Patent Publication Number: US-10317815-B2

Title: Image forming apparatus, method for managing consumable, and storage medium

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image forming apparatus which properly manages a use record and history of replacement about a consumable, such as a toner cartridge. 
     Description of the Related Art 
     Recent image forming apparatuses typically use a cartridge into which toner, a photosensitive drum, and a developing unit are integrated, as a replaceable consumable. Some cartridges are equipped with a storage medium, such as a memory tag. Each time the filled toner is consumed, a use record including the number of print media on which images are formed and the amount of toner consumed in each time is recorded in the memory tag. In such a cartridge, information indicating the total amount of toner consumed so far is recorded in the memory tag. This provides an advantage that the remaining amount of toner can be accurately estimated even if the cartridge is mounted on another image forming apparatus. 
     Nowadays identifiers and use records of cartridges may be stored in a memory on the main body side of the image forming apparatus when the cartridges are mounted or replaced. For example, Japanese Patent Application Laid-Open No. 2008-250087 discusses an image forming apparatus which reads life information changing according to the use of a consumable from a memory tag included in a cartridge, and stores the life information in a memory on the apparatus main body side. 
     Aside from ones provided by the manufacturer of the image forming apparatus, cartridges provided by other than the manufacturer of the image forming apparatus may be mounted on the image forming apparatus. The toner filled in the latter cartridges does not always have the same characteristic as that of toner contained in the former cartridges. Some users consider it a print defect that color developability or color reproducibility varies before and after the replacement of a cartridge, and troubles can occur. As a measure for analyzing causes at the occurrence of such troubles, individual information unique to a cartridge, such as a cartridge identifier, is stored in the memory tag, and the stored individual information is read and recorded on the apparatus main body side. However, there is a problem that if the memory tag on the cartridge side becomes inaccessible for any reason (a failure or non-mounting), the individual information about the cartridge is unable to be recorded in the apparatus main body. 
     Such a problem occurs commonly in apparatuses that perform image formation using consumables that store individual information, being not limited to cartridges. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention are directed to providing an image forming apparatus which, even if individual information about a consumable is not able to be read, properly manages individual information about a replacing consumable on the apparatus side when the consumable is replaced. 
     According to an aspect of the present invention, an image forming apparatus for performing image formation using a consumable container comprising a memory configured to store individual information unique to the consumable container, the image forming apparatus includes at least one processor and at least one memory coupled to the at least one processor that stores instructions and, upon execution of the instructions by the at least one processor controls the at least one processor to act as a reading unit configured to read the individual information from the memory of the consumable container, a storage control unit configured to record the individual information in a storage of the image forming apparatus, and a control unit configured to write, in response to the reading unit failing to read the individual information from the memory of the consumable container, new individual information about the consumable container to the storage of the image forming apparatus. 
     Further features will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram illustrating an image forming apparatus. 
         FIG. 2  is a block configuration diagram illustrating a controller board. 
         FIGS. 3A, 3B, and 3C  are schematic diagrams illustrating a configuration example of the image forming apparatus. 
         FIG. 4  is a diagram illustrating mounted cartridge information stored in a memory tag. 
         FIG. 5  is a diagram illustrating a cartridge replacement log. 
         FIG. 6  is an explanatory diagram illustrating screen transitions by a report print function. 
         FIGS. 7A and 7B  are diagrams illustrating a printed cartridge replacement log. 
         FIG. 8  is a flowchart illustrating a processing procedure for adding a record to a cartridge replacement log. 
         FIG. 9  is a flowchart illustrating a processing procedure for updating a record in executing printing. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a schematic configuration diagram of an image forming apparatus according to the present exemplary embodiment. An image forming apparatus  100  includes an operation unit  101 , a controller board  102 , a power supply unit  103 , a hard disk device  104 , and a printer engine  105 . Option cassettes  111 ,  112 , and  113  for increasing the supply amount of sheets are connected to the image forming apparatus  100 . The controller board  102  includes an interface for enabling connection with a Universal Serial Bus (USB) memory  130  and a personal computer (PC)  150 . The PC  150  is an external apparatus that issues an image formation instruction to the image forming apparatus  100 . The PC  150  and the controller board  102  may be directly connected via a communication cable. Alternatively, the PC  150  and the controller board  102  may be indirectly connected via a network hub, the Internet, an intranet, or the like. The controller board  102  and the PC  150  may be connected in a wired or wireless manner. 
