Patent Publication Number: US-2021166363-A1

Title: Information processing apparatus, control method for information processing apparatus, image forming system, and non-transitory computer-readable storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2019-217617, filed on Nov. 29, 2019, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Embodiments of the present disclosure relate to an information processing apparatus, a control method for the information processing apparatus, an image forming system, and a non-transitory computer-readable storage medium storing computer-readable program code that causes the information processing apparatus to perform the control method. 
     Related Art 
     When a conveying device such as a conveyance roller conveys media in a typical image forming apparatus, the amount of conveyance of the media may fluctuate depending on, e.g., how the conveying device is attached, the eccentricity of the conveying device, and the characteristics of the media. 
     SUMMARY 
     In one embodiment of the present disclosure, a novel information processing apparatus includes circuitry. The circuitry is configured to acquire, as a first image, a read image of an image formed on a medium. The circuitry is configured to generate, as a second image, an image to be compared with the first image, based on document data. The circuitry is configured to detect a plurality of reference points from the second image. The circuitry is configured to compare the first image with the second image to calculate an amount of positional deviation of the medium for each of the plurality of reference points. The circuitry is configured to detect, based on the amount of positional deviation, a malfunction of a conveying device that conveys the medium. The circuitry is configured to cause an image forming apparatus to print a correction chart for correction of conveyance of the medium, in response to detection of the malfunction of the conveying device. The circuitry is configured to calculate, from a read image of the correction chart, an amount of fluctuation in conveyance of the medium performed by the conveying device. The circuitry is configured to calculate a correction value for the calculated amount of fluctuation in conveyance of the medium. 
     Also described are novel control method for the information processing apparatus, image forming system, and non-transitory computer-readable storage medium storing computer-readable program code that causes the information processing apparatus to perform the control method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the embodiments and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a diagram illustrating a configuration of an image forming system, according to an embodiment of the present disclosure; 
         FIG. 2  is a schematic block diagram illustrating a configuration of an information processing system, according to an embodiment of the present disclosure; 
         FIG. 3  is a block diagram illustrating a hardware configuration of a controller of a printer, according to an embodiment of the present disclosure; 
         FIG. 4  is a block diagram illustrating a functional configuration of a printer and an inspection apparatus, according to an embodiment of the present disclosure; 
         FIG. 5  is a diagram illustrating an image from which a plurality of reference points is detected, according to an embodiment of the present disclosure: 
         FIG. 6A  is a diagram illustrating an amount of positional deviation for each reference point, according to an embodiment of the present disclosure; 
         FIG. 6B  is another diagram illustrating an amount of positional deviation for each reference point, according to an embodiment of the present disclosure; 
         FIG. 7A  is a graph illustrating an amount of positional deviation in a sub-scanning direction for each reference point, according to an embodiment of the present disclosure; 
         FIG. 7B  is another graph illustrating an amount of positional deviation in a sub-scanning direction for each reference point, according to an embodiment of the present disclosure; 
         FIG. 8A  is a graph illustrating an absolute value of an amount of positional deviation in a sub-scanning direction for each reference point, according to an embodiment of the present disclosure; 
         FIG. 8B  is another graph illustrating an absolute value of an amount of positional deviation in a sub-scanning direction for each reference point, according to an embodiment of the present disclosure; 
         FIG. 9A  is a graph illustrating a difference value between the amounts of positional deviation in a sub-scanning direction, according to an embodiment of the present disclosure; 
         FIG. 9B  is another graph illustrating a difference value between the amounts of positional deviation in a sub-scanning direction, according to an embodiment of the present disclosure; 
         FIG. 10  is a diagram illustrating a case in which the calculation of an amount of positional deviation fails, according to an embodiment of the present disclosure; 
         FIG. 11  is a diagram illustrating a case in which an abnormal skew occurs, according to an embodiment of the present disclosure: 
         FIG. 12  is a diagram illustrating a correction chart, according to an embodiment of the present disclosure: 
         FIG. 13  is a diagram illustrating a configuration of a reading sensor, according to an embodiment of the present disclosure; 
         FIG. 14  is a flowchart of a process performed by an image forming system, according to an embodiment of the present disclosure; and 
         FIG. 15  is a flowchart of a process of calculating an amount of positional deviation, according to an embodiment of the present disclosure. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. Also, identical or similar reference numerals designate identical or similar components throughout the several views. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of the present specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and not all of the components or elements described in the embodiments of the present disclosure are indispensable to the present disclosure. 
     In a later-described comparative example, embodiment, and exemplary variation, for the sake of simplicity, like reference numerals are given to identical or corresponding constituent elements such as parts and materials having the same functions, and redundant descriptions thereof are omitted unless otherwise required. 
     As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     It is to be noted that, in the following description, suffixes Y, M, C. and K denote colors of yellow, magenta, cyan, and black, respectively. To simplify the description, these suffixes are omitted unless necessary. 
     Referring to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, embodiments of the present disclosure are described below. 
     Initially with reference to  FIG. 1 , a description is given of a configuration of an image forming system. 
       FIG. 1  is a diagram illustrating a configuration of an image forming system  100 , according to an embodiment of the present disclosure. 
     The image forming system  100  includes a digital front end (DFE)  104 , a printer  101 , an inspection apparatus  102 , and a stacker  103 . The printer  101  is connected to the DFE  104  and the inspection apparatus  102  via the respective dedicated interfaces. 
     The DFE  104  is an image processing apparatus. Specifically, the DFE  104  generates print data to be printed and output according to a print job received from an apparatus (i.e., client) such as a personal computer (PC). More specifically, the DFE  104  generates bitmap data, which is data of an output target image. Then, the DFE  104  transmits the generated bitmap data to the printer  101 . 
     The printer  101  causes a print engine  105  to form and output an image according to the bitmap data received from the DFE  104 . The printer  101  also transmits, to the inspection apparatus  102 , the bitmap data received from the DFE  104  as information that is the basis of a master image, which is used by the inspection apparatus  102  as a reference to inspect the image formed and output by the print engine  105 . The printer  101  is an example of an image forming apparatus. 
     Specifically, the printer  101  is an image forming apparatus that forms and outputs an image on a medium such as print paper according to the bitmap data. In addition to the print paper, a sheet-like material on which an image can be formed and output may be used as the medium, such as a film or a plastic sheet. 
