Patent Abstract:
A physical unclonable function (PUF) located on a supply item for an imaging device is disclosed. The PUF has a toothed rack configured to mate with a gear. During reading operations, the gear turns and translates the PUF linearly under a magnetic sensor. This configuration is inexpensive and robust. Other devices are disclosed.

Full Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation-in-part of Ser. No. 14/879,199 filed Oct. 9, 2015 and claims priority to it. The following applications are related and were filed contemporaneously: “INJECTION-MOLDED PHYSICAL UNCLONABLE FUNCTION”, “ELONGATE PHYSICAL UNCLONABLE FUNCTION”, “PHYSICAL UNCLONABLE FUNCTION ON A SUPPLY ITEM”, and “TOOTHED-RACK PHYSICAL UNCLONABLE FUNCTION”. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to anti-counterfeit systems and more particularly to physical unclonable functions. 
     2. Description of the Related Art 
     Counterfeit printer supplies, such as toner bottles, are a problem for consumers. Counterfeit supplies may perform poorly and may damage printers. Printer manufacturers use authentication systems to deter counterfeiters. Physical unclonable functions (PUF) are a type of authentication system that implements a physical one-way function. Ideally, a PUF cannot be identically replicated and thus is difficult to counterfeit. Thus, it is advantageous to maximize the difficulty of replicating a PUF to deter counterfeiters. It is also advantageous for the PUF and PUF reader to be low cost, robust, and repeatable. 
     SUMMARY 
     The invention, in one form thereof, is directed to a supply item for an imaging device having a body; and a PUF having magnetic particles in a non-magnetic substrate having a toothed rack having a longitudinal axis, the PUF is held captive to the body and constrained to move linearly at least ten millimeters relative to the body parallel to the longitudinal axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the present disclosure. 
         FIG. 1  is a block diagram of an imaging system including an image forming device according to one example embodiment. 
         FIG. 2  is a side view of an elongate PUF. 
         FIG. 3  and  FIG. 4  are isometrics views of an imaging device supply item having the elongate PUF. 
         FIG. 5  and  FIG. 7  are isometric views of an imaging device supply item having a toothed-rack PUF. 
         FIG. 6  is a top view of the toothed-rack PUF. 
         FIG. 8  is a flowchart of a method of manufacturing a PUF. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
     Referring to the drawings and particularly to  FIG. 1 , there is shown a block diagram depiction of an imaging system  50  according to one example embodiment. Imaging system  50  includes an image forming device  100  and a computer  60 . Image forming device  100  communicates with computer  60  via a communications link  70 . As used herein, the term “communications link” generally refers to any structure that facilitates electronic communication between multiple components and may operate using wired or wireless technology and may include communications over the Internet. 
     In the example embodiment shown in  FIG. 1 , image forming device  100  is a multifunction device (sometimes referred to as an all-in-one (AIO) device) that includes a controller  102 , a user interface  104 , a print engine  110 , a laser scan unit (LSU)  112 , one or more toner bottles or cartridges  200 , one or more imaging units  300 , a fuser  120 , a media feed system  130  and media input tray  140 , and a scanner system  150 . Image forming device  100  may communicate with computer  60  via a standard communication protocol, such as, for example, universal serial bus (USB), Ethernet or IEEE 802.xx. Image forming device  100  may be, for example, an electrophotographic printer/copier including an integrated scanner system  150  or a standalone electrophotographic printer. 
     Controller  102  includes a processor unit and associated memory  103  and may be formed as one or more Application Specific Integrated Circuits (ASICs). Memory  103  may be any volatile or non-volatile memory or combination thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory and/or non-volatile RAM (NVRAM). Alternatively, memory  103  may be in the form of a separate electronic memory (e.g., RAM, ROM, and/or NVRAM), a hard drive, a CD or DVD drive, or any memory device convenient for use with controller  102 . Controller  102  may be, for example, a combined printer and scanner controller. 
     In the example embodiment illustrated, controller  102  communicates with print engine  110  via a communications link  160 . Controller  102  communicates with imaging unit(s)  300  and processing circuitry  301  on each imaging unit  300  via communications link(s)  161 . Controller  102  communicates with toner cartridge(s)  200  and non-volatile memory  201  on each toner cartridge  200  via communications link(s)  162 . Controller  102  communicates with fuser  120  and processing circuitry  121  thereon via a communications link  163 . Controller  102  communicates with media feed system  130  via a communications link  164 . Controller  102  communicates with scanner system  150  via a communications link  165 . User interface  104  is communicatively coupled to controller  102  via a communications link  166 . Processing circuitry  121  and  301  may include a processor and associated memory such as RAM, ROM, and/or non-volatile memory and may provide authentication functions, safety and operational interlocks, operating parameters and usage information related to fuser  120 , toner cartridge(s)  200  and imaging unit(s)  300 , respectively. Controller  102  processes print and scan data and operates print engine  110  during printing and scanner system  150  during scanning. 