     An application (hereinafter, referred to as “AP”) for causing the image forming apparatus  100  to form an image is installed on the PC  150 . The AP transmits print settings, such as a sheet size and a sheet type, and commands for drawing graphics and text to a printer driver. The printer driver is a print control program, and runs on the PC  150  with the AP. The printer driver generates a print job based on the print settings and drawing commands, and issues the print job to the controller board  102 . 
     The controller board  102  functions as a control unit for controlling an operation of the entire image forming apparatus  100 . The operation unit  101  is an interface module for accepting user&#39;s instructions and notifying the user of a state of the image forming apparatus  100 . The operation unit  101  includes an up button  121 , an execution button  122 , and a down button  123  for accepting the instructions from the user, and a display panel (liquid crystal display (LCD))  124  for notifying the user of the state of the image forming apparatus  100 . The display panel  124  includes an LCD on which a touch sensor is arranged. The up button  121  and the down button  123  are operation buttons for changing a selection item designated by a cursor on the display panel  124 . The execution button  122  is an operation button for executing the selection item designated by the cursor. If the execution button  122  is pressed with the cursor on a selection item B on the display panel  124 , a function associated with the selection item B is executed. 
     The operation unit  101  illustrated in  FIG. 1  is just an example, and may include other input units and output units. For example, a unit for accepting operation instructions by a voice input may be included. An operation result may be pronounced by speech synthesis. A buzzer may be used to issue an alarm. The operation unit  101  may have an arbitrary configuration in carrying out an exemplary embodiment of the present invention. 
     The hard disk device  104  is a storage module in which various programs are installed. The hard disk device  104  temporarily stores a print job and the like received by the controller board  102  from the PC  150 . The hard disk device  104  also temporarily stores a print image rendered based on the print job before the printer engine  105  prints the print image. The hard disk device  104  may be implemented by a semiconductor storage, such as a solid state drive (SSD). The power supply unit  103  is a unit for supplying power to the controller board  102  and the printer engine  105 . 
     The printer engine  105  is a print mechanism which feeds a print sheet from an output sheet feed stage according to the print settings instructed by the controller board  102 , and prints the print image supplied from the controller board  102  on the print sheet. Each of the option cassettes  111 ,  112 , and  113  is a feed stage module additionally mounted on the apparatus main body and operates integrally with the printer engine  105 . The USB memory  130  is a storage device that can store a print job. In the present exemplary embodiment, a print job is stored in the USB memory  130 . Print processing of the print job is performed when a print instruction is issued from the operation unit  101 . 
     In the example of  FIG. 1 , the controller board  102  and the printer engine  105  are provided in the same housing. The controller board  102  and the printer engine  105  may be configured in separate housings. In other words, the image forming apparatus  100  may be configured to be implemented as an image forming system including a printer server. In such a case, part of the functions of the controller board  102  may be provided by a server on a cloud service. The PC  150  may be in charge of the functions corresponding to the controller board  102 , and the image forming apparatus  100  may be configured to be specialized in the control of the printer engine  105 . Such a configuration is called a host-based print system. 
     Next, the controller board  102  according to the present exemplary embodiment will be described in detail.  FIG. 2  is a block configuration diagram of the controller board  102 . The controller board  102  includes a main board  200  and a sub board  220 . Though omitted in  FIG. 2 , peripheral devices, such as a chip set, a bus bridge, and a clock generator, are also mounted on the controller board  102 . The main board  200  includes a central processing unit (CPU)-M  201 , a read only memory (ROM)  202 , and a nonvolatile memory  203 , which constitute a computer. The main board  200  further includes a USB controller  204 , a disk controller  205 , a network controller  206 , a bus controller  207 , and a reset circuit  208 . The CPU-M  201  is a central processing unit for controlling the modules included in the main board  200 . The ROM  202  is a storage module for storing an initial program of the CPU-M  201 . The initial program is a program that is read by the CPU-M  201  immediately after the image forming apparatus  100  is powered on. The initial program includes a command needed to read a main program from the hard disk device  104 . 
