Abstract:
A method of identifying a component of a system, the component including an RFID tag, and the system including a reader to read a signal transmitted by the RFID tag, the method including: varying an angular position of the component relative to the reader, taking readings of the strength of the signal transmitted by the RFID tag at a plurality of angular positions of the component, storing signal strength values at the plurality of angular positions of the component, and comparing the stored signal strength values versus angular position of the component relative to the reader with expected signal strength values versus angular position of the component relative to the reader to identify whether the component is an expected component.

Description:
BACKGROUND 
       [0001]    This invention relates to a method of identifying a component of a system, in particular, but not exclusively to a method for identifying a component of a printing apparatus, and combination of a system and a component, including an identification apparatus, in particular, but not exclusively to a combination including a printing apparatus and a printing consumable. 
         [0002]    It is known to fit RFID (Radio Frequency Identification) tags to items of hardware, for example, the consumables of printers, for identification purposes. U.S. Pat. No. 7,664,257 and 6,099,178 disclose such a procedure, for example. These RFID tags can carry information about the items. An RFID tag contains a memory chip, a wireless interface circuit and a transmitter/transceiver. Another item, for example a printer, is fitted with a wireless interface circuit and an antenna (reader) to communicate with the tag of the item. This arrangement allows the printer to read information from the tag&#39;s memory and, optionally, write data back to the memory. In the example given, the information may be used by the printer to configure itself and optimise its operation with the consumables which are identified by their respective tags. 
       SUMMARY 
       [0003]    Embodiments of the present invention aim to overcome or ameliorate one or more problems associated with the prior art. For example, there is a risk of users fitting incompatible and/or counterfeit supplies, i.e. consumables, to printers which risks damaging the printers. Such users may attempt to provide false information about the consumables by fitting a false RFID tag in front of the printer&#39;s antenna, to ‘deceive’ the printer into identifying an authentic consumable, such that the printer continues to operate despite the use of an incompatible and/or counterfeit consumable. Overcoming or ameliorating the above problem is at least one aim of the present invention. 
         [0004]    In accordance with the present invention, there is provided a method of identifying a component of a system, the component including an RFID tag, and the system including a reader to read a signal transmitted by the RFID tag, the method including: varying an angular position of the component relative to the reader, taking readings of the strength of the signal transmitted by the RFID tag at a plurality of angular positions of the component, storing signal strength values at the plurality of angular positions of the component, and comparing the stored signal strength values versus angular position of the component relative to the reader with expected signal strength values versus angular position of the component relative to the reader (e.g., compare an actual pattern with an expected pattern of signal strength values) to identify whether the component is an expected component. The method can include providing the component and providing the system. 
         [0005]    The method may include the step of identifying the angular position of the component at which the signal strength is at a maximum value. 
         [0006]    A plurality of maximum signal strength values may be identified, the method including determining the largest signal strength value. 
         [0007]    The method may include rotating the component to the angular position at which the maximum signal strength value is identified. 
         [0008]    A plurality of signals may be transmitted by the RFID tag, and the strength of one or more of the plurality of signals may be determined and stored. 
         [0009]    The method may include rotating the component through at least one complete revolution relative to the reader, and preferably through at least two complete revolutions relative to the reader. 
         [0010]    The component may be rotated through at least two complete revolutions relative to the reader, the signal strength values stored in respect of the two complete revolutions are compared with one another to verify the accuracy of the signal strength values. 
         [0011]    The method may include a pause between determining the signal strength value at a current angular position and rotating the component to the next angular position. 
         [0012]    The or each pause may be one of a predetermined duration and randomly generated. 
         [0013]    In the event that the component is not identified as an expected component, the method may include one of reducing the capabilities of the system and preventing operation of the system. 
         [0014]    The system may be a printing apparatus and the component may be a printing consumable. 
         [0015]    The identification of the component may be carried out simultaneously with one or more calibration processes of the printing apparatus. 
         [0016]    According to a second aspect of the invention, there is provided a system including: a component of a printing apparatus, the component including an RFID tag; and the printing apparatus including a reader to read a signal transmitted by the RFID tag; wherein the printing apparatus includes a controller configured to vary an angular position of the component relative to the reader, take readings of the signal transmitted by the RFID tag at a plurality of angular positions of the component, store signal strength values at the plurality of angular positions of the component, and compare the stored signal strength values versus angular position of the component relative to the reader with expected signal strength values versus angular position of the component relative to the reader (e.g., compare an actual pattern with an expected pattern of signal strength values) to identify whether the component is an expected component. 