     The print engine  105  has a tandem structure in which drum-shaped photoconductors  112 Y,  112 M,  112 C, and  112 K for different colors are arranged side by side along an endless conveyor belt  111  serving as a mover. Hereinafter, the photoconductors  112 Y,  112 M,  112 C, and  112 K may be collectively referred to as photoconductors  112 . 
     More specifically, the photoconductors  112 Y,  112 M,  112 C, and  112 K are aligned in this order along the conveyor belt  111 , from an upstream side of a moving direction of the conveyor belt  111 , to form an intermediate transfer image on the conveyor belt  111  serving as an intermediate transfer belt. The intermediate transfer image is then transferred onto a medium fed from an input tray  113  and conveyed by a conveyance roller pair  114  serving as a conveying device that conveys the medium. 
     A latent image is developed with toner into a toner image on a circumferential surface of each of the photoconductors  112  for different colors, namely, black (K), cyan (C), magenta (M), and yellow (Y). The black, cyan, magenta, and yellow toner images are transferred from the respective photoconductors  121  onto the conveyor belt  111  such that the toner images are superimposed one atop another on the conveyor belt  111 . Thus, a composite full-color toner image (i.e., intermediate transfer image) is formed on the conveyor belt  111 . 
     At a position closest to a conveyance passage of the medium indicated by a broken line in  FIG. 1 , a transfer roller  115  transfers the full-color image from the conveyor belt  111  onto the medium conveyed along the conveyance passage. Hereinafter, such a conveyance passage of the medium is referred to as a medium conveyance passage. 
     Note that, in the present embodiment, the print engine  105  of the printer  101  is described as a device that forms an image by electrophotography. In other words, the printer  101  is described as an electrophotographic image forming apparatus employing an electrophotographic printing system. However, the printer  101  is not limited to an electrophotographic image forming apparatus. Alternatively, the printer  101  may be a printer employing another image forming system, such as an inkjet printer employing an inkjet printing system. 
     The medium bearing the full-color image is further conveyed to a fixing roller pair  116 , which fixes the full-color image on the medium. Thereafter, the medium bearing the fixed image is conveyed to the inspection apparatus  102 . 
     The inspection apparatus  102  is an apparatus that detects a malfunction in medium conveyance. In the present example, the inspection apparatus  102  is an information processing apparatus that includes a reading device  131 . Alternatively, the printer  101  serving as an image forming apparatus may include the reading device  131 . The reading device  131  reads each side of the medium conveyed via the fixing roller pair  116 . 
     The inspection apparatus  102  compares the image read by the reading device  131  with a master image described later, to detect the malfunction in medium conveyance. A detailed description of the inspection apparatus  102  is deferred. In the case of single-sided printing, the medium is inspected by the inspection apparatus  102  and then discharged to the stacker  103 . 
     By contrast, in the case of double-sided printing, the medium is inspected by the inspection apparatus  102  and then conveyed to an inversion path  117  through which the medium is inverted. Then, the medium is conveyed again to a transfer position at which the transfer roller  115  is located. At the transfer position, a toner image is transferred onto the other side of the medium opposite the side subjected to the single-sided printing. Then, the medium is conveyed to the fixing roller pair  116 , which fixes the toner image onto the other side of the medium. Thereafter, the inspection apparatus  102  inspects the medium subjected to double-sided printing. After the medium is inspected by the inspection apparatus  102 , the medium is discharged to the stacker  103 . 
     The stacker  103  outputs the medium discharged from the printer  101  onto a tray  141 . Thus, the stacker  103  stacks media on the tray  141 . 
     Referring now to  FIG. 2 , a description is given of an information processing system. 
       FIG. 2  is a schematic block diagram illustrating a configuration of an information processing system  200 , according to an embodiment of the present disclosure. 
     The information processing system  200  including the image forming system  100  includes a client  201 , in addition to the image forming system  100 . 
     The client  201  is connected to each of the DFE  104 , the printer  101 , and the inspection apparatus  102  of the image forming system  100  via a network  202 . The network  202  is, e.g., a local area network (LAN) or the Internet. 
     The client  201  is an information processing apparatus having a communication function and a content output function. The client  201  is a terminal apparatus such as a PC or a tablet terminal. The client  201  transmits a print job to the DFE  104  via the network  202 . 
     Thus, the DFE  104  receives the print job from the client  201 . Alternatively, the DFE  104  may receive a print job from the printer  101  or the inspection apparatus  102  via the network  202 . 
     Referring now to  FIG. 3 , a description is given of a hardware configuration of a controller of each of the printer  101 , the inspection apparatus  102 , the DFE  104 , and the client  201 , according to the present embodiment. 
       FIG. 3  is a block diagram illustrating a hardware configuration of a controller of the printer  101 , according to an embodiment of the present disclosure. 
     The controller of the DFE  104 , the controller of the inspection apparatus  102 , and the controller of the client  201  have substantially the same hardware configurations as the hardware configuration of the controller of the printer  101 .  FIG. 3  illustrates the hardware configuration of the controller the printer  101 , as a representative of the respective controllers of the printer  101 , the DFE  104 , the inspection apparatus  102 , and the client  201 . 
     According to the present embodiment, the controller of the printer  101  has substantially the same configuration as the configuration of general PCs or servers. 
     Specifically, according to the present embodiment, the controller of the printer  101  includes a central processing unit (CPU)  10 , a random access memory (RAM)  20 , a read only memory (ROM)  30 , a storage device  40 , and an interface (I/F)  50 , which are connected to each other via a bus  90 . The I/F  50  is connected to a display  60 , an operation device  70 , and a dedicated device  80 . 
     The CPU  10  is an arithmetic device that controls the operation of the entire printer  101 . The RAM  20  is a volatile storage medium that allows data to be read and written at highspeed. The CPU  10  uses the RAM  20  as a work area for data processing. The ROM  30  is a non-volatile, read-only storage medium that stores a program such as firmware. 
     The storage device  40  is a non-volatile storage medium that allows data to be read and written. The storage device  40  stores an operating system (OS), various kinds of control programs, and application programs. The storage device  40  is, e.g., a hard disk drive (HDD) or a solid state drive (SSD). 
