can be verified as being authentic if the expected symbols or shaped structure are present.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Exemplary embodiments of the invention are described in the drawings in which:
a is a microphotograph of a laser printed image magnified wherein laser toner particles and charms can be seen.
b is a microphotograph of a single laser toner charm of dimension 24×24 microns, magnified.
In accordance with the invention a medium for laser printing is provided, comprising:
a binder suitable for binding particles to a substrate; and
a first plurality of optical effect structures within the binder sized to be suitable for laser printing, wherein said flakes are discernable upon viewing with magnification.
The optical effect structures may be flakes or wherein the flakes are generally planar flakes comprising one or more layers of material, however these flakes may have embossing therein or patterns thereon forming diffraction gratings or forming logos or other indicia that can be seen with magnification but that cannot be seen without magnification. Alternatively other man-made structures can be provided such as pyramidal-like structures or discs.
In accordance with another aspect of the invention a kit is provided comprising laser toner and optical effect flakes for combining to form laser toner having security features therein.
This invention is capable of using a typical commercially available printer or copier/printer and providing an enhanced security to a printed document. Simple inspection with a magnifying loop allows otherwise hidden printed charms within a document to be seen thereby providing some authentication of the printed document.
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In a first embodiment of this invention, non-randomly shaped manufactured structures in the form of flakes having a dimension of approximately 10 microns in size are added to a conventional fine particle dry toner in a concentration of approximately 0.1%. This mixture is placed within a laser toner cartridge and is printed on a document using standard printer commands.
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This invention also provides the flexibility of adding one's personal taggents to standard laser printer toner, buy filling a cartridge with a standard or specialized toner and adding a particular taggent or amount of taggent flakes to the toner.
In yet another embodiment, other structures such as micro-pyramidal, or other shaped micro-structures having dimensions of about 10 microns can be added to laser toner and can be printed with the toner on a document. Although in preferred embodiments of this invention, flakes having a predetermined, same shape are used, the invention is not limited to planar flake-like structures. Diffractive planar-like structures can be added to the toner as well, wherein substantially planar flakes having diffractive structures therein or thereon may be used.
The present invention claims priority from U.S. Patent Application No. 61/028,442 filed Feb. 13, 2008, entitled “Microstructured Covert Taggants On Electrophotographic And Magnetographic Toner Laser Printing”, by Argoitia et al., which is incorporated herein by reference for all purposes.
Number | Date | Country | |
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61028442 | Feb 2008 | US |