         [0017]    The controller of the printing apparatus may be configured to rotate the component through at least two complete revolutions relative to the reader, and compare the stored signal strength values with one another to verify an accuracy of the stored signal strength values. 
         [0018]    The component may be a spool of a printing consumable of the printing apparatus, and the controller of the system may be configured to identify the printing consumable concurrently with performing one or more calibration processes of the printing apparatus. 
         [0019]    According to a third aspect of the invention, there is provided a combination of a system and a component of the system, the combination including an identification apparatus, the identification apparatus including a reader which is operable to read a signal from an RFID tag carried by the component, the component being rotatable relative to the reader, and a controller which is operable to control the rotation of the component relative to the reader, and to store signal strength values detected by the reader, wherein the controller is operable to compare the stored signal strength values versus angular position of the component relative to the reader with expected signal strength values versus angular position of the component relative to the reader (e.g., compare an actual pattern with an expected pattern of signal strength values). 
         [0020]    The system may be a printing apparatus and the component may be a printing consumable. 
         [0021]    The printing apparatus may be a thermal transfer printer and the printing consumable may be a spool of printing ribbon. 
         [0022]    The reader may be mounted in the printing apparatus substantially adjacent to a spool mount for receiving a spool of printing ribbon. 
         [0023]    The reader may be positioned adjacent the spool support upon which a take-up spool is mountable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
           [0025]      FIG. 1  is an illustrative view of a printing apparatus including an identification device in accordance with the present invention; 
           [0026]      FIG. 2  is a spool of ribbon for the printing apparatus of  FIG. 1 , including an RFID tag; and 
           [0027]      FIG. 3  is a polar plot showing variation in signal strength S of the RFID tag as the spool of  FIG. 2  is rotated. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  shows a system, which in the present example includes a printing apparatus  10 . The printing apparatus  10  is a thermal transfer printing apparatus, which includes a housing  12 , in or on which is mounted a first spool support  14  and a second spool support  16 . The spool supports  14 ,  16  are spaced laterally from one another. 
         [0029]    A spool of tape  18 ,  20 , in this case inked printer ribbon  22 , is mountable on each of the supports  14 ,  16 . The spools  18 ,  20  are components of the system. In the present example, the spool  18  is depicted as a ‘supply’ spool, i.e. which is supplied bearing a quantity of substantially unused ribbon  22 , and the spool  20  is depicted as a ‘take-up’ spool, i.e. a spool which is supplied substantially empty, such that it is able to receive the ribbon  22  which is unwound from the supply spool  18  during use of the printing apparatus  10 . 
         [0030]    The printing apparatus  10  also includes a plurality of guide members  26  for guiding the ribbon  22  from one spool  18 ,  20  to the other, past a printhead  28 . The printing apparatus  10  would also typically include a platen or roller for guiding a substrate, which would be positioned adjacent the printhead  28 , but which is not shown in the accompanying drawings. It will be appreciated that this construction of the printing apparatus  10  described herein and as shown in the drawings is exemplary only. 
         [0031]    Each of the spool supports  14 ,  16  is independently drivable by a respective motor. Each motor may be a stepper motor. Each of the spool supports  14 ,  16  is rotatable clockwise and anti-clockwise. The printing apparatus  10  includes a controller  24  which is electrically connected to each motor and is operable to control the amount of drive provided by each of the motors, so as to control the angular positions and velocities of the spool supports  14 ,  16 . The position of the controller  24  is unimportant for the purpose of the invention. The controller  24  receives inputs from other components of the printing apparatus  10  as will be explained in detail below. 
         [0032]    The printing apparatus  10  also includes an identification apparatus which includes an antenna (reader)  30  which is operable to read an RFID tag, and to transfer data to the controller  24 . In the present example, the antenna  30  is positioned adjacent the spool mount  16  upon which the take-up spool  20  is mountable. Such positioning is advantageous, as will become apparent; however, it will be appreciated that the antenna  30  may be otherwise positioned, for example near to the spool support  14  upon which the supply spool  18  is mountable. 
         [0033]    One of the spools  18 ,  20  is provided with an RFID tag  32 . In the present example (as shown in  FIG. 2 ), the take-up spool  20  is provided with the tag  32 . The tag  32  is attached to an outer surface of the spool  20 . It will be appreciated that the tag  32  could be positioned elsewhere on or in the spool, or on the ribbon  22 , for example towards a ‘free’ end of the ribbon  22  which would be one of the first portions of ribbon  22  to be transferred from the supply spool  18  to the take-up spool  20  during use of the printing apparatus  10 . As described above, the RFID tag  32  may be a standard RFID tag which includes a memory chip, a transmitter/transceiver and a wireless interface circuit. 