     The nonvolatile memory  203  is a storage module for recording setting information about the image forming apparatus  100  and individual information unique to each toner cartridge that is a consumable container to be described below. In the following description, in contrast to information storage units on the toner cartridge side, the nonvolatile memory  203  will be referred to as an “apparatus-side memory.” The apparatus-side memory  203  stores information even if the image forming apparatus  100  is powered off. If the image forming apparatus  100  is powered on again, the values before the power-off can be referred to. The apparatus-side memory  203  may be a nonvolatile storage such as Hard Disk Drive (HDD). The USB controller  204  is a control module for controlling communication between the image forming apparatus  100  and USB devices. In the present exemplary embodiment, the USB controller  204  controls data input and output from/to the USB memory  130  described above. In another mode, the PC  150  and the image forming apparatus  100  may be connected by a USB cable. In such a mode, the image forming apparatus  100  controls input and output using the USB controller  204  and operates as a peripheral device of the PC  150 . 
     The disk controller  205  is a control module for inputting and outputting data from/to the hard disk device  104 . The network controller  206  is a control module for inputting and outputting data from/to the PC  150  via a network cable or a wireless communication path. The bus controller  207  is a module having a bridge function with a bus controller  225  of the sub board  220 . The reset circuit  208  is a control module for resetting not-illustrated various pieces of hardware (H/W) of the main board  200  to an initial state. 
     The sub board  220  includes a CPU-S  221 , a power supply monitoring H/W  222 , an image processing processor  223 , a device controller  224 , the bus controller  225 , and a reset circuit  226 . The CPU-S  221  is a central processing unit for controlling the modules included in the sub board  220 . The power supply monitoring H/W  222  is a module for monitoring a power supply control state. If the CPU-S  221  is able to operate normally, the power supply monitoring H/W  222  can reset the entire image forming apparatus  100  via the reset circuit  226  and the reset circuit  208  according to an instruction from the CPU-S  221 . If no power is supplied to the CPU-S  221 , the power supply monitoring H/W  222  can power on the controller board  102  according to an input from a not-illustrated power switch. The power supply monitoring H/W  222  may be implemented by a small-scale system running on another CPU. The reset circuit  226  is a control module for resetting the H/W of the sub board  220  to an initial state. 
     The image processing processor  223  is a module for performing digital image processing in real time. For example, the image processing processor  223  performs image processing for converting intermediate data (display list) obtained by a print job data analysis unit analyzing print job data into a contone image. The image processing processor  223  also performs image processing for generating a print image expressed in halftones that can be output by the printer engine  105 , based on the contone image. Such image processing is referred to as dithering processing. The image processing processor  223  also performs processing for sorting print images in plane order. The image processing processor  223  further performs image processing for adjusting a contone image to user-desired color tones. Such an image processing processor  223  can be implemented by an application specific integrated circuit (ASIC). Alternatively, the image processing processor  223  may be implemented by a field-programmable gate array (FPGA). The present exemplary embodiment will be described on the assumption that the image processing processor  223  performs the digital image processing in real time. However, the real-time digital image processing may be performed by cooperation of the image processing processor  223  and the CPU-M  201  or the CPU-S  221 . 
     The device controller  224  is a module for controlling the printer engine  105 . The bus controller  225  is a module having a bridge function with the bus controller  207  of the main board  200 . The CPU-M  201  and the CPU-S  221  can share and transmit various types of information via the bus controllers  207  and  225 . A random access memory (RAM)  250  is a main storage memory module accessible to both the CPU-M  201  and the CPU-S  221 . 
     When the image forming apparatus  100  is powered on, the CPU-M  201  of the controller board  102  reads the initial program of the ROM  202  into the RAM  205 . The CPU-M  201  then activates the initial program on the RAM  250 . A computer program (main program) intended for the CPU-M  201  and the CPU-S  221 , stored in the hard disk device  104 , is thereby stored into the RAM  250 . The CPU-M  201  and the CPU-S  221  execute the main program to implement the functions of the image forming apparatus  100 . The RAM  250  is also used as a temporary work memory in executing the initial program and the main program. While the present exemplary embodiment is described based on a mode in which the CPU-M  201  and the CPU-S  221  share the RAM  250 , the CPU-M  201  and the CPU-S  221  may be provided with respective dedicated RAMS. 
     In the present exemplary embodiment, the apparatus-side memory  203 , the USB controller  204 , the disk controller  205 , and the network controller  206  are provided on the main board  200  side. However, the configuration is not limited thereto. Some of the modules may be provided on the sub board  220  side. All the functions of the sub board  220  may be implemented on the main board  200 , and the CPU-M  201  may be configured to implement the functions which are implemented on the sub board  220  instead of the CPU-S  221 . 