     The I/F  50  connects the bus  90  to various kinds of hardware components or a network for control. The display  60  is a visual user interface that allows a user to ascertain the state of the printer  101 . The display  60  is a display device such as a liquid crystal display or an organic electroluminescence (OEL) display. The operation device  70  is a user interface, such as a keyboard or a mouse, for a user to input data to the printer  101 . 
     The dedicated device  80  is a hardware component that implements a dedicated function in each of the printer  101 , the inspection apparatus  102 , the DFE  104 , and the client  201 . In the case of the printer  101 , examples of the dedicated device  80  include, but are not limited to, a conveyance assembly that conveys a medium on which an image is formed and output and a plotter that forms and outputs an image on the medium such as a sheet of paper. 
     In the case of the inspection apparatus  102 , the dedicated device  80  is an arithmetic device dedicated to high-speed image processing, for example. Such an arithmetic device is configured as an application specific integrated circuit (ASIC), for example. The reading device  131  that reads an image output on a medium is also implemented by the dedicated device  80 . 
     In such a hardware configuration, the CPU  10  executes calculation according to a program stored in the ROM  30  or a program read into the RAM  20  from a storage medium such as the storage device  40  or an optical disk, thus configuring a software control unit. 
     A combination of the software control unit thus configured and hardware serves as a functional block that describes a function of each of the printer  101 , the inspection apparatus  102 , the DFE  104 , and the client  201  according to the present embodiment. 
     Referring now to  FIG. 4 , a description is given of an image forming system. 
       FIG. 4  is a block diagram illustrating a functional configuration of the printer  101  and the inspection apparatus  102 , according to an embodiment of the present disclosure. 
     In  FIG. 4 , the solid line indicates a flow of data; whereas, the broken line indicates a flow of a printed matter. 
     Now, a description is given of the functional configuration of the printer  101 . The printer  101  includes a data transmission unit  301 , a print control unit  302 , and a conveyance control unit  303 . 
     The data transmission unit  301  performs data transmission with the DFE  104  and the inspection apparatus  102 . In the present embodiment, the data transmission unit  301  receives bitmap data transmitted from the DFE  104 . The data transmission unit  301  transmits the bitmap data received from the DFE  104  to a data transmission unit  401  of the inspection apparatus  102 . 
     The print control unit  302  causes the print engine  105  to print an image on a medium. In the present embodiment, the print control unit  302  prints the bitmap data received by the data transmission unit  301  on a medium. 
     When the data transmission unit  301  receives an instruction of printing a correction chart, which is used to correct an amount of conveyance of a medium, from the data transmission unit  401  of the inspection apparatus  102  described later, the print control unit  302  prints the correction chart stored in the storage device  40  of the controller of the printer  101 . Note that such an amount of conveyance of a medium is hereinafter referred to as a medium conveyance amount. Note that the storage location of the correction chart is not limited to the storage device  40 . Alternatively, for example, the correction chart may be stored in a storage device of the inspection apparatus  102 . 
     The conveyance control unit  303  controls the operation of the conveying device to adjust the medium conveyance amount. In the present embodiment, the conveyance control unit  303  adjusts the medium conveyance amount, based on a correction value for the medium conveyance amount calculated by a third calculation unit  410  of the inspection apparatus  102  and transmitted from the data transmission unit  401  of the inspection apparatus  102 . A detailed description of the third calculation unit  410  is deferred. 
     In the present embodiment, the function of each of the data transmission unit  301 , the print control unit  302 , and the conveyance control unit  303  described above is implemented by the CPU  10  executing a program stored in, e.g., the ROM  30 . Alternatively, for example, at least part of the function of each of the data transmission unit  301 , the print control unit  302 , and the conveyance control unit  303  described above may be implemented by a dedicated hardware circuit. 
     The program executed by the printer  101  of the present embodiment may be stored in a computer-readable storage medium, such as a compact disc read-only memory (CD-ROM), a flexible disk (FD), a compact disc recordable (CD-R), and a digital versatile disk (DVD), in an installable or executable file format, to be provided. 
     Alternatively, the program executed by the printer  101  of the present embodiment may be stored in a computer connected to a network such as the Internet and downloaded via the network, to be provided. The program executed by the printer  101  of the present embodiment may be provided or distributed via a network such as the Internet. 
     Now, a description is given of a functional configuration of the inspection apparatus  102 . 
     The inspection apparatus  102  includes the data transmission unit  401 , a read image acquisition unit  402 , a master image generation unit  403 , a first detection unit  404 , a search unit  405 , a first calculation unit  406 , a second detection unit  407 , and a processing unit  408 , a second calculation unit  409 , and the third calculation unit  410 . 
     The data transmission unit  401  exchanges data with the printer  101 . In the present embodiment, the data transmission unit  401  receives bitmap data transmitted from the data transmission unit  301  of the printer  101 . 
     The data transmission unit  401  transmits, to the data transmission unit  301  of the printer  101 , an instruction of printing the correction chart for correction of the medium conveyance amount. The data transmission unit  401  also transmits, to the data transmission unit  301  of the printer  101 , the correction value for the medium conveyance amount calculated by the third calculation unit  410 . 
     The read image acquisition unit  402  acquires, as a first image, an image formed on a medium by the printer  101  and read by the reading device  131 . The read image acquisition unit  402  is an example of an acquisition unit. 
     In the present embodiment, the first image refers to an image that is inspected to detect a malfunction in medium conveyance. 
     In the present embodiment, the reading device  131  reads an image printed by the print control unit  302  of the printer  101 . The read image acquisition unit  402  acquires the image read by the reading device  131  serving as a first image. The reading device  131  also reads a correction chart printed by the print control unit  302  of the printer  101 . The read image acquisition unit  402  acquires an image of the correction chart read by the reading device  131 . 
     The master image generation unit  403  generates, as a second image, an image to be compared with the first image, based on document data. The master image generation unit  403  is an example of a generation unit. In the present embodiment, the master image generation unit  403  generates a master image, serving as a second image, based on the bitmap data transmitted from the data transmission unit  301  of the printer  101 . Note that the master image generation unit  403  may generate a master image, based on the read image acquired by the read image acquisition unit  402 . 
     The first detection unit  404  detects a plurality of reference points from the second image. In the present embodiment, the first detection unit  404  detects the reference points of the master image generated by the master image generation unit  403 . 
