Abstract:
An anticounterfeit detector (ACD) does both a high and low resolution scan of a document. The video signal resulting from the low resolution scan is used to detect a selected type of image, e.g., currency, negotiable securities, etc., by using ACD hardware or software. A corrective action is taken, e.g., preferably even partial printing from the high resolution scan is prevented, the video signal is invalidated, etc., if the selected image is detected. The low resolution signal can also be obtained by decimating or low pass filtering the high resolution signal.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority from U.S. application Ser. No.: 09/725,397, filed Nov. 29, 2000. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to anti-counterfeit detection (ACD) of currency or negotiable securities, and more particularly, to such detection as used in xerographic, ink jet, etc., copiers and printers. 
     2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
     ACD hardware and software is known from U.S. Pat. No. 5,533,144, hereby incorporated by reference. 
     In copiers, printers, and facsimile machines which have a high resolution scanner, the scanner provides a quick first copy out time by allowing scanning and printing at the same time. In such machines, providing ACD, while at the same time maintaining quick first copy out time, can be expensive. In particular, in order to accomplish this, internal buffers will have to be maintained which capture the high resolution data. These size of these buffers will be dictated by the amount of data needed by the ACD algorithms. There also exists the problem of partially printing currency by these machines before it is detected. 
     It is therefore desirable to have methods and apparatus for performing ACD which also allows quick first page out time. 
     BRIEF SUMMARY OF THE INVENTION 
     A process comprises obtaining a high resolution image signal of an object, obtaining a low resolution image signal of said object, and performing a corrective action if the low resolution signal represents a selected type of image. 
     An apparatus comprises a source of a high resolution image signal of an object, a source of a low resolution image signal of said object, and a corrector for performing a corrective action if the low resolution image signal represents a selected type of image signal. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
     FIG. 1 is a block diagram of an embodiment of the invention; and 
     FIG. 2 is a flow chart of the operation of FIG.  1 ; 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an embodiment, wherein a document  100  is disposed on a platen (not shown) of a scanner  102 , which scanner can be a stand alone one or part of a system, e.g., xerography apparatus. Disposed within scanner  102  is both an added low resolution imager  108 , e.g., a digital cameral for imaging the platen, and a normally present high resolution imager  109 , e.g. a CCD device, which images only a small portion of platen  107  at a time. Signals from both imagers  108  and  109  are provided to a printer  106 , which can be, e.g., a local printer, a network printer, etc. This printer  106  can be an independent printer or be a part of a xerographic or non-xerographic copier, e.g., ink jet, or facsimile (fax) machine. Alternatively, the high resolution signal can be obtained from a remote analog or digital source received at input port  140 . Then the low resolution signal can be obtained by low pass filtering (analog source) or decimating (digital source) the high resolution signal. 
     The details of printer  106  are substantially the same as shown in U.S. Pat. No. 5,991,201. An image processor  114  receives signals from scanner  102  or front end  140  and generates a color image. Digital signals which represent the blue, green and red density signals of the image are converted in the image processing unit into four bitmaps: yellow (Y), cyan (C), magenta (M), and black (K). The bitmap represents the values of the exposure required for each color component of the pixel. Image processor  114  may contain a low pass filter, a decimator a shading correction unit, an undercolor removal unit (UCR), a masking unit, a dithering unit, a gray level processing unit, and other imaging processing sub-systems known in the art. The image processor  114  can store bitmap information for subsequent images or can operate in a real time mode. 
     At stage A, toner of a first color is formed on either a belt or drum  116 . The photoconductive member is preferably a drum of the type which is typically multilayered and has a substrate, a conductive layer, an optional adhesive layer, an optional hole blocking layer, a charge generating layer and a charge transport layer (none shown). The drum is charged by charging unit  101 . Raster output scanner (ROS)  120 , controlled by image processor unit  114 , writes a first color image by selectively erasing charges on the drum  116 . The ROS  120  writes the image information pixel by pixel. It should be noted that either discharged area development (DAD) can be employed in which discharged portions are developed or charged area development (CAD) can be employed in which the charged portions are developed with toner. After the electrostatic latent image has been recorded, drum  116  advances the electrostatic latent image to development station  103 . Dry developer material is supplied by development station  103  to develop the latent image. In the case of CAD development, the charge of the toner particles is opposite in polarity to the charge on the photoconductive surface, thereby attracting toner particles thereto. The latent image is developed with a less than monolayer coverage of toner particles. On the average, the uniformity of the development is such that toner particles are near neighboring toner particles. Development station  103  employs small size toner, preferably having average particles size of about 5 μm. 