       FIGS. 3A to 3C  are schematic diagrams illustrating a physical configuration of the image forming apparatus  100 .  FIG. 3A  is a sectional view illustrating an overall configuration.  FIG. 3B  is a partial enlarged view of an image forming unit.  FIG. 3C  is an enlarged view of  FIG. 3B . In the example illustrated in  FIGS. 3A to 3C , the image forming apparatus  100  is described to be capable of color printing using four color toners of yellow, magenta, cyan, and black. However, this example is not restrictive. The image forming apparatus  100  may be configured to form an image by monochrome printing in one color of the black toner. The image forming apparatus  100  may be configured to use more color toners. The image forming apparatus  100  may be configured to be able to express various textures on the surface of the print product by using a clear toner as well. 
     Referring to  FIG. 3A , the image forming apparatus  100  includes a feed tray  301 , a feed cassette  302   a , and a discharge tray  304 . The option cassettes  111  to  113  are accompanied with respective corresponding feed cassettes  302   b  to  302   d . The feed cassettes  302   a  to  302   d  store print sheets  305   a  to  305   d . The four feed cassettes  302   a  to  302   d  have the same mechanism. The image forming apparatus  100  includes an image forming unit  303  and a fixing device unit. In  FIG. 3A , the image forming unit  303  is illustrated by a broken line.  FIG. 3B  illustrates a partial enlarged view of the image forming unit  303 . The image forming unit  303  forms an image of toner on a print sheet by an electrophotographic process. The fixing device unit includes a fixing roller  308  and a pressure roller  309 , and fixes the toner on the print sheet. For one-sided printing, a sheet fed from the feed cassettes  302   a  to  302   d  is conveyed through paths P 1 , P 2 , and P 3  in order. For two-sided printing, a sheet is conveyed through the paths P 1 , P 2 , and P 3  in order, switched back after passing the path P 3 , conveyed through paths P 6 , P 2 , and P 3  in order, and discharged out of the image forming apparatus  100 . 
     Referring to  FIG. 3B , four toner cartridges  310   a  to  310   d  that are consumable containers used for image formation are replaceably mounted on the image forming unit  303 . The toner cartridge  310   a  is a yellow toner cartridge. The toner cartridge  310   b  is a magenta toner cartridge. The toner cartridge  310   c  is a cyan toner cartridge. The toner cartridge  310   d  is a black toner cartridge. The toner cartridges  310   a  to  310   d  are opposed to transfer rollers  307   a  to  307   d , respectively, with an intermediate transfer belt  306  therebetween. The image forming unit  303  includes memory tag interfaces  330   a  to  330   d  for communicating with memory tags  314   a  to  314   d  to be described below. More specifically, the memory tag interfaces  330   a  to  330   d  function as reading units for reading information stored in the memory tags  314   a  to  314   d . The memory tag interfaces  330   a  to  330   d  also function as update units for updating the information stored in the memory tags  314   a  to  314   d.    
     Referring to  FIG. 3C , a configuration of the toner cartridges  310   a  to  310   d  will be described. The toner cartridge  310   a  will be described in a representative manner. A detailed description of the toner cartridges  310   b  to  310   d  of other colors will be omitted because there is no difference other than the channels of latent images of a print image. In  FIG. 3C , only the reference numerals are so denoted by [a-d]. The toner cartridge  310   a  includes a charging unit including a charging roller  311   a , a developing unit including a developing roller  312   a , a photosensitive drum  313   a , and the memory tag  314   a . A toner remaining life sensor  315   a  is arranged in a predetermined position. The charging unit is a unit that forms a latent image of a print image of corresponding color transmitted from the foregoing controller board  102  on the photosensitive drum  313   a . The developing unit is a unit that applies toner to the photosensitive drum  313   a  and develops the latent image, which is formed on the photosensitive drum  313   a , of the print image of that color. The toner remaining life sensor  315   a  is a sensor that detects the remaining amount of toner. 