         [0034]    In use, the supply spool  18  is mounted on the first spool support  14 , and take up spool  20  is mounted on the second spool support  16 . The tag  32  which is positioned on the take-up spool  20  is thus located adjacent the antenna  30 . The tape  22  extends in a tape path from the supply spool  18  around the guide members  26 , past the printhead  28 , around further guide members  26 , and on to the take-up spool  20 . 
         [0035]    An identification process is carried out, for example when a new spool  18 ,  20  of ribbon is fitted into the printing apparatus  10 , and/or for example upon start-up of the printing apparatus  10 . 
         [0036]    The identification process includes the tag  32  transmitting a signal from its memory to the antenna  30 . The tag  32  may transmit the signal continuously, or may transmit a plurality of intermittent signals. The identification process also includes rotating at least the spool  18 ,  20  which bears the tag  32 . The spool  18 ,  20  bearing the tag  32  may be rotated through one complete revolution. Since the motors which control the rotation of the spools supports  14 ,  16 , and hence the spools  18 ,  20 , are preferably position controlled motors (e.g. stepper motors), the controller  24  has direct control over an angular position θ of the spool  18 ,  20  bearing the tag  32 . 
         [0037]    As a consequence of the rotational movement of the tag  32 , the proximity of the tag  32  to the antenna  30  will vary. Thus the strength of the signal S received by the antenna  30  from the tag  32  will also vary. The angle of the antenna which is incorporated in the tag  32  relative to the antenna  30  of the printing apparatus (which remains stationary) will vary during rotation of the spool  18 ,  20  to which the tag  32  is attached and hence the coupling between the tag  32  and the antenna  30 , will vary, which will also affect the signal strength S received by the antenna  30 . 
         [0038]    The controller  24  monitors the signal strength S received by the antenna  30 . When the signal strength S is plotted on a polar diagram (as shown in  FIG. 3 ), the signal strength S will show a distinctive pattern, with the maximum signal strength S MAX  occurring when the tag  32  is closest to and substantially parallel with the antenna  30 , and a minimum signal strength S MIN  occurring when the tag is perpendicular the antenna  30 . 
         [0039]    If the spool  18 ,  20  bearing the tag  32  is rotated through more than one revolution, the signal strength pattern should repeat. However, it will be appreciated that if an excessive number of rotations are carried out, and ribbon  22  is transferred from the supply spool  18  to the take-up spool  20 , then attenuation of the signal could be experienced (if the tag  32  is provided on the take-up spool  20 ). 
         [0040]    Once the identification process has been carried out, the controller  24  is able to establish the position of a core of the spool  18 ,  20  bearing the tag  32  which provided maximum signal strength S, and whether there is a tight ‘binding’ or relationship between the angular position θ of the spool  18 ,  20  and the received signal strength S received by the antenna  30 , which verifies that the tag  32  is being rotated by the printing apparatus  10  (i.e. by the motor which controls the movement of the spool support  14 ,  16  upon which the spool  18 ,  20  bearing the tag  32  is mounted). 
         [0041]    The controller  24  may be programmed to randomly alter the speed of rotation of the spool support  14 ,  16  upon which the spool  18 ,  20  bearing the tag  32  is mounted, to provide further validation that the changes in signal strength S are being caused by rotation of the spool, and not as a result of a pre-programmed signal transmission by the tag  32 , for example. 