     Computer  60 , which is optional, may be, for example, a personal computer, including memory  62 , such as RAM, ROM, and/or NVRAM, an input device  64 , such as a keyboard and/or a mouse, and a display monitor  66 . Computer  60  also includes a processor, input/output (I/O) interfaces, and may include at least one mass data storage device, such as a hard drive, a CD-ROM and/or a DVD unit (not shown). Computer  60  may also be a device capable of communicating with image forming device  100  other than a personal computer such as, for example, a tablet computer, a smartphone, or other electronic device. 
     In the example embodiment illustrated, computer  60  includes in its memory a software program including program instructions that function as an imaging driver  68 , e.g., printer/scanner driver software, for image forming device  100 . Imaging driver  68  is in communication with controller  102  of image forming device  100  via communications link  70 . Imaging driver  68  facilitates communication between image forming device  100  and computer  60 . One aspect of imaging driver  68  may be, for example, to provide formatted print data to image forming device  100 , and more particularly to print engine  110 , to print an image. Another aspect of imaging driver  68  may be, for example, to facilitate the collection of scanned data from scanner system  150 . 
     In some circumstances, it may be desirable to operate image forming device  100  in a standalone mode. In the standalone mode, image forming device  100  is capable of functioning without computer  60 . Accordingly, all or a portion of imaging driver  68 , or a similar driver, may be located in controller  102  of image forming device  100  so as to accommodate printing and/or scanning functionality when operating in the standalone mode. 
     Several components of the image forming device  100  are user replaceable e.g. toner cartridge  200 , fuser  120 , and imaging unit  300 . It is advantageous to prevent counterfeiting these user replaceable components. A PUF  202  may be attached to the toner cartridge  200  to prevent counterfeiting as described below. A PUF reader  203  may be integrated into the image forming device  100  to verify the authenticity of the PUF  202 . Data related to the PUF  202  may reside in non-volatile memory  201  and is preferably encrypted. This data may be generated at the time of manufacture by measuring the PUF  202  at the factory. The non-volatile memory  201  is preferably located on the supply item along with the PUF  202 . To verify the authenticity of the PUF  202 , the image forming device  100  measures the magnetic field generated by the PUF  202  in one or more directions along a measurement path and compares these measurements to data in the non-volatile memory  201 . 
       FIG. 2  shows a PUF  210  next to a magnet  212 . The PUF  210  is elongate and has a longitudinal axis  214 . The PUF  210  contains a plurality of magnetized particles  216  each having a volume less than one cubic millimeter. The magnetized particles  216  may be, for example, flakes of an alloy of neodymium, iron and boron (NdFeB). The magnet  212  is located on the longitudinal axis  214  and is separated from the PUF  210  by a distance D. Preferably, the magnet  212  has a volume of at least five cubic millimeters so that the magnet&#39;s magnetic field is much greater than the magnetic field of a particle  216 . 
     The PUF  210  may be read by moving a magnetic sensor along the longitudinal axis  214 . The magnetic sensor will have a much higher reading when positioned over the magnet  212  and thus the magnet  212  designates a home position from which readings of the PUF may be referenced spatially. Preferably, the distance D is five millimeters or less to minimize the overall travel of the positioning mechanism of the magnetic sensor to reduce cost. Preferably, the PUF  210  and magnet  212  are mounted to a planar surface, the magnetic sensor measures orthogonal to the surface, the magnet has a magnetic pole orientation that is orthogonal to the surface, and the majority of the particles  216  have a magnetic pole orientation that is not orthogonal to the body surface. This is to maximize the difference between measurements of the magnet  212  and the particles  216  to give a clear home position signal. The magnetic sensor may measure along multiple orthogonal directions. 
     Preferably, the magnet  212  has multiple north poles  218 ,  220  and south poles  222 ,  224  that alternate in polarity along the longitudinal axis of the PUF. The magnet  212  may be fabricated by joining discrete magnets having alternating poles into one magnet. The alternating poles limits the magnetic field seen by the particles  216  and thus limits the effect of the magnet  212  on the particles  216 . This allows the magnet  212  to be placed near the PUF  210  without disturbing the signature of the PUF  210 . 