     The memory tag  314   a  is a noncontact integrated circuit (IC) tag which serves as an example of an information storage unit. Individual information unique to the toner cartridge  310   a  is recorded in the memory tag  314   a . For the sake of convenience, such individual information will be referred to as “mounted cartridge information”.  FIG. 4  illustrates an example of the mounted cartridge information. In the example of  FIG. 4 , a serial number  401 , a type  402 , the number of printed sheets  403 , and a remaining amount  404  are recorded. The serial number  401  is identification information about the toner cartridge  310   a  (in the illustrated example, “1111”). The type  402  is information indicating specifications or a size of the toner cartridge  310   a  (in the illustrated example, “normal”). The number of printed sheets  403  is the total number of sheets printed using the toner cartridge  310   a  (in the illustrated example, “000000”). The remaining amount  404  indicates the remaining amount of toner in the toner cartridge  310   a  (in the illustrated example, “100”%). The remaining amount  404  is calculated from a detection value of the toner remaining life sensor  315   a  or a calculation value of the remaining amount to be described below. 
     A flash memory connected by serial connection and a microcomputer connectable by near field wireless communication may be used instead of the memory tag  314   a . In such a case, the microcomputer receives a command and performs a write or read on the flash memory connected to the microcomputer. From the viewpoint of the printer engine  105 , the toner cartridges  310   a  to  310   d  may appear to have separate interfaces for print control and for memory tag communication. Alternatively, the memory tags  314   a  to  314   d  may be configured to be capable of communicating via the interface for print control. In either case, an exemplary embodiment of the present invention is applicable. 
     Next, an outline of the operation of the printer engine  105  during printing will be described with reference to  FIGS. 2 to 4 . The printer engine  105  develops print images transmitted from the controller board  102  with a print instruction by using the photosensitive drums  313   a  to  313   d , and primarily transfers the print images to the intermediate transfer belt  306  by the transfer rollers  307   a  to  307   d  in succession. The printer engine  105  feeds a print sheet from any one of the feed cassettes  302   a  to  302   d , and secondarily transfers the toner primarily transferred to the intermediate transfer belt  306  to the print sheet being conveyed to the path P 2  via the path P 1 . The printer engine  105  conveys the print sheet to the fixing unit, and fixes the toner to the surface of the print sheet. The printer engine  105  then discharges the toner-fixed print sheet to the discharge tray  304  via the path P 3 . The printer engine  105  detects the remaining amounts of print sheets stored in the feed cassettes  302   a  to  302   d  by using sheet remaining amount sensors  321   a  to  321   d.    
     The controller board  102  controls the operation of the printer engine  105  and monitors an operation state of the printer engine  105 . The controller board  102  calculates the consumed amounts in image formation, i.e., the toner consumption amount and the number of printed sheets, based on the print data, and thereby measures consumption degrees of the toner cartridges  310   a  to  310   d  (measurement unit). A consumption degree includes at least either one of the number of printed sheets and the remaining amount of toner based on the consumed amount of toner. The controller board  102  further detects replacement of the toner cartridges  310   a  to  310   d  (replacement detection unit). If the replacement of the toner cartridges  310   a  to  310   d  is detected, the controller board  102  generates a cartridge replacement log and additionally writes the cartridge replacement log to the apparatus-side memory  203 .  FIG. 5  illustrates an example of the cartridge replacement log generated by the controller board  102 . This cartridge replacement log is an example of that of the yellow toner cartridge  310   a . In the cartridge replacement log, one record is made (additionally written) for each toner cartridge. A record includes a serial number  501 , a type  502 , a remaining amount  503 , the initial number of printed sheets  504 , the final number of printed sheets  505 , a date and time of start of use  506 , and a date and time of last use  507 . The serial number  501  is identification information about the toner cartridge. The type  502  is information indicating the type of the toner cartridge. In the present exemplary embodiment, there are four types “normal”, “high capacity”, “unknown”, and “no tag” (non-mounting information). The type of “normal” represents a toner cartridge containing a typical amount of toner. The type of “high capacity” represents a toner cartridge containing a larger amount of toner than normal. The type of “unknown” represents a toner cartridge having an unexpected standard, neither normal nor high capacity. The type of “no tag” (non-mounting information) represents a fact that information has failed to be read from the memory tag  314   a  of the toner cartridge. The types are not limited to these four. 