     In the present embodiment, the reference point refers to a point existing in the master image that is used for detection of a malfunction in medium conveyance. 
     Referring now to  FIG. 5 , a detailed description is given of the detection of the reference points. 
       FIG. 5  is a diagram illustrating an image from which a plurality of reference points is detected, according to an embodiment of the present disclosure. 
     In the present embodiment, the first detection unit  404  detects, as a reference point, a characteristic portion of a master image. Specifically, the first detection unit  404  detects a corner detected by a corner detection method as a reference point. The corner detection method is, e.g., a Harris operator. 
     Note that the first detection unit  404  detects a plurality of reference points so that the distance between the reference points becomes a given value or more in a sub-scanning direction, which is a medium conveyance direction in which a medium is conveyed, so as to detect an abnormality in medium conveyance speed. Note that the medium conveyance speed is a speed at which a medium is conveyed. 
     In the present example, the master image is divided into six areas. One characteristic portion is detected from each of the six areas as a reference point. Note that, in a case in one or more of the six areas include few characteristic portions of the image, the reference point is detected from a detectable area. In  FIG. 5 , the image is divided into six areas and the reference points are detected by the corner detection method. However, the reference points may be detected in another way provided that a plurality of reference points can be detected for detection of a malfunction in medium conveyance. 
     The search unit  405  matches the positions of the first image and the second image to search the first image for a point corresponding to the reference point of the second image. In the present embodiment, the search unit  405  performs pattern matching on the read image with respect to a given range of area centered on a reference point detected in the master image. Hereinafter, such a reference point detected in the master image is simply referred to as a reference point. 
     From the result of pattern matching, the search unit  405  searches the read image for a best-matching area that best matches with the image in the given range of area centered on the reference point, and defines a center point of the best-matching area as a point corresponding to the reference point in the read image. Hereinafter, such a point corresponding to the reference point in the read image is referred to as a corresponding point. Note that the corresponding point may be searched for in another way provided that the point corresponding to the reference point can be searched for. 
     The first calculation unit  406  compares the first image with the second image to calculate, as an amount of positional deviation of the medium for each of the plurality of reference points, an amount of positional deviation of the corresponding point from each of the plurality of reference points. Specifically, in the present embodiment, the first calculation unit  406  calculates the difference between the coordinates of the reference point and the coordinates of the corresponding point as the amount of positional deviation. The amount of positional deviation is calculated for each of the sub-scanning direction (i.e., Y direction) and a main scanning direction (i.e., X direction) that intersects with the sub-scanning direction. Note that the main scanning direction is ideally a direction perpendicular to the sub-scanning direction. 
     The second detection unit  407  detects a malfunction of the conveying device that conveys a medium, based on the amount of positional deviation. In the present embodiment, the second detection unit  407  detects, in response to satisfaction of a predetermined condition, an abnormality or malfunction corresponding to the condition. 
     Referring now to  FIGS. 6A and 6B , a detailed description is given of how the second detection unit  407  detects a malfunction in medium conveyance. 
       FIG. 6A  is a diagram illustrating an amount of positional deviation from each reference point, according to an embodiment of the present disclosure.  FIG. 6B  is another diagram illustrating an amount of positional deviation from each reference point, according to an embodiment of the present disclosure. 
     In  FIGS. 6A and 6B , the arrows extending from each reference point represent vectors that indicate the magnitude (or amount) of positional deviation and the respective directions of positional deviation along the X and Y directions. 
     In a case in which the conveying device fluctuates in the medium conveyance amount, the conveying device fluctuates in feeding amount. As a consequence, the speed of the medium passing in front of the reading device  131  fluctuates. Therefore, the amount of positional deviation in the Y direction may change between the reference points. At this time, the image read by the reading device  131  changes to shrink when the speed is high; whereas the read image changes to stretch when the speed is low. That is,  FIGS. 6A and 6B  illustrate, for each reference point, an upward direction of positional deviation when the conveyance speed is high while illustrating a downward direction of positional deviation when the conveyance speed is low. 
     Specifically, in  FIG. 6A , reference points (a) to (f) are detected.  FIG. 6A  illustrates a downward direction of positional deviation along the Y direction for each of the reference points (a), (b), (e), and (f). That is, the medium conveyance speed is high in the areas including the reference points (a), (b), (e), and (f). By contrast,  FIG. 6A  illustrates an upward direction of the positional deviation along the Y direction for each of the reference points (c) and (d). That is, the medium conveyance speed is low in the areas including the respective reference points (c) and (d). 
     In  FIG. 6B , reference points (a′) to (f) are detected.  FIG. 6B  illustrates a downward direction of positional deviation along the Y direction for all the reference points (a′) to (f). That is, the tendency of fluctuations in the conveyance speed is substantially the same in the areas including the respective reference points (a′) to (f). 
     However, the amount of positional deviation in the Y direction for the reference points (c′) and (d′) is greater than the amount of positional deviation in the Y direction for the reference points (a′), (b′), (e′), and (f). That is, the conveyance speed changes significantly from the areas including the respective reference points (a′) and (b′) to the areas including the respective reference points (c′) and (d′). 
     Now, a detailed description is given of the detection of an abnormality in medium conveyance speed. 
       FIG. 7A  is a graph illustrating an amount of positional deviation in the sub-scanning direction for each reference point, according to an embodiment of the present disclosure.  FIG. 7B  is another graph illustrating an amount of positional deviation in the sub-scanning direction for each reference point, according to an embodiment of the present disclosure. 
       FIG. 7A  is a bar graph illustrating the amount of positional deviation for each reference point illustrated in  FIG. 6A . In  FIG. 7A , the reference points (a) to (f) are aligned in the order of coordinate values in the Y direction. Similarly,  FIG. 7B  is a bar graph illustrating the amount of positional deviation for each reference point illustrated in  FIG. 6B . In  FIG. 7B , the reference points (a′) to (f′) are aligned in the order of coordinate values in the Y direction. 
     In a case in which the medium conveyance speed does not fluctuate, a direction of positional deviation and an amount of positional deviation for a reference point is similar to a direction of positional deviation and an amount of positional deviation for another reference point close to the reference point. Therefore, the abnormality in medium conveyance speed is detected by comparing the amount of positional deviation between adjacent ones of the reference points arranged in the order of the coordinate values in the Y direction. 