         [0042]    In more detail, the identification process preferably includes the following steps:
       a) the controller  24  clears any stored values relating to a previous or existing spool;   b) the controller  24  interrogates the wireless interface of the antenna  30  to determine the current signal strength S from the RFID tag  32 —this value is a common output of industry standard wireless controllers;   c) the current signal strength value S is stored by the controller  24 , in a free entry (preferably the next free entry) in a list of stored values in the controller (the ‘list’ may be empty before the first value is stored);   d) the controller  24  controls at least the motor which drives the spool support  14 ,  16 , upon which the spool  18 ,  20  bearing the tag  32  is mounted, so as to rotate the spool  18 ,  20  through a portion of a complete revolution, for example one twentieth of a complete revolution)(18°)—the angle of rotation is determined by the number of data points, i.e. samples, required through one revolution of the spool  18 ,  20 ;   e) the controller  24  may pause, preferably until the spool  18 ,  20  has settled at its new position;   f) the controller  24  repeats steps b) to e) until the spool  18 ,  20  has completed at least two revolutions (it will be appreciated that fewer revolutions may be completed, but two revolutions improves accuracy);   g) the controller  24  scans the resulting list of values to determine the maximum signal strength value(s) S MAX  and the minimum signal strength value(s) S MIN —a maximum value can be detected where the gradient of a slope (dS/dθ) between at least three adjacent/consecutive signal strength values S changes from positive to negative and a minimum value can be detected where the gradient of the slope (dS/dθ) between at least three adjacent/consecutive signal strength values S changes from negative to positive;   h) the maxima S MAX  may be examined to confirm that the two largest values occur one revolution apart (i.e. 20 samples apart in this example);   i) the minima S MIN  may be examined to confirm that the smallest values are half a revolution apart (i.e. 10 samples apart in this example)   j) the controller  24  may control the motor driving the spool support  14 ,  16  on which the spool  18 ,  20  bearing the tag  32  is mounted, to the angular position θ indicated by the highest signal strength value S MAX , in order to facilitate error free communication between the tag  32  and the antenna  30 ;   k) the controller  24  may perform an algorithm to match the signal strength versus rotation pattern with an expected pattern which would be exhibited by tag  32  attached to an authentic and compatible spool  18 ,  20 ;   l) the tag  32  may transmit additional data to the antenna  30 , which includes identification data, which is provided as an input to the controller  24 , such that the controller  24  may ascertain whether the spool  18 ,  20  to which the tag  32  is applied is a spool  18 ,  20  which is compatible with the printing apparatus  10 .       
 
         [0055]    It will be appreciated that not all of the steps above are essential, and that some may be omitted from the identification process. Furthermore, the order of the steps may be modified. 
         [0056]    The pause or time delay at step (e) may be predetermined, and/or may be randomly varied, so as to verify that the signal strength variation is due to rotation of the tag  32  relative to the antenna  30 , rather than a predetermined routine being performed by the tag  32  to deceive the antenna  30 , and hence the printing apparatus  10 . 
         [0057]    The exact pattern of signal strength S versus rotation may be different in different printing apparatus, for example as a result of differences in layout of components, in particular metallic components, within the excitation field of the tag  32 . Therefore, an algorithm responsible for pattern matching (as described in step (k)) may be different for different printing apparatus and/or for different spool types, although the general process of matching an expected pattern to the pattern experienced or achieved would remain as described above. 
         [0058]    Failure to detect a valid signal strength versus angular position pattern can indicate that an incompatible or counterfeit spool  18 ,  20  has been mounted in the printing apparatus  10 , and/or that an attempt to circumvent the identification system has been made. If the controller  24  fails to recognise the spool  18 ,  20  as a compatible spool  18 ,  20 , then the controller  24  may cause the printing apparatus  10  to perform only a subset of activities or may cause the printing apparatus  10  not to operate at all. This reduced level of performance may continue unless and/or until a compatible spool  18 ,  20  is mounted in the printing apparatus  10  and has been identified as such by the identification process. 
         [0059]    Thermal transfer printers, of the type described generally above, typically undertake a calibration process, for example to determine or measure the diameters of each of the spools  18 ,  20 , to allow the controller  24  to match the angular speed of the motor(s) driving the spools  18 ,  20  with the linear speed of the ribbon  22  leaving or entering the or each spool  18 ,  20 . Such a calibration process is described in U.S. Pat. No. 8,665,301. The identification process can be incorporated into such a calibration process (or another type of calibration process carried out by the printing apparatus  10 ) to reduce the impact on a user (for example in terms of time before the printing apparatus  10  is operational). 
         [0060]    Whilst the above example is directed to a printing apparatus and a spool of ribbon/tape, it will be appreciated that the identification apparatus and/or the identification method may be used in relation to other items, in particular items which rotate, or could be caused to rotate relative to a second item. 
         [0061]    The above example has described and shown the antenna  30  being positioned adjacent the take-up spool support  16  and the tag  32  being preferably provided on the take-up spool  20 . Advantages of this are that the tag  32  could be damaged during the manufacturing process of the spools  18 ,  20  if the tag  32  were to be positioned on the supply spool  18 . Furthermore, if the tag  32  were positioned on the body of the supply spool  18 , or at the end of the ribbon  22  closest to the body of the supply spool  18 , there is the possibility of the windings of the ribbon  22  around the supply spool  18  causing attenuation of the signal received by the antenna  30 , and false negative results being experienced, for example. 
         [0062]    When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 
         [0063]    The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.