     The remaining amount  503  is an index indicating the degree of consumption of the toner cartridge. The remaining amount  503  is updated as needed with a value calculated based on the amount of consumed toner during printing. The initial number of printed sheets  504  indicates the number of printed sheets when the toner cartridge is mounted. If the number of printed sheets  403  is successfully obtained from the memory tag  314   a , the number is recorded. If the number of printed sheets  403  is not able to be obtained, zero is recorded. The final number of printed sheets  505  indicates the last number of printed sheets while the toner cartridge is mounted. The final number of printed sheets  505  is counted up during printing. The date and time of start of use (initial use)  506  is the date and time when the toner cartridge is first mounted. The date and time of last use  507  is the last date and time when the toner cartridge is mounted. In the present exemplary embodiment, the date and time of last use  507  refers to the date and time when the toner cartridge is last used for printing. The reason is that the date and time of replacement of a toner cartridge is not always easy to be detected if the toner cartridge is replaced when the image forming apparatus  100  is powered off. One of the characteristics of a method for managing a toner cartridge according to the present exemplary embodiment is that a new record is added to the cartridge replacement log illustrated in  FIG. 5  if the replacement of the toner cartridge is detected. In the example of  FIG. 5 , five records Nos. 01 to 05 have been added to the cartridge replacement log. In other words, the cartridge replacement log shows history of five replacements. While only the cartridge replacement log of the yellow toner cartridge  310   a  is illustrated in the diagram, the other color toner cartridges  310   b  to  310   d  (magenta, cyan, and black) have similar cartridge replacement logs. 
     The replacement of a toner cartridge is detected before the toner cartridge is used for image formation. More specifically, the controller board  102  executes processing for recording individual information in the apparatus-side memory  203 . The controller board  102  then reads individual information from the memory tag of the toner cartridge. If the reading fails and the individual information recorded in the apparatus-side memory  203  is not information read from the toner cartridge, the controller board  102  executes processing for additionally writing a new record to the apparatus-side memory  203 . 
     The cartridge replacement log can be output in a predetermined layout and checked when needed. Such a function is referred to as a report print function. The controller board  102  accepts a user operation on a screen of the operation unit  101 , and executes the report print function.  FIG. 6  is an explanatory diagram of screen transitions by the report print function. When the image forming apparatus  100  is activated, the screen of the operation unit  101  transitions to a job wait screen  601 . If the down button  123  is detected to be pressed by the user during the display of the job wait screen  601 , the screen transitions to a utility screen  602 . When the utility screen  602  is initially displayed, a line “CHECK COUNTER” is focused on (inversely displayed or highlighted). If the down button  123  is detected to be pressed in such a state, the controller board  102  focuses on the next line “CHECK CONSUMABLES.” If the execution button  122  is detected to be pressed here, the screen of the operation unit  101  transitions to a consumable check screen  603 . In the consumable check screen  603 , a line “PRINT CARTRIDGE REPLACEMENT LOG” is focused on. If the execution button  122  is detected to be pressed, the screen of the operation unit  101  transitions to a cartridge replacement log print screen  604 . When the cartridge replacement log print screen  604  is initially displayed, a line “&lt;EXECUTE&gt;” is focused on. If the execution button  122  is detected to be pressed in such a state, the printing of the cartridge replacement log is executed. During the printing, a printing screen  605  is displayed on the screen of the operation unit  101 . The screen returns to the job wait screen  601  at a timing in which the printing is completed. 
     In the present exemplary embodiment, the cartridge replacement log is described to be output by printing. However, the controller board  102  may display the same contents on a web browser when accessed by the PC  150  via the web browser. The controller board  102  may output the cartridge replacement log to the PC  150  as display data. 
       FIGS. 7A and 7B  illustrate an example of the output cartridge replacement log. In  FIG. 7A , a cartridge replacement log of four color toner cartridges of yellow (Y), magenta (M), cyan (C), and black (K), is printed.  FIG. 7B  illustrates an example of the printed contents, in which information similar to that of the cartridge replacement log described in  FIG. 5  is included. 
     The controller board  102  updates the cartridge replacement log each time a toner cartridge is detected to be replaced.  FIG. 8  illustrates a processing procedure example of the method for managing a toner cartridge (an example of a consumable management method), including processing for updating the cartridge replacement log described with reference to  FIG. 5 . This processing is executed by the controller board  102 . While the color of the toner cartridge is not mentioned, similar processing is performed on each of the toner cartridges of yellow, magenta, cyan, and black. 