     Specifically, when the amount of positional deviation in the sub-scanning direction calculated, for each reference point, by the first calculation unit  406  exceeds a first threshold value, the second detection unit  407  detects an abnormality in the medium conveyance speed at which the conveying device conveys a medium. More specifically, in the present embodiment, when an absolute value of the amount of positional deviation in the sub-scanning direction calculated, for each reference point, by the first calculation unit  406  exceeds the first threshold value, the second detection unit  407  detects an abnormality in the medium conveyance speed. 
     In the present embodiment, the first threshold value is a threshold value for detection of an abnormality in the medium conveyance speed in the conveying device of the printer  101 . Note that the abnormality in the medium conveyance speed refers to a medium conveyance speed out of specified tolerance. The first threshold value is set based on premeasured fluctuations in the amount of positional deviation in the Y direction in the conveying device of the printer  101 . 
       FIG. 8A  is a graph illustrating an absolute value of an amount of positional deviation in the sub-scanning direction for each reference point, according to an embodiment of the present disclosure.  FIG. 8B  is another graph illustrating an absolute value of an amount of positional deviation in the sub-scanning direction for each reference point, according to an embodiment of the present disclosure. 
       FIGS. 8A and 8B  are bar graphs illustrating the absolute value of the amount of positional deviation for each reference point illustrated in  FIGS. 7A and 7B , respectively. In each of  FIGS. 8A and 8B , the broken line indicates the first threshold value. 
     In  FIG. 8A , none of the reference points (a) to (f) exceeds the first threshold value. It is therefore clear from  FIG. 8A  that the conveying device conveys a medium at a normal medium conveyance speed within the specified tolerance. By contrast, in  FIG. 8B , the absolute value of the amount of positional deviation in the Y direction for each of the reference points (c′) and (d′) exceeds the first threshold value. Therefore, in this case, the second detection unit  407  detects an abnormality in the medium conveyance speed. 
     However, even in a case in which the conveying device conveys a medium at a normal medium conveyance speed within the specified tolerance, the medium conveyance amount may need to be corrected when the conveyance speed changes greatly between the reference points. 
     To address such a situation, the second detection unit  407  detects an abnormality in the medium conveyance speed in a case in which an amount of positional deviation in the sub-scanning direction calculated, for each of a plurality of reference points including first and second reference points adjacent to each other in the sub-scanning direction, by the first calculation unit  406  is equal to or less than the first threshold value and a difference value between the amount of positional deviation in the sub-scanning direction calculated for the first reference point and the amount of positional deviation in the sub-scanning direction calculated for the second reference point exceeds a second threshold value. 
     In the present embodiment, the second threshold value is a threshold value for detection of a change in the medium conveyance speed between the reference points. 
       FIG. 9A  is a graph illustrating a difference value between the amounts of positional deviation in the sub-scanning direction, according to an embodiment of the present disclosure.  FIG. 9B  is another graph illustrating a difference value between the amounts of positional deviation in the sub-scanning direction, according to an embodiment of the present disclosure. 
     In  FIGS. 9A and 9B , each arrow indicates a difference value between an amount of positional deviation in the Y direction for a reference point and an amount of positional deviation in the Y direction for another reference point adjacent to the reference point. In  FIG. 9A , the difference value between the reference points (b) and (d) and the difference value between the reference points (c) and (f) exceed the second threshold value. 
     In this case, the second detection unit  407  detects an abnormality in the medium conveyance speed because the difference value between the reference points (b) and (d) and the difference value between the reference points (c) and (f) exceed the second threshold value. 
     Note that even in a case in which the second detection unit  407  detects an abnormality in the medium conveyance speed from the amount of positional deviation, no malfunction may actually occur in conveyance when the first calculation unit  406  fails to calculate the amount of positional deviation. 
     In a case in which the first detection unit  404  divides the second image into a plurality of areas including first and second areas adjacent to each other in the main scanning direction and detects reference points corresponding to the respective areas, a direction of positional deviation and an amount of positional deviation in the sub-scanning direction for one of the reference points corresponding to the first area may be similar to a direction of positional deviation and an amount of positional deviation in the sub-scanning direction for another one of the reference points corresponding to the second area. 
     Therefore, when a difference value between the amount of positional deviation in the sub-scanning direction for the reference point corresponding to the first area and the amount of positional deviation in the sub-scanning direction for the reference point corresponding to the second area exceeds a given value, the first calculation unit  406  may have failed to calculate the amount of positional deviation for some reasons. 
     To address such a situation, the first detection unit  404  divides the second image into a plurality of areas including first and second areas adjacent to each other and detects reference points corresponding to the respective areas. The second detection unit  407  detects no abnormality in the medium conveyance speed in a case in which a difference value between the amount of positional deviation in the sub-scanning direction for one of the reference points corresponding to the first area and the amount of positional deviation in the sub-scanning direction for another one of the reference points corresponding to the second area exceeds a third threshold value. 
     In the present embodiment, the third threshold value is a threshold value for detecting that the first calculation unit  406  has failed to calculate the amount of positional deviation. 
     Referring now to  FIG. 10 , a description is given of a failure in calculation of the amount of positional deviation. 
       FIG. 10  is a diagram illustrating a case in which the calculation of an amount of positional deviation fails, according to an embodiment of the present disclosure. 
     In  FIG. 10  illustrating reference points ( 1   a ) to ( 1   f ), an absolute value of an amount of positional deviation in they direction for the reference point ( 1   c ) does not exceed the first threshold value. A difference value between an amount of positional deviation in the Y direction for the reference point ( 1   b ) and the amount of positional deviation in the Y direction for the reference point ( 1   c ) exceeds the second threshold value. A difference value between the amount of positional deviation in the Y direction for the reference point ( 1   c ) and an amount of positional deviation in the Y direction for the reference point ( 1   d ) exceeds the third threshold value. 
     In this case, the second detection unit  407  firstly detects an abnormality in the medium conveyance speed because the absolute value of the amount of positional deviation in the Y direction for the reference point ( 1   c ) is equal to or less than the first threshold value and because a difference value between the amount of positional deviation in the Y direction for the reference point ( 1   b ) and the amount of positional deviation in the Y direction for the reference point ( 1   c ) adjacent to the reference point ( 1   b ) in the Y direction exceeds the second threshold value. 