     The developed image is electrostatically transferred to the compliant, low surface energy intermediate member  110  by applying an electrical bias between the drum  116  and intermediate member or belt  110 . Any residual toner on the drum  116  is removed with a cleaner  104 . Intermediate member  110  may be either a roll or an endless belt with a conductive substrate and a compliant overcoat. The path of the belt is defined by a plurality of internal rollers. An optional plurality of heating elements  132  are in close proximity to the toned image such that the heat causes the toner particles present on the surface to soften. The softened toner particles pass through a film layer formation station  130 . Station  130  includes a heated roller (not shown) which is in contact with the softened toner image and a backup pressure roll (not shown) behind intermediate member  110 . Filming station  130  spreads the softened toner particles into a thin film so that the small gaps between neighboring toner particles are covered with toner without degradation of the image. The toner flow required is very small to cover the spaces between the toner particles. Ideally, the film forming station should form a film of the desired thickness (about 1 μm) regardless of the local toner coverage. One possible way of achieving this is to make the heated roller self-spaced from the intermediate belt  110  at the desired thickness. One method for achieving this requirement would be to utilize a gravure-type roll for the heated roller not shown). 
     At stage B illustrated in FIG. 1, formation of a second color takes place in the same manner as described above. The drum  116  is charged with charging unit  101 , and then it is exposed by ROS  120  according to second color image bitmap information. After the electrostatic latent image has been recorded, drum  116  advances the electrostatic latent image to development station  103 . Dry developer material with toner of the second color is supplied by development station  103  to develop the latent image. 
     The developed image is electrostatically transferred to the intermediate member  110  by an electrical bias voltage between drum  116  and belt  110 . (Any residual toner on drum  116  is cleaned by cleaner  104 ). The developed second color image is superimposed on the previous first color image. Heat from the optional heater  132  softens the toner particles. The softened toner particles on the intermediate member  110  pass through the heated filming station  116 , which spreads the softened image into a thin film without degradation of the image. 
     The process is repeated for the next two colors at stages C and D. A multi-layer film image is formed by superimposing black, yellow, magenta, and cyan toners. The full color advances to transfusing stage E. 
     At transfuse nip  134  illustrated in FIG. 1, the multi-layer full-color film image is transfused to the recording sheet or paper  126  by the application of heat and pressure between a heated roll  135  behind the intermediate belt  110  and a backup pressure roll  136  behind the recording sheet. Moreover, recording sheet  126  may have a previously transferred toner image present on the back surface thereof as the result of a prior imaging operation, i.e. duplexing. As the recording sheet  126  passes through the transfuse nip  134 , the multi-layer toner film adheres to the surface of the recording sheet  126 , and due to greater attractive forces between the paper  126  and toner film, as compared to the attraction between the toner film and the low surface energy surface of the compliant intermediate member  110 , the multilayer toner film is transferred to the recording sheet  126  as a full-color image. The transfused image becomes permanent once it advances past the transfuse nip  134  and is allowed to cool below the softening temperature of the toner materials. The cycle for forming another document is initiated following the cleaning of any residual toner from the intermediate belt  110  by cleaner  106 . 
     Normally within the scanner  102  or image processor  114  is software performing the operation as shown in FIG.  2 . The first step  200  is the user placing the document  100  on platen  107 . Other image acquisition methods, e.g., the user placing sheets on a feeder apparatus (not shown), etc., can be used. In particular, as shown by step  201 , a digital document signal enters through a digital front end, e.g., front end  140 . Then the user selects COPY or FAX by clicking on the appropriate icon (not shown) as shown by step  202 . The low resolution imager  108  quickly provides signals representative of the entire platen at step  208 . As shown at step  209 , if the document entered through a front end, the low resolution image is quickly generated by decimation (digital signal) or low pass filtering (analog signal). The hardware or software for performing this can be in imager processor  114 . Then at step  210  ACD analysis is done by e.g., as shown said U.S. Pat. No. 5,533,144, hereby incorporated by reference. Any other ACD hardware or software devices and methods can be used. Simultaneous with the above-described steps, and just after step  206 , a COPY or FAX function is begun at step  204  using high resolution data, which is at a slower data rate than the low resolution data rate from low resolution imager  108  or from the decimator or low pass filter. This is sent to process step  214  as is the ACD results as indicated by step  212 . Process step  214  prepares the document for printing after the appropriate image processing has been applied. Appropriate image processing could include scaling, halftoning, color correction, etc. and the results are sent to decision step  216  where it is determined if currency and/or negotiable securities, etc., are detected. If YES, then the video data is invalidated at step  218 , preferably before even partial printing of currency occurs. This causes printer  106  to not properly print, e.g. to print “INVALID”, print in only one color, completely stop printing, etc. If no currency has been detected, then the printer prints document  100  as indicated by step  220 . 
     It will be appreciated that by adding an inexpensive low resolution imager  108  to scanner  102 , it is possible to quickly perform ACD, thereby preventing even partial printing of currency. This quickness is due to the fact that there is less data from the low resolution imager  108  than from high resolution imager  109  and also that the ACD software does not require high resolution data. 
     While the present invention has been particularly described with respect to preferred embodiments, it will be understood that the invention is not limited to these particular preferred embodiments, the process steps, the sequence, or the final structures depicted in the drawings. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention defined by the appended claims. In addition, other methods and/or devices may be employed in the method and apparatus of the instant invention as claimed with similar results.