     The processing of  FIG. 8  is started when the printer engine  105  is powered on or when a cover (not illustrated) of the image forming unit  303  is opened and closed. In other words, the processing is started if there is a possibility that a toner cartridge is replaced. As a precondition, processing for recording mounted cartridge information in the apparatus-side memory  203  has been performed before the printer engine  105  forms an image by using the toner cartridge. In step S 101 , the controller board  102  reads the cartridge replacement log. The controller board  102  here reads the last record of the cartridge replacement log. In step S 102 , the controller board  102  obtains the mounted cartridge information about the mounted toner cartridge from the memory tag  314  ( 314   a  to  314   d ) via the printer engine  105 . In other words, the controller board  102  performs information reading. The obtained mounted cartridge information includes the serial number  401 , the type  402 , the number of printed sheets  403 , and the remaining amount  404  illustrated in  FIG. 4 . In step S 103 , the controller board  102  obtains a sensor value of the toner remaining life sensor  315  ( 315   a  to  315   d ) which detects the remaining amount of toner in the mounted toner cartridge from the printer engine  105  via the device controller  224 . 
     In step S 104 , the controller board  102  determines whether there is an error in the mounted cartridge information of step S 102 . In other words, the controller board  102  determines whether the information reading is successful. If there is no error (NO in step S 104 ), the serial number is successfully obtained. In step S 105 , the controller board  102  compares the obtained serial number with the serial number in the last record of the cartridge replacement log. If the serial numbers coincide (YES in step S 106 ), the controller board  102  determines that the toner cartridge has not been replaced, and the processing ends. 
     If the serial numbers do not coincide (NO in step S 106 ), the controller board  102  detects that the toner cartridge has been replaced. In steps S 107  to S 113 , the controller board  102  adds a new record to the cartridge replacement log. In steps S 107  to S 110 , the controller board  102  records the serial number, the type, the remaining amount, and the number of printed sheets obtained in step S 102  in the added record. In step S 111 , the controller board  102  sets the same value as the initial number of printed sheets into the final number of printed sheets. Since the number of printed sheets obtained from the printer engine  105  is set into the initial number of printed sheets in step S 110 , the value set into the final number of printed sheets is the same as the number of printed sheets obtained from the printer engine  105 . In step S 112 , the controller board  102  sets a date, hour, minute, and second of a not-illustrated real-time clock (RTC) provided on the controller board  102  into the date and time of initial use. In step S 113 , the controller board  102  sets the same value as the date and time of initial use into the date and time of last use. 
     In step S 104 , if there is determined to be an error in the mounted cartridge information received in step S 102  (YES in step S 104 ), then in step S 114 , the controller board  102  determines that the reading of the mounted cartridge information is failed, and determines whether the type in the last record is “no tag.” If the type is not “no tag” (NO in step S 114 ), the controller board  102  determines that the mounted cartridge information recorded in the apparatus-side memory  203  is not information read from the toner cartridge. The processing proceeds to step S 117  in order for the controller board  102  to additionally write a new record to the apparatus-side memory  203 . 
     In step S 114 , if the type in the last record is “no tag” (YES in step S 114 ), then in step S 115 , the controller board  102  compares the remaining amount recorded in the last record, i.e., the remaining amount last measured and recorded, with the sensor value obtained in step S 103 . In step S 116 , the controller board  102  determines whether there is a difference greater than or equal to a certain level therebetween. If there is a difference greater than or equal to a certain level (YES in step S 116 ), the controller board  102  determines that the remaining amount is not information read from the toner cartridge before replacement. That is, the controller board  102  detects that the toner cartridge has been replaced. The processing proceeds to step S 117 . 
     A specific example of the comparison processing of step S 115  will be described. For example, suppose that the remaining amount of toner in the last record of the apparatus-side memory  203  is 30%, and a threshold serving as the certain level of difference is 50%. Suppose also that the sensor value obtained in step S 103  is 50%. In such a case, the controller board  102  determines that the same toner cartridge is mounted, since there is no difference greater than the threshold. On the other hand, if the sensor value obtained in step S 103  is greater than or equal to 90%, there is a difference greater than the threshold. The controller board  102  thus determines that another toner cartridge refilled with toner is mounted. 
     The threshold may be determined in advance with respect to each image forming apparatus. The threshold may be dynamically determined based on variations of the sensor value during use of one cartridge. 