     Secondly, the second detection unit  407  detects that the first calculation unit  406  has failed to calculate the amount of positional deviation in the Y direction for the reference point ( 1   c ) because the difference value between the amount of positional deviation in the Y direction for the reference point ( 1   c ) and the amount of positional deviation in the Y direction for the reference point ( 1   d ) existing in the area adjacent to the area including the reference point ( 1   c ) in the X direction exceeds the third threshold value. 
     As a consequence, in this case, the second detection unit  407  detects that the first calculation unit  406  has failed to calculate the amount of positional deviation in the Y direction for the reference point ( 1   c ) and that the conveying device has no abnormality in the medium conveyance speed, because the difference value between the amount of positional deviation in the Y direction for the reference point ( 1   b ) and the amount of positional deviation in the Y direction for the reference point ( 1   c ) exceeds the second threshold value and because the difference value between the amount of positional deviation in the Y direction for the reference point ( 1   c ) and the amount of positional deviation in the Y direction for the reference point ( 1   d ) exceeds the third threshold value. 
     Instead of the abnormality in medium conveyance speed, an abnormal skew of a medium may cause the absolute value of the amount of positional deviation in the sub-scanning direction calculated, for each reference point, by the first calculation unit  406  exceeding the first threshold value, or may cause the difference value between the amount of positional deviation in the sub-scanning direction calculated for the first reference point and the amount of positional deviation in the Y direction calculated for the second reference point exceeding the second threshold value. Hereinafter, such an abnormal skew of a medium is referred to as an abnormal medium skew. 
     When an abnormal medium skew does not occur, the direction of positional deviation along the main scanning direction is substantially the same for all the reference points. By contrast, when an abnormal medium skew occurs, a direction of positional deviation along the main scanning direction for one of the reference points for which the abnormality in the medium conveyance speed is detected may be different from a direction of positional deviation along the main scanning direction for another one of the reference points for which the abnormality in the medium conveyance speed is not detected. 
     To address such a situation, the second detection unit  407  detects an abnormal medium skew in the conveying device in a case in which a direction of positional deviation along the main scanning direction for one of the reference points for which the abnormality in the medium conveyance speed is detected is different from a direction of positional deviation along the main scanning direction for another one of the reference points for which the abnormality in the medium conveyance speed is not detected. 
       FIG. 11  is a diagram illustrating a case in which an abnormal skew occurs, according to an embodiment of the present disclosure. 
     In  FIG. 11 , an abnormality in the medium conveyance speed is detected for reference points ( 2   b ), ( 2   d ), and ( 2   f ); whereas the abnormality in the medium conveyance speed is not detected for reference points ( 2   a ), ( 2   c ), and ( 2   e ). 
     In this case, the second detection unit  407  firstly detects the abnormality in the medium conveyance speed for the reference points ( 2   b ), ( 2   d ), and ( 2   f ). 
     However, since the direction of positional deviation along the X direction for the reference points ( 2   b ), ( 2   d ), and ( 2   f ) for which the abnormality in the medium conveyance speed is detected is different from the direction of positional deviation along the X direction for the reference points ( 2   a ), ( 2   c ), and ( 2   e ) for which the abnormality in the medium conveyance speed is not detected, the second detection unit  407  detects an abnormal medium skew, instead of the abnormality in the medium conveyance speed. 
     Referring back to  FIG. 4 , the processing unit  408  performs processing when the second detection unit  407  detects a malfunction of the conveying device. Specifically, in the present embodiment, when the second detection unit  407  detects a malfunction of the conveying device, the processing unit  408  causes the printer  101  to print a correction chart for correction of the medium conveyance amount. The processing unit  408  also causes the printer  101  to pause printing. 
     More specifically, in the present example, when the second detection unit  407  detects a malfunction of the conveying device, the processing unit  408  causes the data transmission unit  401  to transmit an instruction of pausing printing to the printer  101 . At this time, the processing unit  408  causes the data transmission unit  401  to transmit an instruction of printing the correction chart to the printer  101 . 
     Note that the processing unit  408  performs the aforementioned processing in substantially the same manner both when the second detection unit  407  detects an abnormality in medium conveyance speed and when the second detection unit  407  detects an abnormal skew. In response to the aforementioned processing performed by the processing unit  408 , the print control unit  302  of the printer  101  causes the print engine  105  to pause printing and print the correction chart stored in the storage device  40  of the controller of the printer  101 . 
     The second calculation unit  409  calculates an amount of fluctuation in conveyance of a medium performed by the conveying device from a result of reading the correction chart printed, in response to the second detection unit  407  detecting the malfunction of the conveying device, for correction of the medium conveyance amount. 
     Specifically, in the present embodiment, the second calculation unit  409  calculates the amount of fluctuation in conveyance of the medium performed by the conveying device from a read image of the correction chart printed by the print control unit  302  of the printer  101  in response to the instruction of printing the correction chart transmitted from the data transmission unit  401 . 
     The third calculation unit  410  calculates a correction value for the amount of fluctuation in conveyance of the medium calculated by the second calculation unit  409 . 
     Referring now to  FIG. 12 , a detailed description is given of the correction chart. 
       FIG. 12  is a diagram illustrating a correction chart  500 , according to an embodiment of the present disclosure. 
     In the correction chart  500 , ruled lines (hereinafter referred to as marks  501 ) are aligned at equal intervals. The marks  501  are aligned at equal intervals, keeping the line spacing at one. 
     The reading device  131  reads, as an image, the correction chart  500  printed by the printer  101  in response to the processing performed by the processing unit  408 . The read image acquisition unit  402  acquires the image of the correction chart  500  read by the reading device  131 . 
     The second calculation unit  409  detects the marks  501  from the image of the correction chart  500  acquired by the read image acquisition unit  402  to calculate the amount of fluctuation in conveyance of the medium performed by the conveying device. Note that the marks  501  may be detected in another way. For example, a reading sensor  151  may be disposed above the medium conveyance passage to detect the marks  501 . 
     Referring now to  FIG. 13 , a description is given of a case in which the marks  501  are detected with the reading sensor  151 . 
       FIG. 13  is a diagram illustrating a configuration of the reading sensor  151 , according to an embodiment of the present disclosure. 