       FIG. 3  shows an imaging device supply item  300 , for example a toner bottle, with the PUF  210  and magnet  212  located on a surface  310  of a body  312  located on the back side  314  of the body  312 . The PUF  210  and magnet  212  may be used by an imaging device to verify the authenticity of the supply item  300 . 
       FIG. 4  shows the front side  410  of the body  312  including a handle  412  located on the front side  410 . The handle  412  is configured to pivot about a pivot axis  414  that is parallel to the PUF longitudinal axis  214 . The pivot axis  414  is parallel to the longitudinal dimension of the body  312 , which allows a larger, and thus easier to use handle  412  than if the handle was rotated ninety degrees. Similarly, the PUF longitudinal axis  214  is parallel to the longitudinal dimension of the body  312 , which allows a longer and thus more difficult to clone PUF. It is preferential to locate the PUF  210  on the back side  314  so the magnetic sensor may be protected by being as far from the user as possible. Also, the magnetic sensor may be spring biased toward the PUF  210  to insure proper gap spacing for accurate measurements without being in the insertion path of the imaging device supply item  300 . 
       FIG. 5  shows an imaging device supply item  500  having a PUF  510  slidably attached to a body  512  by a pair of snaps  514 ,  516 . At least one face  518  of the PUF  510  contains magnetic particles as described previously. 
       FIG. 6  shows a top view of the PUF  510 , snaps  514 ,  516 , and a spring  520 . The PUF  510  has a toothed rack  522  having a longitudinal axis  524 . The PUF  510  has slots  526 ,  528  that, together with the snaps  514 ,  516 , constrain the PUF  510  to move linearly relative to the body  512  parallel to the longitudinal axis  524 . 
     An imaging device reads the PUF  510  using a stationary magnetic sensor. The PUF  510  is moved linearly by mating a gear with the teeth of the toothed rack  522  and turning the gear. Preferably, the PUF moves at least ten millimeters to read a sufficient length of the PUF  510  to make it difficult to counterfeit the PUF  510 . It is preferable to use a stationary magnetic sensor to reduce cost. The PUF  510  is returned to a home position, e.g. against the snaps  514 ,  516 , by the spring  520 . 
       FIG. 7  shows another view of the supply item  500 . A handle is located on the front side  712  of the body opposite the PUF  510  located on the back side  714  of the body. The insertion path of the supply item  500  is defined by rails  716  that run front-to-back. Thus, it is preferable to locate the PUF  510  on the back side  714  to simplify mating with the gear used to move the PUF  510 . 
       FIG. 8  shows a flowchart of a method of manufacturing a PUF. The method  800  uses an injection molding machine to make an injection-molded PUF. As is known in the art, injection molding machines heat feed material until it is molten and then forces the feed material through a nozzle into a mold cavity. Once the material is cooled enough to harden, the injection molded part is ejected from the injection molding machine. 
     At block  810 , feed material is obtained containing plastic and magnetizable flakes that are not magnetized. The plastic may be, for example, a thermoplastic, a thermosetting polymer, etc. The magnetizable flakes may be, for example, an alloy of neodymium, iron and boron. Other magnetizable particles may be used, for example, spheres, rods, etc. Preferably, the feed material contains between ten and twenty percent, inclusive, by weight magnetizable flakes to maximize the variability in the magnetic signature of the PUF while maintaining good flow within the mold. 
     At block  812 , the flakes are magnetized. Alternatively, feed material may be used that contains pre-magnetized flakes. It is preferable to magnetize the flakes after they are enveloped by the plastic to prevent the flakes from clumping together. 
     At block  814 , the feed material is fed into an injection molding machine. The feed material may be fed as solid pellets containing plastic and magnetic material, pellets containing plastic as well as pellets containing both plastic and magnetic material, etc. 
     At block  816 , the magnetized alloy is heated to below its Curie temperature. It is necessary to heat the feed material so that it will flow into the mold. However, it is preferable to avoid heating the magnetized alloy to above its Curie temperature to avoid degrading the magnetic fields generated by the magnetic particles. 
     At block  818 , the feed material is formed into an injection-molded PUF. For example, the feed material may be forced through one or more nozzles into a mold cavity. The turbulent flow of the feed material through the nozzle and through the mold cavity creates a random distribution and orientation of the magnetic particles, which creates a highly random magnetic signature for each PUF. The random magnetic signature makes it very difficult to reproduce a PUF. This process may economically produce the toothed-rack PUF  510  described above. 
     The foregoing description illustrates various aspects and examples of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.

Technology Classification (CPC): 6