     In the present exemplary embodiment, the sensor value used for the determination is described by using the remaining amount of toner as an example. However, life detection units intended for the photosensitive drum and the developing unit may be provided aside from the toner remaining life sensor, and such sensor values may be used to determine a drum remaining life and a developing unit remaining life. In such a case, the drum remaining life and the developing unit remaining life are similarly recorded as a record in the apparatus-side memory  203  in the image forming apparatus  100 . A method for determining the drum remaining life by using the number of rotations of the photosensitive drum is widely known. The drum remaining life determined by such a method is recorded as a record in the apparatus-side memory  203 . A unit may be used, if there is a difference greater than or equal to a certain level from the drum remaining life obtained in step S 103 , for determining that the toner cartridge has been replaced. 
     When comparing the remaining amount stored in the last record and the sensor value obtained in step S 103 , the controller board  102  can make a determination based on combination of results of a plurality of sensor values. The reason is that in a case where only one sensor value is used as a reference and if another toner cartridge after replacement happens to exhibit the same sensor value with the sensor value obtained in step S 103 , the toner cartridge can be determined to not have been replaced. Taking the conditions of a plurality of sensor values into account can greatly reduce the frequency of occurrence of such a misjudgment. 
     In step S 117 , the controller board  102  rewrites the serial number in the new record with “unknown.” In step S 118 , the controller board  102  rewrites the type with “no tag.” In step S 119 , the controller board  102  sets the sensor value obtained in step S 103  into the remaining amount. In step S 120 , the controller board  102  sets the initial number of printed sheets at zero. In step S 121 , the controller board  102  sets the final number of printed sheets at the initial amount of printed sheets (i.e., zero). In steps S 112  and S 113 , the controller board  102  records the date and time of initial use and the date and time of last use in the same manner as described above. 
       FIG. 9  is a flowchart illustrating a processing procedure for updating a record in executing printing. The controller board  102  performs this processing each time a print instruction from the PC  150  is accepted. In step S 201 , the controller board  102  executes print processing to form an image. In step S 202 , the controller board  102  determines whether the type in the last record is “no tag.” If the type is “no tag” (YES in step S 202 ), then in step S 203 , the controller board  102  obtains the sensor value indicating the remaining amount of toner in the toner cartridge as in step S 103 . On the other hand, if the type is not “no tag” (NO in step S 202 ), i.e., if the mounted cartridge information is normally obtained, then in step S 204 , the controller board  102  calculates the remaining amount. The “remaining amount” is obtained in a manner that, for example, the controller board  102  calculates toner consumption from the number of dots of the print data, and subtracts the calculated value from the previous “remaining amount” to determine the new “remaining amount”. 
     In step S 205 , the controller board  102  updates the remaining amount in the last record with the sensor value obtained in step S 203  or the “remaining amount” calculated in step S 204 . In step S 206 , the controller board  102  updates the final number of printed sheets. In step S 207 , the controller board  102  updates the date and time of last use. In step S 208 , the controller board  102  determines again whether the type in the last record is “no tag.” If the type is “no tag” (YES in step S 208 ), the processing ends. In step S 208 , if the type is not “no tag” (NO in step S 208 ), then in step S 209 , the controller board  102  instructs the printer engine  105  to update the mounted cartridge information, that is, more specifically, to update the type, the number of printed sheets, and the remaining amount in the memory tags  314   a  to  314   d , illustrated in  FIG. 4 , and the processing ends. The purpose of determining whether the type in the last record is “no tag” is to determine whether the update processing of the memory tags  314   a  to  314   d  can be performed. The controller board  102  may therefore obtain any of the records of the mounted cartridge information instead of the last record, and determine whether to perform the update processing of the memory tags  314   a  to  314   d  depending on whether the record is successfully obtained. 
     In the present exemplary embodiment, the update processing of the record and the memory tags  314   a  to  314   d  is described to be performed upon each print instruction. However, the frequency of the update processing may be reduced in view of printing performance. In the present exemplary embodiment, the image forming apparatus  100  is described to be an apparatus having a print function. However, the image forming apparatus  100  may be a digital multifunction peripheral having a scanner function and/or a facsimile (FAX) function as well. 
     Other Embodiments 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2015-181578, filed Sep. 15, 2015, which is hereby incorporated by reference herein in its entirety.