     The reading sensor  151  includes a light emitting unit  151   a  and a light receiving unit  151   b.    
     The light emitting unit  151   a  emits light. The light emitted from the light emitting unit  151   a  is reflected from the surface of the correction chart  500 . The light receiving unit  151   b  detects, as a reflected light intensity, an amount of the light reflected from the surface of the correction chart  500 . The reading sensor  151  detects the marks  501  aligned on the correction chart  500 , based on the amount of the reflected light (i.e., reflected light intensity) detected by the light receiving unit  151   b.    
     The third calculation unit  410  calculates a correction value for the amount of fluctuation in conveyance of the medium performed by the conveying device, the amount being calculated by the second calculation unit  409 . The second calculation unit  409  and the third calculation unit  410  may calculate the amount of fluctuation in conveyance and the correction value, respectively, in a way described in, e.g., JP-2010-201792-A incorporated by reference herein. 
     In the present embodiment, the function of each of the data transmission unit  401 , the read image acquisition unit  402 , the master image generation unit  403 , the first detection unit  404 , the search unit  405 , the first calculation unit  406 , the second detection unit  407 , the processing unit  408 , the second calculation unit  409 , and the third calculation unit  410  described above is implemented by the CPU  10  executing a program stored in, e.g., the ROM  30 . 
     Alternatively, for example, at least part of the function of each of the data transmission unit  401 , the read image acquisition unit  402 , the master image generation unit  403 , the first detection unit  404 , the search unit  405 , the first calculation unit  406 , the second detection unit  407 , the processing unit  408 , the second calculation unit  409 , and the third calculation unit  410  described above may be implemented by a dedicated hardware circuit. 
     The program executed by the inspection apparatus  102  of the present embodiment may be stored in a computer-readable storage medium, such as a CD-ROM, an FD, a CD-R, and a DVD, in an installable or executable file format, to be provided. 
     Alternatively, the program executed by the printer  101  of the present embodiment may be stored in a computer connected to a network such as the Internet and downloaded via the network, to be provided. The program executed by the inspection apparatus  102  of the present embodiment may be provided or distributed via a network such as the Internet. 
     Each of the functions of the embodiments described above may be implemented by one or more processing circuits or circuitry. The processing circuit or circuitry herein includes a processor programmed to execute the functions by software such as a processor implemented by an electronic circuit. The processing circuit or circuitry also includes devices such as an ASIC, a digital signal processor (DSP), a field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions. 
     Referring now to  FIG. 14 , a description is given of a process performed by the image forming system  100 . 
       FIG. 14  is a flowchart of a process performed by the image forming system  100 , according to an embodiment of the present disclosure. 
     Firstly, as a premise, the DFE  104  receives a print job from the client  201 . The DFE  104  generates bitmap data as an output target image, based on the received print job. 
     The DFE  104  transmits the generated bitmap data to the data transmission unit  301  of the printer  101 . The print control unit  302  prints, on a medium, the bitmap data received by the data transmission unit  301 . The printed medium is read by the reading device  131  of the inspection apparatus  102 . 
     In step S 101 , the read image acquisition unit  402  acquires, as a read image, an image read by the reading device  131 . 
     In step S 102 , the master image generation unit  403  generates a master image, based on the bitmap data received from the DFE  104  by the data transmission unit  401  of the inspection apparatus  102 . 
     In step S 103 , the first detection unit  404  detects a reference point from the master image generated by the master image generation unit  403 . The search unit  405  matches the positions of the read image acquired by the read image acquisition unit  402  and the master image generated by the master image generation unit  403 , so as to search for a corresponding point of the read image corresponding to the reference point of the master image. 
     In step S 104 , the first calculation unit  406  calculates an amount of positional deviation from the coordinates of the reference point of the master image and the coordinates of the corresponding point of the read image. 
     A detailed description of the respective operations in steps S 103  and S 104  is deferred. 
     In step S 105 , the second detection unit  407  detects whether the conveying device (e.g., conveyance roller pair  114 ) malfunctions, from the amount of positional deviation calculated by the first calculation unit  406 . 
     When the second detection unit  407  detects a malfunction of the conveying device (YES in step S 105 ), the processing unit  408  causes the data transmission unit  401  of the inspection apparatus  102  to transmit an instruction of pausing printing to the data transmission unit  301  of the printer  101 . 
     In step S 106 , the print control unit  302  pauses printing. 
     The processing unit  408  causes the data transmission unit  401  of the inspection apparatus  102  to transmit an instruction of printing a correction chart to the data transmission unit  301  of the printer  101 . 
     In step S 107 , the print control unit  302  prints the correction chart stored in the storage device  40  of the controller of the printer  101 . 
     The reading device  131  of the inspection apparatus  102  reads the correction chart printed by the print control unit  302 . 
     In step S 108 , the read image acquisition unit  402  acquires a read image of the correction chart. 
     In step S 109 , the second calculation unit  409  calculates an amount of fluctuation in conveyance performed by the conveying device, from the read image of the correction chart acquired by the read image acquisition unit  402 . 
     In step S 110 , the third calculation unit  410  calculates an amount of correction of conveyance performed by the conveying device, based on the amount of fluctuation in conveyance calculated by the second calculation unit  409 . Then, the data transmission unit  401  of the inspection apparatus  102  transmits the amount of correction calculated by the third calculation unit  410  to the data transmission unit  301  of the printer  101 . 
     In step S 111 , the conveyance control unit  303  corrects the amount of conveyance performed by the conveying device, based on the amount of correction received by the data transmission unit  301 . Thus, the present process ends. 
     By contrast, when the second detection unit  407  does not detect a malfunction of the conveying device (NO in step S 105 ), the image forming system  100  continues printing while ending the present process. 
     Referring now to  FIG. 15 , a detailed description is given of a process of calculating the amount of positional deviation. 
       FIG. 15  is a flowchart of a process of calculating an amount of positional deviation, according to an embodiment of the present disclosure. 
     Firstly, in step S 1031 , the first detection unit  404  detects a reference point from a master image generated by the master image generation unit  403 . 
     Next, in step S 1032 , the search unit  405  searches a read image acquired by the read image acquisition unit  402  for a corresponding point corresponding to the reference point of the master image detected by the first detection unit  404 . 
     In step S 1041 , the first calculation unit  406  calculates, as an amount of positional deviation in the X direction, a difference value between the coordinates of the master image (specifically, the coordinates of the reference point) and the coordinates of the read image (specifically, the coordinates of the corresponding point) in the X direction. 
     In step S 1042 , the first calculation unit  406  calculates, as an amount of positional deviation in the Y direction, a difference value between the coordinates of the master image (specifically, the coordinates of the reference point) and the coordinates of the read image (specifically, the coordinates of the corresponding point) in the Y direction. 
     Then, the second detection unit  407  performs the operation of step S 105  illustrated in  FIG. 14 . 
     A typical technique has some difficulties in automatically detecting fluctuations in the medium conveyance amount. When a user visually recognizes the fluctuations in the medium conveyance amount and determines that the medium conveyance amount is to be corrected, the user manually causes a reading device to read a correction chart. Therefore, for example, in the case of unattended printing such as nighttime printing, the fluctuations in the medium conveyance amount remain uncorrected. 
     To address such an unfavorable situation, an image forming system of an embodiment of the present disclosure attains some advantages as described below. 
     According to the present embodiment, the read image acquisition unit  402  of the inspection apparatus  102  acquires, as a read image, an image printed on a medium and read by the reading device  131 . The master image generation unit  403  generates a master image, based on document data. The first calculation unit  406  calculates an amount of positional deviation between the master image and the read image. Based on the amount of positional deviation calculated by the first calculation unit  406 , the second detection unit  407  detects a malfunction of a conveying device that conveys the medium. 
     Since each of the operations described above is performed even without any instruction from a user, the image forming system  100  of the present embodiment automatically detects a malfunction of the conveying device even when printing is performed unattended such as nighttime printing. 
     According to the present embodiment, when the second detection unit  407  detects the malfunction of the conveying device, the processing unit  408  of the inspection apparatus  102  causes the printer  101  to print a correction chart for correction of fluctuations in conveyance of the medium. The second calculation unit  409  calculates, from a read image of the printed correction chart, an amount of fluctuation in conveyance of the medium performed by the conveying device. The third calculation unit  410  calculates a correction value for the amount of fluctuation in conveyance of the medium calculated by the second calculation unit  409 . 
     The conveyance control unit  303  of the printer  101  automatically corrects the fluctuations in conveyance of the medium, based on the correction amount (i.e., correction value) calculated by the third calculation unit  410 . Since each of the operations described above is performed even without any instruction from a user, the image forming system  100  automatically corrects a malfunction of the conveying device even when printing is performed unattended. 
     According to the present embodiment, the second detection unit  407  detects an abnormality in the medium conveyance speed in a case in which an absolute value of an amount of positional deviation in the sub-scanning direction calculated, for each of a plurality of reference points, by the first calculation unit  406  exceeds a first threshold value. Accordingly, the image forming system  100  detects fluctuations out of specified tolerance of speed fluctuations in the conveying device. 
     According to the present embodiment, the second detection unit  407  detects an abnormality in the medium conveyance speed in a case in which the amount of positional deviation in the sub-scanning direction calculated, for each of the plurality of reference points including a first reference point and a second reference point adjacent to the first reference point in the sub-scanning direction, by the first calculation unit  406  is equal to or less than the first threshold value and a difference value between the amount of positional deviation in the sub-scanning direction calculated for the first reference point and the amount of positional deviation in the sub-scanning direction calculated for the second reference point exceeds a second threshold value. 
     Accordingly, the image forming system  100  detects fluctuations in the medium conveyance speed to be corrected in the conveyance device, though the fluctuations are within the specified tolerance of speed fluctuations. 
     According to the present embodiment, the second detection unit  407  detects that the first calculation unit  406  has failed to calculate the amount of positional deviation in a case in which a difference value between the amount of positional deviation in the sub-scanning direction calculated for one of the plurality of reference points corresponding to a first area and the amount of positional deviation in the sub-scanning direction calculated for another one of the reference points corresponding to a second area adjacent to the first area in the main scanning direction exceeds a third threshold value. 
     Accordingly, the image forming system  100  of the present embodiment eliminates a malfunction of the conveying device that is detected due to the failure of the first calculation unit  406  to calculate the amount of positional deviation, thus refraining from performing unnecessary processing such as printing an unnecessary correction chart. In other words, the productivity is enhanced. 
     According to the present embodiment, the second detection unit  407  detects an abnormal medium skew in the conveying device in a case in which a direction of positional deviation along the main scanning direction for one of the reference points for which the abnormality in the medium conveyance speed is detected is different from a direction of positional deviation along the main scanning direction for another one of the reference points for which the abnormality in the medium conveyance speed is not detected. 
     Accordingly, the image forming system  100  of the present embodiment detects an abnormal medium skew, in addition to an abnormality in the medium conveyance speed. 
     According to the embodiments of the present disclosure, a malfunction of a conveying device is automatically detected and automatically corrected. 
     Although the present disclosure makes reference to specific embodiments, it is to be noted that the present disclosure is not limited to the details of the embodiments described above. Thus, various modifications and enhancements are possible in light of the above teachings, without departing from the scope of the present disclosure. It is therefore to be understood that the present disclosure may be practiced otherwise than as specifically described herein. For example, elements and/or features of different embodiments may be combined with each other and/or substituted for each other within the scope of the present disclosure. The number of constituent elements and their locations, shapes, and so forth are not limited to any of the structure for performing the methodology illustrated in the drawings. 
     Any one of the above-described operations may be performed in various other ways, for example, in an order different from that described above. 
     Any of the above-described devices or units can be implemented as a hardware apparatus, such as a special-purpose circuit or device, or as a hardware/software combination, such as a processor executing a software program. 
     Further, as described above, any one of the above-described and other methods of the present disclosure may be embodied in the form of a computer program stored on any kind of storage medium. Examples of storage media include, but are not limited to, floppy disks, hard disks, optical discs, magneto-optical discs, magnetic tapes, nonvolatile memory cards, read only memories (ROMs), etc. 
     Alternatively, any one of the above-described and other methods of the present disclosure may be implemented by the ASIC, prepared by interconnecting an appropriate network of conventional component circuits or by a combination thereof with one or more conventional general-purpose microprocessors and/or signal processors programmed accordingly.